前言：让生活每天都充满憧憬，而不是日复一日的重复，学会用孩子的眼光看待这个世界。

效果图

现象： 下拉中间的白色的按钮没有反应。正常情况下下拉是可以的。 这个控件的触摸事件没有反应。通过对系统app SystemUI的学习，了解到这个控件叫做DividerView，属于多窗口模式下的一个分割两个Activity的view组件 code在

Z:\frameworks\base\packages\SystemUI\src\com\android\systemui\stackdivider

从布局文件

<com.android.systemui.stackdivider.DividerView xmlns:android="http://schemas.android.com/apk/res/android" android:layout_height="match_parent" android:layout_width="match_parent"> <View style="@style/DockedDividerBackground" android:id="@+id/docked_divider_background" android:background="@color/docked_divider_background"/> <com.android.systemui.stackdivider.MinimizedDockShadow style="@style/DockedDividerMinimizedShadow" android:id="@+id/minimized_dock_shadow" android:alpha="0"/>"> <com.android.systemui.stackdivider.DividerHandleView style="@style/DockedDividerHandle" android:id="@+id/docked_divider_handle" android:contentDescription="@string/accessibility_divider" android:background="@null"/> </com.android.systemui.stackdivider.DividerView>

得出这DividerView（分割线的黑色部分）、DividerHandleView(f分割线的白色部分)一个相当于ViewGroup(onTouchEvent、dispatchTouchEvent、onInterceptTouchEvent)，一个是View（onTouchEvent、dispatchTouchEvent）。 看一下code

/** * View for the handle in the docked stack divider. */ public class DividerHandleView extends View{ ... @Override public boolean onTouchEvent(MotionEvent event) { // TODO Auto-generated method stub Log.d("elliotlog","DividerHandleView onTouchEvent"); return super.onTouchEvent(event); } @Override public boolean dispatchTouchEvent(MotionEvent event) { // TODO Auto-generated method stub Log.d("elliotlog","DividerHandleView dispatchTouchEvent"); return super.dispatchTouchEvent(event); } ... } public class DividerView extends FrameLayout implements OnTouchListener{ ... @Override public boolean onTouchEvent(MotionEvent event) { // TODO Auto-generated method stub Log.d("elliotlog","DividerView onTouchEvent"); return onTouch(mHandle,event); } @Override public boolean onInterceptTouchEvent(MotionEvent ev) { // TODO Auto-generated method stub Log.d("elliotlog","DividerView onInterceptTouchEvent"); return super.onInterceptTouchEvent(ev); } @Override public boolean dispatchTouchEvent(MotionEvent ev) { // TODO Auto-generated method stub Log.d("elliotlog","DividerView dispatchTouchEvent"); boolean flag=super.dispatchTouchEvent(ev); if(flag){Log.d("elliotlog","is DividerView dispatchTouchEvent");}else{Log.d("elliotlog","not DividerView dispatchTouchEvent");} return flag; } //拖拽效果实现会调用的方法 public boolean onTouch(View v, MotionEvent event) { Log.d("elliotlog","onTouch"); convertToScreenCoordinates(event); mGestureDetector.onTouchEvent(event); final int action = event.getAction() & MotionEvent.ACTION_MASK switch (action) { case MotionEvent.ACTION_DOWN: Log.d("elliotlog","MotionEvent.ACTION_DOWN:"+MotionEvent.ACTION_DOWN); mVelocityTracker = VelocityTracker.obtain(); mVelocityTracker.addMovement(event); mStartX = (int) event.getX(); mStartY = (int) event.getY(); boolean result = startDragging(true /* animate */, true /* touching */); if (!result) { // Weren't able to start dragging successfully, so cancel it again. stopDragging(); } mStartPosition = getCurrentPosition(); mMoving = false; return result; case MotionEvent.ACTION_MOVE: Log.d("elliotlog","MotionEvent.ACTION_MOVE:"+MotionEvent.ACTION_MOVE); mVelocityTracker.addMovement(event); int x = (int) event.getX(); int y = (int) event.getY(); boolean exceededTouchSlop = isHorizontalDivision() && Math.abs(y - mStartY) > mTouchSlop || (!isHorizontalDivision() && Math.abs(x - mStartX) > mTouchSlop); if (!mMoving && exceededTouchSlop) { mStartX = x; mStartY = y; mMoving = true; } if (mMoving && mDockSide != WindowManager.DOCKED_INVALID) { SnapTarget snapTarget = mSnapAlgorithm.calculateSnapTarget( mStartPosition, 0 /* velocity */, false /* hardDismiss */); resizeStack(calculatePosition(x, y), mStartPosition, snapTarget); } break; case MotionEvent.ACTION_UP: case MotionEvent.ACTION_CANCEL: Log.d("elliotlog","MotionEvent.ACTION_UP:"+MotionEvent.ACTION_UP); mVelocityTracker.addMovement(event); x = (int) event.getRawX(); y = (int) event.getRawY(); mVelocityTracker.computeCurrentVelocity(1000); int position = calculatePosition(x, y); stopDragging(position, isHorizontalDivision() ? mVelocityTracker.getYVelocity() : mVelocityTracker.getXVelocity(), false /* avoidDismissStart */, true /* log */); mMoving = false; break; } return true; } ... }

