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解决RecyclerView无法onItemClick问题
对于RecyclerView的使用，大家可以查看将替代ListView的RecyclerView 的使用（一），单单从代码结构来说RecyclerView确实比ListView优化了很多，也简化了我们编写代码量，但是有一个问题会导致开发者不会去用它，更比说替换ListView了，我不知道使用过RecyclerView的人有没有进一步查看，RecyclerView没有提供Item的点击事件，我们使用列表不仅仅为了显示数据，同时也可以能会交互，所以RecyclerView这个问题导致基本没有人用它，我清楚谷歌是怎么想的，不过RecyclerView也并没有把所有的路给堵死，需要我们写代码来实现Item的点击事件，我们都知道RecyclerView里面新加了ViewHolder这个静态抽象类，这个类里面有一个方法getPosition()可以返回当前ViewHolder实例的位置，实现onItemClick就是使用它来做的，下面有两种方法来实现：
第一种：不修改源码
这种方法不修改源码，问题是只能在RecyclerView.Adapter中实现ItemClick事件
public static class ViewHolder extends RecyclerView.ViewHolder {
public ViewHolder(View itemView) {
super(itemView);
itemView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
Log.e("jwzhangjie", "当前点击的位置："+getPosition());
}
});
}
}这种方式直观上看起来不太好，不过也可以实现ItemClick事件。
第二种方法：修改RecyclerView源码
1、把在RecyClerView类里面定义OnItemClickListener接口
/**
* Interface definition for a callback to be invoked when an item in this
* RecyclerView.Adapter has been clicked.
*/
public interface OnItemClickListener {
/**
* Callback method to be invoked when an item in this RecyclerView.Adapter has
* been clicked.
* <p>
* Implementers can call getPosition(position) if they need
* to access the data associated with the selected item.
*
* @param view The view within the RecyclerView.Adapter that was clicked (this
* will be a view provided by the adapter)
* @param position The position of the view in the adapter.
*/
void onItemClick(View view, int position);
}
public static OnItemClickListener mOnItemClickListener = null;
/**
* Register a callback to be invoked when an item in this AdapterView has
* been clicked.
*
* @param listener The callback that will be invoked.
*/
public void setOnItemClickListener(OnItemClickListener listener) {
mOnItemClickListener = listener;
}
/**
* @return The callback to be invoked with an item in this AdapterView has
* been clicked, or null id no callback has been set.
*/
public final OnItemClickListener getOnItemClickListener() {
return mOnItemClickListener;
}
2、在RecyclerView中的抽象类ViewHolder中添加View的点击事件
public static abstract class ViewHolder implements OnClickListener{
public final View itemView;
int mPosition = NO_POSITION;
int mOldPosition = NO_POSITION;
long mItemId = NO_ID;
int mItemViewType = INVALID_TYPE;
/**
* This ViewHolder has been bound to a position; mPosition, mItemId and mItemViewType
* are all valid.
*/
static final int FLAG_BOUND = 1 << 0;
/**
* The data this ViewHolder's view reflects is stale and needs to be rebound
* by the adapter. mPosition and mItemId are consistent.
*/
static final int FLAG_UPDATE = 1 << 1;
/**
* This ViewHolder's data is invalid. The identity implied by mPosition and mItemId
* are not to be trusted and may no longer match the item view type.
* This ViewHolder must be fully rebound to different data.
*/
static final int FLAG_INVALID = 1 << 2;
/**
* This ViewHolder points at data that represents an item previously removed from the
* data set. Its view may still be used for things like outgoing animations.
*/
static final int FLAG_REMOVED = 1 << 3;
/**
* This ViewHolder should not be recycled. This flag is set via setIsRecyclable()
* and is intended to keep views around during animations.
*/
static final int FLAG_NOT_RECYCLABLE = 1 << 4;
private int mFlags;
private int mIsRecyclableCount = 0;
// If non-null, view is currently considered scrap and may be reused for other data by the
// scrap container.
private Recycler mScrapContainer = null;
@Override
public void onClick(View v) {
if (mOnItemClickListener != null) {
mOnItemClickListener.onItemClick(itemView, getPosition());
}
}
public ViewHolder(View itemView) {
if (itemView == null) {
throw new IllegalArgumentException("itemView may not be null");
}
this.itemView = itemView;
this.itemView.setOnClickListener(this);
}
void offsetPosition(int offset) {
if (mOldPosition == NO_POSITION) {
mOldPosition = mPosition;
}
mPosition += offset;
}
void clearOldPosition() {
mOldPosition = NO_POSITION;
}
public final int getPosition() {
return mOldPosition == NO_POSITION ? mPosition : mOldPosition;
}
public final long getItemId() {
return mItemId;
}
public final int getItemViewType() {
return mItemViewType;
}
boolean isScrap() {
return mScrapContainer != null;
}
void unScrap() {
mScrapContainer.unscrapView(this);
mScrapContainer = null;
}
void setScrapContainer(Recycler recycler) {
mScrapContainer = recycler;
}
boolean isInvalid() {
return (mFlags & FLAG_INVALID) != 0;
}
boolean needsUpdate() {
return (mFlags & FLAG_UPDATE) != 0;
}
boolean isBound() {
return (mFlags & FLAG_BOUND) != 0;
}
boolean isRemoved() {
return (mFlags & FLAG_REMOVED) != 0;
}
void setFlags(int flags, int mask) {
mFlags = (mFlags & ~mask) | (flags & mask);
}
void addFlags(int flags) {
mFlags |= flags;
}
void clearFlagsForSharedPool() {
mFlags = 0;
}
@Override
public String toString() {
final StringBuilder sb = new StringBuilder("ViewHolder{" +
Integer.toHexString(hashCode()) + " position=" + mPosition + " id=" + mItemId);
if (isScrap()) sb.append(" scrap");
if (isInvalid()) sb.append(" invalid");
if (!isBound()) sb.append(" unbound");
if (needsUpdate()) sb.append(" update");
if (isRemoved()) sb.append(" removed");
sb.append("}");
return sb.toString();
}3、完成上面的步骤，就可以使用RecyclerView来完成itemClick事件了
cashAccountList.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(View view, int position) {
AppLog.e("position： "+position);
}
});下面是完整的RecyclerView源码：
/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.support.v7.widget;
import android.content.Context;
import android.database.Observable;
import android.graphics.Canvas;
import android.graphics.PointF;
import android.graphics.Rect;
import android.os.Build;
import android.os.Parcel;
import android.os.Parcelable;
import android.support.annotation.Nullable;
import android.support.v4.util.ArrayMap;
import android.support.v4.util.Pools;
import android.support.v4.view.MotionEventCompat;
import android.support.v4.view.VelocityTrackerCompat;
import android.support.v4.view.ViewCompat;
import android.support.v4.widget.EdgeEffectCompat;
import android.support.v4.widget.ScrollerCompat;
import android.util.AttributeSet;
import android.util.Log;
import android.util.SparseArray;
import android.util.SparseIntArray;
import android.view.FocusFinder;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.view.animation.Interpolator;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
/**
* A flexible view for providing a limited window into a large data set.
*
* <h3>Glossary of terms:</h3>
*
* <ul>
* <li><em>Adapter:</em> A subclass of {@link Adapter} responsible for providing views
* that represent items in a data set.</li>
* <li><em>Position:</em> The position of a data item within an <em>Adapter</em>.</li>
* <li><em>Index:</em> The index of an attached child view as used in a call to
* {@link ViewGroup#getChildAt}. Contrast with <em>Position.</em></li>
* <li><em>Binding:</em> The process of preparing a child view to display data corresponding
* to a <em>position</em> within the adapter.</li>
* <li><em>Recycle (view):</em> A view previously used to display data for a specific adapter
* position may be placed in a cache for later reuse to display the same type of data again
* later. This can drastically improve performance by skipping initial layout inflation
* or construction.</li>
* <li><em>Scrap (view):</em> A child view that has entered into a temporarily detached
* state during layout. Scrap views may be reused without becoming fully detached
* from the parent RecyclerView, either unmodified if no rebinding is required or modified
* by the adapter if the view was considered <em>dirty</em>.</li>
* <li><em>Dirty (view):</em> A child view that must be rebound by the adapter before
* being displayed.</li>
* </ul>
*/
public class RecyclerView extends ViewGroup {
private static final String TAG = "RecyclerView";
private static final boolean DEBUG = false;
private static final boolean ENABLE_PREDICTIVE_ANIMATIONS = false;
private static final boolean DISPATCH_TEMP_DETACH = false;
public static final int HORIZONTAL = 0;
public static final int VERTICAL = 1;
public static final int NO_POSITION = -1;
public static final long NO_ID = -1;
public static final int INVALID_TYPE = -1;
private static final int MAX_SCROLL_DURATION = 2000;
private final RecyclerViewDataObserver mObserver = new RecyclerViewDataObserver();
private final Recycler mRecycler = new Recycler();
private SavedState mPendingSavedState;
/**
* Note: this Runnable is only ever posted if:
* 1) We've been through first layout
* 2) We know we have a fixed size (mHasFixedSize)
* 3) We're attached
*/
private final Runnable mUpdateChildViewsRunnable = new Runnable() {
public void run() {
if (mPendingUpdates.isEmpty()) {
return;
}
eatRequestLayout();
updateChildViews();
resumeRequestLayout(true);
}
};
private final Rect mTempRect = new Rect();
private final ArrayList<UpdateOp> mPendingUpdates = new ArrayList<UpdateOp>();
private final ArrayList<UpdateOp> mPendingLayoutUpdates = new ArrayList<UpdateOp>();
private Pools.Pool<UpdateOp> mUpdateOpPool = new Pools.SimplePool<UpdateOp>(UpdateOp.POOL_SIZE);
private Adapter mAdapter;
private LayoutManager mLayout;
private RecyclerListener mRecyclerListener;
private final ArrayList<ItemDecoration> mItemDecorations = new ArrayList<ItemDecoration>();
private final ArrayList<OnItemTouchListener> mOnItemTouchListeners =
new ArrayList<OnItemTouchListener>();
private OnItemTouchListener mActiveOnItemTouchListener;
private boolean mIsAttached;
private boolean mHasFixedSize;
private boolean mFirstLayoutComplete;
private boolean mEatRequestLayout;
private boolean mLayoutRequestEaten;
private boolean mAdapterUpdateDuringMeasure;
private final boolean mPostUpdatesOnAnimation;
private EdgeEffectCompat mLeftGlow, mTopGlow, mRightGlow, mBottomGlow;
ItemAnimator mItemAnimator = new DefaultItemAnimator();
private static final int INVALID_POINTER = -1;
/**
* The RecyclerView is not currently scrolling.
* @see #getScrollState()
*/
public static final int SCROLL_STATE_IDLE = 0;
/**
* The RecyclerView is currently being dragged by outside input such as user touch input.
* @see #getScrollState()
*/
public static final int SCROLL_STATE_DRAGGING = 1;
/**
* The RecyclerView is currently animating to a final position while not under
* outside control.
* @see #getScrollState()
*/
public static final int SCROLL_STATE_SETTLING = 2;
// Touch/scrolling handling
private int mScrollState = SCROLL_STATE_IDLE;
private int mScrollPointerId = INVALID_POINTER;
private VelocityTracker mVelocityTracker;
private int mInitialTouchX;
private int mInitialTouchY;
private int mLastTouchX;
private int mLastTouchY;
private final int mTouchSlop;
private final int mMinFlingVelocity;
private final int mMaxFlingVelocity;
private final ViewFlinger mViewFlinger = new ViewFlinger();
private final State mState = new State();
private OnScrollListener mScrollListener;
// For use in item animations
boolean mItemsAddedOrRemoved = false;
boolean mItemsChanged = false;
int mAnimatingViewIndex = -1;
int mNumAnimatingViews = 0;
boolean mInPreLayout = false;
private ItemAnimator.ItemAnimatorListener mItemAnimatorListener =
new ItemAnimatorRestoreListener();
private boolean mPostedAnimatorRunner = false;
private Runnable mItemAnimatorRunner = new Runnable() {
@Override
public void run() {
if (mItemAnimator != null) {
mItemAnimator.runPendingAnimations();
}
mPostedAnimatorRunner = false;
}
};
private static final Interpolator sQuinticInterpolator = new Interpolator() {
public float getInterpolation(float t) {
t -= 1.0f;
return t * t * t * t * t + 1.0f;
}
};
public RecyclerView(Context context) {
this(context, null);
}
public RecyclerView(Context context, AttributeSet attrs) {
this(context, attrs, 0);
}
public RecyclerView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
final int version = Build.VERSION.SDK_INT;
mPostUpdatesOnAnimation = version >= 16;
final ViewConfiguration vc = ViewConfiguration.get(context);
mTouchSlop = vc.getScaledTouchSlop();
mMinFlingVelocity = vc.getScaledMinimumFlingVelocity();
mMaxFlingVelocity = vc.getScaledMaximumFlingVelocity();
setWillNotDraw(ViewCompat.getOverScrollMode(this) == ViewCompat.OVER_SCROLL_NEVER);
mItemAnimator.setListener(mItemAnimatorListener);
}
/**
* RecyclerView can perform several optimizations if it can know in advance that changes in
* adapter content cannot change the size of the RecyclerView itself.
* If your use of RecyclerView falls into this category, set this to true.
*
* @param hasFixedSize true if adapter changes cannot affect the size of the RecyclerView.
*/
public void setHasFixedSize(boolean hasFixedSize) {
mHasFixedSize = hasFixedSize;
}
/**
* @return true if the app has specified that changes in adapter content cannot change
* the size of the RecyclerView itself.
*/
public boolean hasFixedSize() {
return mHasFixedSize;
}
/**
* Set a new adapter to provide child views on demand.
*
* @param adapter The new adapter to set, or null to set no adapter.
*/
public void setAdapter(Adapter adapter) {
if (mAdapter != null) {
mAdapter.unregisterAdapterDataObserver(mObserver);
}
// end all running animations
if (mItemAnimator != null) {
mItemAnimator.endAnimations();
}
// Since animations are ended, mLayout.children should be equal to recyclerView.children.
// This may not be true if item animator's end does not work as expected. (e.g. not release
// children instantly). It is safer to use mLayout's child count.
if (mLayout != null) {
mLayout.removeAndRecycleAllViews(mRecycler);
mLayout.removeAndRecycleScrapInt(mRecycler, true);
}
final Adapter oldAdapter = mAdapter;
mAdapter = adapter;
if (adapter != null) {
adapter.registerAdapterDataObserver(mObserver);
}
if (mLayout != null) {
mLayout.onAdapterChanged(oldAdapter, mAdapter);
}
mRecycler.onAdapterChanged(oldAdapter, mAdapter);
mState.mStructureChanged = true;
markKnownViewsInvalid();
requestLayout();
}
/**
* Retrieves the previously set adapter or null if no adapter is set.
*
* @return The previously set adapter
* @see #setAdapter(Adapter)
*/
public Adapter getAdapter() {
return mAdapter;
}
/**
* Register a listener that will be notified whenever a child view is recycled.
*
* <p>This listener will be called when a LayoutManager or the RecyclerView decides
* that a child view is no longer needed. If an application associates expensive
* or heavyweight data with item views, this may be a good place to release
* or free those resources.</p>
*
* @param listener Listener to register, or null to clear
*/
public void setRecyclerListener(RecyclerListener listener) {
mRecyclerListener = listener;
}
/**
* Set the {@link LayoutManager} that this RecyclerView will use.
*
* <p>In contrast to other adapter-backed views such as {@link android.widget.ListView}
* or {@link android.widget.GridView}, RecyclerView allows client code to provide custom
* layout arrangements for child views. These arrangements are controlled by the
* {@link LayoutManager}. A LayoutManager must be provided for RecyclerView to function.</p>
*
* <p>Several default strategies are provided for common uses such as lists and grids.</p>
*
* @param layout LayoutManager to use
*/
public void setLayoutManager(LayoutManager layout) {
if (layout == mLayout) {
return;
}
mRecycler.clear();
removeAllViews();
if (mLayout != null) {
if (mIsAttached) {
mLayout.onDetachedFromWindow(this);
}
mLayout.mRecyclerView = null;
}
mLayout = layout;
if (layout != null) {
if (layout.mRecyclerView != null) {
throw new IllegalArgumentException("LayoutManager " + layout +
" is already attached to a RecyclerView: " + layout.mRecyclerView);
}
layout.mRecyclerView = this;
if (mIsAttached) {
mLayout.onAttachedToWindow(this);
}
}
requestLayout();
}
@Override
protected Parcelable onSaveInstanceState() {
SavedState state = new SavedState(super.onSaveInstanceState());
if (mPendingSavedState != null) {
state.copyFrom(mPendingSavedState);
} else if (mLayout != null) {
state.mLayoutState = mLayout.onSaveInstanceState();
} else {
state.mLayoutState = null;
}
return state;
}
@Override
protected void onRestoreInstanceState(Parcelable state) {
mPendingSavedState = (SavedState) state;
super.onRestoreInstanceState(mPendingSavedState.getSuperState());
if (mLayout != null && mPendingSavedState.mLayoutState != null) {
mLayout.onRestoreInstanceState(mPendingSavedState.mLayoutState);
}
}
/**
* Adds a view to the animatingViews list.
* mAnimatingViews holds the child views that are currently being kept around
* purely for the purpose of being animated out of view. They are drawn as a regular
* part of the child list of the RecyclerView, but they are invisible to the LayoutManager
* as they are managed separately from the regular child views.
* @param view The view to be removed
*/
private void addAnimatingView(View view) {
boolean alreadyAdded = false;
if (mNumAnimatingViews > 0) {
for (int i = mAnimatingViewIndex; i < getChildCount(); ++i) {
if (getChildAt(i) == view) {
alreadyAdded = true;
break;
}
}
}
if (!alreadyAdded) {
if (mNumAnimatingViews == 0) {
mAnimatingViewIndex = getChildCount();
}
++mNumAnimatingViews;
addView(view);
}
mRecycler.unscrapView(getChildViewHolder(view));
}
/**
* Removes a view from the animatingViews list.
* @param view The view to be removed
* @see #addAnimatingView(View)
*/
private void removeAnimatingView(View view) {
if (mNumAnimatingViews > 0) {
for (int i = mAnimatingViewIndex; i < getChildCount(); ++i) {
if (getChildAt(i) == view) {
removeViewAt(i);
--mNumAnimatingViews;
if (mNumAnimatingViews == 0) {
mAnimatingViewIndex = -1;
}
mRecycler.recycleView(view);
return;
}
}
}
}
private View getAnimatingView(int position, int type) {
if (mNumAnimatingViews > 0) {
for (int i = mAnimatingViewIndex; i < getChildCount(); ++i) {
final View view = getChildAt(i);
ViewHolder holder = getChildViewHolder(view);
if (holder.getPosition() == position &&
( type == INVALID_TYPE || holder.getItemViewType() == type)) {
return view;
}
}
}
return null;
}
/**
* Return the {@link LayoutManager} currently responsible for
* layout policy for this RecyclerView.
*
* @return The currently bound LayoutManager
*/
public LayoutManager getLayoutManager() {
return mLayout;
}
/**
* Retrieve this RecyclerView's {@link RecycledViewPool}. This method will never return null;
* if no pool is set for this view a new one will be created. See
* {@link #setRecycledViewPool(RecycledViewPool) setRecycledViewPool} for more information.
*
* @return The pool used to store recycled item views for reuse.
* @see #setRecycledViewPool(RecycledViewPool)
*/
public RecycledViewPool getRecycledViewPool() {
return mRecycler.getRecycledViewPool();
}
/**
* Recycled view pools allow multiple RecyclerViews to share a common pool of scrap views.
* This can be useful if you have multiple RecyclerViews with adapters that use the same
* view types, for example if you have several data sets with the same kinds of item views
* displayed by a {@link android.support.v4.view.ViewPager ViewPager}.
*
* @param pool Pool to set. If this parameter is null a new pool will be created and used.
*/
public void setRecycledViewPool(RecycledViewPool pool) {
mRecycler.setRecycledViewPool(pool);
}
/**
* Set the number of offscreen views to retain before adding them to the potentially shared
* {@link #getRecycledViewPool() recycled view pool}.
*
* <p>The offscreen view cache stays aware of changes in the attached adapter, allowing
* a LayoutManager to reuse those views unmodified without needing to return to the adapter
* to rebind them.</p>
*
* @param size Number of views to cache offscreen before returning them to the general
* recycled view pool
*/
public void setItemViewCacheSize(int size) {
mRecycler.setViewCacheSize(size);
}
/**
* Return the current scrolling state of the RecyclerView.
*
* @return {@link #SCROLL_STATE_IDLE}, {@link #SCROLL_STATE_DRAGGING} or
* {@link #SCROLL_STATE_SETTLING}
*/
public int getScrollState() {
return mScrollState;
}
private void setScrollState(int state) {
if (state == mScrollState) {
return;
}
mScrollState = state;
if (state != SCROLL_STATE_SETTLING) {
stopScroll();
}
if (mScrollListener != null) {
mScrollListener.onScrollStateChanged(state);
}
}
/**
* Add an {@link ItemDecoration} to this RecyclerView. Item decorations can
* affect both measurement and drawing of individual item views.
*
* <p>Item decorations are ordered. Decorations placed earlier in the list will
* be run/queried/drawn first for their effects on item views. Padding added to views
* will be nested; a padding added by an earlier decoration will mean further
* item decorations in the list will be asked to draw/pad within the previous decoration's
* given area.</p>
*
* @param decor Decoration to add
* @param index Position in the decoration chain to insert this decoration at. If this value
* is negative the decoration will be added at the end.
*/
public void addItemDecoration(ItemDecoration decor, int index) {
if (mItemDecorations.isEmpty()) {
setWillNotDraw(false);
}
if (index < 0) {
mItemDecorations.add(decor);
} else {
mItemDecorations.add(index, decor);
}
markItemDecorInsetsDirty();
requestLayout();
}
/**
* Add an {@link ItemDecoration} to this RecyclerView. Item decorations can
* affect both measurement and drawing of individual item views.
*
* <p>Item decorations are ordered. Decorations placed earlier in the list will
* be run/queried/drawn first for their effects on item views. Padding added to views
* will be nested; a padding added by an earlier decoration will mean further
* item decorations in the list will be asked to draw/pad within the previous decoration's
* given area.</p>
*
* @param decor Decoration to add
*/
public void addItemDecoration(ItemDecoration decor) {
addItemDecoration(decor, -1);
}
/**
* Remove an {@link ItemDecoration} from this RecyclerView.
*
* <p>The given decoration will no longer impact the measurement and drawing of
* item views.</p>
*
* @param decor Decoration to remove
* @see #addItemDecoration(ItemDecoration)
*/
public void removeItemDecoration(ItemDecoration decor) {
mItemDecorations.remove(decor);
if (mItemDecorations.isEmpty()) {
setWillNotDraw(ViewCompat.getOverScrollMode(this) == ViewCompat.OVER_SCROLL_NEVER);
}
markItemDecorInsetsDirty();
requestLayout();
}
/**
* Set a listener that will be notified of any changes in scroll state or position.
