Android 触摸消息处理
1. WindowInputEventReceiver.onInputEvent() ----ViewRootImpl.java
从InputDispatch中publish一个Eent事件后，会由WindowInputEventReceiver.onInputEvent作为回调函数被调用。
@Override
public void onInputEvent(InputEvent event) {
enqueueInputEvent(event, this, 0, true);
}
1.2. ViewRootImpl.enqueueInputEvent()
把event作为一个QueuedInputEvent放到列表队列最后，如果processImmediately == true那么就直接执行doProcessInputEvents()去立即处理这个event事件，如果不是就调用scheduleProcessInputEvents把Eent通过hander放入到主线程的Looper中。
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) {
doProcessInputEvents();
} else {
scheduleProcessInputEvents();
}
}
2. ViewRootImpl.deliverInputEvent()
最后都会调用deliverInputEvent去分发事件，如果是KeyEent就调用deliverKeyEent(),同理如果是Touch，Pointer Event就调用deliverPointerEvent。
private void deliverInputEvent(QueuedInputEvent q) {
Trace.traceBegin(Trace.TRACE_TAG_VIEW, "deliverInputEvent");
try {
if (q.mEvent instanceof KeyEvent) {
deliverKeyEvent(q);
} else {
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);
}
}
2.1 ViewRootImpl.deliverPointerEvent()
1. 如果mView == null || !mAdded, 就直接调用fininshInputEvent去告诉InputDispatcher;
2. 如果是ActionDown就是通过ensureTouchMode(true)告诉WMS去设置对应WindowState的touch mode，并且调用ensureTouchModeLocally来handle the change
3. 如果是touchevent就是用mLastTouchPoint去记录此次的Point的Position用于possible drag-initiation
4. mView.dispatchPointerEvent(event); 通过DecorView去dispatchPointerEvent;
5. 无论Event是否被处理，都会调用finishInputEvent(q, true);去告诉InputDispatcher。
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) {
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) {
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.
if (isTouchEvent) {
mLastTouchPoint.x = event.getRawX();
mLastTouchPoint.y = event.getRawY();
}
// Dispatch touch to view hierarchy.
boolean handled = mView.dispatchPointerEvent(event);
if (MEASURE_LATENCY) {
lt.sample("B Dispatched PointerEvents ", System.nanoTime() - event.getEventTimeNano());
}
if (handled) {
finishInputEvent(q, true);
return;
}
// Pointer event was unhandled.
finishInputEvent(q, false);
}
2.1.4 DecorView.dispatchPointerEvent
DecorView继承FrameLayout也就间接继承了ViewGroup，View。
1. 调用父类View的dispatchPointerEvent(), 然后去调用自己的dispatchTouchEvent;
2. dispatchTouchEvent中调用callback.dispatchTouchEvent，这里的Callback就是Activity对象。
public final boolean dispatchPointerEvent(MotionEvent event) {
if (event.isTouchEvent()) {
return dispatchTouchEvent(event);
} else {
return dispatchGenericMotionEvent(event);
}
}
@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
final Callback cb = getCallback();
return cb != null && !isDestroyed() && mFeatureId < 0 ? cb.dispatchTouchEvent(ev)
: super.dispatchTouchEvent(ev);
}
2.1.4.2 Activity.dispatchtouchEvent
1. onUserInteraction(), 在dispatch之前做一些操作
2. getwindow().superDispatchtouchEvent就是调用PhoneWindow中的superDispatchTouchEvent。而PhoneWindow也是直接调用mDecorView的对应的方法。而DoverView的superDispatchTouchEvent方法中是去调用了父类ViewGroup的dispatchTouchEvent。
3. 当Activity中所有的View都不处理Event的时候，就用由Activity的onTouchEvent()来处理。
这里的调用顺序从DoverView---->Activity-->PhoneWindow--->DocerView---->ViewGroup
public boolean dispatchTouchEvent(MotionEvent ev) {
if (ev.getAction() == MotionEvent.ACTION_DOWN) {
onUserInteraction();
}
if (getWindow().superDispatchTouchEvent(ev)) {
return true;
}
return onTouchEvent(ev);
}
2.1.4.2.1 ViewGroupdispatchTouchEvent(MotionEvent ev)
1. 如果是Action_Down事件，那么把之前的TouchTargets和TouchState都clear掉，mFirstTouchTarget = null
2. onInterceptTouchEvent()，通过这个函数去告诉当前的View是否拦截掉这个Event，如果return就不会把这个event往下dispatch了
3. 如果不去Intercept当前的Event，就通过遍历自己的child views去找到处在Touch所在区域的view，找到之后通过getTouchTarget(View)去查找View是否在TouchTarget中了；如果不在，则调用dispatchTransformedTouchEvent(ev, false, child, idBitsToAssign)，把Event分发给child view。
4. 如果child没有消耗掉event事件，那么mFirstTouchTarget == null)，这时候就会调用handled = dispatchTransformedTouchEvent(ev, canceled, null,TouchTarget.ALL_POINTER_IDS)自己去处理此次Event; 参数中child为null。
如果ViewGroup也没处理，就会以此回溯上去给父View处理。
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.
