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Android自定义View学习

Android自定义View之常用工具源码分析

Android自定义View之onMeasure()源码分析

Android自定义View之onLayout()源码分析

Android自定义View之对TouchEvent的处理

Android自定义View之draw原理分析

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前言

大家好啊！好久没有见到我了吧！为什么呢！当然是因为开学啦，这学期很多课，身为部长实验室也也很多活动和一堆小师弟，同时还有蓝桥杯和华为软件开发大赛，而且最近在做一个综合性比较高的作品，没错了，就是酷云，一款仿网易云音乐的在线播放器。当然了，现在我还没有完成这个作品，而且只是刚刚开始写而已，不过也遇到了很多坑，所以写下这篇文章来记录一下这次开发中各种各样的坑，希望对各位有所帮助，文章会随着我的开发进度而不定期更新，各位有问题也可以给我发私信，我们一起讨论解决。

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自定义View控件

不知道各位有没有体验过网易云音乐APP,通过我最近的体验，发现它有着很好的用户界面，对各种操作都有着很好的响应，大家可以先去体验一下，下面给出几张网易云音乐的UI。

接下来放上酷云相对应的页面

说实话从开始接触自定义View到现在也不久，学的不多，但是比较喜欢挑战，因此便有了这个项目的开始。好了，相信大家也已经体验过网易云的用户界面了，就算没有，接下来我也会一点点为你解答。

ViewPager＋PagerTabStrip实现滑动切屏

进去网易云后，主界面如下一个最大的特点就是滑动切屏了，这个效果既方便又帅气，所以网易云音乐中大量应用了这一效果，那么我们首先便来讲解一下滑动切屏的实现。

首先构建在activity_main.xml中构建ViewPager，代码如下：

<android.support.v4.view.ViewPager
             android:layout_width="match_parent"
             android:layout_height="match_parent"
             android:layout_gravity="center"
             android:gravity="center"
             android:id="@+id/vp">
             <android.support.v4.view.PagerTabStrip
                android:layout_width="match_parent"
                 android:layout_height="wrap_content"
                 android:id="@+id/tap">
             </android.support.v4.view.PagerTabStrip>
    </android.support.v4.view.ViewPager>

然后构建切换的子View，为了方便颜色，这里简单的设置显示不同的颜色，main_layout_1

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:id="@+id/view_1"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:src="#76ff03"/>

</LinearLayout>

然后在Activity中进行设置，MainActivity.java

package com.androxue.coolcloud.activity;

import android.content.Intent;
import android.graphics.Color;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.PagerTabStrip;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

import com.androxue.coolcloud.R;

import java.util.ArrayList;

/**
 * Created by JimCharles on 2017/3/11.
 */

public class MainActivity extends AppCompatActivity {

    private ViewPager vp;
     //声明存储ViewPager下子视图的集合
     ArrayList<View> views = new ArrayList<>();
     //显示效果中每个视图的标题
     String[] titles={"私信", "评论", "@我", "通知"};

     @Override
     protected void onCreate(@Nullable Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_message);
         vp = (ViewPager) findViewById(R.id.vp);
         initView();//调用初始化视图方法
         vp.setAdapter(new MyAdapter());//设置适配器
         ImageView back = (ImageView) findViewById(R.id.back);
         back.setOnClickListener(new View.OnClickListener() {
             @Override
             public void onClick(View v) {
                 Intent intent = new Intent(MessageActivity.this, MainActivity.class);
                 startActivity(intent);
             }
         });
     }

    //初始化视图的方法（通过布局填充器获取用于滑动的视图并存入对应的的集合）
    private void initView() {
        View v1 = getLayoutInflater().inflate(R.layout.main_layout_1, null);
        View v2 = getLayoutInflater().inflate(R.layout.main_layout_2, null);
        View v3 = getLayoutInflater().inflate(R.layout.main_layout_3, null);
        View v4 = getLayoutInflater().inflate(R.layout.main_layout_4, null);
        views.add(v1);
        views.add(v2);
        views.add(v3);
        views.add(v4);

        PagerTabStrip pagerTabStrip= (PagerTabStrip)findViewById(R.id.tap);
        pagerTabStrip.setDrawFullUnderline(false);//取消标题栏子View之间的分割线
        pagerTabStrip.setTabIndicatorColor(Color.RED);//改变指示器颜色为红色
        pagerTabStrip.setTextColor(Color.RED);//该变字体颜色为红色
    }

     private class MyAdapter extends PagerAdapter {

         @Override
         public int getCount() {
             return views.size();
         }

        @Override
         public boolean isViewFromObject(View view, Object object) {
            return view == object;
        }

