在InputReader从EventHub中获取输入事件,包含触摸屏事件、物理按键事件等,然后转交给InputDispatcher线程,InputDispatcher经过筛选,过滤输入事件。对于触摸事件通过调用findTouchedWindowTargetsLocked()函数找到合适的InputTarget,然后通过dispatchEventLocked()->prepareDispatchCycleLocked()->enqueueDispatchEntriesLocked()->enqueueDispatchEntryLocked()-> connection->outboundQueue.enqueueAtTail(dispatchEntry)添加到与InputTarget一一对应的connection中的一个队列中。如果之前该队列无数据,并且当前触摸事件已成功加入该队列,则继续调用startDispatchCycleLocked()函数进行分发处理。在startDispatchCycleLocked()中,有一个while循环,该循环从connection->outboundQueue队列中取出输入事件,如果该输入事件是按键(key)事件,则调用connection->inputPublisher.publishKeyEvent()函数,如果是触摸事件则调用connection->inputPublisher.publishMotionEvent()。publishKeyEvent()和publishMotionEvent()都是调用mChannel->sendMessage()将输入事件发送出去。mChannel是一个C++层InputChannel对象,该对象的赋值过程如下:registerInputChannel()->new Connection->Connection()构造函数->InputPublisher()构造函数。事实上,在registerInputChannel()被调用之前,ViewRootImple在增加一个窗口时调用ViewRootImpl.setView()->mWindowSession.addToDisplay()-WindowManagerService.addWindow(),在addWindow()中会创建一对InputChannel(Nativie层),实际上是创建一对Socket,服务端InputChanel被WMS注册到InputDispatcher中,客户端InputChannel被返回给ViewRootImpl,ViewRootImpl将客户端InputChannel作为参数new一个InputEventReceiver对象,在InputEventReceiver()构造函数中继续调用nativeInit()函数来创建一个native层的NativeInputEventReceiver对象,前面创建的客户端InputChannel会保存在该对象中。
总结:WMS会调用native层接口创建一对套接字,服务端保存在InputDispatcher中,客户端保存在NativeInputEventReceiver中(android_view_inputEventReceiver.cpp)。
很容易想到输入事件是从InputDispatcher流向NativeInputEventReceiver中。在创建一个native层的NativeInputEventReceiver对象后会立即调用NativeInputEventReceiver->initialize(),该函数调用mMessageQueue->getLooper()->addFd(fd,0,
events, this, NULL)将客户端socket句柄添加到Looper的轮询队列中,参数this指向NativeInputEventReceiver本身,意味着只要服务端InputDispatcher发送输入事件,客户端收到这个事件,就调用NativeInputEventReceiver的某个函数,具体调用哪个函数,自然是NativeInputEventReceiver实现了LooperCallback的接口函数handleEvent()。但此时收到的事件只是代表socket客户端有事件来,并没有把具体的事件读取出来,这点需要注意。
总结:客户端收到输入事件,即调用NativeInputEventReceiver->handleEvent()函数。
在handleEvent()函数中,继续调用consumeEvents()->mInputConsumer.consume()->mChannel->receiveMessage(&mMsg)将具体输入事件读取出来,然后调用env->CallVoidMethod(receiverObj.get(), gInputEventReceiverClassInfo.dispatchInputEvent,seq,
inputEventObj),可以知道native层读取输入事件后,然后会回调java层InputEventReceiver.java中的dispatchInputEvent()函数。事实上,
dispatchInputEvent继续调用onInputEvent(event);
此时可能并不调用InputEventReceiver类中的onInputEvent()方法,而是调用子类onInputEvent()方法。在
ViewRootImpl中存在WindowInputEventReceiver类型变量
mInputEventReceiver,WindowInputEventReceiver类继承InputEventReceiver,并实现
onInputEvent()方法由此可得出结论:native层socket客户端读取输入事件,最终调用InputEventReceiver类子类
的onInputEvent()方法,ViewRootImpl继承InputEventReceiver,因此
ViewRootImpl.onInputEvent()将被调用。
总结:对于一般的触摸屏事件最终处理者是ViewRootImpl类,对于输入法则处理者是IInputMethodSessionWrapper类,当然WMS是不会处理这些输入事件的。
继
续研究ViewRootImpl.onInputEvent()函