*
* @param listener Listener to set or null to clear
*/
public void setOnScrollListener(OnScrollListener listener) {
mScrollListener = listener;
}
/**
* Convenience method to scroll to a certain position.
*
* RecyclerView does not implement scrolling logic, rather forwards the call to
* {@link android.support.v7.widget.RecyclerView.LayoutManager#scrollToPosition(int)}
* @param position Scroll to this adapter position
* @see android.support.v7.widget.RecyclerView.LayoutManager#scrollToPosition(int)
*/
public void scrollToPosition(int position) {
stopScroll();
mLayout.scrollToPosition(position);
awakenScrollBars();
}
/**
* Starts a smooth scroll to an adapter position.
* <p>
* To support smooth scrolling, you must override
* {@link LayoutManager#smoothScrollToPosition(RecyclerView, State, int)} and create a
* {@link SmoothScroller}.
* <p>
* {@link LayoutManager} is responsible for creating the actual scroll action. If you want to
* provide a custom smooth scroll logic, override
* {@link LayoutManager#smoothScrollToPosition(RecyclerView, State, int)} in your
* LayoutManager.
*
* @param position The adapter position to scroll to
* @see LayoutManager#smoothScrollToPosition(RecyclerView, State, int)
*/
public void smoothScrollToPosition(int position) {
mLayout.smoothScrollToPosition(this, mState, position);
}
@Override
public void scrollTo(int x, int y) {
throw new UnsupportedOperationException(
"RecyclerView does not support scrolling to an absolute position.");
}
@Override
public void scrollBy(int x, int y) {
if (mLayout == null) {
throw new IllegalStateException("Cannot scroll without a LayoutManager set. " +
"Call setLayoutManager with a non-null argument.");
}
final boolean canScrollHorizontal = mLayout.canScrollHorizontally();
final boolean canScrollVertical = mLayout.canScrollVertically();
if (canScrollHorizontal || canScrollVertical) {
scrollByInternal(canScrollHorizontal ? x : 0, canScrollVertical ? y : 0);
}
}
/**
* Helper method reflect data changes to the state.
* <p>
* Adapter changes during a scroll may trigger a crash because scroll assumes no data change
* but data actually changed.
* <p>
* This method consumes all deferred changes to avoid that case.
* <p>
* This also ends all pending animations. It will be changed once we can support
* animations during scroll.
*/
private void consumePendingUpdateOperations() {
if (mItemAnimator != null) {
mItemAnimator.endAnimations();
}
if (mPendingUpdates.size() > 0) {
mUpdateChildViewsRunnable.run();
}
}
/**
* Does not perform bounds checking. Used by internal methods that have already validated input.
*/
void scrollByInternal(int x, int y) {
int overscrollX = 0, overscrollY = 0;
consumePendingUpdateOperations();
if (mAdapter != null) {
eatRequestLayout();
if (x != 0) {
final int hresult = mLayout.scrollHorizontallyBy(x, mRecycler, mState);
overscrollX = x - hresult;
}
if (y != 0) {
final int vresult = mLayout.scrollVerticallyBy(y, mRecycler, mState);
overscrollY = y - vresult;
}
resumeRequestLayout(false);
}
if (!mItemDecorations.isEmpty()) {
invalidate();
}
if (ViewCompat.getOverScrollMode(this) != ViewCompat.OVER_SCROLL_NEVER) {
pullGlows(overscrollX, overscrollY);
}
if (mScrollListener != null && (x != 0 || y != 0)) {
mScrollListener.onScrolled(x, y);
}
if (!awakenScrollBars()) {
invalidate();
}
}
/**
* <p>Compute the horizontal offset of the horizontal scrollbar's thumb within the horizontal
* range. This value is used to compute the length of the thumb within the scrollbar's track.
* </p>
*
* <p>The range is expressed in arbitrary units that must be the same as the units used by
* {@link #computeHorizontalScrollRange()} and {@link #computeHorizontalScrollExtent()}.</p>
*
* <p>Default implementation returns 0.</p>
*
* <p>If you want to support scroll bars, override
* {@link RecyclerView.LayoutManager#computeHorizontalScrollOffset(RecyclerView.State)} in your
* LayoutManager. </p>
*
* @return The horizontal offset of the scrollbar's thumb
* @see android.support.v7.widget.RecyclerView.LayoutManager#computeHorizontalScrollOffset
* (RecyclerView.Adapter)
*/
@Override
protected int computeHorizontalScrollOffset() {
return mLayout.canScrollHorizontally() ? mLayout.computeHorizontalScrollOffset(mState)
: 0;
}
/**
* <p>Compute the horizontal extent of the horizontal scrollbar's thumb within the
* horizontal range. This value is used to compute the length of the thumb within the
* scrollbar's track.</p>
*
* <p>The range is expressed in arbitrary units that must be the same as the units used by
* {@link #computeHorizontalScrollRange()} and {@link #computeHorizontalScrollOffset()}.</p>
*
* <p>Default implementation returns 0.</p>
*
* <p>If you want to support scroll bars, override
* {@link RecyclerView.LayoutManager#computeHorizontalScrollExtent(RecyclerView.State)} in your
* LayoutManager.</p>
*
* @return The horizontal extent of the scrollbar's thumb
* @see RecyclerView.LayoutManager#computeHorizontalScrollExtent(RecyclerView.State)
*/
@Override
protected int computeHorizontalScrollExtent() {
return mLayout.canScrollHorizontally() ? mLayout.computeHorizontalScrollExtent(mState) : 0;
}
/**
* <p>Compute the horizontal range that the horizontal scrollbar represents.</p>
*
* <p>The range is expressed in arbitrary units that must be the same as the units used by
* {@link #computeHorizontalScrollExtent()} and {@link #computeHorizontalScrollOffset()}.</p>
*
* <p>Default implementation returns 0.</p>
*
* <p>If you want to support scroll bars, override
* {@link RecyclerView.LayoutManager#computeHorizontalScrollRange(RecyclerView.State)} in your
* LayoutManager.</p>
*
* @return The total horizontal range represented by the vertical scrollbar
* @see RecyclerView.LayoutManager#computeHorizontalScrollRange(RecyclerView.State)
*/
@Override
protected int computeHorizontalScrollRange() {
return mLayout.canScrollHorizontally() ? mLayout.computeHorizontalScrollRange(mState) : 0;
}
/**
* <p>Compute the vertical offset of the vertical scrollbar's thumb within the vertical range.
* This value is used to compute the length of the thumb within the scrollbar's track. </p>
*
* <p>The range is expressed in arbitrary units that must be the same as the units used by
* {@link #computeVerticalScrollRange()} and {@link #computeVerticalScrollExtent()}.</p>
*
* <p>Default implementation returns 0.</p>
*
* <p>If you want to support scroll bars, override
* {@link RecyclerView.LayoutManager#computeVerticalScrollOffset(RecyclerView.State)} in your
* LayoutManager.</p>
*
* @return The vertical offset of the scrollbar's thumb
* @see android.support.v7.widget.RecyclerView.LayoutManager#computeVerticalScrollOffset
* (RecyclerView.Adapter)
*/
@Override
protected int computeVerticalScrollOffset() {
return mLayout.canScrollVertically() ? mLayout.computeVerticalScrollOffset(mState) : 0;
}
/**
* <p>Compute the vertical extent of the vertical scrollbar's thumb within the vertical range.
* This value is used to compute the length of the thumb within the scrollbar's track.</p>
*
* <p>The range is expressed in arbitrary units that must be the same as the units used by
* {@link #computeVerticalScrollRange()} and {@link #computeVerticalScrollOffset()}.</p>
*
* <p>Default implementation returns 0.</p>
*
* <p>If you want to support scroll bars, override
* {@link RecyclerView.LayoutManager#computeVerticalScrollExtent(RecyclerView.State)} in your
* LayoutManager.</p>
*
* @return The vertical extent of the scrollbar's thumb
* @see RecyclerView.LayoutManager#computeVerticalScrollExtent(RecyclerView.State)
*/
@Override
protected int computeVerticalScrollExtent() {
return mLayout.canScrollVertically() ? mLayout.computeVerticalScrollExtent(mState) : 0;
}
/**
* <p>Compute the vertical range that the vertical scrollbar represents.</p>
*
* <p>The range is expressed in arbitrary units that must be the same as the units used by
* {@link #computeVerticalScrollExtent()} and {@link #computeVerticalScrollOffset()}.</p>
*
* <p>Default implementation returns 0.</p>
*
* <p>If you want to support scroll bars, override
* {@link RecyclerView.LayoutManager#computeVerticalScrollRange(RecyclerView.State)} in your
* LayoutManager.</p>
*
* @return The total vertical range represented by the vertical scrollbar
* @see RecyclerView.LayoutManager#computeVerticalScrollRange(RecyclerView.State)
*/
@Override
protected int computeVerticalScrollRange() {
return mLayout.canScrollVertically() ? mLayout.computeVerticalScrollRange(mState) : 0;
}
void eatRequestLayout() {
if (!mEatRequestLayout) {
mEatRequestLayout = true;
mLayoutRequestEaten = false;
}
}
void resumeRequestLayout(boolean performLayoutChildren) {
if (mEatRequestLayout) {
if (performLayoutChildren && mLayoutRequestEaten &&
mLayout != null && mAdapter != null) {
dispatchLayout();
}
mEatRequestLayout = false;
mLayoutRequestEaten = false;
}
}
/**
* Animate a scroll by the given amount of pixels along either axis.
*
* @param dx Pixels to scroll horizontally
* @param dy Pixels to scroll vertically
*/
public void smoothScrollBy(int dx, int dy) {
if (dx != 0 || dy != 0) {
mViewFlinger.smoothScrollBy(dx, dy);
}
}
/**
* Begin a standard fling with an initial velocity along each axis in pixels per second.
* If the velocity given is below the system-defined minimum this method will return false
* and no fling will occur.
*
* @param velocityX Initial horizontal velocity in pixels per second
* @param velocityY Initial vertical velocity in pixels per second
* @return true if the fling was started, false if the velocity was too low to fling
*/
public boolean fling(int velocityX, int velocityY) {
if (Math.abs(velocityX) < mMinFlingVelocity) {
velocityX = 0;
}
if (Math.abs(velocityY) < mMinFlingVelocity) {
velocityY = 0;
}
velocityX = Math.max(-mMaxFlingVelocity, Math.min(velocityX, mMaxFlingVelocity));
velocityY = Math.max(-mMaxFlingVelocity, Math.min(velocityY, mMaxFlingVelocity));
if (velocityX != 0 || velocityY != 0) {
mViewFlinger.fling(velocityX, velocityY);
return true;
}
return false;
}
/**
* Stop any current scroll in progress, such as one started by
* {@link #smoothScrollBy(int, int)}, {@link #fling(int, int)} or a touch-initiated fling.
*/
public void stopScroll() {
mViewFlinger.stop();
mLayout.stopSmoothScroller();
}
/**
* Apply a pull to relevant overscroll glow effects
*/
private void pullGlows(int overscrollX, int overscrollY) {
if (overscrollX < 0) {
if (mLeftGlow == null) {
mLeftGlow = new EdgeEffectCompat(getContext());
mLeftGlow.setSize(getMeasuredHeight() - getPaddingTop() - getPaddingBottom(),
getMeasuredWidth() - getPaddingLeft() - getPaddingRight());
}
mLeftGlow.onPull(-overscrollX / (float) getWidth());
} else if (overscrollX > 0) {
if (mRightGlow == null) {
mRightGlow = new EdgeEffectCompat(getContext());
mRightGlow.setSize(getMeasuredHeight() - getPaddingTop() - getPaddingBottom(),
getMeasuredWidth() - getPaddingLeft() - getPaddingRight());
}
mRightGlow.onPull(overscrollX / (float) getWidth());
}
if (overscrollY < 0) {
if (mTopGlow == null) {
mTopGlow = new EdgeEffectCompat(getContext());
mTopGlow.setSize(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(),
getMeasuredHeight() - getPaddingTop() - getPaddingBottom());
}
mTopGlow.onPull(-overscrollY / (float) getHeight());
} else if (overscrollY > 0) {
if (mBottomGlow == null) {
mBottomGlow = new EdgeEffectCompat(getContext());
mBottomGlow.setSize(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(),
getMeasuredHeight() - getPaddingTop() - getPaddingBottom());
}
mBottomGlow.onPull(overscrollY / (float) getHeight());
}
if (overscrollX != 0 || overscrollY != 0) {
ViewCompat.postInvalidateOnAnimation(this);
}
}
private void releaseGlows() {
boolean needsInvalidate = false;
if (mLeftGlow != null) needsInvalidate = mLeftGlow.onRelease();
if (mTopGlow != null) needsInvalidate |= mTopGlow.onRelease();
if (mRightGlow != null) needsInvalidate |= mRightGlow.onRelease();
if (mBottomGlow != null) needsInvalidate |= mBottomGlow.onRelease();
if (needsInvalidate) {
ViewCompat.postInvalidateOnAnimation(this);
}
}
void absorbGlows(int velocityX, int velocityY) {
if (velocityX < 0) {
if (mLeftGlow == null) {
mLeftGlow = new EdgeEffectCompat(getContext());
mLeftGlow.setSize(getMeasuredHeight() - getPaddingTop() - getPaddingBottom(),
getMeasuredWidth() - getPaddingLeft() - getPaddingRight());
}
mLeftGlow.onAbsorb(-velocityX);
} else if (velocityX > 0) {
if (mRightGlow == null) {
mRightGlow = new EdgeEffectCompat(getContext());
mRightGlow.setSize(getMeasuredHeight() - getPaddingTop() - getPaddingBottom(),
getMeasuredWidth() - getPaddingLeft() - getPaddingRight());
}
mRightGlow.onAbsorb(velocityX);
}
if (velocityY < 0) {
if (mTopGlow == null) {
mTopGlow = new EdgeEffectCompat(getContext());
mTopGlow.setSize(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(),
getMeasuredHeight() - getPaddingTop() - getPaddingBottom());
}
mTopGlow.onAbsorb(-velocityY);
} else if (velocityY > 0) {
if (mBottomGlow == null) {
mBottomGlow = new EdgeEffectCompat(getContext());
mBottomGlow.setSize(getMeasuredWidth() - getPaddingLeft() - getPaddingRight(),
getMeasuredHeight() - getPaddingTop() - getPaddingBottom());
}
mBottomGlow.onAbsorb(velocityY);
}
if (velocityX != 0 || velocityY != 0) {
ViewCompat.postInvalidateOnAnimation(this);
}
}
// Focus handling
@Override
public View focusSearch(View focused, int direction) {
View result = mLayout.onInterceptFocusSearch(focused, direction);
if (result != null) {
return result;
}
final FocusFinder ff = FocusFinder.getInstance();
result = ff.findNextFocus(this, focused, direction);
if (result == null && mAdapter != null) {
eatRequestLayout();
result = mLayout.onFocusSearchFailed(focused, direction, mRecycler, mState);
resumeRequestLayout(false);
}
return result != null ? result : super.focusSearch(focused, direction);
}
@Override
public void requestChildFocus(View child, View focused) {
if (!mLayout.onRequestChildFocus(this, child, focused)) {
mTempRect.set(0, 0, focused.getWidth(), focused.getHeight());
offsetDescendantRectToMyCoords(focused, mTempRect);
offsetRectIntoDescendantCoords(child, mTempRect);
requestChildRectangleOnScreen(child, mTempRect, !mFirstLayoutComplete);
}
super.requestChildFocus(child, focused);
}
@Override
public boolean requestChildRectangleOnScreen(View child, Rect rect, boolean immediate) {
return mLayout.requestChildRectangleOnScreen(this, child, rect, immediate);
}
@Override
public void addFocusables(ArrayList<View> views, int direction, int focusableMode) {
if (!mLayout.onAddFocusables(this, views, direction, focusableMode)) {
super.addFocusables(views, direction, focusableMode);
}
}
@Override
protected void onAttachedToWindow() {
super.onAttachedToWindow();
mIsAttached = true;
mFirstLayoutComplete = false;
if (mLayout != null) {
mLayout.onAttachedToWindow(this);
}
mPostedAnimatorRunner = false;
}
@Override
protected void onDetachedFromWindow() {
super.onDetachedFromWindow();
mFirstLayoutComplete = false;
stopScroll();
// TODO Mark what our target position was if relevant, then we can jump there
// on reattach.
mIsAttached = false;
if (mLayout != null) {
mLayout.onDetachedFromWindow(this);
}
removeCallbacks(mItemAnimatorRunner);
}
/**
* Add an {@link OnItemTouchListener} to intercept touch events before they are dispatched
* to child views or this view's standard scrolling behavior.
*
* <p>Client code may use listeners to implement item manipulation behavior. Once a listener
* returns true from
* {@link OnItemTouchListener#onInterceptTouchEvent(RecyclerView, MotionEvent)} its
* {@link OnItemTouchListener#onTouchEvent(RecyclerView, MotionEvent)} method will be called
* for each incoming MotionEvent until the end of the gesture.</p>
*
* @param listener Listener to add
*/
public void addOnItemTouchListener(OnItemTouchListener listener) {
mOnItemTouchListeners.add(listener);
}
/**
* Remove an {@link OnItemTouchListener}. It will no longer be able to intercept touch events.
*
* @param listener Listener to remove
*/
public void removeOnItemTouchListener(OnItemTouchListener listener) {
mOnItemTouchListeners.remove(listener);
if (mActiveOnItemTouchListener == listener) {
mActiveOnItemTouchListener = null;
}
}
private boolean dispatchOnItemTouchIntercept(MotionEvent e) {
final int action = e.getAction();
if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_DOWN) {
mActiveOnItemTouchListener = null;
}
final int listenerCount = mOnItemTouchListeners.size();
for (int i = 0; i < listenerCount; i++) {
final OnItemTouchListener listener = mOnItemTouchListeners.get(i);
if (listener.onInterceptTouchEvent(this, e) && action != MotionEvent.ACTION_CANCEL) {
mActiveOnItemTouchListener = listener;
return true;
}
}
return false;
}
private boolean dispatchOnItemTouch(MotionEvent e) {
final int action = e.getAction();
if (mActiveOnItemTouchListener != null) {
if (action == MotionEvent.ACTION_DOWN) {
// Stale state from a previous gesture, we're starting a new one. Clear it.
mActiveOnItemTouchListener = null;
} else {
mActiveOnItemTouchListener.onTouchEvent(this, e);
if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP) {
// Clean up for the next gesture.
mActiveOnItemTouchListener = null;
}
return true;
}
}
// Listeners will have already received the ACTION_DOWN via dispatchOnItemTouchIntercept
// as called from onInterceptTouchEvent; skip it.
if (action != MotionEvent.ACTION_DOWN) {
final int listenerCount = mOnItemTouchListeners.size();
for (int i = 0; i < listenerCount; i++) {
final OnItemTouchListener listener = mOnItemTouchListeners.get(i);
if (listener.onInterceptTouchEvent(this, e)) {
mActiveOnItemTouchListener = listener;
return true;
}
}
}
return false;
}
@Override
public boolean onInterceptTouchEvent(MotionEvent e) {
if (dispatchOnItemTouchIntercept(e)) {
cancelTouch();
return true;
}
final boolean canScrollHorizontally = mLayout.canScrollHorizontally();
final boolean canScrollVertically = mLayout.canScrollVertically();
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(e);
final int action = MotionEventCompat.getActionMasked(e);
final int actionIndex = MotionEventCompat.getActionIndex(e);
switch (action) {
case MotionEvent.ACTION_DOWN:
mScrollPointerId = MotionEventCompat.getPointerId(e, 0);
mInitialTouchX = mLastTouchX = (int) (e.getX() + 0.5f);
mInitialTouchY = mLastTouchY = (int) (e.getY() + 0.5f);
if (mScrollState == SCROLL_STATE_SETTLING) {
getParent().requestDisallowInterceptTouchEvent(true);
setScrollState(SCROLL_STATE_DRAGGING);
}
break;
case MotionEventCompat.ACTION_POINTER_DOWN:
mScrollPointerId = MotionEventCompat.getPointerId(e, actionIndex);
mInitialTouchX = mLastTouchX = (int) (MotionEventCompat.getX(e, actionIndex) + 0.5f);
mInitialTouchY = mLastTouchY = (int) (MotionEventCompat.getY(e, actionIndex) + 0.5f);
break;
case MotionEvent.ACTION_MOVE: {
final int index = MotionEventCompat.findPointerIndex(e, mScrollPointerId);
if (index < 0) {
Log.e(TAG, "Error processing scroll; pointer index for id " +
mScrollPointerId + " not found. Did any MotionEvents get skipped?");
return false;
}
final int x = (int) (MotionEventCompat.getX(e, index) + 0.5f);
final int y = (int) (MotionEventCompat.getY(e, index) + 0.5f);
if (mScrollState != SCROLL_STATE_DRAGGING) {
final int dx = x - mInitialTouchX;
final int dy = y - mInitialTouchY;
boolean startScroll = false;
if (canScrollHorizontally && Math.abs(dx) > mTouchSlop) {
mLastTouchX = mInitialTouchX + mTouchSlop * (dx < 0 ? -1 : 1);
startScroll = true;
}
if (canScrollVertically && Math.abs(dy) > mTouchSlop) {
mLastTouchY = mInitialTouchY + mTouchSlop * (dy < 0 ? -1 : 1);
startScroll = true;
}
if (startScroll) {
getParent().requestDisallowInterceptTouchEvent(true);
setScrollState(SCROLL_STATE_DRAGGING);
}
}
} break;
case MotionEventCompat.ACTION_POINTER_UP: {
onPointerUp(e);
} break;
case MotionEvent.ACTION_UP: {
mVelocityTracker.clear();
} break;
case MotionEvent.ACTION_CANCEL: {
cancelTouch();
}
}
return mScrollState == SCROLL_STATE_DRAGGING;
}
@Override
public boolean onTouchEvent(MotionEvent e) {
if (dispatchOnItemTouch(e)) {
cancelTouch();
return true;
}
final boolean canScrollHorizontally = mLayout.canScrollHorizontally();
final boolean canScrollVertically = mLayout.canScrollVertically();
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(e);
final int action = MotionEventCompat.getActionMasked(e);
final int actionIndex = MotionEventCompat.getActionIndex(e);
switch (action) {
case MotionEvent.ACTION_DOWN: {
mScrollPointerId = MotionEventCompat.getPointerId(e, 0);
mInitialTouchX = mLastTouchX = (int) (e.getX() + 0.5f);
mInitialTouchY = mLastTouchY = (int) (e.getY() + 0.5f);
} break;
case MotionEventCompat.ACTION_POINTER_DOWN: {
mScrollPointerId = MotionEventCompat.getPointerId(e, actionIndex);
mInitialTouchX = mLastTouchX = (int) (MotionEventCompat.getX(e, actionIndex) + 0.5f);
mInitialTouchY = mLastTouchY = (int) (MotionEventCompat.getY(e, actionIndex) + 0.5f);
} break;
case MotionEvent.ACTION_MOVE: {
final int index = MotionEventCompat.findPointerIndex(e, mScrollPointerId);
if (index < 0) {
Log.e(TAG, "Error processing scroll; pointer index for id " +
mScrollPointerId + " not found. Did any MotionEvents get skipped?");
return false;
}
final int x = (int) (MotionEventCompat.getX(e, index) + 0.5f);
final int y = (int) (MotionEventCompat.getY(e, index) + 0.5f);
if (mScrollState != SCROLL_STATE_DRAGGING) {
final int dx = x - mInitialTouchX;
final int dy = y - mInitialTouchY;
boolean startScroll = false;
if (canScrollHorizontally && Math.abs(dx) > mTouchSlop) {
mLastTouchX = mInitialTouchX + mTouchSlop * (dx < 0 ? -1 : 1);
startScroll = true;
}
if (canScrollVertically && Math.abs(dy) > mTouchSlop) {
mLastTouchY = mInitialTouchY + mTouchSlop * (dy < 0 ? -1 : 1);
startScroll = true;
}
if (startScroll) {
getParent().requestDisallowInterceptTouchEvent(true);
setScrollState(SCROLL_STATE_DRAGGING);
}
}
if (mScrollState == SCROLL_STATE_DRAGGING) {
final int dx = x - mLastTouchX;
final int dy = y - mLastTouchY;
scrollByInternal(canScrollHorizontally ? -dx : 0,
canScrollVertically ? -dy : 0);
}
mLastTouchX = x;
mLastTouchY = y;
} break;
case MotionEventCompat.ACTION_POINTER_UP: {
onPointerUp(e);
} break;
case MotionEvent.ACTION_UP: {
mVelocityTracker.computeCurrentVelocity(1000, mMaxFlingVelocity);
final float xvel = canScrollHorizontally ?