         //重写销毁滑动视图布局（将子视图移出视图存储集合（ViewGroup））
         @Override
         public void destroyItem(ViewGroup container, int position, Object object) {
             container.removeView(views.get(position));
         }

         //重写初始化滑动视图布局（从视图集合中取出对应视图，添加到ViewGroup）
         @Override
         public Object instantiateItem(ViewGroup container, int position) {
             View v = views.get(position);
             container.addView(v);
             return v;
         }

         @Override
         public CharSequence getPageTitle(int position) {
             return titles[position];
         }
    }
}

好了，一个滑动切屏的功能就这样完成了。

圆形头像

关于圆形头像的实现在之前Android自定义View之draw原理分析一文已经有讲到，这里简单的讲解一下，顺便讲解另一种实现方式，两种方式都是通过自定义View控件来实现的。

方式一：Shader+onDraw()实现圆形头像

protected void onDraw(Canvas canvas) {
     super.onDraw(canvas);
     Paint paint = new Paint();
     paint.setAntiAlias(true);
     Bitmap bitmap = BitmapFactory.decodeResource(getResources(),R.drawable.girl);
     int radius = bitmap.getWidth()/2;
     BitmapShader bitmapShader = new BitmapShader(bitmap,Shader.TileMode.REPEAT,Shader.TileMode.REPEAT);
     paint.setShader(bitmapShader);
     canvas.translate(250,430);
     canvas.drawCircle(radius, radius, radius, paint);
}

方式二：自定义CircleImageView实现圆形头像

package com.androxue.coolcloud.widget;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.BitmapShader;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.ColorFilter;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.Shader;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.ColorDrawable;
import android.graphics.drawable.Drawable;
import android.net.Uri;
import android.support.annotation.ColorInt;
import android.support.annotation.ColorRes;
import android.support.annotation.DrawableRes;
import android.util.AttributeSet;

import com.androxue.coolcloud.R;

/**
 * Created by JimCharles on 2017/3/9.
 */

public class CircleImageView extends android.support.v7.widget.AppCompatImageView {

    private static final ScaleType SCALE_TYPE = ScaleType.CENTER_CROP;

    private static final Bitmap.Config BITMAP_CONFIG = Bitmap.Config.ARGB_8888;
    private static final int COLORDRAWABLE_DIMENSION = 2;

    private static final int DEFAULT_BORDER_WIDTH = 0;
    private static final int DEFAULT_BORDER_COLOR = Color.BLACK;
    private static final int DEFAULT_FILL_COLOR = Color.TRANSPARENT;
    private static final boolean DEFAULT_BORDER_OVERLAY = false;

    private final RectF mDrawableRect = new RectF();
    private final RectF mBorderRect = new RectF();

    private final Matrix mShaderMatrix = new Matrix();
    private final Paint mBitmapPaint = new Paint();
    private final Paint mBorderPaint = new Paint();
    private final Paint mFillPaint = new Paint();

    private int mBorderColor = DEFAULT_BORDER_COLOR;
    private int mBorderWidth = DEFAULT_BORDER_WIDTH;
    private int mFillColor = DEFAULT_FILL_COLOR;

    private Bitmap mBitmap;
    private BitmapShader mBitmapShader;
    private int mBitmapWidth;
    private int mBitmapHeight;

    private float mDrawableRadius;
    private float mBorderRadius;

    private ColorFilter mColorFilter;

    private boolean mReady;
    private boolean mSetupPending;
    private boolean mBorderOverlay;
    private boolean mDisableCircularTransformation;

    public CircleImageView(Context context) {
        super(context);

        init();
    }

    public CircleImageView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public CircleImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CircleImageView, defStyle, 0);

        mBorderWidth = a.getDimensionPixelSize(R.styleable.CircleImageView_civ_border_width, DEFAULT_BORDER_WIDTH);
        mBorderColor = a.getColor(R.styleable.CircleImageView_civ_border_color, DEFAULT_BORDER_COLOR);
        mBorderOverlay = a.getBoolean(R.styleable.CircleImageView_civ_border_overlay, DEFAULT_BORDER_OVERLAY);
        mFillColor = a.getColor(R.styleable.CircleImageView_civ_fill_color, DEFAULT_FILL_COLOR);

        a.recycle();

        init();
    }

    private void init() {
        super.setScaleType(SCALE_TYPE);
        mReady = true;

        if (mSetupPending) {
            setup();
            mSetupPending = false;
        }
    }

    @Override
    public ScaleType getScaleType() {
        return SCALE_TYPE;
    }

    @Override
    public void setScaleType(ScaleType scaleType) {
        if (scaleType != SCALE_TYPE) {
            throw new IllegalArgumentException(String.format("ScaleType %s not supported.", scaleType));
        }
    }