点击DividerHandleView，并且尝试向下滑动。log打印如下

03-02 04:38:33.973 D/elliotlog( 1403): DividerView dispatchTouchEvent 03-02 04:38:33.973 D/elliotlog( 1403): DividerView onTouchEvent 03-02 04:38:33.973 D/elliotlog( 1403): not DividerView dispatchTouchEvent 03-02 04:38:35.030 D/elliotlog( 1403): DividerView dispatchTouchEvent 03-02 04:38:35.030 D/elliotlog( 1403): DividerView onTouchEvent 03-02 04:38:35.030 D/elliotlog( 1403): not DividerView dispatchTouchEvent

会发现连onInterceptTouchEvent事件都没有执行。而是DividerView分发了之后就直接自己消费掉了onTouchEvent。

这显然不符合我们正常的逻辑，当我们不复现这个bug时，会发现打印的很正常

03-02 06:00:31.919 D/elliotlog( 1397): DividerView dispatchTouchEvent 03-02 06:00:31.919 D/elliotlog( 1397): DividerView onInterceptTouchEvent 03-02 06:00:31.919 D/elliotlog( 1397): DividerHandleView dispatchTouchEvent 03-02 06:00:31.920 D/elliotlog( 1397): onTouch 03-02 06:00:31.920 D/elliotlog( 1397): MotionEvent.ACTION_DOWN:0 03-02 06:00:31.922 D/elliotlog( 1397): is DividerView dispatchTouchEvent 03-02 06:00:32.045 D/elliotlog( 1397): DividerView dispatchTouchEvent 03-02 06:00:32.045 D/elliotlog( 1397): DividerView onInterceptTouchEvent 03-02 06:00:32.045 D/elliotlog( 1397): DividerHandleView dispatchTouchEvent 03-02 06:00:32.045 D/elliotlog( 1397): onTouch 03-02 06:00:32.046 D/elliotlog( 1397): MotionEvent.ACTION_MOVE:2

首先是DividerView dispatchTouchEvent，然后内部会调用onInterceptTouchEvent，于是子View DividerHandleView会分发dispatchTouchEvent，view是没有onInterceptTouchEvent，即不会拦截 ，内部会调用 OnTouchListener的onTouch，上面贴的代码中这个方法返回了ture。消费了，所以子view的onTouchEvent方法不会执行了。

回到原点，我们还是要分析错误的情况。 我们发现，在Divider.java中存在这样的一个监听接口，

class DockDividerVisibilityListener extends IDockedStackListener.Stub { ... @Override public void onAdjustedForImeChanged(boolean adjustedForIme, long animDuration) throws RemoteException { mView.post(() -> { if (mAdjustedForIme != adjustedForIme) { mAdjustedForIme = adjustedForIme; updateTouchable(); if (!mMinimized) { if (animDuration > 0) { mView.setAdjustedForIme(adjustedForIme, animDuration); } else { mView.setAdjustedForIme(adjustedForIme); } } } }); } ... } private void updateTouchable() { mWindowManager.setTouchable(!mMinimized && !mAdjustedForIme); }

也就说当Divider最小化，或者需要调整（如出现输入法时）会设为不可触摸（由framework层控制），这就出现了刚才的分发机制不符合规矩的做法，从而出现这个bug。

着个监听器是如何注册的 在Divider.java（SystemUI）

SystemServicesProxy ssp = Recents.getSystemServices(); ssp.registerDockedStackListener(mDockDividerVisibilityListener);

在SystemServicesProxy.java中（SystemUI）

public void registerDockedStackListener(IDockedStackListener listener) { if (mWm == null) return; try { WindowManagerGlobal.getWindowManagerService().registerDockedStackListener(listener); } catch (Exception e) { e.printStackTrace(); } }

在WindowManagerService.java(framework)

@Override public void registerDockedStackListener(IDockedStackListener listener) { if (!checkCallingPermission(android.Manifest.permission.REGISTER_WINDOW_MANAGER_LISTENERS, "registerDockedStackListener()")) { return; } // TODO(multi-display): The listener is registered on the default display only. getDefaultDisplayContentLocked().mDividerControllerLocked.registerDockedStackListener( listener); }

在DockedStackDividerController.java

void registerDockedStackListener(IDockedStackListener listener) { mDockedStackListeners.register(listener); notifyDockedDividerVisibilityChanged(wasVisible()); notifyDockedStackExistsChanged( mDisplayContent.mService.mStackIdToStack.get(DOCKED_STACK_ID) != null); notifyDockedStackMinimizedChanged(mMinimizedDock, 0 /* animDuration */); notifyAdjustedForImeChanged(mAdjustedForIme, 0 /* animDuration */); }

notifyAdjustedForImeChanged

void notifyAdjustedForImeChanged(boolean adjustedForIme, long animDuration) { final int size = mDockedStackListeners.beginBroadcast(); for (int i = 0; i < size; ++i) { final IDockedStackListener listener = mDockedStackListeners.getBroadcastItem(i); try { listener.onAdjustedForImeChanged(adjustedForIme, animDuration); } catch (RemoteException e) { Slog.e(TAG_WM, "Error delivering adjusted for ime changed event.", e); } } mDock

这里面完成了注册