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仿ViewPager效果二
1、采用ViewGroup实现
/** * 可以左右滑动切换屏幕的类 * @author libin * */ public class ScrollLayout extends ViewGroup { private static final String TAG = "ScrollLayout"; private Scroller mScroller; private VelocityTracker mVelocityTracker; private int mCurScreen; private int mDefaultScreen = 0; private static final int TOUCH_STATE_REST = 0; private static final int TOUCH_STATE_SCROLLING = 1; private static final int SNAP_VELOCITY = 600; private int mTouchState = TOUCH_STATE_REST; private int mTouchSlop; private float mLastMotionX; public ScrollLayout(Context context, AttributeSet attrs) { this(context, attrs, 0); } public ScrollLayout(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); // TODO Auto-generated constructor stub mScroller = new Scroller(context); mCurScreen = mDefaultScreen; mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop(); } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { if (changed) { int childLeft = 0; final int childCount = getChildCount(); for (int i = 0; i < childCount; i++) { final View childView = getChildAt(i); if (childView.getVisibility() != View.GONE) { final int childWidth = childView.getMeasuredWidth(); childView.layout(childLeft, 0, childLeft + childWidth, childView.getMeasuredHeight()); childLeft += childWidth; } } } } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { Log.e(TAG, "onMeasure"); super.onMeasure(widthMeasureSpec, heightMeasureSpec); final int width = MeasureSpec.getSize(widthMeasureSpec); final int widthMode = MeasureSpec.getMode(widthMeasureSpec); if (widthMode != MeasureSpec.EXACTLY) { throw new IllegalStateException( "ScrollLayout only canmCurScreen run at EXACTLY mode!"); } final int heightMode = MeasureSpec.getMode(heightMeasureSpec); if (heightMode != MeasureSpec.EXACTLY) { throw new IllegalStateException( "ScrollLayout only can run at EXACTLY mode!"); } final int count = getChildCount(); for (int i = 0; i < count; i++) { getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec); } scrollTo(mCurScreen * width, 0); } /** * * According to the position of current layout * scroll to the destination * page. */ private void snapToDestination() { final int screenWidth = getWidth(); final int destScreen = (getScrollX() + screenWidth / 2) / screenWidth; snapToScreen(destScreen); } private void snapToScreen(int whichScreen) { // get the valid layout page whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1)); if (getScrollX() != (whichScreen * getWidth())) { final int delta = whichScreen * getWidth() - getScrollX(); mScroller.startScroll(getScrollX(), 0, delta, 0, Math.abs(delta) * 2); mCurScreen = whichScreen; invalidate(); } } public void setToScreen(int whichScreen) { whichScreen = Math.max(0, Math.min(whichScreen, getChildCount() - 1)); mCurScreen = whichScreen; scrollTo(whichScreen * getWidth(), 0); } public int getCurScreen() { return mCurScreen; } //在执行了invalidate()方法之后,程序便会执行computeScroll()方法 @Override public void computeScroll() { // 判断动画是否完成,返回true表示动画没有完成 if (mScroller.computeScrollOffset()) { scrollTo(mScroller.getCurrX(), mScroller.getCurrY()); postInvalidate(); } Log.i(TAG, "computeScroll -- "+mScroller.getCurrX()); } @Override public boolean onTouchEvent(MotionEvent event) { if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(event); final int action = event.getAction(); final float x = event.getX(); switch (action) { case MotionEvent.ACTION_DOWN: Log.e(TAG, "event down!"); //是否完成 if (!mScroller.isFinished()) { mScroller.abortAnimation(); } mLastMotionX = x; break; case MotionEvent.ACTION_MOVE: int deltaX = (int) (mLastMotionX - x); mLastMotionX = x; scrollBy(deltaX, 0); break; case MotionEvent.ACTION_UP: Log.e(TAG, "event : up"); // if (mTouchState == TOUCH_STATE_SCROLLING) { final VelocityTracker velocityTracker = mVelocityTracker; velocityTracker.computeCurrentVelocity(1000); int velocityX = (int) velocityTracker.getXVelocity();//得到对应的速度值,大于0往做滑动,小于0往右 Log.e(TAG, "velocityX:" + velocityX); if (velocityX > SNAP_VELOCITY && mCurScreen > 0) { //向左边 Log.e(TAG, "snap left"); snapToScreen(mCurScreen - 1); } else if (velocityX < -SNAP_VELOCITY && mCurScreen < getChildCount() - 1) { // Fling enough to move right Log.e(TAG, "snap right"); snapToScreen(mCurScreen + 1); } else { snapToDestination(); } //回收 if (mVelocityTracker != null) { mVelocityTracker.recycle(); mVelocityTracker = null; } mTouchState = TOUCH_STATE_REST; break; case MotionEvent.ACTION_CANCEL: mTouchState = TOUCH_STATE_REST; break; } return true; } @Override public boolean onInterceptTouchEvent(MotionEvent ev) { Log.e(TAG, "onInterceptTouchEvent-slop:" + mTouchSlop); final int action = ev.getAction(); if ((action == MotionEvent.ACTION_MOVE) && (mTouchState != TOUCH_STATE_REST)) { return true; } final float x = ev.getX(); switch (action) { case MotionEvent.ACTION_MOVE: final int xDiff = (int) Math.abs(mLastMotionX - x); if (xDiff > mTouchSlop) { mTouchState = TOUCH_STATE_SCROLLING; } break; case MotionEvent.ACTION_DOWN: mLastMotionX = x; mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST : TOUCH_STATE_SCROLLING; break; case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: mTouchState = TOUCH_STATE_REST; break; } return mTouchState != TOUCH_STATE_REST; } }
2、继承HorizontalScrollView
public class MyScrollView extends HorizontalScrollView { private int subChildCount = 0; private ViewGroup firstChild = null; private int downX = 0; private int currentPage = 0; private ArrayList<Integer> pointList = new ArrayList<Integer>(); public MyScrollView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); init(); } public MyScrollView(Context context, AttributeSet attrs) { super(context, attrs); init(); } public MyScrollView(Context context) { super(context); init(); } private void init() { setHorizontalScrollBarEnabled(false); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); receiveChildInfo(); } public void receiveChildInfo() { firstChild = (ViewGroup) getChildAt(0); if (firstChild != null) { subChildCount = firstChild.getChildCount(); for (int i = 0; i < subChildCount; i++) { if (((View) firstChild.getChildAt(i)).getWidth() > 0) { pointList.add(((View) firstChild.getChildAt(i)).getLeft()); } } } } @Override public boolean onTouchEvent(MotionEvent ev) { switch (ev.getAction()) { case MotionEvent.ACTION_DOWN: downX = (int) ev.getX(); break; case MotionEvent.ACTION_MOVE: { } break; case MotionEvent.ACTION_UP: case MotionEvent.ACTION_CANCEL: { if (Math.abs((ev.getX() - downX)) > getWidth() / 4) { if (ev.getX() - downX > 0) { smoothScrollToPrePage(); } else { smoothScrollToNextPage(); } } else { smoothScrollToCurrent(); } return true; } } return super.onTouchEvent(ev); } private void smoothScrollToCurrent() { smoothScrollTo(pointList.get(currentPage), 0); } private void smoothScrollToNextPage() { if (currentPage < subChildCount - 1) { currentPage++; smoothScrollTo(pointList.get(currentPage), 0); } } private void smoothScrollToPrePage() { if (currentPage > 0) { currentPage--; smoothScrollTo(pointList.get(currentPage), 0); } } /** * 下一页 */ public void nextPage() { smoothScrollToNextPage(); } /** * 上一页 */ public void prePage() { smoothScrollToPrePage(); } /** * 跳转到指定的页面 * * @param page * @return */ public boolean gotoPage(int page) { if (page > 0 && page < subChildCount - 1) { smoothScrollTo(pointList.get(page), 0); currentPage = page; return true; } return false; } }
仿ViewPager效果二
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