-VelocityTrackerCompat.getXVelocity(mVelocityTracker, mScrollPointerId) : 0;
final float yvel = canScrollVertically ?
-VelocityTrackerCompat.getYVelocity(mVelocityTracker, mScrollPointerId) : 0;
if (!((xvel != 0 || yvel != 0) && fling((int) xvel, (int) yvel))) {
setScrollState(SCROLL_STATE_IDLE);
}
mVelocityTracker.clear();
releaseGlows();
} break;
case MotionEvent.ACTION_CANCEL: {
cancelTouch();
} break;
}
return true;
}
private void cancelTouch() {
mVelocityTracker.clear();
releaseGlows();
setScrollState(SCROLL_STATE_IDLE);
}
private void onPointerUp(MotionEvent e) {
final int actionIndex = MotionEventCompat.getActionIndex(e);
if (MotionEventCompat.getPointerId(e, actionIndex) == mScrollPointerId) {
// Pick a new pointer to pick up the slack.
final int newIndex = actionIndex == 0 ? 1 : 0;
mScrollPointerId = MotionEventCompat.getPointerId(e, newIndex);
mInitialTouchX = mLastTouchX = (int) (MotionEventCompat.getX(e, newIndex) + 0.5f);
mInitialTouchY = mLastTouchY = (int) (MotionEventCompat.getY(e, newIndex) + 0.5f);
}
}
@Override
protected void onMeasure(int widthSpec, int heightSpec) {
if (mAdapterUpdateDuringMeasure) {
eatRequestLayout();
updateChildViews();
mAdapterUpdateDuringMeasure = false;
resumeRequestLayout(false);
}
if (mAdapter != null) {
mState.mItemCount = mAdapter.getItemCount();
}
mLayout.onMeasure(mRecycler, mState, widthSpec, heightSpec);
final int widthSize = getMeasuredWidth();
final int heightSize = getMeasuredHeight();
if (mLeftGlow != null) mLeftGlow.setSize(heightSize, widthSize);
if (mTopGlow != null) mTopGlow.setSize(widthSize, heightSize);
if (mRightGlow != null) mRightGlow.setSize(heightSize, widthSize);
if (mBottomGlow != null) mBottomGlow.setSize(widthSize, heightSize);
}
/**
* Sets the {@link ItemAnimator} that will handle animations involving changes
* to the items in this RecyclerView. By default, RecyclerView instantiates and
* uses an instance of {@link DefaultItemAnimator}. Whether item animations are
* enabled for the RecyclerView depends on the ItemAnimator and whether
* the LayoutManager {@link LayoutManager#supportsPredictiveItemAnimations()
* supports item animations}.
*
* @param animator The ItemAnimator being set. If null, no animations will occur
* when changes occur to the items in this RecyclerView.
*/
public void setItemAnimator(ItemAnimator animator) {
if (mItemAnimator != null) {
mItemAnimator.setListener(null);
}
mItemAnimator = animator;
if (mItemAnimator != null) {
mItemAnimator.setListener(mItemAnimatorListener);
}
}
/**
* Gets the current ItemAnimator for this RecyclerView. A null return value
* indicates that there is no animator and that item changes will happen without
* any animations. By default, RecyclerView instantiates and
* uses an instance of {@link DefaultItemAnimator}.
*
* @return ItemAnimator The current ItemAnimator. If null, no animations will occur
* when changes occur to the items in this RecyclerView.
*/
public ItemAnimator getItemAnimator() {
return mItemAnimator;
}
/**
* Post a runnable to the next frame to run pending item animations. Only the first such
* request will be posted, governed by the mPostedAnimatorRunner flag.
*/
private void postAnimationRunner() {
if (!mPostedAnimatorRunner && mIsAttached) {
ViewCompat.postOnAnimation(this, mItemAnimatorRunner);
mPostedAnimatorRunner = true;
}
}
private boolean predictiveItemAnimationsEnabled() {
return (mItemAnimator != null && mLayout.supportsPredictiveItemAnimations());
}
/**
* Wrapper around layoutChildren() that handles animating changes caused by layout.
* Animations work on the assumption that there are five different kinds of items
* in play:
* PERSISTENT: items are visible before and after layout
* REMOVED: items were visible before layout and were removed by the app
* ADDED: items did not exist before layout and were added by the app
* DISAPPEARING: items exist in the data set before/after, but changed from
* visible to non-visible in the process of layout (they were moved off
* screen as a side-effect of other changes)
* APPEARING: items exist in the data set before/after, but changed from
* non-visible to visible in the process of layout (they were moved on
* screen as a side-effect of other changes)
* The overall approach figures out what items exist before/after layout and
* infers one of the five above states for each of the items. Then the animations
* are set up accordingly:
* PERSISTENT views are moved ({@link ItemAnimator#animateMove(ViewHolder, int, int, int, int)})
* REMOVED views are removed ({@link ItemAnimator#animateRemove(ViewHolder)})
* ADDED views are added ({@link ItemAnimator#animateAdd(ViewHolder)})
* DISAPPEARING views are moved off screen
* APPEARING views are moved on screen
*/
void dispatchLayout() {
if (mAdapter == null) {
Log.e(TAG, "No adapter attached; skipping layout");
return;
}
eatRequestLayout();
// simple animations are a subset of advanced animations (which will cause a
// prelayout step)
boolean animateChangesSimple = mItemAnimator != null && mItemsAddedOrRemoved
&& !mItemsChanged;
final boolean animateChangesAdvanced = ENABLE_PREDICTIVE_ANIMATIONS &&
animateChangesSimple && predictiveItemAnimationsEnabled();
mItemsAddedOrRemoved = mItemsChanged = false;
ArrayMap<View, Rect> appearingViewInitialBounds = null;
mState.mInPreLayout = animateChangesAdvanced;
mState.mItemCount = mAdapter.getItemCount();
if (animateChangesSimple) {
// Step 0: Find out where all non-removed items are, pre-layout
mState.mPreLayoutHolderMap.clear();
mState.mPostLayoutHolderMap.clear();
int count = getChildCount();
for (int i = 0; i < count; ++i) {
final ViewHolder holder = getChildViewHolderInt(getChildAt(i));
final View view = holder.itemView;
mState.mPreLayoutHolderMap.put(holder, new ItemHolderInfo(holder,
view.getLeft(), view.getTop(), view.getRight(), view.getBottom(),
holder.mPosition));
}
}
if (animateChangesAdvanced) {
// Step 1: run prelayout: This will use the old positions of items. The layout manager
// is expected to layout everything, even removed items (though not to add removed
// items back to the container). This gives the pre-layout position of APPEARING views
// which come into existence as part of the real layout.
mInPreLayout = true;
final boolean didStructureChange = mState.mStructureChanged;
mState.mStructureChanged = false;
// temporarily disable flag because we are asking for previous layout
mLayout.onLayoutChildren(mRecycler, mState);
mState.mStructureChanged = didStructureChange;
mInPreLayout = false;
appearingViewInitialBounds = new ArrayMap<View, Rect>();
for (int i = 0; i < getChildCount(); ++i) {
boolean found = false;
View child = getChildAt(i);
for (int j = 0; j < mState.mPreLayoutHolderMap.size(); ++j) {
ViewHolder holder = mState.mPreLayoutHolderMap.keyAt(j);
if (holder.itemView == child) {
found = true;
continue;
}
}
if (!found) {
appearingViewInitialBounds.put(child, new Rect(child.getLeft(), child.getTop(),
child.getRight(), child.getBottom()));
}
}
}
clearOldPositions();
dispatchLayoutUpdates();
mState.mItemCount = mAdapter.getItemCount();
// Step 2: Run layout
mState.mInPreLayout = false;
mLayout.onLayoutChildren(mRecycler, mState);
mState.mStructureChanged = false;
mPendingSavedState = null;
// onLayoutChildren may have caused client code to disable item animations; re-check
animateChangesSimple = animateChangesSimple && mItemAnimator != null;
if (animateChangesSimple) {
// Step 3: Find out where things are now, post-layout
int count = getChildCount();
for (int i = 0; i < count; ++i) {
ViewHolder holder = getChildViewHolderInt(getChildAt(i));
final View view = holder.itemView;
mState.mPostLayoutHolderMap.put(holder, new ItemHolderInfo(holder,
view.getLeft(), view.getTop(), view.getRight(), view.getBottom(),
holder.mPosition));
}
// Step 4: Animate DISAPPEARING and REMOVED items
int preLayoutCount = mState.mPreLayoutHolderMap.size();
for (int i = preLayoutCount - 1; i >= 0; i--) {
ViewHolder itemHolder = mState.mPreLayoutHolderMap.keyAt(i);
if (!mState.mPostLayoutHolderMap.containsKey(itemHolder)) {
ItemHolderInfo disappearingItem = mState.mPreLayoutHolderMap.valueAt(i);
mState.mPreLayoutHolderMap.removeAt(i);
View disappearingItemView = disappearingItem.holder.itemView;
removeDetachedView(disappearingItemView, false);
mRecycler.unscrapView(disappearingItem.holder);
animateDisappearance(disappearingItem);
}
}
// Step 5: Animate APPEARING and ADDED items
int postLayoutCount = mState.mPostLayoutHolderMap.size();
if (postLayoutCount > 0) {
for (int i = postLayoutCount - 1; i >= 0; i--) {
ViewHolder itemHolder = mState.mPostLayoutHolderMap.keyAt(i);
ItemHolderInfo info = mState.mPostLayoutHolderMap.valueAt(i);
if ((mState.mPreLayoutHolderMap.isEmpty() ||
!mState.mPreLayoutHolderMap.containsKey(itemHolder))) {
mState.mPostLayoutHolderMap.removeAt(i);
Rect initialBounds = (appearingViewInitialBounds != null) ?
appearingViewInitialBounds.get(itemHolder.itemView) : null;
animateAppearance(itemHolder, initialBounds,
info.left, info.top);
}
}
}
// Step 6: Animate PERSISTENT items
count = mState.mPostLayoutHolderMap.size();
for (int i = 0; i < count; ++i) {
ViewHolder postHolder = mState.mPostLayoutHolderMap.keyAt(i);
ItemHolderInfo postInfo = mState.mPostLayoutHolderMap.valueAt(i);
ItemHolderInfo preInfo = mState.mPreLayoutHolderMap.get(postHolder);
if (preInfo != null && postInfo != null) {
if (preInfo.left != postInfo.left || preInfo.top != postInfo.top) {
postHolder.setIsRecyclable(false);
if (DEBUG) {
Log.d(TAG, "PERSISTENT: " + postHolder +
" with view " + postHolder.itemView);
}
if (mItemAnimator.animateMove(postHolder,
preInfo.left, preInfo.top, postInfo.left, postInfo.top)) {
postAnimationRunner();
}
}
}
}
}
resumeRequestLayout(false);
mLayout.removeAndRecycleScrapInt(mRecycler, !animateChangesAdvanced);
mState.mPreviousLayoutItemCount = mState.mItemCount;
mState.mDeletedInvisibleItemCountSincePreviousLayout = 0;
}
private void animateAppearance(ViewHolder itemHolder, Rect beforeBounds, int afterLeft,
int afterTop) {
View newItemView = itemHolder.itemView;
if (beforeBounds != null &&
(beforeBounds.left != afterLeft || beforeBounds.top != afterTop)) {
// slide items in if before/after locations differ
itemHolder.setIsRecyclable(false);
if (DEBUG) {
Log.d(TAG, "APPEARING: " + itemHolder + " with view " + newItemView);
}
if (mItemAnimator.animateMove(itemHolder,
beforeBounds.left, beforeBounds.top,
afterLeft, afterTop)) {
postAnimationRunner();
}
} else {
if (DEBUG) {
Log.d(TAG, "ADDED: " + itemHolder + " with view " + newItemView);
}
itemHolder.setIsRecyclable(false);
if (mItemAnimator.animateAdd(itemHolder)) {
postAnimationRunner();
}
}
}
private void animateDisappearance(ItemHolderInfo disappearingItem) {
View disappearingItemView = disappearingItem.holder.itemView;
addAnimatingView(disappearingItemView);
int oldLeft = disappearingItem.left;
int oldTop = disappearingItem.top;
int newLeft = disappearingItemView.getLeft();
int newTop = disappearingItemView.getTop();
if (oldLeft != newLeft || oldTop != newTop) {
disappearingItem.holder.setIsRecyclable(false);
disappearingItemView.layout(newLeft, newTop,
newLeft + disappearingItemView.getWidth(),
newTop + disappearingItemView.getHeight());
if (DEBUG) {
Log.d(TAG, "DISAPPEARING: " + disappearingItem.holder +
" with view " + disappearingItemView);
}
if (mItemAnimator.animateMove(disappearingItem.holder, oldLeft, oldTop,
newLeft, newTop)) {
postAnimationRunner();
}
} else {
if (DEBUG) {
Log.d(TAG, "REMOVED: " + disappearingItem.holder +
" with view " + disappearingItemView);
}
disappearingItem.holder.setIsRecyclable(false);
if (mItemAnimator.animateRemove(disappearingItem.holder)) {
postAnimationRunner();
}
}
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
eatRequestLayout();
dispatchLayout();
resumeRequestLayout(false);
mFirstLayoutComplete = true;
}
@Override
public void requestLayout() {
if (!mEatRequestLayout) {
super.requestLayout();
} else {
mLayoutRequestEaten = true;
}
}
void markItemDecorInsetsDirty() {
final int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
final View child = getChildAt(i);
((LayoutParams) child.getLayoutParams()).mInsetsDirty = true;
}
}
@Override
public void draw(Canvas c) {
super.draw(c);
final int count = mItemDecorations.size();
for (int i = 0; i < count; i++) {
mItemDecorations.get(i).onDrawOver(c, this);
}
boolean needsInvalidate = false;
if (mLeftGlow != null && !mLeftGlow.isFinished()) {
final int restore = c.save();
c.rotate(270);
c.translate(-getHeight() + getPaddingTop(), 0);
needsInvalidate = mLeftGlow != null && mLeftGlow.draw(c);
c.restoreToCount(restore);
}
if (mTopGlow != null && !mTopGlow.isFinished()) {
c.translate(getPaddingLeft(), getPaddingTop());
needsInvalidate |= mTopGlow != null && mTopGlow.draw(c);
}
if (mRightGlow != null && !mRightGlow.isFinished()) {
final int restore = c.save();
final int width = getWidth();
c.rotate(90);
c.translate(-getPaddingTop(), -width);
needsInvalidate |= mRightGlow != null && mRightGlow.draw(c);
c.restoreToCount(restore);
}
if (mBottomGlow != null && !mBottomGlow.isFinished()) {
final int restore = c.save();
c.rotate(180);
c.translate(-getWidth() + getPaddingLeft(), -getHeight() + getPaddingTop());
needsInvalidate |= mBottomGlow != null && mBottomGlow.draw(c);
c.restoreToCount(restore);
}
if (needsInvalidate) {
ViewCompat.postInvalidateOnAnimation(this);
}
}
@Override
public void onDraw(Canvas c) {
super.onDraw(c);
final int count = mItemDecorations.size();
for (int i = 0; i < count; i++) {
mItemDecorations.get(i).onDraw(c, this);
}
}
@Override
protected boolean checkLayoutParams(ViewGroup.LayoutParams p) {
return p instanceof LayoutParams && mLayout.checkLayoutParams((LayoutParams) p);
}
@Override
protected ViewGroup.LayoutParams generateDefaultLayoutParams() {
if (mLayout == null) {
throw new IllegalStateException("RecyclerView has no LayoutManager");
}
return mLayout.generateDefaultLayoutParams();
}
@Override
public ViewGroup.LayoutParams generateLayoutParams(AttributeSet attrs) {
if (mLayout == null) {
throw new IllegalStateException("RecyclerView has no LayoutManager");
}
return mLayout.generateLayoutParams(getContext(), attrs);
}
@Override
protected ViewGroup.LayoutParams generateLayoutParams(ViewGroup.LayoutParams p) {
if (mLayout == null) {
throw new IllegalStateException("RecyclerView has no LayoutManager");
}
return mLayout.generateLayoutParams(p);
}
private int findPositionOffset(int position) {
int offset = 0;
int count = mPendingLayoutUpdates.size();
for (int i = 0; i < count; ++i) {
UpdateOp op = mPendingLayoutUpdates.get(i);
if (op.positionStart <= position) {
if (op.cmd == UpdateOp.REMOVE) {
offset -= op.itemCount;
} else if (op.cmd == UpdateOp.ADD) {
offset += op.itemCount;
}
}
}
return position + offset;
}
void dispatchLayoutUpdates() {
final int opCount = mPendingLayoutUpdates.size();
for (int i = 0; i < opCount; i++) {
final UpdateOp op = mPendingLayoutUpdates.get(i);
switch (op.cmd) {
case UpdateOp.ADD:
mLayout.onItemsAdded(this, op.positionStart, op.itemCount);
break;
case UpdateOp.REMOVE:
mLayout.onItemsRemoved(this, op.positionStart, op.itemCount);
break;
case UpdateOp.UPDATE:
// TODO: tell the layout manager
break;
}
recycleUpdateOp(op);
}
mPendingLayoutUpdates.clear();
}
void updateChildViews() {
final int opCount = mPendingUpdates.size();
for (int i = 0; i < opCount; i++) {
final UpdateOp op = mPendingUpdates.get(i);
switch (op.cmd) {
case UpdateOp.ADD:
if (DEBUG) {
Log.d(TAG, "UpdateOp.ADD start=" + op.positionStart + " count=" +
op.itemCount);
}
offsetPositionRecordsForInsert(op.positionStart, op.itemCount);
mItemsAddedOrRemoved = true;
break;
case UpdateOp.REMOVE:
if (DEBUG) {
Log.d(TAG, "UpdateOp.REMOVE start=" + op.positionStart + " count=" +
op.itemCount);
}
for (int j = 0; j < op.itemCount; ++j) {
ViewHolder holder = findViewHolderForPosition(op.positionStart + j, true);
if (holder != null) {
holder.setIsRecyclable(false);
} else {
mState.mDeletedInvisibleItemCountSincePreviousLayout ++;
}
}
offsetPositionRecordsForRemove(op.positionStart, op.itemCount);
mItemsAddedOrRemoved = true;
break;
case UpdateOp.UPDATE:
if (DEBUG) {
Log.d(TAG, "UpdateOp.UPDATE start=" + op.positionStart + " count=" +
op.itemCount);
}
viewRangeUpdate(op.positionStart, op.itemCount);
mItemsChanged = true;
break;
}
mPendingLayoutUpdates.add(op);
// TODO: recycle the op if no animator (also don't bother stashing in pending layout updates?)
}
mPendingUpdates.clear();
}
void clearOldPositions() {
final int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
final ViewHolder holder = getChildViewHolderInt(getChildAt(i));
holder.clearOldPosition();
}
mRecycler.clearOldPositions();
}
void offsetPositionRecordsForInsert(int positionStart, int itemCount) {
final int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
final ViewHolder holder = getChildViewHolderInt(getChildAt(i));
if (holder != null && holder.mPosition >= positionStart) {
if (DEBUG) {
Log.d(TAG, "offsetPositionRecordsForInsert attached child " + i + " holder " +
holder + " now at position " + (holder.mPosition + itemCount));
}
holder.offsetPosition(itemCount);
mState.mStructureChanged = true;
}
}
mRecycler.offsetPositionRecordsForInsert(positionStart, itemCount);
requestLayout();
}
void offsetPositionRecordsForRemove(int positionStart, int itemCount) {
final int positionEnd = positionStart + itemCount;
final int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
final ViewHolder holder = getChildViewHolderInt(getChildAt(i));
if (holder != null) {
if (holder.mPosition >= positionEnd) {
if (DEBUG) {
Log.d(TAG, "offsetPositionRecordsForRemove attached child " + i +
" holder " + holder + " now at position " +
(holder.mPosition - itemCount));
}
holder.offsetPosition(-itemCount);
mState.mStructureChanged = true;
} else if (holder.mPosition >= positionStart) {
if (DEBUG) {
Log.d(TAG, "offsetPositionRecordsForRemove attached child " + i +
" holder " + holder + " now REMOVED");
}
holder.addFlags(ViewHolder.FLAG_REMOVED);
mState.mStructureChanged = true;
}
}
}
mRecycler.offsetPositionRecordsForRemove(positionStart, itemCount);
requestLayout();
}
/**
* Rebind existing views for the given range, or create as needed.
*
* @param positionStart Adapter position to start at
* @param itemCount Number of views that must explicitly be rebound
*/
void viewRangeUpdate(int positionStart, int itemCount) {
final int childCount = getChildCount();
final int positionEnd = positionStart + itemCount;
for (int i = 0; i < childCount; i++) {
final ViewHolder holder = getChildViewHolderInt(getChildAt(i));
if (holder == null) {
continue;
}
final int position = holder.getPosition();
if (position >= positionStart && position < positionEnd) {
holder.addFlags(ViewHolder.FLAG_UPDATE);
// Binding an attached view will request a layout if needed.
mAdapter.bindViewHolder(holder, holder.getPosition());
}
}
mRecycler.viewRangeUpdate(positionStart, itemCount);
}
/**
* Mark all known views as invalid. Used in response to a, "the whole world might have changed"
* data change event.
*/
void markKnownViewsInvalid() {
final int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
final ViewHolder holder = getChildViewHolderInt(getChildAt(i));
if (holder != null) {
holder.addFlags(ViewHolder.FLAG_UPDATE | ViewHolder.FLAG_INVALID);
}
}
mRecycler.markKnownViewsInvalid();
}
/**
* Schedule an update of data from the adapter to occur on the next frame.
