java onInterceptTouchEvent 只获得 ACTION_DOWN
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onInterceptTouchEvent only gets ACTION_DOWN
提问by user123321
Why do ViewGroup's only get ACTION_DOWNin the onInterceptTouchEvent? According to the docs, as long as false is returned it should receive all the event types.
http://developer.android.com/reference/android/view/ViewGroup.html#onInterceptTouchEvent%28android.view.MotionEvent%29Point #3.
为什么ViewGroup“唯一得到ACTION_DOWN的onInterceptTouchEvent？根据文档，只要返回 false，它就应该接收所有事件类型。
http://developer.android.com/reference/android/view/ViewGroup.html#onInterceptTouchEvent%28android.view.MotionEvent%29第 3 点。
Sample code:
示例代码：
public class MainActivity extends Activity {
private static final String TAG = MainActivity.class.getSimpleName();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new Container(this));
}
private class Container extends LinearLayout {
public Container(Context context) {
super(context);
setBackgroundColor(0xFF0000FF);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
Log.i(TAG, "onInterceptTouchEvent");
int action = ev.getActionMasked();
switch (action) {
case MotionEvent.ACTION_DOWN:
Log.i(TAG, "onInterceptTouchEvent.ACTION_DOWN");
break;
case MotionEvent.ACTION_MOVE:
Log.i(TAG, "onInterceptTouchEvent.ACTION_MOVE");
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
Log.i(TAG, "onInterceptTouchEvent.ACTION_UP");
break;
}
return super.onInterceptTouchEvent(ev);
}
}
}
回答by user123321
I'll answer my own question: onInterceptTouchEvent only get called if the parent has a child view which returns "true" from onTouchEvent. Once the child returns true, the parent now has a chance to intercept that event.
我将回答我自己的问题：只有当父视图有一个从 onTouchEvent 返回“true”的子视图时，才会调用 onInterceptTouchEvent。一旦孩子返回真，父母现在有机会拦截该事件。
回答by hyyou2010
I get the same problem. I had read many posts about it:
onInterceptTouchEvent only gets ACTION_DOWN
onInterceptTouchEvent's ACTION_UP and ACTION_MOVE never gets called
onInterceptTouchEvent, onTouchEvent only see ACTION_DOWN
onInterceptTouchEvent never receives action_move
我遇到同样的问题。我读过很多关于它的帖子：
onInterceptTouchEvent only gets ACTION_DOWN
onInterceptTouchEvent's ACTION_UP 和 ACTION_MOVE 永远不会被调用
onInterceptTouchEvent, onTouchEvent only see ACTION_DOWN
onInterceptTouchEvent never received action_move
I also had read android doc:
http://developer.android.com/training/gestures/viewgroup.html
http://developer.android.com/reference/android/view/ViewGroup.html#onInterceptTouchEvent(android.view.MotionEvent)
我也读过 android 文档：
http: //developer.android.com/training/gestures/viewgroup.html
http://developer.android.com/reference/android/view/ViewGroup.html#onInterceptTouchEvent(android.view.运动事件）
All answers are same. I tried many times, always not get onInterceptTouchEvent
() be called if not down event.
所有的答案都是一样的。我试了很多次，总是得不到onInterceptTouchEvent() if not down 事件被调用。
I read source code, I guess that something is changed:
我阅读了源代码，我想有些东西已经改变了：
@Override
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 {
// There are no touch targets and this action is not an initial down
// so this view group continues to intercept touches.
intercepted = true;
}
According above code, onInterceptTouchEvent(ev)is only be called when MotionEvent.ACTION_DOWN, this is what we tried and found. So, what I guess is, the code is changed, but doc not.
根据上面的代码，onInterceptTouchEvent(ev)只被调用 when MotionEvent.ACTION_DOWN，这是我们尝试和发现的。所以，我猜是，代码已更改，但文档未更改。
If you want spy or monitor all the events include those been sent to child views, you can override dispatchTouchEvent()like this:
如果您想监视或监视所有事件，包括发送到子视图的事件，您可以dispatchTouchEvent()像这样覆盖：
@Override
public boolean dispatchTouchEvent(MotionEvent event) {
MyLog.d(MyLog.DEBUG, "dispatchTouchEvent(): "+event.getAction());
if (isEnabled()) {
MyLog.d(MyLog.DEBUG, "dispatchTouchEvent()2: "+event.getAction());
processEvent(event);//here you get all events include move & up
super.dispatchTouchEvent(event);
return true; //to keep receive event that follow down event
}
return super.dispatchTouchEvent(event);
}
I have the runnable code at: https://github.com/maxyou/gesturebutton/blob/master/src/com/maxproj/gesturebutton/GestureButtonLayout.java
我有可运行的代码：https: //github.com/maxyou/gesturebutton/blob/master/src/com/maxproj/gesturebutton/GestureButtonLayout.java
回答by yoAlex5
The official doc
官方文档
Activity.dispatchTouchEvent(MotionEvent)- This allows your Activity to intercept all touch events before they are dispatched to the window.
ViewGroup.onInterceptTouchEvent(MotionEvent)- This allows a ViewGroup to watch events as they are dispatched to child Views. It is recursively function (from parent to parent)
ViewParent.requestDisallowInterceptTouchEvent(boolean)- Call this upon a parent View to indicate that it should not intercept touch events with onInterceptTouchEvent(MotionEvent).
Activity.dispatchTouchEvent(MotionEvent)- 这允许您的 Activity 在将它们分派到窗口之前拦截所有触摸事件。
ViewGroup.onInterceptTouchEvent(MotionEvent)- 这允许 ViewGroup 在事件被分派到子视图时观看事件。它是递归函数（从父级到父级）
ViewParent.requestDisallowInterceptTouchEvent(boolean)- 在父视图上调用它以指示它不应使用 onInterceptTouchEvent(MotionEvent) 拦截触摸事件。
