在ViewRootImpl的setView方法中。用户的触摸按键消息是体如今窗体上的。而windowManagerService则是管理这些窗体，它一旦接收到用户对窗体的一些触摸按键消息，会进行对应的动作，这样的动作是须要体如今详细的view上面。在Android中。一个详细的界面是由一个Activity呈现的，而Activity中则包括了一个window，此window中又包括了一个phoneWindow。这个phoneWindow才是真正意义上的窗体。它把一个框架布局进行了一定的包装。并提供了详细的窗体操作接口，phoneWindow中包括了一个DecorView，这个view才是包括整个Activity的ui，它将被attach到Activity主窗体中。所以说用户触摸按键的消息是由windowManagerService捕捉到然后交给phoneWindow中的DecorView进行对应的处理。而连接两者的桥梁则是一个ViewRoot类，ViewRoot类由windowManagerService创建，其内部有一个W类。这个W类是一个binder，负责WindowManagerService的ipc调用。W接收到windowManagerService发送过来的消息后。把消息传递给ViewRoot，进而传递给ActivityThread解析做出处理，
1、在ViewRootImpl.java类的setView方法中：
<span style="font-size:14px;"><span style="white-space:pre"> </span>res = mWindowSession.addToDisplay(mWindow, mSeq, mWindowAttributes,
getHostVisibility(), mDisplay.getDisplayId(),mAttachInfo.mContentInsets, mInputChannel);</span>
在这里把mWindow传递给了window，这个mWindow就是W类的一个实例
2、当详细的触摸按键消息发生后，会由ViewRootImpl类中WindowInputEventReceiver这个类的onInputEvent方法负责接收。事实上也就是个回调。
<span style="font-size:14px;"><span style="white-space:pre"> </span>public void onInputEvent(InputEvent event) {
<span style="white-space:pre"> </span> enqueueInputEvent(event, this, 0, true);
<span style="white-space:pre"> </span>}</span>
<span style="font-size:14px;">void enqueueInputEvent(InputEvent event,
InputEventReceiver receiver, int flags, boolean processImmediately) {
QueuedInputEvent q = obtainQueuedInputEvent(event, receiver, flags); // Always enqueue the input event in order, regardless of its time stamp.
// We do this because the application or the IME may inject key events
// in response to touch events and we want to ensure that the injected keys
// are processed in the order they were received and we cannot trust that
// the time stamp of injected events are monotonic.
QueuedInputEvent last = mFirstPendingInputEvent;
if (last == null) {
mFirstPendingInputEvent = q;
} else {
while (last.mNext != null) {
last = last.mNext;
}
last.mNext = q;
} if (processImmediately) {
// 马上处理事件
doProcessInputEvents();
} else {
// 将事件放到队列的最后
scheduleProcessInputEvents();
}
}</span>
在enqueueInputEvent方法中。把event增加到队列的最后面，假设processImmediately为true，则直接调用doProcessInputEvents方法。否则scheduleProcessInputEvents被调用，这两个方法最后都调用了deliverInputEvent方法。用于分发输入事件。在这种方法中推断假设是按键事件，比方说back、home等，就会调用deliverKeyEvent分发事件，一些一般的移动事件调用deliverGenericMotionEvent方法。
<span style="font-size:14px;"> private void deliverInputEvent(QueuedInputEvent q) {
Trace.traceBegin(Trace.TRACE_TAG_VIEW, "deliverInputEvent");
try {
if (q.mEvent instanceof KeyEvent) {
// 假设是按键事件，也就是back、home等按键
deliverKeyEvent(q);
} else {
// touch事件
final int source = q.mEvent.getSource();
if ((source & InputDevice.SOURCE_CLASS_POINTER) != 0) {
deliverPointerEvent(q);
} else if ((source & InputDevice.SOURCE_CLASS_TRACKBALL) != 0) {
deliverTrackballEvent(q);
} else {
deliverGenericMotionEvent(q);
}
}
} finally {
Trace.traceEnd(Trace.TRACE_TAG_VIEW);
}
}</span>
在deliverPointerEvent方法中，假设view对象不存在，或者没有被加入，则这个event不会被处理，直接finishInputEvent。接着推断action是否是MotionEvent.ACTION_DOWN。假设是。则表示触摸方式改变了，须要告诉windowManager在本地进行处理，由于每一次的按下操作都代表了一个新的event事件的到来。然后记录触摸的位置，这个位置就代表了应该是哪一个view来接收这个事件，然后直接调用mView.dispatchPointerEvent(event)来分发这个事件。假设这个事件被分发下去了，则结束事件。
<span style="font-size:14px;"> private void deliverPointerEvent(QueuedInputEvent q) {
final MotionEvent event = (MotionEvent)q.mEvent;
final boolean isTouchEvent = event.isTouchEvent();
if (mInputEventConsistencyVerifier != null) {
if (isTouchEvent) {
mInputEventConsistencyVerifier.onTouchEvent(event, 0);
} else {
mInputEventConsistencyVerifier.onGenericMotionEvent(event, 0);
}
}
// If there is no view, then the event will not be handled.