    @Override
    public void setAdjustViewBounds(boolean adjustViewBounds) {
        if (adjustViewBounds) {
            throw new IllegalArgumentException("adjustViewBounds not supported.");
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        if (mDisableCircularTransformation) {
            super.onDraw(canvas);
            return;
        }

        if (mBitmap == null) {
            return;
        }

        if (mFillColor != Color.TRANSPARENT) {
            canvas.drawCircle(mDrawableRect.centerX(), mDrawableRect.centerY(), mDrawableRadius, mFillPaint);
        }
        canvas.drawCircle(mDrawableRect.centerX(), mDrawableRect.centerY(), mDrawableRadius, mBitmapPaint);
        if (mBorderWidth > 0) {
            canvas.drawCircle(mBorderRect.centerX(), mBorderRect.centerY(), mBorderRadius, mBorderPaint);
        }
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        setup();
    }

    @Override
    public void setPadding(int left, int top, int right, int bottom) {
        super.setPadding(left, top, right, bottom);
        setup();
    }

    @Override
    public void setPaddingRelative(int start, int top, int end, int bottom) {
        super.setPaddingRelative(start, top, end, bottom);
        setup();
    }

    public int getBorderColor() {
        return mBorderColor;
    }

    public void setBorderColor(@ColorInt int borderColor) {
        if (borderColor == mBorderColor) {
            return;
        }

        mBorderColor = borderColor;
        mBorderPaint.setColor(mBorderColor);
        invalidate();
    }

    /**
     * @deprecated Use {@link #setBorderColor(int)} instead
     */
    @Deprecated
    public void setBorderColorResource(@ColorRes int borderColorRes) {
        setBorderColor(getContext().getResources().getColor(borderColorRes));
    }

    /**
     * Return the color drawn behind the circle-shaped drawable.
     *
     * @return The color drawn behind the drawable
     *
     * @deprecated Fill color support is going to be removed in the future
     */
    @Deprecated
    public int getFillColor() {
        return mFillColor;
    }

    /**
     * Set a color to be drawn behind the circle-shaped drawable. Note that
     * this has no effect if the drawable is opaque or no drawable is set.
     *
     * @param fillColor The color to be drawn behind the drawable
     *
     * @deprecated Fill color support is going to be removed in the future
     */
    @Deprecated
    public void setFillColor(@ColorInt int fillColor) {
        if (fillColor == mFillColor) {
            return;
        }

        mFillColor = fillColor;
        mFillPaint.setColor(fillColor);
        invalidate();
    }

    /**
     * Set a color to be drawn behind the circle-shaped drawable. Note that
     * this has no effect if the drawable is opaque or no drawable is set.
     *
     * @param fillColorRes The color resource to be resolved to a color and
     *                     drawn behind the drawable
     *
     * @deprecated Fill color support is going to be removed in the future
     */
    @Deprecated
    public void setFillColorResource(@ColorRes int fillColorRes) {
        setFillColor(getContext().getResources().getColor(fillColorRes));
    }

    public int getBorderWidth() {
        return mBorderWidth;
    }

    public void setBorderWidth(int borderWidth) {
        if (borderWidth == mBorderWidth) {
            return;
        }

        mBorderWidth = borderWidth;
        setup();
    }

    public boolean isBorderOverlay() {
        return mBorderOverlay;
    }

    public void setBorderOverlay(boolean borderOverlay) {
        if (borderOverlay == mBorderOverlay) {
            return;
        }

        mBorderOverlay = borderOverlay;
        setup();
    }

    public boolean isDisableCircularTransformation() {
        return mDisableCircularTransformation;
    }

    public void setDisableCircularTransformation(boolean disableCircularTransformation) {
        if (mDisableCircularTransformation == disableCircularTransformation) {
            return;
        }

        mDisableCircularTransformation = disableCircularTransformation;
        initializeBitmap();
    }

    @Override
    public void setImageBitmap(Bitmap bm) {
        super.setImageBitmap(bm);
        initializeBitmap();
    }

    @Override
    public void setImageDrawable(Drawable drawable) {
        super.setImageDrawable(drawable);
        initializeBitmap();
    }

    @Override
    public void setImageResource(@DrawableRes int resId) {
        super.setImageResource(resId);
        initializeBitmap();
    }

    @Override
    public void setImageURI(Uri uri) {
        super.setImageURI(uri);
        initializeBitmap();
    }