* On newer platform versions this happens via the postOnAnimation mechanism and RecyclerView
* attempts to avoid relayouts if possible.
* On older platform versions the RecyclerView requests a layout the same way ListView does.
*/
void postAdapterUpdate(UpdateOp op) {
mPendingUpdates.add(op);
if (mPendingUpdates.size() == 1) {
if (mPostUpdatesOnAnimation && mHasFixedSize && mIsAttached) {
ViewCompat.postOnAnimation(this, mUpdateChildViewsRunnable);
} else {
mAdapterUpdateDuringMeasure = true;
requestLayout();
}
}
}
/**
* Retrieve the {@link ViewHolder} for the given child view.
*
* @param child Child of this RecyclerView to query for its ViewHolder
* @return The child view's ViewHolder
*/
public ViewHolder getChildViewHolder(View child) {
final ViewParent parent = child.getParent();
if (parent != null && parent != this) {
throw new IllegalArgumentException("View " + child + " is not a direct child of " +
this);
}
return getChildViewHolderInt(child);
}
static ViewHolder getChildViewHolderInt(View child) {
if (child == null) {
return null;
}
return ((LayoutParams) child.getLayoutParams()).mViewHolder;
}
/**
* Return the adapter position that the given child view corresponds to.
*
* @param child Child View to query
* @return Adapter position corresponding to the given view or {@link #NO_POSITION}
*/
public int getChildPosition(View child) {
final ViewHolder holder = getChildViewHolderInt(child);
return holder != null ? holder.getPosition() : NO_POSITION;
}
/**
* Return the stable item id that the given child view corresponds to.
*
* @param child Child View to query
* @return Item id corresponding to the given view or {@link #NO_ID}
*/
public long getChildItemId(View child) {
if (mAdapter == null || !mAdapter.hasStableIds()) {
return NO_ID;
}
final ViewHolder holder = getChildViewHolderInt(child);
return holder != null ? holder.getItemId() : NO_ID;
}
/**
* Return the ViewHolder for the item in the given position of the data set.
*
* @param position The position of the item in the data set of the adapter
* @return The ViewHolder at <code>position</code>
*/
public ViewHolder findViewHolderForPosition(int position) {
return findViewHolderForPosition(position, false);
}
ViewHolder findViewHolderForPosition(int position, boolean checkNewPosition) {
final int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
final ViewHolder holder = getChildViewHolderInt(getChildAt(i));
if (holder != null) {
if (checkNewPosition) {
if (holder.mPosition == position) {
return holder;
}
} else if(holder.getPosition() == position) {
return holder;
}
}
}
return mRecycler.findViewHolderForPosition(position);
}
/**
* Return the ViewHolder for the item with the given id. The RecyclerView must
* use an Adapter with {@link Adapter#setHasStableIds(boolean) stableIds} to
* return a non-null value.
*
* @param id The id for the requested item
* @return The ViewHolder with the given <code>id</code>, of null if there
* is no such item.
*/
public ViewHolder findViewHolderForItemId(long id) {
final int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
final ViewHolder holder = getChildViewHolderInt(getChildAt(i));
if (holder != null && holder.getItemId() == id) {
return holder;
}
}
return mRecycler.findViewHolderForItemId(id);
}
/**
* Find the topmost view under the given point.
*
* @param x Horizontal position in pixels to search
* @param y Vertical position in pixels to search
* @return The child view under (x, y) or null if no matching child is found
*/
public View findChildViewUnder(float x, float y) {
final int count = getChildCount();
for (int i = count - 1; i >= 0; i--) {
final View child = getChildAt(i);
final float translationX = ViewCompat.getTranslationX(child);
final float translationY = ViewCompat.getTranslationY(child);
if (x >= child.getLeft() + translationX &&
x <= child.getRight() + translationX &&
y >= child.getTop() + translationY &&
y <= child.getBottom() + translationY) {
return child;
}
}
return null;
}
/**
* Offset the bounds of all child views by <code>dy</code> pixels.
* Useful for implementing simple scrolling in {@link LayoutManager LayoutManagers}.
*
* @param dy Vertical pixel offset to apply to the bounds of all child views
*/
public void offsetChildrenVertical(int dy) {
final int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
getChildAt(i).offsetTopAndBottom(dy);
}
}
/**
* Called when an item view is attached to this RecyclerView.
*
* <p>Subclasses of RecyclerView may want to perform extra bookkeeping or modifications
* of child views as they become attached. This will be called before a
* {@link LayoutManager} measures or lays out the view and is a good time to perform these
* changes.</p>
*
* @param child Child view that is now attached to this RecyclerView and its associated window
*/
public void onChildAttachedToWindow(View child) {
}
/**
* Called when an item view is detached from this RecyclerView.
*
* <p>Subclasses of RecyclerView may want to perform extra bookkeeping or modifications
* of child views as they become detached. This will be called as a
* {@link LayoutManager} fully detaches the child view from the parent and its window.</p>
*
* @param child Child view that is now detached from this RecyclerView and its associated window
*/
public void onChildDetachedFromWindow(View child) {
}
/**
* Offset the bounds of all child views by <code>dx</code> pixels.
* Useful for implementing simple scrolling in {@link LayoutManager LayoutManagers}.
*
* @param dx Horizontal pixel offset to apply to the bounds of all child views
*/
public void offsetChildrenHorizontal(int dx) {
final int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
getChildAt(i).offsetLeftAndRight(dx);
}
}
Rect getItemDecorInsetsForChild(View child) {
final LayoutParams lp = (LayoutParams) child.getLayoutParams();
if (!lp.mInsetsDirty) {
return lp.mDecorInsets;
}
final Rect insets = lp.mDecorInsets;
insets.set(0, 0, 0, 0);
final int decorCount = mItemDecorations.size();
for (int i = 0; i < decorCount; i++) {
mTempRect.set(0, 0, 0, 0);
mItemDecorations.get(i).getItemOffsets(mTempRect, lp.getViewPosition(), this);
insets.left += mTempRect.left;
insets.top += mTempRect.top;
insets.right += mTempRect.right;
insets.bottom += mTempRect.bottom;
}
lp.mInsetsDirty = false;
return insets;
}
private class ViewFlinger implements Runnable {
private int mLastFlingX;
private int mLastFlingY;
private ScrollerCompat mScroller;
private Interpolator mInterpolator = sQuinticInterpolator;
// When set to true, postOnAnimation callbacks are delayed until the run method completes
private boolean mEatRunOnAnimationRequest = false;
// Tracks if postAnimationCallback should be re-attached when it is done
private boolean mReSchedulePostAnimationCallback = false;
public ViewFlinger() {
mScroller = ScrollerCompat.create(getContext(), sQuinticInterpolator);
}
@Override
public void run() {
disableRunOnAnimationRequests();
consumePendingUpdateOperations();
// keep a local reference so that if it is changed during onAnimation method, it wont cause
// unexpected behaviors
final ScrollerCompat scroller = mScroller;
final SmoothScroller smoothScroller = mLayout.mSmoothScroller;
if (scroller.computeScrollOffset()) {
final int x = scroller.getCurrX();
final int y = scroller.getCurrY();
final int dx = x - mLastFlingX;
final int dy = y - mLastFlingY;
mLastFlingX = x;
mLastFlingY = y;
int overscrollX = 0, overscrollY = 0;
if (mAdapter != null) {
eatRequestLayout();
if (dx != 0) {
final int hresult = mLayout.scrollHorizontallyBy(dx, mRecycler, mState);
overscrollX = dx - hresult;
}
if (dy != 0) {
final int vresult = mLayout.scrollVerticallyBy(dy, mRecycler, mState);
overscrollY = dy - vresult;
}
if (smoothScroller != null && !smoothScroller.isPendingInitialRun() &&
smoothScroller.isRunning()) {
smoothScroller.onAnimation(dx - overscrollX, dy - overscrollY);
}
resumeRequestLayout(false);
}
if (!mItemDecorations.isEmpty()) {
invalidate();
}
if (overscrollX != 0 || overscrollY != 0) {
final int vel = (int) scroller.getCurrVelocity();
int velX = 0;
if (overscrollX != x) {
velX = overscrollX < 0 ? -vel : overscrollX > 0 ? vel : 0;
}
int velY = 0;
if (overscrollY != y) {
velY = overscrollY < 0 ? -vel : overscrollY > 0 ? vel : 0;
}
if (ViewCompat.getOverScrollMode(RecyclerView.this) !=
ViewCompat.OVER_SCROLL_NEVER) {
absorbGlows(velX, velY);
}
if ((velX != 0 || overscrollX == x || scroller.getFinalX() == 0) &&
(velY != 0 || overscrollY == y || scroller.getFinalY() == 0)) {
scroller.abortAnimation();
}
}
if (mScrollListener != null && (x != 0 || y != 0)) {
mScrollListener.onScrolled(dx, dy);
}
if (!awakenScrollBars()) {
invalidate();
}
if (scroller.isFinished()) {
setScrollState(SCROLL_STATE_IDLE);
} else {
postOnAnimation();
}
}
// call this after the onAnimation is complete not to have inconsistent callbacks etc.
if (smoothScroller != null && smoothScroller.isPendingInitialRun()) {
smoothScroller.onAnimation(0, 0);
}
enableRunOnAnimationRequests();
}
private void disableRunOnAnimationRequests() {
mReSchedulePostAnimationCallback = false;
mEatRunOnAnimationRequest = true;
}
private void enableRunOnAnimationRequests() {
mEatRunOnAnimationRequest = false;
if (mReSchedulePostAnimationCallback) {
postOnAnimation();
}
}
void postOnAnimation() {
if (mEatRunOnAnimationRequest) {
mReSchedulePostAnimationCallback = true;
} else {
ViewCompat.postOnAnimation(RecyclerView.this, this);
}
}
public void fling(int velocityX, int velocityY) {
setScrollState(SCROLL_STATE_SETTLING);
mLastFlingX = mLastFlingY = 0;
mScroller.fling(0, 0, velocityX, velocityY,
Integer.MIN_VALUE, Integer.MAX_VALUE, Integer.MIN_VALUE, Integer.MAX_VALUE);
postOnAnimation();
}
public void smoothScrollBy(int dx, int dy) {
smoothScrollBy(dx, dy, 0, 0);
}
public void smoothScrollBy(int dx, int dy, int vx, int vy) {
smoothScrollBy(dx, dy, computeScrollDuration(dx, dy, vx, vy));
}
private float distanceInfluenceForSnapDuration(float f) {
f -= 0.5f; // center the values about 0.
f *= 0.3f * Math.PI / 2.0f;
return (float) Math.sin(f);
}
private int computeScrollDuration(int dx, int dy, int vx, int vy) {
final int absDx = Math.abs(dx);
final int absDy = Math.abs(dy);
final boolean horizontal = absDx > absDy;
final int velocity = (int) Math.sqrt(vx * vx + vy * vy);
final int delta = (int) Math.sqrt(dx * dx + dy * dy);
final int containerSize = horizontal ? getWidth() : getHeight();
final int halfContainerSize = containerSize / 2;
final float distanceRatio = Math.min(1.f, 1.f * delta / containerSize);
final float distance = halfContainerSize + halfContainerSize *
distanceInfluenceForSnapDuration(distanceRatio);
final int duration;
if (velocity > 0) {
duration = 4 * Math.round(1000 * Math.abs(distance / velocity));
} else {
float absDelta = (float) (horizontal ? absDx : absDy);
duration = (int) (((absDelta / containerSize) + 1) * 300);
}
return Math.min(duration, MAX_SCROLL_DURATION);
}
public void smoothScrollBy(int dx, int dy, int duration) {
smoothScrollBy(dx, dy, duration, sQuinticInterpolator);
}
public void smoothScrollBy(int dx, int dy, int duration, Interpolator interpolator) {
if (mInterpolator != interpolator) {
mInterpolator = interpolator;
mScroller = ScrollerCompat.create(getContext(), interpolator);
}
setScrollState(SCROLL_STATE_SETTLING);
mLastFlingX = mLastFlingY = 0;
mScroller.startScroll(0, 0, dx, dy, duration);
postOnAnimation();
}
public void stop() {
removeCallbacks(this);
mScroller.abortAnimation();
}
}
private class RecyclerViewDataObserver extends AdapterDataObserver {
@Override
public void onChanged() {
if (mAdapter.hasStableIds()) {
// TODO Determine what actually changed
markKnownViewsInvalid();
mState.mStructureChanged = true;
requestLayout();
} else {
markKnownViewsInvalid();
mState.mStructureChanged = true;
requestLayout();
}
}
@Override
public void onItemRangeChanged(int positionStart, int itemCount) {
postAdapterUpdate(obtainUpdateOp(UpdateOp.UPDATE, positionStart, itemCount));
}
@Override
public void onItemRangeInserted(int positionStart, int itemCount) {
postAdapterUpdate(obtainUpdateOp(UpdateOp.ADD, positionStart, itemCount));
}
@Override
public void onItemRangeRemoved(int positionStart, int itemCount) {
postAdapterUpdate(obtainUpdateOp(UpdateOp.REMOVE, positionStart, itemCount));
}
}
public static class RecycledViewPool {
private SparseArray<ArrayList<ViewHolder>> mScrap =
new SparseArray<ArrayList<ViewHolder>>();
private SparseIntArray mMaxScrap = new SparseIntArray();
private int mAttachCount = 0;
private static final int DEFAULT_MAX_SCRAP = 5;
public void clear() {
mScrap.clear();
}
public void setMaxRecycledViews(int viewType, int max) {
mMaxScrap.put(viewType, max);
final ArrayList<ViewHolder> scrapHeap = mScrap.get(viewType);
if (scrapHeap != null) {
while (scrapHeap.size() > max) {
scrapHeap.remove(scrapHeap.size() - 1);
}
}
}
public ViewHolder getRecycledView(int viewType) {
final ArrayList<ViewHolder> scrapHeap = mScrap.get(viewType);
if (scrapHeap != null && !scrapHeap.isEmpty()) {
final int index = scrapHeap.size() - 1;
final ViewHolder scrap = scrapHeap.get(index);
scrapHeap.remove(index);
return scrap;
}
return null;
}
public void putRecycledView(ViewHolder scrap) {
final int viewType = scrap.getItemViewType();
final ArrayList scrapHeap = getScrapHeapForType(viewType);
if (mMaxScrap.get(viewType) <= scrapHeap.size()) {
return;
}
scrap.mPosition = NO_POSITION;
scrap.mOldPosition = NO_POSITION;
scrap.mItemId = NO_ID;
scrap.clearFlagsForSharedPool();
scrapHeap.add(scrap);
}
void attach(Adapter adapter) {
mAttachCount++;
}
void detach() {
mAttachCount--;
}
void onAdapterChanged(Adapter oldAdapter, Adapter newAdapter) {
if (mAttachCount == 1) {
clear();
}
}
private ArrayList<ViewHolder> getScrapHeapForType(int viewType) {
ArrayList<ViewHolder> scrap = mScrap.get(viewType);
if (scrap == null) {
scrap = new ArrayList<ViewHolder>();
mScrap.put(viewType, scrap);
if (mMaxScrap.indexOfKey(viewType) < 0) {
mMaxScrap.put(viewType, DEFAULT_MAX_SCRAP);
}
}
return scrap;
}
}
/**
* A Recycler is responsible for managing scrapped or detached item views for reuse.
*
* <p>A "scrapped" view is a view that is still attached to its parent RecyclerView but
* that has been marked for removal or reuse.</p>
*
* <p>Typical use of a Recycler by a {@link LayoutManager} will be to obtain views for
* an adapter's data set representing the data at a given position or item ID.
* If the view to be reused is considered "dirty" the adapter will be asked to rebind it.
* If not, the view can be quickly reused by the LayoutManager with no further work.
* Clean views that have not {@link android.view.View#isLayoutRequested() requested layout}
* may be repositioned by a LayoutManager without remeasurement.</p>
*/
public final class Recycler {
private final ArrayList<ViewHolder> mAttachedScrap = new ArrayList<ViewHolder>();
private final ArrayList<ViewHolder> mCachedViews = new ArrayList<ViewHolder>();
private final List<ViewHolder>
mUnmodifiableAttachedScrap = Collections.unmodifiableList(mAttachedScrap);
private int mViewCacheMax = DEFAULT_CACHE_SIZE;
private RecycledViewPool mRecyclerPool;
private static final int DEFAULT_CACHE_SIZE = 2;
/**
* Clear scrap views out of this recycler. Detached views contained within a
* recycled view pool will remain.
*/
public void clear() {
mAttachedScrap.clear();
recycleCachedViews();
}
/**
* Set the maximum number of detached, valid views we should retain for later use.
*
* @param viewCount Number of views to keep before sending views to the shared pool
*/
public void setViewCacheSize(int viewCount) {
mViewCacheMax = viewCount;
while (mCachedViews.size() > viewCount) {
mCachedViews.remove(mCachedViews.size() - 1);
}
}
/**
* Returns an unmodifiable list of ViewHolders that are currently in the scrap list.
*
* @return List of ViewHolders in the scrap list.
*/
public List<ViewHolder> getScrapList() {
return mUnmodifiableAttachedScrap;
}
/**
* Helper method for getViewForPosition.
* <p>
* Checks whether a given view holder can be used for the provided position.
*
* @param holder ViewHolder
* @param offsetPosition The position which is updated by UPDATE_OP changes on the adapter
* @return true if ViewHolder matches the provided position, false otherwise
*/
boolean validateViewHolderForOffsetPosition(ViewHolder holder, int offsetPosition) {
// if it is a removed holder, nothing to verify since we cannot ask adapter anymore
// if it is not removed, verify the type and id.
if (holder.isRemoved()) {
return true;
}
if (offsetPosition < 0 || offsetPosition >= mAdapter.getItemCount()) {
if (DEBUG) {
Log.d(TAG, "validateViewHolderForOffsetPosition: invalid position, returning "
+ "false");
}
return false;
}
final int type = mAdapter.getItemViewType(offsetPosition);
if (type != holder.getItemViewType()) {
return false;
}
if (mAdapter.hasStableIds()) {
return holder.getItemId() == mAdapter.getItemId(offsetPosition);
}
return true;
}
/**
* Obtain a view initialized for the given position.
*
* <p>This method should be used by {@link LayoutManager} implementations to obtain
* views to represent data from an {@link Adapter}.</p>
*
* <p>The Recycler may reuse a scrap or detached view from a shared pool if one is
* available for the correct view type. If the adapter has not indicated that the
* data at the given position has changed, the Recycler will attempt to hand back
* a scrap view that was previously initialized for that data without rebinding.</p>
*
* @param position Position to obtain a view for
* @return A view representing the data at <code>position</code> from <code>adapter</code>
*/
public View getViewForPosition(int position) {
ViewHolder holder;
holder = getScrapViewForPosition(position, INVALID_TYPE);
final int offsetPosition = findPositionOffset(position);
if (holder != null) {
if (!validateViewHolderForOffsetPosition(holder, offsetPosition)) {
// recycle this scrap
removeDetachedView(holder.itemView, false);
quickRecycleScrapView(holder.itemView);
// if validate fails, we can query scrap again w/ type. that may return a
// different view holder from cache.
final int type = mAdapter.getItemViewType(offsetPosition);
if (mAdapter.hasStableIds()) {
final long id = mAdapter.getItemId(offsetPosition);
holder = getScrapViewForId(id, type);
} else {
holder = getScrapViewForPosition(offsetPosition, type);
}
}
} else {
// try recycler.
holder = getRecycledViewPool()
.getRecycledView(mAdapter.getItemViewType(offsetPosition));
}
if (holder == null) {
if (offsetPosition < 0 || offsetPosition >= mAdapter.getItemCount()) {
throw new IndexOutOfBoundsException("Invalid item position " + position
+ "(" + offsetPosition + ")");
} else {
holder = mAdapter.createViewHolder(RecyclerView.this,
mAdapter.getItemViewType(offsetPosition));
if (DEBUG) {
Log.d(TAG, "getViewForPosition created new ViewHolder");
}
}
}
if (!holder.isRemoved() && (!holder.isBound() || holder.needsUpdate())) {
if (DEBUG) {
Log.d(TAG, "getViewForPosition unbound holder or needs update; updating...");
}
// TODO: think through when getOffsetPosition() is called. I use it here because
// existing views have already been offset appropriately through the mOldOffset
// mechanism, but new views do not have this mechanism.
mAdapter.bindViewHolder(holder, offsetPosition);
}
ViewGroup.LayoutParams lp = holder.itemView.getLayoutParams();
if (lp == null) {
lp = generateDefaultLayoutParams();
holder.itemView.setLayoutParams(lp);
} else if (!checkLayoutParams(lp)) {
lp = generateLayoutParams(lp);
holder.itemView.setLayoutParams(lp);
}
((LayoutParams) lp).mViewHolder = holder;
return holder.itemView;
}
/**
* Recycle a detached view. The specified view will be added to a pool of views
* for later rebinding and reuse.
*
* <p>A view must be fully detached before it may be recycled.</p>
*
* @param view Removed view for recycling
*/
public void recycleView(View view) {
recycleViewHolder(getChildViewHolderInt(view));
}
void recycleCachedViews() {
final int count = mCachedViews.size();
for (int i = count - 1; i >= 0; i--) {
final ViewHolder cachedView = mCachedViews.get(i);
if (cachedView.isRecyclable()) {
getRecycledViewPool().putRecycledView(cachedView);
dispatchViewRecycled(cachedView);
}
mCachedViews.remove(i);
}
}
void recycleViewHolder(ViewHolder holder) {
if (holder.isScrap() || holder.itemView.getParent() != null) {
throw new IllegalArgumentException(
"Scrapped or attached views may not be recycled.");
}
boolean cached = false;
if (!holder.isInvalid() && (mInPreLayout || !holder.isRemoved())) {
// Retire oldest cached views first
if (mCachedViews.size() == mViewCacheMax && !mCachedViews.isEmpty()) {
for (int i = 0; i < mCachedViews.size(); i++) {
final ViewHolder cachedView = mCachedViews.get(i);
if (cachedView.isRecyclable()) {
mCachedViews.remove(i);
getRecycledViewPool().putRecycledView(cachedView);
dispatchViewRecycled(cachedView);
break;
}
}
}
if (mCachedViews.size() < mViewCacheMax) {
mCachedViews.add(holder);
cached = true;
}
}
if (!cached && holder.isRecyclable()) {
getRecycledViewPool().putRecycledView(holder);
dispatchViewRecycled(holder);
}
// Remove from pre/post maps that are used to animate items; a recycled holder
// should not be animated
mState.mPreLayoutHolderMap.remove(holder);
mState.mPostLayoutHolderMap.remove(holder);
}
/**
* Used as a fast path for unscrapping and recycling a view during a bulk operation.
* The caller must call {@link #clearScrap()} when it's done to update the recycler's
* internal bookkeeping.