if (mView == null || !mAdded) {
// view对象为空。或者没有被加入，这个事件就不会被处理
finishInputEvent(q, false);
return;
}
// 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) {
// 假设是MotionEvent.ACTION_DOWN
// 假设是假设触摸方式改变，告诉wm。在本地进行处理
// 每一次的按下操作就是一个触摸事件的改变
ensureTouchMode(true);
}
// Offset the scroll position.
if (mCurScrollY != 0) {
event.offsetLocation(0, mCurScrollY);
}
if (MEASURE_LATENCY) {
lt.sample("A Dispatching PointerEvents", System.nanoTime() - event.getEventTimeNano());
}
// Remember the touch position for possible drag-initiation.
// 有可能拖拽開始。记录触摸的位置
if (isTouchEvent) {
mLastTouchPoint.x = event.getRawX();
mLastTouchPoint.y = event.getRawY();
}
// Dispatch touch to view hierarchy.
// 给view的层级上view分发事件
// DecorView继承FrameLayout也就间接继承了ViewGroup，View
// DoverView---->Activity-->PhoneWindow--->DocerView---->ViewGroup
boolean handled = mView.dispatchPointerEvent(event);
if (MEASURE_LATENCY) {
lt.sample("B Dispatched PointerEvents ", System.nanoTime() - event.getEventTimeNano());
}
if (handled) {
// 结束事件
finishInputEvent(q, true);
return;
}
// Pointer event was unhandled.
// 暗示事件已经被处理
finishInputEvent(q, false);
</span>
在DecorView中没有dispatchPointerEvent方法。所以调用的是View.java的dispatchPointerEvent方法中推断详细的是哪一类的事件，然后又调用了自身的dispatchTouchEvent。
<span style="font-size:14px;">public final boolean dispatchPointerEvent(MotionEvent event) {
if (event.isTouchEvent()) {
// 假设是触摸事件
return dispatchTouchEvent(event);
} else {
// 假设是一般的移动事件
return dispatchGenericMotionEvent(event);
}
}</span>
在DecorView.java的dispatchTouchEvent方法中，假设Activity不为空，而且没有被销毁。则调用Activity的dispatchTouchEvent方法，否则调用父类View的dispatchTouchEvent方法。
<span style="white-space:pre"> </span>@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
// callback就是Activity本身
final Callback cb = getCallback();
// 假设Activity不为空，而且没有被销毁,则调用Activity的dispatchTouchEvent
// 否则调用父类的dispatchTouchEvent
return cb != null && !isDestroyed() && mFeatureId < 0 ? cb.dispatchTouchEvent(ev)
: super.dispatchTouchEvent(ev);
}
在Activity的dispatchTouchEvent方法中。调用的是PhoneWindow的superDispatchTouchEvent的方法去分发事件。假设到最后Activity中的全部的view都不去处理这个事件时，就有Activity的OnTouchEvent来处理。
public boolean dispatchTouchEvent(MotionEvent ev) {
if (ev.getAction() == MotionEvent.ACTION_DOWN) {
// 在dispatch之前做一些操作，事实上什么也没做
onUserInteraction();
}
// 调用PhoneWindow中的superDispatchTouchEvent
// PhoneWindow中superDispatchTouchEvent 直接调用了mDecor的superDispatchTouchEvent
// mDecore的superDispatchTouchEvent方法中直接调用super.dispatchOnTouchEvent
// 也就是開始进入了viewGroup中的dispatchOnTouchEvent方法
if (getWindow().superDispatchTouchEvent(ev)) {
return true;
}
// 当Activity中全部的View都不处理Event的时候，就用由Activity的onTouchEvent()来处理
// 通知window关闭这个touch事件
return onTouchEvent(ev);
}
public boolean onTouchEvent(MotionEvent event) {
if (mWindow.shouldCloseOnTouch(this, event)) {
finish();
return true;
}
return false;
}
在PhoneWindow的superDispatchTouchEvent中。调用了DecorView的superDispatchTouchEvent方法，进而调用了super.dispatchTouchEvent(event)方法，也就是进入了viewGroup中開始事件的分发。
@Override
public boolean superDispatchTouchEvent(MotionEvent event) {
return mDecor.superDispatchTouchEvent(event);
}
public boolean superDispatchTouchEvent(MotionEvent event) {
return super.dispatchTouchEvent(event);