    @Override
    public void setColorFilter(ColorFilter cf) {
        if (cf == mColorFilter) {
            return;
        }

        mColorFilter = cf;
        applyColorFilter();
        invalidate();
    }

    @Override
    public ColorFilter getColorFilter() {
        return mColorFilter;
    }

    private void applyColorFilter() {
        if (mBitmapPaint != null) {
            mBitmapPaint.setColorFilter(mColorFilter);
        }
    }

    private Bitmap getBitmapFromDrawable(Drawable drawable) {
        if (drawable == null) {
            return null;
        }

        if (drawable instanceof BitmapDrawable) {
            return ((BitmapDrawable) drawable).getBitmap();
        }

        try {
            Bitmap bitmap;

            if (drawable instanceof ColorDrawable) {
                bitmap = Bitmap.createBitmap(COLORDRAWABLE_DIMENSION, COLORDRAWABLE_DIMENSION, BITMAP_CONFIG);
            } else {
                bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), BITMAP_CONFIG);
            }

            Canvas canvas = new Canvas(bitmap);
            drawable.setBounds(0, 0, canvas.getWidth(), canvas.getHeight());
            drawable.draw(canvas);
            return bitmap;
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }

    private void initializeBitmap() {
        if (mDisableCircularTransformation) {
            mBitmap = null;
        } else {
            mBitmap = getBitmapFromDrawable(getDrawable());
        }
        setup();
    }

    private void setup() {
        if (!mReady) {
            mSetupPending = true;
            return;
        }

        if (getWidth() == 0 && getHeight() == 0) {
            return;
        }

        if (mBitmap == null) {
            invalidate();
            return;
        }

        mBitmapShader = new BitmapShader(mBitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);

        mBitmapPaint.setAntiAlias(true);
        mBitmapPaint.setShader(mBitmapShader);

        mBorderPaint.setStyle(Paint.Style.STROKE);
        mBorderPaint.setAntiAlias(true);
        mBorderPaint.setColor(mBorderColor);
        mBorderPaint.setStrokeWidth(mBorderWidth);

        mFillPaint.setStyle(Paint.Style.FILL);
        mFillPaint.setAntiAlias(true);
        mFillPaint.setColor(mFillColor);

        mBitmapHeight = mBitmap.getHeight();
        mBitmapWidth = mBitmap.getWidth();

        mBorderRect.set(calculateBounds());
        mBorderRadius = Math.min((mBorderRect.height() - mBorderWidth) / 2.0f, (mBorderRect.width() - mBorderWidth) / 2.0f);

        mDrawableRect.set(mBorderRect);
        if (!mBorderOverlay && mBorderWidth > 0) {
            mDrawableRect.inset(mBorderWidth - 1.0f, mBorderWidth - 1.0f);
        }
        mDrawableRadius = Math.min(mDrawableRect.height() / 2.0f, mDrawableRect.width() / 2.0f);

        applyColorFilter();
        updateShaderMatrix();
        invalidate();
    }

    private RectF calculateBounds() {
        int availableWidth  = getWidth() - getPaddingLeft() - getPaddingRight();
        int availableHeight = getHeight() - getPaddingTop() - getPaddingBottom();

        int sideLength = Math.min(availableWidth, availableHeight);

        float left = getPaddingLeft() + (availableWidth - sideLength) / 2f;
        float top = getPaddingTop() + (availableHeight - sideLength) / 2f;

        return new RectF(left, top, left + sideLength, top + sideLength);
    }

    private void updateShaderMatrix() {
        float scale;
        float dx = 0;
        float dy = 0;

        mShaderMatrix.set(null);

        if (mBitmapWidth * mDrawableRect.height() > mDrawableRect.width() * mBitmapHeight) {
            scale = mDrawableRect.height() / (float) mBitmapHeight;
            dx = (mDrawableRect.width() - mBitmapWidth * scale) * 0.5f;
        } else {
            scale = mDrawableRect.width() / (float) mBitmapWidth;
            dy = (mDrawableRect.height() - mBitmapHeight * scale) * 0.5f;
        }

        mShaderMatrix.setScale(scale, scale);
        mShaderMatrix.postTranslate((int) (dx + 0.5f) + mDrawableRect.left, (int) (dy + 0.5f) + mDrawableRect.top);

        mBitmapShader.setLocalMatrix(mShaderMatrix);
    }

}

夜间模式

关于夜间模式的实现是在我开发过程中遇到的一个比较大坑，但我们都知道夜间模式是一款APP应该具备的，通过我最近的了解，总结出了两种实现方式。一是定义两套主题，对每一个需要实现夜间模式的控件都另外定义一套夜间主题，但这样子工程量大，我是一个人开发的，所以并没有采用这种方式；二是调用开源框架。

Light_Style + Night_Style实现夜间模式

自定义换肤的实现

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