*/
void quickRecycleScrapView(View view) {
final ViewHolder holder = getChildViewHolderInt(view);
holder.mScrapContainer = null;
recycleViewHolder(holder);
}
/**
* Mark an attached view as scrap.
*
* <p>"Scrap" views are still attached to their parent RecyclerView but are eligible
* for rebinding and reuse. Requests for a view for a given position may return a
* reused or rebound scrap view instance.</p>
*
* @param view View to scrap
*/
void scrapView(View view) {
final ViewHolder holder = getChildViewHolderInt(view);
holder.setScrapContainer(this);
mAttachedScrap.add(holder);
}
/**
* Remove a previously scrapped view from the pool of eligible scrap.
*
* <p>This view will no longer be eligible for reuse until re-scrapped or
* until it is explicitly removed and recycled.</p>
*/
void unscrapView(ViewHolder holder) {
mAttachedScrap.remove(holder);
holder.mScrapContainer = null;
}
int getScrapCount() {
return mAttachedScrap.size();
}
View getScrapViewAt(int index) {
return mAttachedScrap.get(index).itemView;
}
void clearScrap() {
mAttachedScrap.clear();
}
/**
* Returns a scrap view for the position. If type is not INVALID_TYPE, it also checks if
* ViewHolder's type matches the provided type.
*
* @param position Item position
* @param type View type
* @return a ViewHolder that can be re-used for this position.
*/
ViewHolder getScrapViewForPosition(int position, int type) {
final int scrapCount = mAttachedScrap.size();
// Try first for an exact, non-invalid match from scrap.
for (int i = 0; i < scrapCount; i++) {
final ViewHolder holder = mAttachedScrap.get(i);
if (holder.getPosition() == position && !holder.isInvalid() &&
(mInPreLayout || !holder.isRemoved())) {
if (type != INVALID_TYPE && holder.getItemViewType() != type) {
Log.e(TAG, "Scrap view for position " + position + " isn't dirty but has" +
" wrong view type! (found " + holder.getItemViewType() +
" but expected " + type + ")");
break;
}
mAttachedScrap.remove(i);
holder.setScrapContainer(null);
if (DEBUG) {
Log.d(TAG, "getScrapViewForPosition(" + position + ", " + type +
") found exact match in scrap: " + holder);
}
return holder;
}
}
if (mNumAnimatingViews != 0) {
View view = getAnimatingView(position, type);
if (view != null) {
// ending the animation should cause it to get recycled before we reuse it
mItemAnimator.endAnimation(getChildViewHolder(view));
}
}
// Search in our first-level recycled view cache.
final int cacheSize = mCachedViews.size();
for (int i = 0; i < cacheSize; i++) {
final ViewHolder holder = mCachedViews.get(i);
if (holder.getPosition() == position) {
mCachedViews.remove(i);
if (holder.isInvalid() &&
(type != INVALID_TYPE && holder.getItemViewType() != type)) {
// Can't use it. We don't know where it's been.
if (DEBUG) {
Log.d(TAG, "getScrapViewForPosition(" + position + ", " + type +
") found position match, but holder is invalid with type " +
holder.getItemViewType());
}
if (holder.isRecyclable()) {
getRecycledViewPool().putRecycledView(holder);
}
// Even if the holder wasn't officially recycleable, dispatch that it
// was recycled anyway in case there are resources to unbind.
dispatchViewRecycled(holder);
// Drop out of the cache search and try something else instead,
// we won't find another match here.
break;
}
if (DEBUG) {
Log.d(TAG, "getScrapViewForPosition(" + position + ", " + type +
") found match in cache: " + holder);
}
return holder;
}
}
// Give up. Head to the shared pool.
if (DEBUG) {
Log.d(TAG, "getScrapViewForPosition(" + position + ", " + type +
") fetching from shared pool");
}
return type == INVALID_TYPE ? null : getRecycledViewPool().getRecycledView(type);
}
ViewHolder getScrapViewForId(long id, int type) {
// Look in our attached views first
final int count = mAttachedScrap.size();
for (int i = 0; i < count; i++) {
final ViewHolder holder = mAttachedScrap.get(i);
if (holder.getItemId() == id) {
if (type == holder.getItemViewType()) {
mAttachedScrap.remove(i);
holder.setScrapContainer(null);
return holder;
} else {
break;
}
}
}
// Search the first-level cache
final int cacheSize = mCachedViews.size();
for (int i = 0; i < cacheSize; i++) {
final ViewHolder holder = mCachedViews.get(i);
if (holder.getItemId() == id) {
mCachedViews.remove(i);
return holder;
}
}
// That didn't work, look for an unordered view of the right type instead.
// The holder's position won't match so the calling code will need to have
// the adapter rebind it.
return getRecycledViewPool().getRecycledView(type);
}
void dispatchViewRecycled(ViewHolder holder) {
if (mRecyclerListener != null) {
mRecyclerListener.onViewRecycled(holder);
}
if (mAdapter != null) {
mAdapter.onViewRecycled(holder);
}
if (DEBUG) Log.d(TAG, "dispatchViewRecycled: " + holder);
}
void onAdapterChanged(Adapter oldAdapter, Adapter newAdapter) {
clear();
getRecycledViewPool().onAdapterChanged(oldAdapter, newAdapter);
}
void offsetPositionRecordsForInsert(int insertedAt, int count) {
final int cachedCount = mCachedViews.size();
for (int i = 0; i < cachedCount; i++) {
final ViewHolder holder = mCachedViews.get(i);
if (holder != null && holder.getPosition() >= insertedAt) {
if (DEBUG) {
Log.d(TAG, "offsetPositionRecordsForInsert cached " + i + " holder " +
holder + " now at position " + (holder.mPosition + count));
}
holder.offsetPosition(count);
}
}
}
void offsetPositionRecordsForRemove(int removedFrom, int count) {
final int removedEnd = removedFrom + count;
final int cachedCount = mCachedViews.size();
for (int i = cachedCount - 1; i >= 0; i--) {
final ViewHolder holder = mCachedViews.get(i);
if (holder != null) {
if (holder.getPosition() >= removedEnd) {
if (DEBUG) {
Log.d(TAG, "offsetPositionRecordsForRemove cached " + i +
" holder " + holder + " now at position " +
(holder.mPosition - count));
}
holder.offsetPosition(-count);
} else if (holder.getPosition() >= removedFrom) {
// Item for this view was removed. Dump it from the cache.
if (DEBUG) {
Log.d(TAG, "offsetPositionRecordsForRemove cached " + i +
" holder " + holder + " now placed in pool");
}
mCachedViews.remove(i);
getRecycledViewPool().putRecycledView(holder);
dispatchViewRecycled(holder);
}
}
}
}
void setRecycledViewPool(RecycledViewPool pool) {
if (mRecyclerPool != null) {
mRecyclerPool.detach();
}
mRecyclerPool = pool;
if (pool != null) {
mRecyclerPool.attach(getAdapter());
}
}
RecycledViewPool getRecycledViewPool() {
if (mRecyclerPool == null) {
mRecyclerPool = new RecycledViewPool();
}
return mRecyclerPool;
}
ViewHolder findViewHolderForPosition(int position) {
final int cachedCount = mCachedViews.size();
for (int i = 0; i < cachedCount; i++) {
final ViewHolder holder = mCachedViews.get(i);
if (holder != null && holder.getPosition() == position) {
mCachedViews.remove(i);
return holder;
}
}
return null;
}
ViewHolder findViewHolderForItemId(long id) {
if (!mAdapter.hasStableIds()) {
return null;
}
final int cachedCount = mCachedViews.size();
for (int i = 0; i < cachedCount; i++) {
final ViewHolder holder = mCachedViews.get(i);
if (holder != null && holder.getItemId() == id) {
mCachedViews.remove(i);
return holder;
}
}
return null;
}
void viewRangeUpdate(int positionStart, int itemCount) {
final int positionEnd = positionStart + itemCount;
final int cachedCount = mCachedViews.size();
for (int i = 0; i < cachedCount; i++) {
final ViewHolder holder = mCachedViews.get(i);
if (holder == null) {
continue;
}
final int pos = holder.getPosition();
if (pos >= positionStart && pos < positionEnd) {
holder.addFlags(ViewHolder.FLAG_UPDATE);
}
}
}
void markKnownViewsInvalid() {
final int cachedCount = mCachedViews.size();
for (int i = 0; i < cachedCount; i++) {
final ViewHolder holder = mCachedViews.get(i);
if (holder != null) {
holder.addFlags(ViewHolder.FLAG_UPDATE | ViewHolder.FLAG_INVALID);
}
}
}
void clearOldPositions() {
final int cachedCount = mCachedViews.size();
for (int i = 0; i < cachedCount; i++) {
final ViewHolder holder = mCachedViews.get(i);
holder.clearOldPosition();
}
}
}
/**
* Base class for an Adapter
*
* <p>Adapters provide a binding from an app-specific data set to views that are displayed
* within a {@link RecyclerView}.</p>
*/
public static abstract class Adapter<VH extends ViewHolder> {
private final AdapterDataObservable mObservable = new AdapterDataObservable();
private boolean mHasStableIds = false;
public abstract VH onCreateViewHolder(ViewGroup parent, int viewType);
public abstract void onBindViewHolder(VH holder, int position);
public final VH createViewHolder(ViewGroup parent, int viewType) {
final VH holder = onCreateViewHolder(parent, viewType);
holder.mItemViewType = viewType;
return holder;
}
public final void bindViewHolder(VH holder, int position) {
holder.mPosition = position;
if (hasStableIds()) {
holder.mItemId = getItemId(position);
}
onBindViewHolder(holder, position);
holder.setFlags(ViewHolder.FLAG_BOUND,
ViewHolder.FLAG_BOUND | ViewHolder.FLAG_UPDATE | ViewHolder.FLAG_INVALID);
}
/**
* Return the view type of the item at <code>position</code> for the purposes
* of view recycling.
*
* <p>The default implementation of this method returns 0, making the assumption of
* a single view type for the adapter. Unlike ListView adapters, types need not
* be contiguous. Consider using id resources to uniquely identify item view types.
*
* @param position position to query
* @return integer value identifying the type of the view needed to represent the item at
* <code>position</code>. Type codes need not be contiguous.
*/
public int getItemViewType(int position) {
return 0;
}
public void setHasStableIds(boolean hasStableIds) {
if (hasObservers()) {
throw new IllegalStateException("Cannot change whether this adapter has " +
"stable IDs while the adapter has registered observers.");
}
mHasStableIds = hasStableIds;
}
/**
* Return the stable ID for the item at <code>position</code>. If {@link #hasStableIds()}
* would return false this method should return {@link #NO_ID}. The default implementation
* of this method returns {@link #NO_ID}.
*
* @param position Adapter position to query
* @return the stable ID of the item at position
*/
public long getItemId(int position) {
return NO_ID;
}
public abstract int getItemCount();
/**
* Returns true if this adapter publishes a unique <code>long</code> value that can
* act as a key for the item at a given position in the data set. If that item is relocated
* in the data set, the ID returned for that item should be the same.
*
* @return true if this adapter's items have stable IDs
*/
public final boolean hasStableIds() {
return mHasStableIds;
}
/**
* Called when a view created by this adapter has been recycled.
*
* <p>A view is recycled when a {@link LayoutManager} decides that it no longer
* needs to be attached to its parent {@link RecyclerView}. This can be because it has
* fallen out of visibility or a set of cached views represented by views still
* attached to the parent RecyclerView. If an item view has large or expensive data
* bound to it such as large bitmaps, this may be a good place to release those
* resources.</p>
*
* @param holder The ViewHolder for the view being recycled
*/
public void onViewRecycled(VH holder) {
}
/**
* Called when a view created by this adapter has been attached to a window.
*
* <p>This can be used as a reasonable signal that the view is about to be seen
* by the user. If the adapter previously freed any resources in
* {@link #onViewDetachedFromWindow(RecyclerView.ViewHolder) onViewDetachedFromWindow}
* those resources should be restored here.</p>
*
* @param holder Holder of the view being attached
*/
public void onViewAttachedToWindow(VH holder) {
}
/**
* Called when a view created by this adapter has been detached from its window.
*
* <p>Becoming detached from the window is not necessarily a permanent condition;
* the consumer of an Adapter's views may choose to cache views offscreen while they
* are not visible, attaching an detaching them as appropriate.</p>
*
* @param holder Holder of the view being detached
*/
public void onViewDetachedFromWindow(VH holder) {
}
/**
* Returns true if one or more observers are attached to this adapter.
* @return true if this adapter has observers
*/
public final boolean hasObservers() {
return mObservable.hasObservers();
}
/**
* Register a new observer to listen for data changes.
*
* <p>The adapter may publish a variety of events describing specific changes.
* Not all adapters may support all change types and some may fall back to a generic
* {@link android.support.v7.widget.RecyclerView.AdapterDataObserver#onChanged()
* "something changed"} event if more specific data is not available.</p>
*
* <p>Components registering observers with an adapter are responsible for
* {@link #unregisterAdapterDataObserver(android.support.v7.widget.RecyclerView.AdapterDataObserver)
* unregistering} those observers when finished.</p>
*
* @param observer Observer to register
*
* @see #unregisterAdapterDataObserver(android.support.v7.widget.RecyclerView.AdapterDataObserver)
*/
public void registerAdapterDataObserver(AdapterDataObserver observer) {
mObservable.registerObserver(observer);
}
/**
* Unregister an observer currently listening for data changes.
*
* <p>The unregistered observer will no longer receive events about changes
* to the adapter.</p>
*
* @param observer Observer to unregister
*
* @see #registerAdapterDataObserver(android.support.v7.widget.RecyclerView.AdapterDataObserver)
*/
public void unregisterAdapterDataObserver(AdapterDataObserver observer) {
mObservable.unregisterObserver(observer);
}
/**
* Notify any registered observers that the data set has changed.
*
* <p>There are two different classes of data change events, item changes and structural
* changes. Item changes are when a single item has its data updated but no positional
* changes have occurred. Structural changes are when items are inserted, removed or moved
* within the data set.</p>
*
* <p>This event does not specify what about the data set has changed, forcing
* any observers to assume that all existing items and structure may no longer be valid.
* LayoutManagers will be forced to fully rebind and relayout all visible views.</p>
*
* <p><code>RecyclerView</code> will attempt to synthesize visible structural change events
* for adapters that report that they have {@link #hasStableIds() stable IDs} when
* this method is used. This can help for the purposes of animation and visual
* object persistence but individual item views will still need to be rebound
* and relaid out.</p>
*
* <p>If you are writing an adapter it will always be more efficient to use the more
* specific change events if you can. Rely on <code>notifyDataSetChanged()</code>
* as a last resort.</p>
*
* @see #notifyItemChanged(int)
* @see #notifyItemInserted(int)
* @see #notifyItemRemoved(int)
* @see #notifyItemRangeChanged(int, int)
* @see #notifyItemRangeInserted(int, int)
* @see #notifyItemRangeRemoved(int, int)
*/
public final void notifyDataSetChanged() {
mObservable.notifyChanged();
}
/**
* Notify any registered observers that the item at <code>position</code> has changed.
*
* <p>This is an item change event, not a structural change event. It indicates that any
* reflection of the data at <code>position</code> is out of date and should be updated.
* The item at <code>position</code> retains the same identity.</p>
*
* @param position Position of the item that has changed
*
* @see #notifyItemRangeChanged(int, int)
*/
public final void notifyItemChanged(int position) {
mObservable.notifyItemRangeChanged(position, 1);
}
/**
* Notify any registered observers that the <code>itemCount</code> items starting at
* position <code>positionStart</code> have changed.
*
* <p>This is an item change event, not a structural change event. It indicates that
* any reflection of the data in the given position range is out of date and should
* be updated. The items in the given range retain the same identity.</p>
*
* @param positionStart Position of the first item that has changed
* @param itemCount Number of items that have changed
*
* @see #notifyItemChanged(int)
*/
public final void notifyItemRangeChanged(int positionStart, int itemCount) {
mObservable.notifyItemRangeChanged(positionStart, itemCount);
}
/**
* Notify any registered observers that the item reflected at <code>position</code>
* has been newly inserted. The item previously at <code>position</code> is now at
* position <code>position + 1</code>.
*
* <p>This is a structural change event. Representations of other existing items in the
* data set are still considered up to date and will not be rebound, though their
* positions may be altered.</p>
*
* @param position Position of the newly inserted item in the data set
*
* @see #notifyItemRangeInserted(int, int)
*/
public final void notifyItemInserted(int position) {
mObservable.notifyItemRangeInserted(position, 1);
}
/**
* Notify any registered observers that the currently reflected <code>itemCount</code>
* items starting at <code>positionStart</code> have been newly inserted. The items
* previously located at <code>positionStart</code> and beyond can now be found starting
* at position <code>positionStart + itemCount</code>.
*
* <p>This is a structural change event. Representations of other existing items in the
* data set are still considered up to date and will not be rebound, though their positions
* may be altered.</p>
*
* @param positionStart Position of the first item that was inserted
* @param itemCount Number of items inserted
*
* @see #notifyItemInserted(int)
*/
public final void notifyItemRangeInserted(int positionStart, int itemCount) {
mObservable.notifyItemRangeInserted(positionStart, itemCount);
}
/**
* Notify any registered observers that the item previously located at <code>position</code>
* has been removed from the data set. The items previously located at and after
* <code>position</code> may now be found at <code>oldPosition - 1</code>.
*
* <p>This is a structural change event. Representations of other existing items in the
* data set are still considered up to date and will not be rebound, though their positions
* may be altered.</p>
*
* @param position Position of the item that has now been removed
*
* @see #notifyItemRangeRemoved(int, int)
*/
public final void notifyItemRemoved(int position) {
mObservable.notifyItemRangeRemoved(position, 1);
}
/**
* Notify any registered observers that the <code>itemCount</code> items previously
* located at <code>positionStart</code> have been removed from the data set. The items
* previously located at and after <code>positionStart + itemCount</code> may now be found
* at <code>oldPosition - itemCount</code>.
*
* <p>This is a structural change event. Representations of other existing items in the data
* set are still considered up to date and will not be rebound, though their positions
* may be altered.</p>
*
* @param positionStart Previous position of the first item that was removed
* @param itemCount Number of items removed from the data set
*/
public final void notifyItemRangeRemoved(int positionStart, int itemCount) {
mObservable.notifyItemRangeRemoved(positionStart, itemCount);
}
}
/**
* A <code>LayoutManager</code> is responsible for measuring and positioning item views
* within a <code>RecyclerView</code> as well as determining the policy for when to recycle
* item views that are no longer visible to the user. By changing the <code>LayoutManager</code>
* a <code>RecyclerView</code> can be used to implement a standard vertically scrolling list,
* a uniform grid, staggered grids, horizontally scrolling collections and more. Several stock
* layout managers are provided for general use.
*/
public static abstract class LayoutManager {
RecyclerView mRecyclerView;
@Nullable
SmoothScroller mSmoothScroller;
/**
* Calls {@code RecyclerView#requestLayout} on the underlying RecyclerView
*/
public void requestLayout() {
if(mRecyclerView != null) {
mRecyclerView.requestLayout();
}
}
/**
* Returns whether this LayoutManager supports automatic item animations.
* A LayoutManager wishing to support item animations should obey certain
* rules as outlined in {@link #onLayoutChildren(Recycler, State)}.
* The default return value is <code>false</code>, so subclasses of LayoutManager
* will not get predictive item animations by default.
*
* <p>Whether item animations are enabled in a RecyclerView is determined both
* by the return value from this method and the
* {@link RecyclerView#setItemAnimator(ItemAnimator) ItemAnimator} set on the
* RecyclerView itself. If the RecyclerView has a non-null ItemAnimator but this
* method returns false, then simple item animations will be enabled, in which
* views that are moving onto or off of the screen are simply faded in/out. If
* the RecyclerView has a non-null ItemAnimator and this method returns true,
* then there will be two calls to {@link #onLayoutChildren(Recycler, State)} to
* setup up the information needed to more intelligently predict where appearing
* and disappearing views should be animated from/to.</p>
*
* @return true if predictive item animations should be enabled, false otherwise
*/
public boolean supportsPredictiveItemAnimations() {
return false;
}
/**
* Called when this LayoutManager is both attached to a RecyclerView and that RecyclerView
* is attached to a window.
*
* <p>Subclass implementations should always call through to the superclass implementation.
* </p>
*
* @param view The RecyclerView this LayoutManager is bound to
*/
public void onAttachedToWindow(RecyclerView view) {
}
/**
* Called when this LayoutManager is detached from its parent RecyclerView or when
* its parent RecyclerView is detached from its window.
*
* <p>Subclass implementations should always call through to the superclass implementation.
* </p>
*
* @param view The RecyclerView this LayoutManager is bound to
*/
public void onDetachedFromWindow(RecyclerView view) {
}
/**
* Lay out all relevant child views from the given adapter.
*
* The LayoutManager is in charge of the behavior of item animations. By default,
* RecyclerView has a non-null {@link #getItemAnimator() ItemAnimator}, and simple
* item animations are enabled. This means that add/remove operations on the
* adapter will result in animations to add new or appearing items, removed or
* disappearing items, and moved items. If a LayoutManager returns false from
* {@link #supportsPredictiveItemAnimations()}, which is the default, and runs a
* normal layout operation during {@link #onLayoutChildren(Recycler, State)}, the
* RecyclerView will have enough information to run those animations in a simple
* way. For example, the default ItemAnimator, {@link DefaultItemAnimator}, will
* simple fade views in and out, whether they are actuall added/removed or whether
* they are moved on or off the screen due to other add/remove operations.
*
* <p>A LayoutManager wanting a better item animation experience, where items can be
* animated onto and off of the screen according to where the items exist when they
* are not on screen, then the LayoutManager should return true from
* {@link #supportsPredictiveItemAnimations()} and add additional logic to
* {@link #onLayoutChildren(Recycler, State)}. Supporting predictive animations
* means that {@link #onLayoutChildren(Recycler, State)} will be called twice;
* once as a "pre" layout step to determine where items would have been prior to
* a real layout, and again to do the "real" layout. In the pre-layout phase,
* items will remember their pre-layout positions to allow them to be laid out
* appropriately. Also, {@link LayoutParams#isItemRemoved() removed} items will
* be returned from the scrap to help determine correct placement of other items.
* These removed items should not be added to the child list, but should be used
* to help calculate correct positioning of other views, including views that
* were not previously onscreen (referred to as APPEARING views), but whose
* pre-layout offscreen position can be determined given the extra
* information about the pre-layout removed views.</p>
*
* <p>The second layout pass is the real layout in which only non-removed views
* will be used. The only additional requirement during this pass is, if
* {@link #supportsPredictiveItemAnimations()} returns true, to note which
* views exist in the child list prior to layout and which are not there after
* layout (referred to as DISAPPEARING views), and to position/layout those views
* appropriately, without regard to the actual bounds of the RecyclerView. This allows
* the animation system to know the location to which to animate these disappearing
* views.</p>
*
* <p>The default LayoutManager implementations for RecyclerView handle all of these
* requirements for animations already. Clients of RecyclerView can either use one
* of these layout managers directly or look at their implementations of
* onLayoutChildren() to see how they account for the APPEARING and
* DISAPPEARING views.</p>
*
* @param recycler Recycler to use for fetching potentially cached views for a
* position
* @param state Transient state of RecyclerView
*/
public void onLayoutChildren(Recycler recycler, State state) {
Log.e(TAG, "You must override onLayoutChildren(Recycler recycler, State state) ");
}
/**
* Create a default <code>LayoutParams</code> object for a child of the RecyclerView.