}
ViewGroup的dispatchTouchEvent中，处理例如以下，假设action是MotionEvent.ACTION_DOWN，则须要重置触摸的状态。
继而推断是否拦截此事件，然后遍历全部的孩子以便找到一个能够接收此事件的孩子，假设child不存在TouchTarget中，则把事件分发给子view，这个寻找是依据view的区域来寻找的。假设childView没有消费掉此事件，则
自己处理的事件，假设自己也没有处理。回溯至父view处理，否则viewGroup把事件一级一级的递归传递，假设child是一个viewGroup，则反复上述的步骤，假设是view，直接调用dispatchTouchEvent方法。
public boolean dispatchTouchEvent(MotionEvent ev) {
if (mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onTouchEvent(ev, 1);
}
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.
// ACTION_DOWN意味着touch事件的改变，所以须要把之前的TouchTargets和TouchState都clear掉。mFirstTouchTarget = null
cancelAndClearTouchTargets(ev);
// 重置触摸的状态
resetTouchState();
}
// Check for interception.
final boolean intercepted;
if (actionMasked == MotionEvent.ACTION_DOWN
|| mFirstTouchTarget != null) {
final boolean disallowIntercept = (mGroupFlags & FLAG_DISALLOW_INTERCEPT) != 0;
if (!disallowIntercept) {
// 拦截事件，默认返回false，表示不拦截，假设拦截了就不继续往以下运行了
intercepted = onInterceptTouchEvent(ev);
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;
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 (childrenCount != 0) {
// Find a child that can receive the event.
// Scan children from front to back.
// 遍历全部的孩子，以便找到一个能够接收这个事件的孩子
// 某个区域内的孩子
final View[] children = mChildren;
final float x = ev.getX(actionIndex);
final float y = ev.getY(actionIndex);
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)) {
continue;
}
// 推断child是否在TouchTarget中
newTouchTarget = getTouchTarget(child);
if (newTouchTarget != null) {
// 存在
// 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);
// child不存在TouchTarget中，则调用dispatchTransformedTouchEvent
// 把event分发给子view，这里并非做处理。应该就是找到touch区域
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) {
// mFirstTouchTarget 为空。表示childview没有将此事件消费掉，则自己处理这个event
// 假设viewGroup自己也没有处理。则回溯到父view进行处理
// 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;
// viewGroup把事件递归传递，假设child是一个gourp。则反复上述步骤
// 假设是view,则直接调用dispatchTouchEvent方法
if (dispatchTransformedTouchEvent(ev, cancelChild,
target.child, target.pointerIdBits)) {
handled = true;
}
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 (!handled && mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onUnhandledEvent(ev, 1);
}
return handled;
}
在View.java中的 dispatchTouchEvent方法中，假设已经注冊了listener监听器而且是enable的。而且监听器的onTouch返回true，则onTouchEvent不会被调用。
public boolean dispatchTouchEvent(MotionEvent event) {
if (mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onTouchEvent(event, 0);
}
if (onFilterTouchEventForSecurity(event)) {
//noinspection SimplifiableIfStatement
ListenerInfo li = mListenerInfo;
if (li != null && li.mOnTouchListener != null && (mViewFlags & ENABLED_MASK) == ENABLED
&& li.mOnTouchListener.onTouch(this, event)) {
// 要想运行onTouchEvent方法上述三个条件仅仅要一个不满足就能够了
//
return true;
}
if (onTouchEvent(event)) {
return true;
}
// 假设全部的View都不处理TouchEvent，最后由Activity来处理
}
if (mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onUnhandledEvent(event, 0);
}
return false;
}
假设Activity中全部的view都不处理这个事件。则由Activity自己处理
public boolean onTouchEvent(MotionEvent event) {
if (mWindow.shouldCloseOnTouch(this, event)) {
finish();
return true;
}
return false;
}