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);
ev.setAction(action); // restore action in case it was changed
} else {
intercepted = false;
}
} else {
... ...
}
// 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.
final View[] children = mChildren;
final float x = ev.getX(actionIndex);
final float y = ev.getY(actionIndex);
for (int i = childrenCount - 1; i >= 0; i--) {
final View child = children[i];
if (!canViewReceivePointerEvents(child)
|| !isTransformedTouchPointInView(x, y, child, null)) {
continue;
}
newTouchTarget = getTouchTarget(child); //通过getTouchTarget去查找View是否在TouchTarget中了。
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 = i;
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 (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;
}
2.1.4.2.1.3 ViewGroup.dispatchTransformedTouchEvent()
1. 主要是调用child.dispatchTouchEvent(transformedEvent);把事件递归传下去，如果child还是一个ViewGroup那么步骤和上面有一样，如果是View就调用View.dispatchTouchEvent(MotionEvent event)
private boolean dispatchTransformedTouchEvent(MotionEvent event, boolean cancel,
View child, int desiredPointerIdBits) {
final boolean handled;
// Calculate the number of pointers to deliver.
final int oldPointerIdBits = event.getPointerIdBits();
final int newPointerIdBits = oldPointerIdBits & desiredPointerIdBits;
// If the number of pointers is the same and we don't need to perform any fancy
// irreversible transformations, then we can reuse the motion event for this
// dispatch as long as we are careful to revert any changes we make.
// Otherwise we need to make a copy.
final MotionEvent transformedEvent;
if (newPointerIdBits == oldPointerIdBits) {
if (child == null || child.hasIdentityMatrix()) {
if (child == null) {
handled = super.dispatchTouchEvent(event);
} else {
final float offsetX = mScrollX - child.mLeft;
final float offsetY = mScrollY - child.mTop;
event.offsetLocation(offsetX, offsetY);
handled = child.dispatchTouchEvent(event);
event.offsetLocation(-offsetX, -offsetY);
}
return handled;
}
transformedEvent = MotionEvent.obtain(event);
} else {
transformedEvent = event.split(newPointerIdBits);
}
// Perform any necessary transformations and dispatch.
if (child == null) {
handled = super.dispatchTouchEvent(transformedEvent);
} else {
final float offsetX = mScrollX - child.mLeft;
final float offsetY = mScrollY - child.mTop;
transformedEvent.offsetLocation(offsetX, offsetY);
if (! child.hasIdentityMatrix()) {
transformedEvent.transform(child.getInverseMatrix());
}
handled = child.dispatchTouchEvent(transformedEvent);
}
// Done.
transformedEvent.recycle();
return handled;
}
2.1.4.2.1.3.1View.dispatchTouchEvent(MotionEvent event)
1. 如果有TouchListener就去调用注册过的TouchListener的回调函数onTouch事件并直接返回。这就是为什么我们想接收一个touch event的时候只要写一个listener的原故。
2. 如果没有TouchListener，则调用默认的onTouchEvent(event)事件
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)) {
return true;
}
if (onTouchEvent(event)) {
return true;
}
}
if (mInputEventConsistencyVerifier != null) {
mInputEventConsistencyVerifier.onUnhandledEvent(event, 0);
}
return false;
}
2.1.4.2.1.4 Activity.onTouchEvent(MotionEvent event)
如果所有的View都不处理TouchEvent，最后由Activity来处理。
判断一下mWindow是否因此此Event要close掉，如果不close，就return false。
最后调用FinishInputEvent(false), 返回这个没有处理的Event。
public boolean onTouchEvent(MotionEvent event) {
if (mWindow.shouldCloseOnTouch(this, event)) {
finish();
return true;
}
return false;
}