*
* <p>LayoutManagers will often want to use a custom <code>LayoutParams</code> type
* to store extra information specific to the layout. Client code should subclass
* {@link RecyclerView.LayoutParams} for this purpose.</p>
*
* <p><em>Important:</em> if you use your own custom <code>LayoutParams</code> type
* you must also override
* {@link #checkLayoutParams(LayoutParams)},
* {@link #generateLayoutParams(android.view.ViewGroup.LayoutParams)} and
* {@link #generateLayoutParams(android.content.Context, android.util.AttributeSet)}.</p>
*
* @return A new LayoutParams for a child view
*/
public abstract LayoutParams generateDefaultLayoutParams();
/**
* Determines the validity of the supplied LayoutParams object.
*
* <p>This should check to make sure that the object is of the correct type
* and all values are within acceptable ranges. The default implementation
* returns <code>true</code> for non-null params.</p>
*
* @param lp LayoutParams object to check
* @return true if this LayoutParams object is valid, false otherwise
*/
public boolean checkLayoutParams(LayoutParams lp) {
return lp != null;
}
/**
* Create a LayoutParams object suitable for this LayoutManager, copying relevant
* values from the supplied LayoutParams object if possible.
*
* <p><em>Important:</em> if you use your own custom <code>LayoutParams</code> type
* you must also override
* {@link #checkLayoutParams(LayoutParams)},
* {@link #generateLayoutParams(android.view.ViewGroup.LayoutParams)} and
* {@link #generateLayoutParams(android.content.Context, android.util.AttributeSet)}.</p>
*
* @param lp Source LayoutParams object to copy values from
* @return a new LayoutParams object
*/
public LayoutParams generateLayoutParams(ViewGroup.LayoutParams lp) {
if (lp instanceof LayoutParams) {
return new LayoutParams((LayoutParams) lp);
} else if (lp instanceof MarginLayoutParams) {
return new LayoutParams((MarginLayoutParams) lp);
} else {
return new LayoutParams(lp);
}
}
/**
* Create a LayoutParams object suitable for this LayoutManager from
* an inflated layout resource.
*
* <p><em>Important:</em> if you use your own custom <code>LayoutParams</code> type
* you must also override
* {@link #checkLayoutParams(LayoutParams)},
* {@link #generateLayoutParams(android.view.ViewGroup.LayoutParams)} and
* {@link #generateLayoutParams(android.content.Context, android.util.AttributeSet)}.</p>
*
* @param c Context for obtaining styled attributes
* @param attrs AttributeSet describing the supplied arguments
* @return a new LayoutParams object
*/
public LayoutParams generateLayoutParams(Context c, AttributeSet attrs) {
return new LayoutParams(c, attrs);
}
/**
* Scroll horizontally by dx pixels in screen coordinates and return the distance traveled.
* The default implementation does nothing and returns 0.
*
* @param dx distance to scroll by in pixels. X increases as scroll position
* approaches the right.
* @param recycler Recycler to use for fetching potentially cached views for a
* position
* @param state Transient state of RecyclerView
* @return The actual distance scrolled. The return value will be negative if dx was
* negative and scrolling proceeeded in that direction.
* <code>Math.abs(result)</code> may be less than dx if a boundary was reached.
*/
public int scrollHorizontallyBy(int dx, Recycler recycler, State state) {
return 0;
}
/**
* Scroll vertically by dy pixels in screen coordinates and return the distance traveled.
* The default implementation does nothing and returns 0.
*
* @param dy distance to scroll in pixels. Y increases as scroll position
* approaches the bottom.
* @param recycler Recycler to use for fetching potentially cached views for a
* position
* @param state Transient state of RecyclerView
* @return The actual distance scrolled. The return value will be negative if dy was
* negative and scrolling proceeeded in that direction.
* <code>Math.abs(result)</code> may be less than dy if a boundary was reached.
*/
public int scrollVerticallyBy(int dy, Recycler recycler, State state) {
return 0;
}
/**
* Query if horizontal scrolling is currently supported. The default implementation
* returns false.
*
* @return True if this LayoutManager can scroll the current contents horizontally
*/
public boolean canScrollHorizontally() {
return false;
}
/**
* Query if vertical scrolling is currently supported. The default implementation
* returns false.
*
* @return True if this LayoutManager can scroll the current contents vertically
*/
public boolean canScrollVertically() {
return false;
}
/**
* Scroll to the specified adapter position.
*
* Actual position of the item on the screen depends on the LayoutManager implementation.
* @param position Scroll to this adapter position.
*/
public void scrollToPosition(int position) {
if (DEBUG) {
Log.e(TAG, "You MUST implement scrollToPosition. It will soon become abstract");
}
}
/**
* <p>Smooth scroll to the specified adapter position.</p>
* <p>To support smooth scrolling, override this method, create your {@link SmoothScroller}
* instance and call {@link #startSmoothScroll(SmoothScroller)}.
* </p>
* @param recyclerView The RecyclerView to which this layout manager is attached
* @param state Current State of RecyclerView
* @param position Scroll to this adapter position.
*/
public void smoothScrollToPosition(RecyclerView recyclerView, State state,
int position) {
Log.e(TAG, "You must override smoothScrollToPosition to support smooth scrolling");
}
/**
* <p>Starts a smooth scroll using the provided SmoothScroller.</p>
* <p>Calling this method will cancel any previous smooth scroll request.</p>
* @param smoothScroller Unstance which defines how smooth scroll should be animated
*/
public void startSmoothScroll(SmoothScroller smoothScroller) {
if (mSmoothScroller != null && smoothScroller != mSmoothScroller
&& mSmoothScroller.isRunning()) {
mSmoothScroller.stop();
}
mSmoothScroller = smoothScroller;
mSmoothScroller.start(mRecyclerView, this);
}
/**
* @return true if RecycylerView is currently in the state of smooth scrolling.
*/
public boolean isSmoothScrolling() {
return mSmoothScroller != null && mSmoothScroller.isRunning();
}
/**
* Returns the resolved layout direction for this RecyclerView.
*
* @return {@link android.support.v4.view.ViewCompat#LAYOUT_DIRECTION_RTL} if the layout
* direction is RTL or returns
* {@link android.support.v4.view.ViewCompat#LAYOUT_DIRECTION_LTR} if the layout direction
* is not RTL.
*/
public int getLayoutDirection() {
return ViewCompat.getLayoutDirection(mRecyclerView);
}
/**
* Add a view to the currently attached RecyclerView if needed. LayoutManagers should
* use this method to add views obtained from a {@link Recycler} using
* {@link Recycler#getViewForPosition(int)}.
*
* @param child View to add
* @param index Index to add child at
*/
public void addView(View child, int index) {
if (mRecyclerView.mAnimatingViewIndex >= 0) {
if (index > mRecyclerView.mAnimatingViewIndex) {
throw new IndexOutOfBoundsException("index=" + index + " count="
+ mRecyclerView.mAnimatingViewIndex);
}
mRecyclerView.mAnimatingViewIndex++;
}
final ViewHolder holder = getChildViewHolderInt(child);
if (holder.isScrap()) {
holder.unScrap();
mRecyclerView.attachViewToParent(child, index, child.getLayoutParams());
if (DISPATCH_TEMP_DETACH) {
ViewCompat.dispatchFinishTemporaryDetach(child);
}
} else {
mRecyclerView.addView(child, index);
final LayoutParams lp = (LayoutParams) child.getLayoutParams();
lp.mInsetsDirty = true;
final Adapter adapter = mRecyclerView.getAdapter();
if (adapter != null) {
adapter.onViewAttachedToWindow(getChildViewHolderInt(child));
}
mRecyclerView.onChildAttachedToWindow(child);
if (mSmoothScroller != null && mSmoothScroller.isRunning()) {
mSmoothScroller.onChildAttachedToWindow(child);
}
}
}
/**
* Add a view to the currently attached RecyclerView if needed. LayoutManagers should
* use this method to add views obtained from a {@link Recycler} using
* {@link Recycler#getViewForPosition(int)}.
*
* @param child View to add
*/
public void addView(View child) {
if (mRecyclerView.mAnimatingViewIndex >= 0) {
addView(child, mRecyclerView.mAnimatingViewIndex);
} else {
addView(child, -1);
}
}
/**
* Remove a view from the currently attached RecyclerView if needed. LayoutManagers should
* use this method to completely remove a child view that is no longer needed.
* LayoutManagers should strongly consider recycling removed views using
* {@link Recycler#recycleView(android.view.View)}.
*
* @param child View to remove
*/
public void removeView(View child) {
final Adapter adapter = mRecyclerView.getAdapter();
if (adapter != null) {
adapter.onViewDetachedFromWindow(getChildViewHolderInt(child));
}
mRecyclerView.onChildDetachedFromWindow(child);
mRecyclerView.removeView(child);
if (mRecyclerView.mAnimatingViewIndex >= 0) {
mRecyclerView.mAnimatingViewIndex--;
}
}
/**
* Remove a view from the currently attached RecyclerView if needed. LayoutManagers should
* use this method to completely remove a child view that is no longer needed.
* LayoutManagers should strongly consider recycling removed views using
* {@link Recycler#recycleView(android.view.View)}.
*
* @param index Index of the child view to remove
*/
public void removeViewAt(int index) {
final View child = mRecyclerView.getChildAt(index);
if (child != null) {
final Adapter adapter = mRecyclerView.getAdapter();
if (adapter != null) {
adapter.onViewDetachedFromWindow(getChildViewHolderInt(child));
}
mRecyclerView.onChildDetachedFromWindow(child);
mRecyclerView.removeViewAt(index);
if (mRecyclerView.mAnimatingViewIndex >= 0) {
mRecyclerView.mAnimatingViewIndex--;
}
}
}
/**
* Remove all views from the currently attached RecyclerView. This will not recycle
* any of the affected views; the LayoutManager is responsible for doing so if desired.
*/
public void removeAllViews() {
final Adapter adapter = mRecyclerView.getAdapter();
// Only remove non-animating views
final int childCount = mRecyclerView.getChildCount() - mRecyclerView.mNumAnimatingViews;
for (int i = 0; i < childCount; i++) {
final View child = mRecyclerView.getChildAt(i);
if (adapter != null) {
adapter.onViewDetachedFromWindow(getChildViewHolderInt(child));
}
mRecyclerView.onChildDetachedFromWindow(child);
}
for (int i = childCount - 1; i >= 0; i--) {
mRecyclerView.removeViewAt(i);
if (mRecyclerView.mAnimatingViewIndex >= 0) {
mRecyclerView.mAnimatingViewIndex--;
}
}
}
/**
* Returns the adapter position of the item represented by the given View.
*
* @param view The view to query
* @return The adapter position of the item which is rendered by this View.
*/
public int getPosition(View view) {
return ((RecyclerView.LayoutParams) view.getLayoutParams()).getViewPosition();
}
/**
* <p>Finds the view which represents the given adapter position.</p>
* <p>This method traverses each child since it has no information about child order.
* Override this method to improve performance if your LayoutManager keeps data about
* child views.</p>
*
* @param position Position of the item in adapter
* @return The child view that represents the given position or null if the position is not
* visible
*/
public View findViewByPosition(int position) {
final int childCount = getChildCount();
for (int i = 0; i < childCount; i++) {
View child = getChildAt(i);
if (getPosition(child) == position) {
return child;
}
}
return null;
}
/**
* Temporarily detach a child view.
*
* <p>LayoutManagers may want to perform a lightweight detach operation to rearrange
* views currently attached to the RecyclerView. Generally LayoutManager implementations
* will want to use {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)}
* so that the detached view may be rebound and reused.</p>
*
* <p>If a LayoutManager uses this method to detach a view, it <em>must</em>
* {@link #attachView(android.view.View, int, RecyclerView.LayoutParams) reattach}
* or {@link #removeDetachedView(android.view.View) fully remove} the detached view
* before the LayoutManager entry point method called by RecyclerView returns.</p>
*
* @param child Child to detach
*/
public void detachView(View child) {
if (DISPATCH_TEMP_DETACH) {
ViewCompat.dispatchStartTemporaryDetach(child);
}
mRecyclerView.detachViewFromParent(child);
}
/**
* Temporarily detach a child view.
*
* <p>LayoutManagers may want to perform a lightweight detach operation to rearrange
* views currently attached to the RecyclerView. Generally LayoutManager implementations
* will want to use {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)}
* so that the detached view may be rebound and reused.</p>
*
* <p>If a LayoutManager uses this method to detach a view, it <em>must</em>
* {@link #attachView(android.view.View, int, RecyclerView.LayoutParams) reattach}
* or {@link #removeDetachedView(android.view.View) fully remove} the detached view
* before the LayoutManager entry point method called by RecyclerView returns.</p>
*
* @param index Index of the child to detach
*/
public void detachViewAt(int index) {
if (DISPATCH_TEMP_DETACH) {
ViewCompat.dispatchStartTemporaryDetach(mRecyclerView.getChildAt(index));
}
mRecyclerView.detachViewFromParent(index);
if (mRecyclerView.mAnimatingViewIndex >= 0) {
--mRecyclerView.mAnimatingViewIndex;
}
}
/**
* Reattach a previously {@link #detachView(android.view.View) detached} view.
* This method should not be used to reattach views that were previously
* {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)} scrapped}.
*
* @param child Child to reattach
* @param index Intended child index for child
* @param lp LayoutParams for child
*/
public void attachView(View child, int index, LayoutParams lp) {
mRecyclerView.attachViewToParent(child, index, lp);
if (mRecyclerView.mAnimatingViewIndex >= 0) {
++mRecyclerView.mAnimatingViewIndex;
}
if (DISPATCH_TEMP_DETACH) {
ViewCompat.dispatchFinishTemporaryDetach(child);
}
}
/**
* Reattach a previously {@link #detachView(android.view.View) detached} view.
* This method should not be used to reattach views that were previously
* {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)} scrapped}.
*
* @param child Child to reattach
* @param index Intended child index for child
*/
public void attachView(View child, int index) {
attachView(child, index, (LayoutParams) child.getLayoutParams());
}
/**
* Reattach a previously {@link #detachView(android.view.View) detached} view.
* This method should not be used to reattach views that were previously
* {@link #detachAndScrapView(android.view.View, RecyclerView.Recycler)} scrapped}.
*
* @param child Child to reattach
*/
public void attachView(View child) {
attachView(child, -1);
}
/**
* Finish removing a view that was previously temporarily
* {@link #detachView(android.view.View) detached}.
*
* @param child Detached child to remove
*/
public void removeDetachedView(View child) {
mRecyclerView.removeDetachedView(child, false);
}
/**
* Detach a child view and add it to a {@link Recycler Recycler's} scrap heap.
*
* <p>Scrapping a view allows it to be rebound and reused to show updated or
* different data.</p>
*
* @param child Child to detach and scrap
* @param recycler Recycler to deposit the new scrap view into
*/
public void detachAndScrapView(View child, Recycler recycler) {
detachView(child);
recycler.scrapView(child);
}
/**
* Detach a child view and add it to a {@link Recycler Recycler's} scrap heap.
*
* <p>Scrapping a view allows it to be rebound and reused to show updated or
* different data.</p>
*
* @param index Index of child to detach and scrap
* @param recycler Recycler to deposit the new scrap view into
*/
public void detachAndScrapViewAt(int index, Recycler recycler) {
final View child = getChildAt(index);
detachViewAt(index);
recycler.scrapView(child);
}
/**
* Remove a child view and recycle it using the given Recycler.
*
* @param child Child to remove and recycle
* @param recycler Recycler to use to recycle child
*/
public void removeAndRecycleView(View child, Recycler recycler) {
removeView(child);
recycler.recycleView(child);
}
/**
* Remove a child view and recycle it using the given Recycler.
*
* @param index Index of child to remove and recycle
* @param recycler Recycler to use to recycle child
*/
public void removeAndRecycleViewAt(int index, Recycler recycler) {
final View view = getChildAt(index);
removeViewAt(index);
recycler.recycleView(view);
}
/**
* Return the current number of child views attached to the parent RecyclerView.
* This does not include child views that were temporarily detached and/or scrapped.
*
* @return Number of attached children
*/
public int getChildCount() {
return mRecyclerView != null ?
mRecyclerView.getChildCount() - mRecyclerView.mNumAnimatingViews : 0;
}
/**
* Return the child view at the given index
* @param index Index of child to return
* @return Child view at index
*/
public View getChildAt(int index) {
return mRecyclerView != null ? mRecyclerView.getChildAt(index) : null;
}
/**
* Return the width of the parent RecyclerView
*
* @return Width in pixels
*/
public int getWidth() {
return mRecyclerView != null ? mRecyclerView.getWidth() : 0;
}
/**
* Return the height of the parent RecyclerView
*
* @return Height in pixels
*/
public int getHeight() {
return mRecyclerView != null ? mRecyclerView.getHeight() : 0;
}
/**
* Return the left padding of the parent RecyclerView
*
* @return Padding in pixels
*/
public int getPaddingLeft() {
return mRecyclerView != null ? mRecyclerView.getPaddingLeft() : 0;
}
/**
* Return the top padding of the parent RecyclerView
*
* @return Padding in pixels
*/
public int getPaddingTop() {
return mRecyclerView != null ? mRecyclerView.getPaddingTop() : 0;
}
/**
* Return the right padding of the parent RecyclerView
*
* @return Padding in pixels
*/
public int getPaddingRight() {
return mRecyclerView != null ? mRecyclerView.getPaddingRight() : 0;
}
/**
* Return the bottom padding of the parent RecyclerView
*
* @return Padding in pixels
*/
public int getPaddingBottom() {
return mRecyclerView != null ? mRecyclerView.getPaddingBottom() : 0;
}
/**
* Return the start padding of the parent RecyclerView
*
* @return Padding in pixels
*/
public int getPaddingStart() {
return mRecyclerView != null ? ViewCompat.getPaddingStart(mRecyclerView) : 0;
}
/**
* Return the end padding of the parent RecyclerView
*
* @return Padding in pixels
*/
public int getPaddingEnd() {
return mRecyclerView != null ? ViewCompat.getPaddingEnd(mRecyclerView) : 0;
}
/**
* Returns true if the RecyclerView this LayoutManager is bound to has focus.
*
* @return True if the RecyclerView has focus, false otherwise.
* @see View#isFocused()
*/
public boolean isFocused() {
return mRecyclerView != null && mRecyclerView.isFocused();
}
/**
* Returns true if the RecyclerView this LayoutManager is bound to has or contains focus.
*
* @return true if the RecyclerView has or contains focus
* @see View#hasFocus()
*/
public boolean hasFocus() {
return mRecyclerView != null && mRecyclerView.hasFocus();
}
/**
* Return the number of items in the adapter bound to the parent RecyclerView
*
* @return Items in the bound adapter
*/
public int getItemCount() {
final Adapter a = mRecyclerView != null ? mRecyclerView.getAdapter() : null;
return a != null ? a.getItemCount() : 0;
}
/**
* Offset all child views attached to the parent RecyclerView by dx pixels along
* the horizontal axis.
*
* @param dx Pixels to offset by
*/
public void offsetChildrenHorizontal(int dx) {
if (mRecyclerView != null) {
mRecyclerView.offsetChildrenHorizontal(dx);
}
}
/**
* Offset all child views attached to the parent RecyclerView by dy pixels along
* the vertical axis.
*
* @param dy Pixels to offset by
*/
public void offsetChildrenVertical(int dy) {
if (mRecyclerView != null) {
mRecyclerView.offsetChildrenVertical(dy);
}
}
/**
* Temporarily detach and scrap all currently attached child views. Views will be scrapped
* into the given Recycler. The Recycler may prefer to reuse scrap views before
* other views that were previously recycled.
*
* @param recycler Recycler to scrap views into
*/
public void detachAndScrapAttachedViews(Recycler recycler) {
final int childCount = getChildCount();
for (int i = childCount - 1; i >= 0; i--) {
final View v = getChildAt(i);
detachViewAt(i);
recycler.scrapView(v);
}
}
/**
* Recycles the scrapped views.
* <p>
* When a view is detached and removed, it does not trigger a ViewGroup invalidate. This is
* the expected behavior if scrapped views are used for animations. Otherwise, we need to
* call remove and invalidate RecyclerView to ensure UI update.
*
* @param recycler Recycler
* @param remove Whether scrapped views should be removed from ViewGroup or not. This
* method will invalidate RecyclerView if it removes any scrapped child.
*/
void removeAndRecycleScrapInt(Recycler recycler, boolean remove) {
final int scrapCount = recycler.getScrapCount();
for (int i = 0; i < scrapCount; i++) {
final View scrap = recycler.getScrapViewAt(i);
if (remove) {
mRecyclerView.removeDetachedView(scrap, false);
}
recycler.quickRecycleScrapView(scrap);
}
recycler.clearScrap();
if (remove && scrapCount > 0) {
mRecyclerView.invalidate();
}
}
/**
* Measure a child view using standard measurement policy, taking the padding
* of the parent RecyclerView and any added item decorations into account.
*
* <p>If the RecyclerView can be scrolled in either dimension the caller may
* pass 0 as the widthUsed or heightUsed parameters as they will be irrelevant.</p>
*
* @param child Child view to measure
* @param widthUsed Width in pixels currently consumed by other views, if relevant
* @param heightUsed Height in pixels currently consumed by other views, if relevant
*/
public void measureChild(View child, int widthUsed, int heightUsed) {
final LayoutParams lp = (LayoutParams) child.getLayoutParams();
final Rect insets = mRecyclerView.getItemDecorInsetsForChild(child);
widthUsed += insets.left + insets.right;
heightUsed += insets.top + insets.bottom;
final int widthSpec = getChildMeasureSpec(getWidth(),
getPaddingLeft() + getPaddingRight() + widthUsed, lp.width,
canScrollHorizontally());
final int heightSpec = getChildMeasureSpec(getHeight(),
getPaddingTop() + getPaddingBottom() + heightUsed, lp.height,
canScrollVertically());
child.measure(widthSpec, heightSpec);
}
/**
* Measure a child view using standard measurement policy, taking the padding
* of the parent RecyclerView, any added item decorations and the child margins
* into account.
