先上流程图

WindowInputEventReceiver
WindowInputEventReceiver为InputEventReceiver的子类
是接收InputManagerService派发事件的APP端，在InputEventReceiver.cpp 中可以看到 接收到input事件后回调Java层的dispatchInputEvent 即 InputEventReceiver的dispatchInputEvent 方法，dispatchInputEvent 调用onInputEvent方法，
onInputEvent进行重写，即调用WindowInputEventReceiver的onInputEvent

InputEventReceiver.cppstatus_t NativeInputEventReceiver::consumeEvents(JNIEnv* env,bool consumeBatches, nsecs_t frameTime, bool* outConsumedBatch) {//........if (inputEventObj) {if (kDebugDispatchCycle) {ALOGD("channel '%s' ~ Dispatching input event.", getInputChannelName());}//回调Java层dispatchInputEvent env->CallVoidMethod(receiverObj.get(),gInputEventReceiverClassInfo.dispatchInputEvent, seq, inputEventObj);//.............}
}InputEventReceiver.javaprivate void dispatchInputEvent(int seq, InputEvent event, int displayId) {mSeqMap.put(event.getSequenceNumber(), seq);onInputEvent(event, displayId);}

WindowInputEventReceiver的onInputEvent调用

ViewRootImpl的enqueueInputEvent -->doProcessInputEvents-->deliverInputEvent

在deliverInputEvent方法内进行 InputStage的链式调用如下

//WindowInputEventReceiver 继承于 InputEventReceiver
final class WindowInputEventReceiver extends InputEventReceiver {public WindowInputEventReceiver(InputChannel inputChannel, Looper looper) {super(inputChannel, looper);}@Overridepublic void onInputEvent(InputEvent event, int displayId) {enqueueInputEvent(event, this, 0, true);}
}void enqueueInputEvent(InputEvent event,InputEventReceiver receiver, int flags, boolean processImmediately) {....doProcessInputEvents();....}void doProcessInputEvents() {....deliverInputEvent(q);....}private void deliverInputEvent(QueuedInputEvent q) {InputStage stage;if (q.shouldSendToSynthesizer()) {stage = mSyntheticInputStage;} else {stage = q.shouldSkipIme() ? mFirstPostImeInputStage : mFirstInputStage;}if (q.mEvent instanceof KeyEvent) {mUnhandledKeyManager.preDispatch((KeyEvent) q.mEvent);}if (stage != null) {handleWindowFocusChanged();//InputStage 进行链式调用//层层过滤,如果不处理交则给下一个(FORWARD)，处理则返回FINISH_HANDLEstage.deliver(q);} else {finishInputEvent(q);}
}

InputStage 

ViewPostImeInputStage是将InputEvent分发到View层的实现所在 onProcess 方法如下

  final class ViewPostImeInputStage extends InputStage {.......@Overrideprotected int onProcess(QueuedInputEvent q) {if (q.mEvent instanceof KeyEvent) {//处理按键事件return processKeyEvent(q);} else {final int source = q.mEvent.getSource();if ((source & InputDevice.SOURCE_CLASS_POINTER) != 0) {//处理指针事件 （触摸或者鼠标等输入设备）return processPointerEvent(q);} else if ((source & InputDevice.SOURCE_CLASS_TRACKBALL) != 0) {//轨迹球事件return processTrackballEvent(q);} else {//其他return processGenericMotionEvent(q);}}}......
}private int processPointerEvent(QueuedInputEvent q) {//.....//调用View层分发  这里的mView 为boolean handled = mView.dispatchPointerEvent(event);.....return handled ? FINISH_HANDLED : FORWARD;}

processPointerEvent 调用了mView层的dispatchPointerEvent分发, 这里的mView 为DecorView

DecorView 的dispatch方法会先调用Window.CallBack 或者KeyEvent.CallBack在进行View层的分发,

这里的Widow.CallBack的实现有Activity， Dialog等 先回调 Window.CallBack如果 返回false不处理则进行View层分发

DecorView.java@Overridepublic boolean dispatchTouchEvent(MotionEvent ev) {final Window.Callback cb = mWindow.getCallback();return cb != null && !mWindow.isDestroyed() && mFeatureId < 0? cb.dispatchTouchEvent(ev) : super.dispatchTouchEvent(ev);}

此后就是我们熟悉的View或ViewGroup的dispatchTouchEvent相关流程了

例如 ViewGroup判断 point的X，Y在那个子控件内，命中子控件后，再调用子控件的dispatchTouchEvent

如果命中的子控件不处理（比如setClickable(false)），或没有命中 则调用自身的dispatchTouchEvent