数,onInputEvent()->doProcessInputEvents()->deliverInputEvent(),deliverInputEvent()
函数中会调用stage.deliver(q),stage是mFirstPostImeInputStage
或 mFirstInputStage,这个两个InputStage对象在setView中赋值。InputStage类设计就是责任链模式。因为触摸事件是要分发到具体的View上来,所以对于一般的触摸事件最后是传递到ViewPostImeInputStage类中来处理,处理函数是processPointerEvent(q),这个函数调用mView.dispatchPointerEvent(event)将事件分发出去,mView具体是什么呢?mView其实就是DecorView,每一个窗口有且仅有一个DecorView,且处在最顶层,由于DecorView未重写dispatchPointerEvent(),所以调用还是父类View类的dispatchPointerEvent()方法。
[java] view plaincopy
- public final boolean dispatchPointerEvent(MotionEvent event) {
- if (event.isTouchEvent()) {
- return dispatchTouchEvent(event);
- } else {
- return dispatchGenericMotionEvent(event);
- }
- }
该方法继续调用dispatchTouchEvent(event),DecorView重新了该方法:
[java] view plaincopy
- @Override
- public boolean dispatchTouchEvent(MotionEvent ev) {
- final Callback cb = getCallback();
- return cb != null && !isDestroyed() && mFeatureId < 0 ? cb.dispatchTouchEvent(ev)
- : super.dispatchTouchEvent(ev);
- }
getCallback()
函数获取apk注册的用于拦截按键、触摸等事件的回调函数。一般window不会拦截处理触摸事件,所以会继续调用
super.dispatchTouchEvent(ev),即父类ViewGroup的dispatchTouchEvent()函数,在该函数中寻找
到对应的View再继续调用dispatchTransformedTouchEvent()
[java] view plaincopy
- for (int i = childrenCount - 1; i >= 0; i--) {
- final int childIndex = customOrder ?
- getChildDrawingOrder(childrenCount, i) : i;
- final View child = children[childIndex];
- if (!canViewReceivePointerEvents(child)
- || !isTransformedTouchPointInView(x, y, child, null)) {
- continue;
- }
- newTouchTarget = getTouchTarget(child);
- if (newTouchTarget != null) {
- // Child is already receiving touch within its bounds.
- // Give it the new pointer in addition to the ones it is handling.
- newTouchTarget.pointerIdBits |= idBitsToAssign;
- break;
- }
- resetCancelNextUpFlag(child);
- if (dispatchTransformedTouchEvent(ev, false, child, idBitsToAssign)) {
- // Child wants to receive touch within its bounds.
- mLastTouchDownTime = ev.getDownTime();
- mLastTouchDownIndex = childIndex;
- mLastTouchDownX = ev.getX();
- mLastTouchDownY = ev.getY();
- newTouchTarget = addTouchTarget(child, idBitsToAssign);
- alreadyDispatchedToNewTouchTarget = true;
- break;
- }
具体的分发规则可自行研究代码。
ViewGroup.dispatchTouchEvent()函数分析
[html] view plaincopy
- @Override
- public boolean dispatchTouchEvent(MotionEvent ev) {
- if (mInputEventConsistencyVerifier != null) {
- mInputEventConsistencyVerifier.onTouchEvent(ev, 1);
- }
- if (DBG_MOTION || DBG_TOUCH) {
- Xlog.d(TAG, "(ViewGroup)dispatchTouchEvent 1: ev = " + ev + ",mFirstTouchTarget = "
- + mFirstTouchTarget + ",this = " + this);
- }
- boolean handled = false;
- if (onFilterTouchEventForSecurity(ev)) {
- final int action = ev.getAction();
- final int actionMasked = action & MotionEvent.ACTION_MASK;
- // Handle an initial down.
