仿微信右滑销毁Activity

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一直想自己实现Activity的侧滑销毁，无奈在finish activity的时候遇到了瓶颈。今天看到一个开源库，那哥们把Activity的背景设置成了透明，这才恍然大悟。这里share一下。

大体思路讲解：

• 1.获取Activity的DecorView
• 2.自定义布局，重写onInterceptTouchEvent与onTouchEvent函数对触摸事件进行处理，根据手势滑动对DecorView(内容)进行滑动
• 3.根据滑动的距离判断是销毁当前的Activity还是滑动恢复到原来位置

知识储备：

• Android事件分发，请看我这篇博文
• Activity、Window、DecorView讲解，请看这里
• Scroller详解，请看xiaanming大神的博文

贴出核心类

public class SlidingFinishLayout extends FrameLayout {    private Scroller mScroller;      private int mTouchSlop;      private ViewGroup parentView;      private int screenWidth;      private int last_x;      private int last_y;    private int delay_x;    private int delay_y;    private boolean isFinish = false;    private Activity mActivity;    private SlidingFinishLayout.OnActivityFinishListener onActivityFinish;    public SlidingFinishLayout(Context context, AttributeSet attrs) {        super(context, attrs);        mScroller = new Scroller(context);        mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();    }    public void attachActivity(Activity activity) {        this.mActivity = activity;    }    public void detachActivity() {        if (this.mActivity != null) {            mActivity = null;        }    }    @Override    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {        super.onLayout(changed, left, top, right, bottom);        if (changed) {            ViewGroup decor = (ViewGroup) mActivity.getWindow().getDecorView();            mActivity.getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));            mActivity.getWindow().getDecorView().setBackgroundColor(Color.TRANSPARENT);            View decorChild = decor.findViewById(android.R.id.content);            while (decorChild.getParent() != decor) {                decorChild = (View) decorChild.getParent();            }            parentView = decor;            screenWidth = getWidth();        }    }    /**     * 进行事件拦截     *     * @param ev     * @return     */    @Override    public boolean onInterceptTouchEvent(MotionEvent ev) {        boolean isIntercept = false;        switch (ev.getAction()) {            case MotionEvent.ACTION_DOWN:                last_x = (int) ev.getRawX();                last_y = (int) ev.getRawY();                break;            case MotionEvent.ACTION_MOVE:                int current_x = (int) ev.getRawX();                int current_y = (int) ev.getRawY();                delay_x = current_x - last_x;                delay_y = current_y - last_y;                if ((Math.abs(delay_x) / (Math.abs(delay_y) + 1) >= 2)) { //30度角的时候才开始拦截事件                    isIntercept = true;                }                break;            case MotionEvent.ACTION_UP:                break;        }        return isIntercept;    }    /**     * 进行事件处理     *     * @param ev     * @return     */    @Override    public boolean onTouchEvent(MotionEvent ev) {        switch (ev.getAction()) {            case MotionEvent.ACTION_DOWN:                last_x = (int) ev.getRawX();                last_y = (int) ev.getRawY();                break;            case MotionEvent.ACTION_MOVE:                int current_x = (int) ev.getRawX();                int current_y = (int) ev.getRawY();                delay_x = current_x - last_x;                delay_y = current_y - last_y;                if (Math.abs(delay_x) > mTouchSlop) {                    if ((Math.abs(delay_x) / (Math.abs(delay_y) + 1) >= 2)) { //30度角的时候才开始处理事件                        parentView.scrollBy(-delay_x, 0); //开始滑动                    } else {                        return false;                    }                } else {                    return false;                }                last_x = current_x;                last_y = current_y;                break;            case MotionEvent.ACTION_UP:                if (Math.abs(parentView.getScrollX()) > (screenWidth / 3)) { //如果滑动距离超出屏幕三分之一，则进行滑动销毁，否则恢复原位                    scrollFinish();                } else {                    scrollOriginal();                }                break;        }        return true;    }    /**     * 滑动销毁     */    private void scrollFinish() {        final int delta = (screenWidth + parentView.getScrollX());        mScroller.startScroll(parentView.getScrollX(), 0, -delta + 1, 0);        postInvalidate();        isFinish = true;    }    /**     * 恢复到原始状态     */    private void scrollOriginal() {        mScroller.startScroll(parentView.getScrollX(), 0, -parentView.getScrollX(), 0);        postInvalidate();        isFinish = false;    }    /**     * Activity销毁的时候通知回调     *     * @param onActivityFinish     */    public void setOnActivityFinishListener(SlidingFinishLayout.OnActivityFinishListener onActivityFinish) {        this.onActivityFinish = onActivityFinish;    }    @Override    public void computeScroll() {        if (mScroller.computeScrollOffset()) {            parentView.scrollTo(mScroller.getCurrX(), mScroller.getCurrY());            postInvalidate();            if (mScroller.isFinished() && isFinish) {                onActivityFinish.onActivityFinish();            }        }    }
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在希望右滑销毁的Activity中使用

public class SlideFinishActivity extends AppCompatActivity implements SlidingFinishLayout.OnActivityFinishListener {    SlidingFinishLayout sf_test;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_slide_finish);        sf_test = (SlidingFinishLayout) findViewById(R.id.sf_test);        sf_test.setOnActivityFinishListener(this); //设置销毁的监听器        sf_test.attachActivity(this);    }    @Override    protected void onDestroy() {        super.onDestroy();        sf_test.detachActivity();    }    @Override    public void onActivityFinish() {        finish();    }}
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注意，该Activity的Style文件应该加入下面代码才可以生效 Android:windowIsTranslucent。本代码是把Activity设置成透明状态

收工。
项目源码：https://github.com/WillSprint/SlideFinish

推荐一个侧滑库，本博客中的一些思想来源于该作者
https://github.com/Jude95/SwipeBackHelper