当消息获取模块通过pipe将消息传递到客户端

由native调用InputEventReceiver的dispatchInputEvent

// Called from native code.
    @SuppressWarnings("unused")
    private void dispatchInputEvent(int seq, InputEvent event) {
        mSeqMap.put(event.getSequenceNumber(), seq);
        // MIUI ADD: START
        if (android.os.AnrMonitor.isAllowedMonitorInput(Looper.myLooper())) {
            android.os.AnrMonitor.dispatchInputEventStart(event);
        }
        // END
        onInputEvent(event);
    }

而在ViewRootImp中的WindowInputEventReceiver中:

final class WindowInputEventReceiver extends InputEventReceiver {
        public WindowInputEventReceiver(InputChannel inputChannel, Looper looper) {
            super(inputChannel, looper);
        }

        @Override
        public void onInputEvent(InputEvent event) {
            enqueueInputEvent(event, this, 0, true);
        }

     ...
    }

然后发送消息MSG_PROCESS_INPUT_EVENTS, 然后调deliverInputEvent, 调用
stage.deliver(q);

// Set up the input pipeline.
                CharSequence counterSuffix = attrs.getTitle();
                mSyntheticInputStage = new SyntheticInputStage();
                InputStage viewPostImeStage = new ViewPostImeInputStage(mSyntheticInputStage);
                InputStage nativePostImeStage = new NativePostImeInputStage(viewPostImeStage,
                        "aq:native-post-ime:" + counterSuffix);
                InputStage earlyPostImeStage = new EarlyPostImeInputStage(nativePostImeStage);
                InputStage imeStage = new ImeInputStage(earlyPostImeStage,
                        "aq:ime:" + counterSuffix);
                InputStage viewPreImeStage = new ViewPreImeInputStage(imeStage);
                InputStage nativePreImeStage = new NativePreImeInputStage(viewPreImeStage,
                        "aq:native-pre-ime:" + counterSuffix);

                mFirstInputStage = nativePreImeStage;
                mFirstPostImeInputStage = earlyPostImeStage;

在EarlyPostImeInputStage中, onProcess中:

@Override
        protected int onProcess(QueuedInputEvent q) {
            if (q.mEvent instanceof KeyEvent) {
                return processKeyEvent(q);
            } else {
                final int source = q.mEvent.getSource();
                if ((source & InputDevice.SOURCE_CLASS_POINTER) != 0) {
                    return processPointerEvent(q);
                }
            }
            return FORWARD;
        }

processPointerEvent:

private int processPointerEvent(QueuedInputEvent q) {
            final MotionEvent event = (MotionEvent)q.mEvent;

            // Translate the pointer event for compatibility, if needed.
            if (mTranslator != null) {
                mTranslator.translateEventInScreenToAppWindow(event);
            }

            // Enter touch mode on down or scroll.
            final int action = event.getAction();
            if (action == MotionEvent.ACTION_DOWN || action == MotionEvent.ACTION_SCROLL) {
                ensureTouchMode(true);
            }

            // Offset the scroll position.
            if (mCurScrollY != 0) {
                event.offsetLocation(0, mCurScrollY);
            }

            // Remember the touch position for possible drag-initiation.
            if (event.isTouchEvent()) {
                mLastTouchPoint.x = event.getRawX();
                mLastTouchPoint.y = event.getRawY();
                mLastTouchSource = event.getSource();
            }
            return FORWARD;
        }
    }

终于调到processPointerEvent, 如果是Down消息,调用ensureTouchMode(true)函数进入触摸模式. 然后将屏幕坐标转换为视图坐标.
在ViewPostImeInputStage的processPointerEvent中有:

final View eventTarget =
                    (event.isFromSource(InputDevice.SOURCE_MOUSE) && mCapturingView != null) ?
                            mCapturingView : mView;
            mAttachInfo.mHandlingPointerEvent = true;
            boolean handled = eventTarget.dispatchPointerEvent(event);

在View的dispatchPointerEvent中有:

  public final boolean dispatchPointerEvent(MotionEvent event) {
        if (event.isTouchEvent()) {
            return dispatchTouchEvent(event);
        } else {
            return dispatchGenericMotionEvent(event);
        }
    }

而在DecorView中的dispatchTouchEvent中有:

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

先判断是否有回调,如果有就执行回调,如果没有回调,就执行FrameLayout的dispatchTouchEvent.