- if (actionMasked == MotionEvent.ACTION_DOWN) {
- // Throw away all previous state when starting a new touch gesture.
- // The framework may have dropped the up or cancel event for the previous gesture
- // due to an app switch, ANR, or some other state change.
- cancelAndClearTouchTargets(ev);
- resetTouchState();
- }
- // Check for interception.
- final boolean intercepted;
- if (actionMasked == MotionEvent.ACTION_DOWN
- || mFirstTouchTarget != null) {
- final boolean disallowIntercept = (mGroupFlags & FLAG_DISALLOW_INTERCEPT) != 0;
- if (!disallowIntercept) {
- intercepted = onInterceptTouchEvent(ev);
- /// M : add log to help debugging
- if (intercepted == true) {
- if (DBG_TOUCH) {
- Xlog.d(TAG, "Touch event was intercepted event = " + ev + ",this = " + this);
- }
- }
- ev.setAction(action); // restore action in case it was changed
- } else {
- intercepted = false;
- }
- } else {
- // There are no touch targets and this action is not an initial down
- // so this view group continues to intercept touches.
- intercepted = true;
- }
- // Check for cancelation.
- final boolean canceled = resetCancelNextUpFlag(this)
- || actionMasked == MotionEvent.ACTION_CANCEL;
- // Update list of touch targets for pointer down, if needed.
- final boolean split = (mGroupFlags & FLAG_SPLIT_MOTION_EVENTS) != 0;
- if (DBG_MOTION) {
- Xlog.d(TAG, "(ViewGroup)dispatchTouchEvent 2: actionMasked = " + actionMasked
- + ",intercepted = " + intercepted + ",canceled = " + canceled + ",split = "
- + split + ",mChildrenCount = " + mChildrenCount + ",mFirstTouchTarget = "
- + mFirstTouchTarget + ",this = " + this);
- }
- TouchTarget newTouchTarget = null;
- boolean alreadyDispatchedToNewTouchTarget = false;
- if (!canceled && !intercepted) {
- if (actionMasked == MotionEvent.ACTION_DOWN
- || (split && actionMasked == MotionEvent.ACTION_POINTER_DOWN)
- || actionMasked == MotionEvent.ACTION_HOVER_MOVE) {
- final int actionIndex = ev.getActionIndex(); // always 0 for down
- final int idBitsToAssign = split ? 1 << ev.getPointerId(actionIndex)
- : TouchTarget.ALL_POINTER_IDS;
- // Clean up earlier touch targets for this pointer id in case they
- // have become out of sync.
- removePointersFromTouchTargets(idBitsToAssign);
- final int childrenCount = mChildrenCount;
- if (newTouchTarget == null && childrenCount != 0) {
- final float x = ev.getX(actionIndex);
- final float y = ev.getY(actionIndex);
- // Find a child that can receive the event.
- // Scan children from front to back.
- final View[] children = mChildren;
- final boolean customOrder = isChildrenDrawingOrderEnabled();
- for (int i = childrenCount - 1; i >= 0; i--) {
- final int childIndex = customOrder ?
- getChildDrawingOrder(childrenCount, i) : i;
- final View child = children[childIndex];
- if (!canViewReceivePointerEvents(child)
- || !isTransformedTouchPointInView(x, y, child, null)) {
- if (DBG_MOTION) {
- Xlog.d(TAG, "(ViewGroup)dispatchTouchEvent continue 6: i = "
- + i + ",count = " + childrenCount + ",child = " + child
- + ",this = " + this);
- }
- continue;
- }
- newTouchTarget = getTouchTarget(child);
- if (DBG_MOTION) {
- Xlog.d(TAG, "(ViewGroup)dispatchTouchEvent to child 3: child = "
- + child + ",childrenCount = " + childrenCount + ",i = " + i
- + ",newTouchTarget = " + newTouchTarget + ",idBitsToAssign = "
- + idBitsToAssign + ",mFirstTouchTarget = " + mFirstTouchTarget
- + ",this = " + this);
- }
- if (newTouchTarget != null) {
- // Child is already receiving touch within its bounds.