*
* <p>If the RecyclerView can be scrolled in either dimension the caller may
* pass 0 as the widthUsed or heightUsed parameters as they will be irrelevant.</p>
*
* @param child Child view to measure
* @param widthUsed Width in pixels currently consumed by other views, if relevant
* @param heightUsed Height in pixels currently consumed by other views, if relevant
*/
public void measureChildWithMargins(View child, int widthUsed, int heightUsed) {
final LayoutParams lp = (LayoutParams) child.getLayoutParams();
final Rect insets = mRecyclerView.getItemDecorInsetsForChild(child);
widthUsed += insets.left + insets.right;
heightUsed += insets.top + insets.bottom;
final int widthSpec = getChildMeasureSpec(getWidth(),
getPaddingLeft() + getPaddingRight() +
lp.leftMargin + lp.rightMargin + widthUsed, lp.width,
canScrollHorizontally());
final int heightSpec = getChildMeasureSpec(getHeight(),
getPaddingTop() + getPaddingBottom() +
lp.topMargin + lp.bottomMargin + heightUsed, lp.height,
canScrollVertically());
child.measure(widthSpec, heightSpec);
}
/**
* Calculate a MeasureSpec value for measuring a child view in one dimension.
*
* @param parentSize Size of the parent view where the child will be placed
* @param padding Total space currently consumed by other elements of parent
* @param childDimension Desired size of the child view, or MATCH_PARENT/WRAP_CONTENT.
* Generally obtained from the child view's LayoutParams
* @param canScroll true if the parent RecyclerView can scroll in this dimension
*
* @return a MeasureSpec value for the child view
*/
public static int getChildMeasureSpec(int parentSize, int padding, int childDimension,
boolean canScroll) {
int size = Math.max(0, parentSize - padding);
int resultSize = 0;
int resultMode = 0;
if (canScroll) {
if (childDimension >= 0) {
resultSize = childDimension;
resultMode = MeasureSpec.EXACTLY;
} else {
// MATCH_PARENT can't be applied since we can scroll in this dimension, wrap
// instead using UNSPECIFIED.
resultSize = 0;
resultMode = MeasureSpec.UNSPECIFIED;
}
} else {
if (childDimension >= 0) {
resultSize = childDimension;
resultMode = MeasureSpec.EXACTLY;
} else if (childDimension == LayoutParams.FILL_PARENT) {
resultSize = size;
resultMode = MeasureSpec.EXACTLY;
} else if (childDimension == LayoutParams.WRAP_CONTENT) {
resultSize = size;
resultMode = MeasureSpec.AT_MOST;
}
}
return MeasureSpec.makeMeasureSpec(resultSize, resultMode);
}
/**
* Returns the measured width of the given child, plus the additional size of
* any insets applied by {@link ItemDecoration ItemDecorations}.
*
* @param child Child view to query
* @return child's measured width plus <code>ItemDecoration</code> insets
*
* @see View#getMeasuredWidth()
*/
public int getDecoratedMeasuredWidth(View child) {
final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets;
return child.getMeasuredWidth() + insets.left + insets.right;
}
/**
* Returns the measured height of the given child, plus the additional size of
* any insets applied by {@link ItemDecoration ItemDecorations}.
*
* @param child Child view to query
* @return child's measured height plus <code>ItemDecoration</code> insets
*
* @see View#getMeasuredHeight()
*/
public int getDecoratedMeasuredHeight(View child) {
final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets;
return child.getMeasuredHeight() + insets.top + insets.bottom;
}
/**
* Lay out the given child view within the RecyclerView using coordinates that
* include any current {@link ItemDecoration ItemDecorations}.
*
* <p>LayoutManagers should prefer working in sizes and coordinates that include
* item decoration insets whenever possible. This allows the LayoutManager to effectively
* ignore decoration insets within measurement and layout code. See the following
* methods:</p>
* <ul>
* <li>{@link #measureChild(View, int, int)}</li>
* <li>{@link #measureChildWithMargins(View, int, int)}</li>
* <li>{@link #getDecoratedLeft(View)}</li>
* <li>{@link #getDecoratedTop(View)}</li>
* <li>{@link #getDecoratedRight(View)}</li>
* <li>{@link #getDecoratedBottom(View)}</li>
* <li>{@link #getDecoratedMeasuredWidth(View)}</li>
* <li>{@link #getDecoratedMeasuredHeight(View)}</li>
* </ul>
*
* @param child Child to lay out
* @param left Left edge, with item decoration insets included
* @param top Top edge, with item decoration insets included
* @param right Right edge, with item decoration insets included
* @param bottom Bottom edge, with item decoration insets included
*
* @see View#layout(int, int, int, int)
*/
public void layoutDecorated(View child, int left, int top, int right, int bottom) {
final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets;
child.layout(left + insets.left, top + insets.top, right - insets.right,
bottom - insets.bottom);
}
/**
* Returns the left edge of the given child view within its parent, offset by any applied
* {@link ItemDecoration ItemDecorations}.
*
* @param child Child to query
* @return Child left edge with offsets applied
*/
public int getDecoratedLeft(View child) {
final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets;
return child.getLeft() - insets.left;
}
/**
* Returns the top edge of the given child view within its parent, offset by any applied
* {@link ItemDecoration ItemDecorations}.
*
* @param child Child to query
* @return Child top edge with offsets applied
*/
public int getDecoratedTop(View child) {
final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets;
return child.getTop() - insets.top;
}
/**
* Returns the right edge of the given child view within its parent, offset by any applied
* {@link ItemDecoration ItemDecorations}.
*
* @param child Child to query
* @return Child right edge with offsets applied
*/
public int getDecoratedRight(View child) {
final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets;
return child.getRight() + insets.right;
}
/**
* Returns the bottom edge of the given child view within its parent, offset by any applied
* {@link ItemDecoration ItemDecorations}.
*
* @param child Child to query
* @return Child bottom edge with offsets applied
*/
public int getDecoratedBottom(View child) {
final Rect insets = ((LayoutParams) child.getLayoutParams()).mDecorInsets;
return child.getBottom() + insets.bottom;
}
/**
* Called when searching for a focusable view in the given direction has failed
* for the current content of the RecyclerView.
*
* <p>This is the LayoutManager's opportunity to populate views in the given direction
* to fulfill the request if it can. The LayoutManager should attach and return
* the view to be focused. The default implementation returns null.</p>
*
* @param focused The currently focused view
* @param direction One of {@link View#FOCUS_UP}, {@link View#FOCUS_DOWN},
* {@link View#FOCUS_LEFT}, {@link View#FOCUS_RIGHT},
* {@link View#FOCUS_BACKWARD}, {@link View#FOCUS_FORWARD}
* or 0 for not applicable
* @param recycler The recycler to use for obtaining views for currently offscreen items
* @param state Transient state of RecyclerView
* @return The chosen view to be focused
*/
public View onFocusSearchFailed(View focused, int direction, Recycler recycler,
State state) {
return null;
}
/**
* This method gives a LayoutManager an opportunity to intercept the initial focus search
* before the default behavior of {@link FocusFinder} is used. If this method returns
* null FocusFinder will attempt to find a focusable child view. If it fails
* then {@link #onFocusSearchFailed(View, int, RecyclerView.Recycler, RecyclerView.State)}
* will be called to give the LayoutManager an opportunity to add new views for items
* that did not have attached views representing them. The LayoutManager should not add
* or remove views from this method.
*
* @param focused The currently focused view
* @param direction One of {@link View#FOCUS_UP}, {@link View#FOCUS_DOWN},
* {@link View#FOCUS_LEFT}, {@link View#FOCUS_RIGHT},
* {@link View#FOCUS_BACKWARD}, {@link View#FOCUS_FORWARD}
* @return A descendant view to focus or null to fall back to default behavior.
* The default implementation returns null.
*/
public View onInterceptFocusSearch(View focused, int direction) {
return null;
}
/**
* Called when a child of the RecyclerView wants a particular rectangle to be positioned
* onto the screen. See {@link ViewParent#requestChildRectangleOnScreen(android.view.View,
* android.graphics.Rect, boolean)} for more details.
*
* <p>The base implementation will attempt to perform a standard programmatic scroll
* to bring the given rect into view, within the padded area of the RecyclerView.</p>
*
* @param child The direct child making the request.
* @param rect The rectangle in the child's coordinates the child
* wishes to be on the screen.
* @param immediate True to forbid animated or delayed scrolling,
* false otherwise
* @return Whether the group scrolled to handle the operation
*/
public boolean requestChildRectangleOnScreen(RecyclerView parent, View child, Rect rect,
boolean immediate) {
final int parentLeft = getPaddingLeft();
final int parentTop = getPaddingTop();
final int parentRight = getWidth() - getPaddingRight();
final int parentBottom = getHeight() - getPaddingBottom();
final int childLeft = child.getLeft() + rect.left;
final int childTop = child.getTop() + rect.top;
final int childRight = childLeft + rect.right;
final int childBottom = childTop + rect.bottom;
final int offScreenLeft = Math.min(0, childLeft - parentLeft);
final int offScreenTop = Math.min(0, childTop - parentTop);
final int offScreenRight = Math.max(0, childRight - parentRight);
final int offScreenBottom = Math.max(0, childBottom - parentBottom);
// Favor the "start" layout direction over the end when bringing one side or the other
// of a large rect into view.
final int dx;
if (ViewCompat.getLayoutDirection(parent) == ViewCompat.LAYOUT_DIRECTION_RTL) {
dx = offScreenRight != 0 ? offScreenRight : offScreenLeft;
} else {
dx = offScreenLeft != 0 ? offScreenLeft : offScreenRight;
}
// Favor bringing the top into view over the bottom
final int dy = offScreenTop != 0 ? offScreenTop : offScreenBottom;
if (dx != 0 || dy != 0) {
if (immediate) {
parent.scrollBy(dx, dy);
} else {
parent.smoothScrollBy(dx, dy);
}
return true;
}
return false;
}
/**
* Called when a descendant view of the RecyclerView requests focus.
*
* <p>A LayoutManager wishing to keep focused views aligned in a specific
* portion of the view may implement that behavior in an override of this method.</p>
*
* <p>If the LayoutManager executes different behavior that should override the default
* behavior of scrolling the focused child on screen instead of running alongside it,
* this method should return true.</p>
*
* @param parent The RecyclerView hosting this LayoutManager
* @param child Direct child of the RecyclerView containing the newly focused view
* @param focused The newly focused view. This may be the same view as child
* @return true if the default scroll behavior should be suppressed
*/
public boolean onRequestChildFocus(RecyclerView parent, View child, View focused) {
return false;
}
/**
* Called if the RecyclerView this LayoutManager is bound to has a different adapter set.
* The LayoutManager may use this opportunity to clear caches and configure state such
* that it can relayout appropriately with the new data and potentially new view types.
*
* <p>The default implementation removes all currently attached views.</p>
*
* @param oldAdapter The previous adapter instance. Will be null if there was previously no
* adapter.
* @param newAdapter The new adapter instance. Might be null if
* {@link #setAdapter(RecyclerView.Adapter)} is called with {@code null}.
*/
public void onAdapterChanged(Adapter oldAdapter, Adapter newAdapter) {
}
/**
* Called to populate focusable views within the RecyclerView.
*
* <p>The LayoutManager implementation should return <code>true</code> if the default
* behavior of {@link ViewGroup#addFocusables(java.util.ArrayList, int)} should be
* suppressed.</p>
*
* <p>The default implementation returns <code>false</code> to trigger RecyclerView
* to fall back to the default ViewGroup behavior.</p>
*
* @param recyclerView The RecyclerView hosting this LayoutManager
* @param views List of output views. This method should add valid focusable views
* to this list.
* @param direction One of {@link View#FOCUS_UP}, {@link View#FOCUS_DOWN},
* {@link View#FOCUS_LEFT}, {@link View#FOCUS_RIGHT},
* {@link View#FOCUS_BACKWARD}, {@link View#FOCUS_FORWARD}
* @param focusableMode The type of focusables to be added.
*
* @return true to suppress the default behavior, false to add default focusables after
* this method returns.
*
* @see #FOCUSABLES_ALL
* @see #FOCUSABLES_TOUCH_MODE
*/
public boolean onAddFocusables(RecyclerView recyclerView, ArrayList<View> views,
int direction, int focusableMode) {
return false;
}
/**
* Called when items have been added to the adapter. The LayoutManager may choose to
* requestLayout if the inserted items would require refreshing the currently visible set
* of child views. (e.g. currently empty space would be filled by appended items, etc.)
*
* @param recyclerView
* @param positionStart
* @param itemCount
*/
public void onItemsAdded(RecyclerView recyclerView, int positionStart, int itemCount) {
}
/**
* Called when items have been removed from the adapter.
*
* @param recyclerView
* @param positionStart
* @param itemCount
*/
public void onItemsRemoved(RecyclerView recyclerView, int positionStart, int itemCount) {
}
/**
* <p>Override this method if you want to support scroll bars.</p>
*
* <p>Read {@link RecyclerView#computeHorizontalScrollExtent()} for details.</p>
*
* <p>Default implementation returns 0.</p>
*
* @param state Current state of RecyclerView
* @return The horizontal extent of the scrollbar's thumb
* @see RecyclerView#computeHorizontalScrollExtent()
*/
public int computeHorizontalScrollExtent(State state) {
return 0;
}
/**
* <p>Override this method if you want to support scroll bars.</p>
*
* <p>Read {@link RecyclerView#computeHorizontalScrollOffset()} for details.</p>
*
* <p>Default implementation returns 0.</p>
*
* @param state Current State of RecyclerView where you can find total item count
* @return The horizontal offset of the scrollbar's thumb
* @see RecyclerView#computeHorizontalScrollOffset()
*/
public int computeHorizontalScrollOffset(State state) {
return 0;
}
/**
* <p>Override this method if you want to support scroll bars.</p>
*
* <p>Read {@link RecyclerView#computeHorizontalScrollRange()} for details.</p>
*
* <p>Default implementation returns 0.</p>
*
* @param state Current State of RecyclerView where you can find total item count
* @return The total horizontal range represented by the vertical scrollbar
* @see RecyclerView#computeHorizontalScrollRange()
*/
public int computeHorizontalScrollRange(State state) {
return 0;
}
/**
* <p>Override this method if you want to support scroll bars.</p>
*
* <p>Read {@link RecyclerView#computeVerticalScrollExtent()} for details.</p>
*
* <p>Default implementation returns 0.</p>
*
* @param state Current state of RecyclerView
* @return The vertical extent of the scrollbar's thumb
* @see RecyclerView#computeVerticalScrollExtent()
*/
public int computeVerticalScrollExtent(State state) {
return 0;
}
/**
* <p>Override this method if you want to support scroll bars.</p>
*
* <p>Read {@link RecyclerView#computeVerticalScrollOffset()} for details.</p>
*
* <p>Default implementation returns 0.</p>
*
* @param state Current State of RecyclerView where you can find total item count
* @return The vertical offset of the scrollbar's thumb
* @see RecyclerView#computeVerticalScrollOffset()
*/
public int computeVerticalScrollOffset(State state) {
return 0;
}
/**
* <p>Override this method if you want to support scroll bars.</p>
*
* <p>Read {@link RecyclerView#computeVerticalScrollRange()} for details.</p>
*
* <p>Default implementation returns 0.</p>
*
* @param state Current State of RecyclerView where you can find total item count
* @return The total vertical range represented by the vertical scrollbar
* @see RecyclerView#computeVerticalScrollRange()
*/
public int computeVerticalScrollRange(State state) {
return 0;
}
/**
* Measure the attached RecyclerView. Implementations must call
* {@link #setMeasuredDimension(int, int)} before returning.
*
* <p>The default implementation will handle EXACTLY measurements and respect
* the minimum width and height properties of the host RecyclerView if measured
* as UNSPECIFIED. AT_MOST measurements will be treated as EXACTLY and the RecyclerView
* will consume all available space.</p>
*
* @param recycler Recycler
* @param state Transient state of RecyclerView
* @param widthSpec Width {@link android.view.View.MeasureSpec}
* @param heightSpec Height {@link android.view.View.MeasureSpec}
*/
public void onMeasure(Recycler recycler, State state, int widthSpec, int heightSpec) {
final int widthMode = MeasureSpec.getMode(widthSpec);
final int heightMode = MeasureSpec.getMode(heightSpec);
final int widthSize = MeasureSpec.getSize(widthSpec);
final int heightSize = MeasureSpec.getSize(heightSpec);
int width = 0;
int height = 0;
switch (widthMode) {
case MeasureSpec.EXACTLY:
case MeasureSpec.AT_MOST:
width = widthSize;
break;
case MeasureSpec.UNSPECIFIED:
default:
width = getMinimumWidth();
break;
}
switch (heightMode) {
case MeasureSpec.EXACTLY:
case MeasureSpec.AT_MOST:
height = heightSize;
break;
case MeasureSpec.UNSPECIFIED:
default:
height = getMinimumHeight();
break;
}
setMeasuredDimension(width, height);
}
/**
* {@link View#setMeasuredDimension(int, int) Set the measured dimensions} of the
* host RecyclerView.
*
* @param widthSize Measured width
* @param heightSize Measured height
*/
public void setMeasuredDimension(int widthSize, int heightSize) {
mRecyclerView.setMeasuredDimension(widthSize, heightSize);
}
/**
* @return The host RecyclerView's {@link View#getMinimumWidth()}
*/
public int getMinimumWidth() {
return ViewCompat.getMinimumWidth(mRecyclerView);
}
/**
* @return The host RecyclerView's {@link View#getMinimumHeight()}
*/
public int getMinimumHeight() {
return ViewCompat.getMinimumHeight(mRecyclerView);
}
/**
* <p>Called when the LayoutManager should save its state. This is a good time to save your
* scroll position, configuration and anything else that may be required to restore the same
* layout state if the LayoutManager is recreated.</p>
* <p>RecyclerView does NOT verify if the LayoutManager has changed between state save and
* restore. This will let you share information between your LayoutManagers but it is also
* your responsibility to make sure they use the same parcelable class.</p>
*
* @return Necessary information for LayoutManager to be able to restore its state
*/
public Parcelable onSaveInstanceState() {
return null;
}
public void onRestoreInstanceState(Parcelable state) {
}
void stopSmoothScroller() {
if (mSmoothScroller != null) {
mSmoothScroller.stop();
}
}
private void onSmoothScrollerStopped(SmoothScroller smoothScroller) {
if (mSmoothScroller == smoothScroller) {
mSmoothScroller = null;
}
}
void removeAndRecycleAllViews(Recycler recycler) {
for (int i = getChildCount() - 1; i >= 0; i--) {
removeAndRecycleViewAt(i, recycler);
}
}
}
/**
* An ItemDecoration allows the application to add a special drawing and layout offset
* to specific item views from the adapter's data set. This can be useful for drawing dividers
* between items, highlights, visual grouping boundaries and more.
*
* <p>All ItemDecorations are drawn in the order they were added, before the item
* views (in {@link ItemDecoration#onDraw(Canvas, RecyclerView) onDraw()} and after the items
* (in {@link ItemDecoration#onDrawOver(Canvas, RecyclerView)}.</p>
*/
public static abstract class ItemDecoration {
/**
* Draw any appropriate decorations into the Canvas supplied to the RecyclerView.
* Any content drawn by this method will be drawn before the item views are drawn,
* and will thus appear underneath the views.
*
* @param c Canvas to draw into
* @param parent RecyclerView this ItemDecoration is drawing into
*/
public void onDraw(Canvas c, RecyclerView parent) {
}
/**
* Draw any appropriate decorations into the Canvas supplied to the RecyclerView.
* Any content drawn by this method will be drawn after the item views are drawn
* and will thus appear over the views.
*
* @param c Canvas to draw into
* @param parent RecyclerView this ItemDecoration is drawing into
*/
public void onDrawOver(Canvas c, RecyclerView parent) {
}
/**
* Retrieve any offsets for the given item. Each field of <code>outRect</code> specifies
* the number of pixels that the item view should be inset by, similar to padding or margin.
* The default implementation sets the bounds of outRect to 0 and returns.
*
* <p>If this ItemDecoration does not affect the positioning of item views it should set
* all four fields of <code>outRect</code> (left, top, right, bottom) to zero
* before returning.</p>
*
* @param outRect Rect to receive the output.
* @param itemPosition Adapter position of the item to offset
* @param parent RecyclerView this ItemDecoration is decorating
*/
public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
outRect.set(0, 0, 0, 0);
}
}
/**
* An OnItemTouchListener allows the application to intercept touch events in progress at the
* view hierarchy level of the RecyclerView before those touch events are considered for
* RecyclerView's own scrolling behavior.
*
* <p>This can be useful for applications that wish to implement various forms of gestural
* manipulation of item views within the RecyclerView. OnItemTouchListeners may intercept
* a touch interaction already in progress even if the RecyclerView is already handling that
* gesture stream itself for the purposes of scrolling.</p>
*/
public interface OnItemTouchListener {
/**
* Silently observe and/or take over touch events sent to the RecyclerView
* before they are handled by either the RecyclerView itself or its child views.
*
* <p>The onInterceptTouchEvent methods of each attached OnItemTouchListener will be run
* in the order in which each listener was added, before any other touch processing
* by the RecyclerView itself or child views occurs.</p>
*
* @param e MotionEvent describing the touch event. All coordinates are in
* the RecyclerView's coordinate system.
* @return true if this OnItemTouchListener wishes to begin intercepting touch events, false
* to continue with the current behavior and continue observing future events in
* the gesture.
*/
public boolean onInterceptTouchEvent(RecyclerView rv, MotionEvent e);
/**
* Process a touch event as part of a gesture that was claimed by returning true from
* a previous call to {@link #onInterceptTouchEvent}.
*
* @param e MotionEvent describing the touch event. All coordinates are in
* the RecyclerView's coordinate system.
*/
public void onTouchEvent(RecyclerView rv, MotionEvent e);
}
/**
* An OnScrollListener can be set on a RecyclerView to receive messages
* when a scrolling event has occurred on that RecyclerView.
*
* @see RecyclerView#setOnScrollListener(OnScrollListener)
*/
public interface OnScrollListener {
public void onScrollStateChanged(int newState);
public void onScrolled(int dx, int dy);
}
/**
* A RecyclerListener can be set on a RecyclerView to receive messages whenever
* a view is recycled.
*
* @see RecyclerView#setRecyclerListener(RecyclerListener)
*/
public interface RecyclerListener {
/**
* This method is called whenever the view in the ViewHolder is recycled.
*
* @param holder The ViewHolder containing the view that was recycled
*/
public void onViewRecycled(ViewHolder holder);
}
/**
* Interface definition for a callback to be invoked when an item in this
* RecyclerView.Adapter has been clicked.
*/
public interface OnItemClickListener {
/**
* Callback method to be invoked when an item in this RecyclerView.Adapter has
* been clicked.
* <p>
* Implementers can call getPosition(position) if they need
* to access the data associated with the selected item.
*
* @param view The view within the RecyclerView.Adapter that was clicked (this
* will be a view provided by the adapter)
* @param position The position of the view in the adapter.
*/
void onItemClick(View view, int position);
}
public static OnItemClickListener mOnItemClickListener = null;
/**
* Register a callback to be invoked when an item in this AdapterView has
* been clicked.
*
* @param listener The callback that will be invoked.
*/
public void setOnItemClickListener(OnItemClickListener listener) {
mOnItemClickListener = listener;
}
/**
* @return The callback to be invoked with an item in this AdapterView has
* been clicked, or null id no callback has been set.