- // Give it the new pointer in addition to the ones it is handling.
- newTouchTarget.pointerIdBits |= idBitsToAssign;
- break;
- }
- resetCancelNextUpFlag(child);
- if (dispatchTransformedTouchEvent(ev, false, child, idBitsToAssign)) {
- // Child wants to receive touch within its bounds.
- mLastTouchDownTime = ev.getDownTime();
- mLastTouchDownIndex = childIndex;
- mLastTouchDownX = ev.getX();
- mLastTouchDownY = ev.getY();
- newTouchTarget = addTouchTarget(child, idBitsToAssign);
- alreadyDispatchedToNewTouchTarget = true;
- break;
- }
- }
- }
- if (newTouchTarget == null && mFirstTouchTarget != null) {
- // Did not find a child to receive the event.
- // Assign the pointer to the least recently added target.
- newTouchTarget = mFirstTouchTarget;
- while (newTouchTarget.next != null) {
- newTouchTarget = newTouchTarget.next;
- }
- newTouchTarget.pointerIdBits |= idBitsToAssign;
- }
- }
- }
- // Dispatch to touch targets.
- if (mFirstTouchTarget == null) {
- // No touch targets so treat this as an ordinary view.
- handled = dispatchTransformedTouchEvent(ev, canceled, null,
- TouchTarget.ALL_POINTER_IDS);
- } else {
- // Dispatch to touch targets, excluding the new touch target if we already
- // dispatched to it. Cancel touch targets if necessary.
- TouchTarget predecessor = null;
- TouchTarget target = mFirstTouchTarget;
- while (target != null) {
- final TouchTarget next = target.next;
- if (alreadyDispatchedToNewTouchTarget && target == newTouchTarget) {
- handled = true;
- } else {
- final boolean cancelChild = resetCancelNextUpFlag(target.child)
- || intercepted;
- if (dispatchTransformedTouchEvent(ev, cancelChild,
- target.child, target.pointerIdBits)) {
- handled = true;
- }
- if (DBG_MOTION) {
- Xlog.d(TAG, "dispatchTouchEvent middle 5: cancelChild = " + cancelChild
- + ",mFirstTouchTarget = " + mFirstTouchTarget + ",target = "
- + target + ",predecessor = " + predecessor + ",next = " + next
- + ",this = " + this);
- }
- if (cancelChild) {
- if (predecessor == null) {
- mFirstTouchTarget = next;
- } else {
- predecessor.next = next;
- }
- target.recycle();
- target = next;
- continue;
- }
- }
- predecessor = target;
- target = next;
- }
- }
- // Update list of touch targets for pointer up or cancel, if needed.
- if (canceled
- || actionMasked == MotionEvent.ACTION_UP
- || actionMasked == MotionEvent.ACTION_HOVER_MOVE) {
- resetTouchState();
- } else if (split && actionMasked == MotionEvent.ACTION_POINTER_UP) {
- final int actionIndex = ev.getActionIndex();
- final int idBitsToRemove = 1 << ev.getPointerId(actionIndex);
- removePointersFromTouchTargets(idBitsToRemove);
- }
- }
- if (DBG_MOTION) {
- Xlog.d(TAG, "(ViewGroup)dispatchTouchEvent end 4: handled = " + handled + ",mFirstTouchTarget = "
- + mFirstTouchTarget + ",this = " + this);
- }
- if (!handled && mInputEventConsistencyVerifier != null) {
- mInputEventConsistencyVerifier.onUnhandledEvent(ev, 1);
- }
- return handled;
- }