*/
public final OnItemClickListener getOnItemClickListener() {
return mOnItemClickListener;
}
/**
* A ViewHolder describes an item view and metadata about its place within the RecyclerView.
*
* <p>{@link Adapter} implementations should subclass ViewHolder and add fields for caching
* potentially expensive {@link View#findViewById(int)} results.</p>
*
* <p>While {@link LayoutParams} belong to the {@link LayoutManager},
* {@link ViewHolder ViewHolders} belong to the adapter. Adapters should feel free to use
* their own custom ViewHolder implementations to store data that makes binding view contents
* easier. Implementations should assume that individual item views will hold strong references
* to <code>ViewHolder</code> objects and that <code>RecyclerView</code> instances may hold
* strong references to extra off-screen item views for caching purposes</p>
*/
public static abstract class ViewHolder implements OnClickListener{
public final View itemView;
int mPosition = NO_POSITION;
int mOldPosition = NO_POSITION;
long mItemId = NO_ID;
int mItemViewType = INVALID_TYPE;
/**
* This ViewHolder has been bound to a position; mPosition, mItemId and mItemViewType
* are all valid.
*/
static final int FLAG_BOUND = 1 << 0;
/**
* The data this ViewHolder's view reflects is stale and needs to be rebound
* by the adapter. mPosition and mItemId are consistent.
*/
static final int FLAG_UPDATE = 1 << 1;
/**
* This ViewHolder's data is invalid. The identity implied by mPosition and mItemId
* are not to be trusted and may no longer match the item view type.
* This ViewHolder must be fully rebound to different data.
*/
static final int FLAG_INVALID = 1 << 2;
/**
* This ViewHolder points at data that represents an item previously removed from the
* data set. Its view may still be used for things like outgoing animations.
*/
static final int FLAG_REMOVED = 1 << 3;
/**
* This ViewHolder should not be recycled. This flag is set via setIsRecyclable()
* and is intended to keep views around during animations.
*/
static final int FLAG_NOT_RECYCLABLE = 1 << 4;
private int mFlags;
private int mIsRecyclableCount = 0;
// If non-null, view is currently considered scrap and may be reused for other data by the
// scrap container.
private Recycler mScrapContainer = null;
@Override
public void onClick(View v) {
if (mOnItemClickListener != null) {
mOnItemClickListener.onItemClick(itemView, getPosition());
}
}
public ViewHolder(View itemView) {
if (itemView == null) {
throw new IllegalArgumentException("itemView may not be null");
}
this.itemView = itemView;
this.itemView.setOnClickListener(this);
}
void offsetPosition(int offset) {
if (mOldPosition == NO_POSITION) {
mOldPosition = mPosition;
}
mPosition += offset;
}
void clearOldPosition() {
mOldPosition = NO_POSITION;
}
public final int getPosition() {
return mOldPosition == NO_POSITION ? mPosition : mOldPosition;
}
public final long getItemId() {
return mItemId;
}
public final int getItemViewType() {
return mItemViewType;
}
boolean isScrap() {
return mScrapContainer != null;
}
void unScrap() {
mScrapContainer.unscrapView(this);
mScrapContainer = null;
}
void setScrapContainer(Recycler recycler) {
mScrapContainer = recycler;
}
boolean isInvalid() {
return (mFlags & FLAG_INVALID) != 0;
}
boolean needsUpdate() {
return (mFlags & FLAG_UPDATE) != 0;
}
boolean isBound() {
return (mFlags & FLAG_BOUND) != 0;
}
boolean isRemoved() {
return (mFlags & FLAG_REMOVED) != 0;
}
void setFlags(int flags, int mask) {
mFlags = (mFlags & ~mask) | (flags & mask);
}
void addFlags(int flags) {
mFlags |= flags;
}
void clearFlagsForSharedPool() {
mFlags = 0;
}
@Override
public String toString() {
final StringBuilder sb = new StringBuilder("ViewHolder{" +
Integer.toHexString(hashCode()) + " position=" + mPosition + " id=" + mItemId);
if (isScrap()) sb.append(" scrap");
if (isInvalid()) sb.append(" invalid");
if (!isBound()) sb.append(" unbound");
if (needsUpdate()) sb.append(" update");
if (isRemoved()) sb.append(" removed");
sb.append("}");
return sb.toString();
}
/**
* Informs the recycler whether this item can be recycled. Views which are not
* recyclable will not be reused for other items until setIsRecyclable() is
* later set to true. Calls to setIsRecyclable() should always be paired (one
* call to setIsRecyclabe(false) should always be matched with a later call to
* setIsRecyclable(true)). Pairs of calls may be nested, as the state is internally
* reference-counted.
*
* @param recyclable Whether this item is available to be recycled. Default value
* is true.
*/
public final void setIsRecyclable(boolean recyclable) {
mIsRecyclableCount = recyclable ? mIsRecyclableCount - 1 : mIsRecyclableCount + 1;
if (mIsRecyclableCount < 0) {
mIsRecyclableCount = 0;
Log.e(VIEW_LOG_TAG, "isRecyclable decremented below 0: " +
"unmatched pair of setIsRecyable() calls");
} else if (!recyclable && mIsRecyclableCount == 1) {
mFlags |= FLAG_NOT_RECYCLABLE;
} else if (recyclable && mIsRecyclableCount == 0) {
mFlags &= ~FLAG_NOT_RECYCLABLE;
}
}
/**
* @see {@link #setIsRecyclable(boolean)}
*
* @return true if this item is available to be recycled, false otherwise.
*/
public final boolean isRecyclable() {
return (mFlags & FLAG_NOT_RECYCLABLE) == 0 &&
!ViewCompat.hasTransientState(itemView);
}
}
/**
* Queued operation to happen when child views are updated.
*/
private static class UpdateOp {
public static final int ADD = 0;
public static final int REMOVE = 1;
public static final int UPDATE = 2;
static final int POOL_SIZE = 30;
public int cmd;
public int positionStart;
public int itemCount;
public UpdateOp(int cmd, int positionStart, int itemCount) {
this.cmd = cmd;
this.positionStart = positionStart;
this.itemCount = itemCount;
}
}
UpdateOp obtainUpdateOp(int cmd, int positionStart, int itemCount) {
UpdateOp op = mUpdateOpPool.acquire();
if (op == null) {
op = new UpdateOp(cmd, positionStart, itemCount);
} else {
op.cmd = cmd;
op.positionStart = positionStart;
op.itemCount = itemCount;
}
return op;
}
void recycleUpdateOp(UpdateOp op) {
mUpdateOpPool.release(op);
}
/**
* {@link android.view.ViewGroup.MarginLayoutParams LayoutParams} subclass for children of
* {@link RecyclerView}. Custom {@link LayoutManager layout managers} are encouraged
* to create their own subclass of this <code>LayoutParams</code> class
* to store any additional required per-child view metadata about the layout.
*/
public static class LayoutParams extends MarginLayoutParams {
ViewHolder mViewHolder;
final Rect mDecorInsets = new Rect();
boolean mInsetsDirty = true;
public LayoutParams(Context c, AttributeSet attrs) {
super(c, attrs);
}
public LayoutParams(int width, int height) {
super(width, height);
}
public LayoutParams(MarginLayoutParams source) {
super(source);
}
public LayoutParams(ViewGroup.LayoutParams source) {
super(source);
}
public LayoutParams(LayoutParams source) {
super((ViewGroup.LayoutParams) source);
}
/**
* Returns true if the view this LayoutParams is attached to needs to have its content
* updated from the corresponding adapter.
*
* @return true if the view should have its content updated
*/
public boolean viewNeedsUpdate() {
return mViewHolder.needsUpdate();
}
/**
* Returns true if the view this LayoutParams is attached to is now representing
* potentially invalid data. A LayoutManager should scrap/recycle it.
*
* @return true if the view is invalid
*/
public boolean isViewInvalid() {
return mViewHolder.isInvalid();
}
/**
* Returns true if the adapter data item corresponding to the view this LayoutParams
* is attached to has been removed from the data set. A LayoutManager may choose to
* treat it differently in order to animate its outgoing or disappearing state.
*
* @return true if the item the view corresponds to was removed from the data set
*/
public boolean isItemRemoved() {
return mViewHolder.isRemoved();
}
/**
* Returns the position that the view this LayoutParams is attached to corresponds to.
*
* @return the adapter position this view was bound from
*/
public int getViewPosition() {
return mViewHolder.getPosition();
}
}
/**
* Observer base class for watching changes to an {@link Adapter}.
* See {@link Adapter#registerAdapterDataObserver(AdapterDataObserver)}.
*/
public static abstract class AdapterDataObserver {
public void onChanged() {
// Do nothing
}
public void onItemRangeChanged(int positionStart, int itemCount) {
// do nothing
}
public void onItemRangeInserted(int positionStart, int itemCount) {
// do nothing
}
public void onItemRangeRemoved(int positionStart, int itemCount) {
// do nothing
}
}
/**
* <p>Base class for smooth scrolling. Handles basic tracking of the target view position and
* provides methods to trigger a programmatic scroll.</p>
*
* @see LinearSmoothScroller
*/
public static abstract class SmoothScroller {
private int mTargetPosition = RecyclerView.NO_POSITION;
private RecyclerView mRecyclerView;
private LayoutManager mLayoutManager;
private boolean mPendingInitialRun;
private boolean mRunning;
private View mTargetView;
private final Action mRecyclingAction;
public SmoothScroller() {
mRecyclingAction = new Action(0, 0);
}
/**
* Starts a smooth scroll for the given target position.
* <p>In each animation step, {@link RecyclerView} will check
* for the target view and call either
* {@link #onTargetFound(android.view.View, RecyclerView.State, SmoothScroller.Action)} or
* {@link #onSeekTargetStep(int, int, RecyclerView.State, SmoothScroller.Action)} until
* SmoothScroller is stopped.</p>
*
* <p>Note that if RecyclerView finds the target view, it will automatically stop the
* SmoothScroller. This <b>does not</b> mean that scroll will stop, it only means it will
* stop calling SmoothScroller in each animation step.</p>
*/
void start(RecyclerView recyclerView, LayoutManager layoutManager) {
mRecyclerView = recyclerView;
mLayoutManager = layoutManager;
if (mTargetPosition == RecyclerView.NO_POSITION) {
throw new IllegalArgumentException("Invalid target position");
}
mRecyclerView.mState.mTargetPosition = mTargetPosition;
mRunning = true;
mPendingInitialRun = true;
mTargetView = findViewByPosition(getTargetPosition());
onStart();
mRecyclerView.mViewFlinger.postOnAnimation();
}
public void setTargetPosition(int targetPosition) {
mTargetPosition = targetPosition;
}
/**
* @return The LayoutManager to which this SmoothScroller is attached
*/
public LayoutManager getLayoutManager() {
return mLayoutManager;
}
/**
* Stops running the SmoothScroller in each animation callback. Note that this does not
* cancel any existing {@link Action} updated by
* {@link #onTargetFound(android.view.View, RecyclerView.State, SmoothScroller.Action)} or
* {@link #onSeekTargetStep(int, int, RecyclerView.State, SmoothScroller.Action)}.
*/
final protected void stop() {
if (!mRunning) {
return;
}
onStop();
mRecyclerView.mState.mTargetPosition = RecyclerView.NO_POSITION;
mTargetView = null;
mTargetPosition = RecyclerView.NO_POSITION;
mPendingInitialRun = false;
mRunning = false;
// trigger a cleanup
mLayoutManager.onSmoothScrollerStopped(this);
// clear references to avoid any potential leak by a custom smooth scroller
mLayoutManager = null;
mRecyclerView = null;
}
/**
* Returns true if SmoothScroller has beens started but has not received the first
* animation
* callback yet.
*
* @return True if this SmoothScroller is waiting to start
*/
public boolean isPendingInitialRun() {
return mPendingInitialRun;
}
/**
* @return True if SmoothScroller is currently active
*/
public boolean isRunning() {
return mRunning;
}
/**
* Returns the adapter position of the target item
*
* @return Adapter position of the target item or
* {@link RecyclerView#NO_POSITION} if no target view is set.
*/
public int getTargetPosition() {
return mTargetPosition;
}
private void onAnimation(int dx, int dy) {
if (!mRunning || mTargetPosition == RecyclerView.NO_POSITION) {
stop();
}
mPendingInitialRun = false;
if (mTargetView != null) {
// verify target position
if (getChildPosition(mTargetView) == mTargetPosition) {
onTargetFound(mTargetView, mRecyclerView.mState, mRecyclingAction);
mRecyclingAction.runInNecessary(mRecyclerView);
stop();
} else {
Log.e(TAG, "Passed over target position while smooth scrolling.");
mTargetView = null;
}
}
if (mRunning) {
onSeekTargetStep(dx, dy, mRecyclerView.mState, mRecyclingAction);
mRecyclingAction.runInNecessary(mRecyclerView);
}
}
/**
* @see RecyclerView#getChildPosition(android.view.View)
*/
public int getChildPosition(View view) {
return mRecyclerView.getChildPosition(view);
}
/**
* @see RecyclerView#getChildCount()
*/
public int getChildCount() {
return mRecyclerView.getChildCount();
}
/**
* @see RecyclerView.LayoutManager#findViewByPosition(int)
*/
public View findViewByPosition(int position) {
return mRecyclerView.mLayout.findViewByPosition(position);
}
/**
* @see RecyclerView#scrollToPosition(int)
*/
public void instantScrollToPosition(int position) {
mRecyclerView.scrollToPosition(position);
}
protected void onChildAttachedToWindow(View child) {
if (getChildPosition(child) == getTargetPosition()) {
mTargetView = child;
if (DEBUG) {
Log.d(TAG, "smooth scroll target view has been attached");
}
}
}
/**
* Normalizes the vector.
* @param scrollVector The vector that points to the target scroll position
*/
protected void normalize(PointF scrollVector) {
final double magnitute = Math.sqrt(scrollVector.x * scrollVector.x + scrollVector.y *
scrollVector.y);
scrollVector.x /= magnitute;
scrollVector.y /= magnitute;
}
/**
* Called when smooth scroll is started. This might be a good time to do setup.
*/
abstract protected void onStart();
/**
* Called when smooth scroller is stopped. This is a good place to cleanup your state etc.
* @see #stop()
*/
abstract protected void onStop();
/**
* <p>RecyclerView will call this method each time it scrolls until it can find the target
* position in the layout.</p>
* <p>SmoothScroller should check dx, dy and if scroll should be changed, update the
* provided {@link Action} to define the next scroll.</p>
*
* @param dx Last scroll amount horizontally
* @param dy Last scroll amount verticaully
* @param state Transient state of RecyclerView
* @param action If you want to trigger a new smooth scroll and cancel the previous one,
* update this object.
*/
abstract protected void onSeekTargetStep(int dx, int dy, State state, Action action);
/**
* Called when the target position is laid out. This is the last callback SmoothScroller
* will receive and it should update the provided {@link Action} to define the scroll
* details towards the target view.
* @param targetView The view element which render the target position.
* @param state Transient state of RecyclerView
* @param action Action instance that you should update to define final scroll action
* towards the targetView
* @return An {@link Action} to finalize the smooth scrolling
*/
abstract protected void onTargetFound(View targetView, State state, Action action);
/**
* Holds information about a smooth scroll request by a {@link SmoothScroller}.
*/
public static class Action {
public static final int UNDEFINED_DURATION = Integer.MIN_VALUE;
private int mDx;
private int mDy;
private int mDuration;
private Interpolator mInterpolator;
private boolean changed = false;
// we track this variable to inform custom implementer if they are updating the action
// in every animation callback
private int consecutiveUpdates = 0;
/**
* @param dx Pixels to scroll horizontally
* @param dy Pixels to scroll vertically
*/
public Action(int dx, int dy) {
this(dx, dy, UNDEFINED_DURATION, null);
}
/**
* @param dx Pixels to scroll horizontally
* @param dy Pixels to scroll vertically
* @param duration Duration of the animation in milliseconds
*/
public Action(int dx, int dy, int duration) {
this(dx, dy, duration, null);
}
/**
* @param dx Pixels to scroll horizontally
* @param dy Pixels to scroll vertically
* @param duration Duration of the animation in milliseconds
* @param interpolator Interpolator to be used when calculating scroll position in each
* animation step
*/
public Action(int dx, int dy, int duration, Interpolator interpolator) {
mDx = dx;
mDy = dy;
mDuration = duration;
mInterpolator = interpolator;
}
private void runInNecessary(RecyclerView recyclerView) {
if (changed) {
validate();
if (mInterpolator == null) {
if (mDuration == UNDEFINED_DURATION) {
recyclerView.mViewFlinger.smoothScrollBy(mDx, mDy);
} else {
recyclerView.mViewFlinger.smoothScrollBy(mDx, mDy, mDuration);
}
} else {
recyclerView.mViewFlinger.smoothScrollBy(mDx, mDy, mDuration, mInterpolator);
}
consecutiveUpdates ++;
if (consecutiveUpdates > 10) {
// A new action is being set in every animation step. This looks like a bad
// implementation. Inform developer.
Log.e(TAG, "Smooth Scroll action is being updated too frequently. Make sure"
+ " you are not changing it unless necessary");
}
changed = false;
} else {
consecutiveUpdates = 0;
}
}
private void validate() {
if (mInterpolator != null && mDuration < 1) {
throw new IllegalStateException("If you provide an interpolator, you must"
+ " set a positive duration");
} else if (mDuration < 1) {
throw new IllegalStateException("Scroll duration must be a positive number");
}
}
public int getDx() {
return mDx;
}
public void setDx(int dx) {
changed = true;
mDx = dx;
}
public int getDy() {
return mDy;
}
public void setDy(int dy) {
changed = true;
mDy = dy;
}
public int getDuration() {
return mDuration;
}
public void setDuration(int duration) {
changed = true;
mDuration = duration;
}
public Interpolator getInterpolator() {
return mInterpolator;
}
/**
* Sets the interpolator to calculate scroll steps
* @param interpolator The interpolator to use. If you specify an interpolator, you must
* also set the duration.
* @see #setDuration(int)
*/
public void setInterpolator(Interpolator interpolator) {
changed = true;
mInterpolator = interpolator;
}
/**
* Updates the action with given parameters.
* @param dx Pixels to scroll horizontally
* @param dy Pixels to scroll vertically
* @param duration Duration of the animation in milliseconds
* @param interpolator Interpolator to be used when calculating scroll position in each
* animation step
*/
public void update(int dx, int dy, int duration, Interpolator interpolator) {
mDx = dx;
mDy = dy;
mDuration = duration;
mInterpolator = interpolator;
changed = true;
}
}
}
static class AdapterDataObservable extends Observable<AdapterDataObserver> {
public boolean hasObservers() {
return !mObservers.isEmpty();
}
public void notifyChanged() {
// since onChanged() is implemented by the app, it could do anything, including
// removing itself from {@link mObservers} - and that could cause problems if
// an iterator is used on the ArrayList {@link mObservers}.
// to avoid such problems, just march thru the list in the reverse order.
for (int i = mObservers.size() - 1; i >= 0; i--) {
mObservers.get(i).onChanged();
}
}
public void notifyItemRangeChanged(int positionStart, int itemCount) {
// since onItemRangeChanged() is implemented by the app, it could do anything, including
// removing itself from {@link mObservers} - and that could cause problems if
// an iterator is used on the ArrayList {@link mObservers}.
// to avoid such problems, just march thru the list in the reverse order.
for (int i = mObservers.size() - 1; i >= 0; i--) {
mObservers.get(i).onItemRangeChanged(positionStart, itemCount);
}
}
public void notifyItemRangeInserted(int positionStart, int itemCount) {
// since onItemRangeInserted() is implemented by the app, it could do anything,
// including removing itself from {@link mObservers} - and that could cause problems if
// an iterator is used on the ArrayList {@link mObservers}.
// to avoid such problems, just march thru the list in the reverse order.
for (int i = mObservers.size() - 1; i >= 0; i--) {
mObservers.get(i).onItemRangeInserted(positionStart, itemCount);
}
}
public void notifyItemRangeRemoved(int positionStart, int itemCount) {
// since onItemRangeRemoved() is implemented by the app, it could do anything, including
// removing itself from {@link mObservers} - and that could cause problems if
// an iterator is used on the ArrayList {@link mObservers}.
// to avoid such problems, just march thru the list in the reverse order.
for (int i = mObservers.size() - 1; i >= 0; i--) {
mObservers.get(i).onItemRangeRemoved(positionStart, itemCount);
}
}
}
static class SavedState extends BaseSavedState {
Parcelable mLayoutState;
/**
* called by CREATOR
*/
SavedState(Parcel in) {
super(in);
mLayoutState = in.readParcelable(LayoutManager.class.getClassLoader());
}
/**
* Called by onSaveInstanceState
*/
SavedState(Parcelable superState) {
super(superState);
}
@Override
public void writeToParcel(Parcel dest, int flags) {
super.writeToParcel(dest, flags);
dest.writeParcelable(mLayoutState, 0);
}
private void copyFrom(SavedState other) {
mLayoutState = other.mLayoutState;
}
public static final Parcelable.Creator<SavedState> CREATOR
= new Parcelable.Creator<SavedState>() {
@Override
public SavedState createFromParcel(Parcel in) {
return new SavedState(in);
}
@Override
public SavedState[] newArray(int size) {
return new SavedState[size];
}
};
}
/**
* <p>Contains useful information about the current RecyclerView state like target scroll
* position or view focus. State object can also keep arbitrary data, identified by resource
* ids.</p>
* <p>Often times, RecyclerView components will need to pass information between each other.
* To provide a well defined data bus between components, RecyclerView passes the same State
* object to component callbacks and these components can use it to exchange data.</p>
* <p>If you implement custom components, you can use State's put/get/remove methods to pass
* data between your components without needing to manage their lifecycles.</p>
*/
public static class State {
private int mTargetPosition = RecyclerView.NO_POSITION;
private ArrayMap<ViewHolder, ItemHolderInfo> mPreLayoutHolderMap =
new ArrayMap<ViewHolder, ItemHolderInfo>();
private ArrayMap<ViewHolder, ItemHolderInfo> mPostLayoutHolderMap =
new ArrayMap<ViewHolder, ItemHolderInfo>();
private SparseArray<Object> mData;
/**
* Number of items adapter has.
*/
private int mItemCount = 0;
/**
* Number of items adapter had in the previous layout.
*/
private int mPreviousLayoutItemCount = 0;
/**
* Number of items that were NOT laid out but has been deleted from the adapter after the
* previous layout.
*/
private int mDeletedInvisibleItemCountSincePreviousLayout = 0;
private boolean mStructureChanged = false;
private boolean mInPreLayout = false;
State reset() {
mTargetPosition = RecyclerView.NO_POSITION;
if (mData != null) {
mData.clear();
}
mItemCount = 0;
mStructureChanged = false;
return this;
}
public boolean isPreLayout() {
return mInPreLayout;
}
/**
* Removes the mapping from the specified id, if there was any.
* @param resourceId Id of the resource you want to remove. It is suggested to use R.id.* to
* preserve cross functionality and avoid conflicts.
*/
public void remove(int resourceId) {
if (mData =http://www.mamicode.com/= null) {>
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