Question

我认为“ScaleGestureDetector”实例的方法“onTouchEvent（）”只有在真正处理触摸事件时才会返回“true” ，i。即如果它检测到多点触控缩放手势（用两根手指）。否则我认为它应该返回“false”以便让其他处理程序处理事件，例如： G。长按以触发上下文菜单。

我发现了一些不同的东西：scaleGestureDetector.onTouchEvent（）总是在我的情况下返回“true”。我的MyView类的以下代码片段：

public boolean onTouchEvent(MotionEvent event) {
  boolean retval = scaleGestureDetector.onTouchEvent(event);
   Log.v("MyView.onTouchEvent()", "Action: " + event.getAction() +
         "; PointerCount: " + event.getPointerCount() +
         "; scaleGestureDetector.onTouchEvent() RetVal: " + retval);
   return(retval);
}

用一根手指触摸视图约1秒后产生了以下日志输出，然后用两根手指进行了缩放手势：

01-01 19:09:54.484: VERBOSE/MyView.onTouchEvent()(5930): Action: 0; PointerCount: 1; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:09:54.510: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 1; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:09:54.541: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 1; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:09:54.580: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 1; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:09:54.820: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 1; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:09:54.910: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 1; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:09:55.050: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 1; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:09:55.350: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 1; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:09:55.400: VERBOSE/MyView.onTouchEvent()(5930): Action: 1; PointerCount: 1; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:09:57.160: INFO/BatteryStatsImpl(96): notePhoneSignalStrengthLocked: 4->3
01-01 19:10:00.060: ERROR/ClockWidget(215): weatherClock onReceive~ mUseAnimation:false
01-01 19:10:00.060: ERROR/ClockWidget(215): handleUiMessage~ in pause. msg:36867
01-01 19:10:00.070: ERROR/ClockWidget(215): weatherClock onReceive~ mUseAnimation:false
01-01 19:10:00.090: INFO/PI.Alarms(699): Update Alarms start
01-01 19:10:00.090: INFO/PI.Alarms(699): Task Notifications: Already displaying the same alarms, no update
01-01 19:10:00.100: INFO/PI.Alarms(699): Event Notifications: Already displaying the same alarms, no update
01-01 19:10:00.830: VERBOSE/MyView.onTouchEvent()(5930): Action: 0; PointerCount: 1; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:00.840: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 1; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:00.870: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 1; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:00.900: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 1; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:00.922: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 1; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:00.931: VERBOSE/MyView.onTouchEvent()(5930): Action: 261; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:00.950: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.002: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.030: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.060: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.090: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.120: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.140: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.172: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.200: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.230: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.252: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.280: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.310: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.342: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.370: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.390: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.424: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.450: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.480: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.510: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.530: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.580: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.690: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.780: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.815: VERBOSE/MyView.onTouchEvent()(5930): Action: 2; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.830: VERBOSE/MyView.onTouchEvent()(5930): Action: 262; PointerCount: 2; scaleGestureDetector.onTouchEvent() RetVal: true
01-01 19:10:01.840: VERBOSE/MyView.onTouchEvent()(5930): Action: 1; PointerCount: 1; scaleGestureDetector.onTouchEvent() RetVal: true

正如我所说：返回值总是“真实”！这是ScaleGestureDetector.onTouchEvent（）的错误吗？我可以做些什么来让其他处理程序处理所有非缩放手势事件（例如，用一根手指长按）？请帮忙！

Nemax

Answer 1

不知道这是一个bug还是故意的，但这绝对是源代码所做的事（ScaleGestureDetector.java:156）：

public boolean onTouchEvent(MotionEvent event) {
   final int action = event.getAction();
   boolean handled = true;

   /* ... bunch of code that never updates 'handled' */

   return handled;
}

我解决这个问题的方法是先检查我可能想要处理的所有其他类型的触摸事件，然后调用手势检测器，例如

    if (mLongPressGestureDetector != null && mLongPressGestureDetector.onTouchEvent(event))
        return true;
    else if (mIsInMoveMode && mScaleGestureDetector != null) {
        // Check for a move
        if (action == MotionEvent.ACTION_MOVE && !mScaleGestureDetector.isInProgress()) {
            handleMove(event);
            return true;
        }

        // Now a scale
        mScaleGestureDetector.onTouchEvent(event);
        return true;
    }

Answer 2

ScaleGestureDetector提供方法isInProgress（）可能会做你想要的...

以下是使用中的示例：

public boolean onTouch(View v, MotionEvent event) {

    mScaleDetector.onTouchEvent(event);

    if (!mScaleDetector.isInProgress()) {
        if (event.getAction() == MotionEvent.ACTION_DOWN || (event.getAction() == MotionEvent.ACTION_MOVE)) {
            touchX = (int) event.getX();
            touchY = (int) event.getY();
            isTouched = true;
        }

        if (event.getAction() == MotionEvent.ACTION_UP) {
            isTouched = false;
        }
    } else {
        isTouched = false;
    }

    return true;
}

Answer 3

这就是我解决问题的方法：通过覆盖Acitivity的onDispatchTouchEvent（）方法。任何其他解决方案似乎都不起作用。关于onDispatchTouchEvent（）方法的好处是在将任何触摸事件转发到任何其他接收器之前总是被调用，因此您可以在此拦截每个触摸事件。

如果事件在这里处理（缩放或滑动），我立即返回而不将事件转发给超类，i。即到视图层次结构的其余部分。如果不是，我将它转发给超类，所以其他视图可以处理它，例如。 G。检测短期或长期点击。

还有一些问题需要解决： 1.如果用户开始缩放手势，我不得不取消任何长时间点击检测过程，因为接收视图将获得第一个DOWN事件，然后再没有任何东西（在第二个手指下降并开始缩放之后），然后虚假地思考正在进行长按。 2.当执行长按并且出现上下文菜单时，我必须在dispatchOnTouchEvent（）中防止滑动和缩放手势检测，直到下一个UP事件，否则即使上下文菜单存在也会执行滑动和缩放。

相当复杂，但我花费了数小时和大量的试验和错误，并且找不到任何更简单的解决方案。无论如何，处理1.缩放手势，2。水平滑动手势，3。垂直滚动手势，4。长按和5.短按，都在同一目标视图上，完成任务并不是一件非常简单的事情。。

以下是代码（相关部分）：

    @Override
public boolean dispatchTouchEvent(MotionEvent e) {
    if (eventInProgress) {
        // View shall only receive scale gesture event if visible
        if (targetView.isShown())
            scaleGestureDetector.onTouchEvent(e);
        if (scaleGestureDetector.isInProgress())
            motionEventConsumed = true;
    }

    if (motionEventConsumed) {
        if (e.getAction() == MotionEvent.ACTION_UP)
            motionEventConsumed = false;
        if (cancelLongPressEvent) {
            cancelLongPressEvent = false;
            targetView.cancelLongPress();
        }
        return (true);
    }

    // Get the action that was done on this touch event
    switch (e.getAction()) {
    case MotionEvent.ACTION_DOWN: {
        // store the X value when the user's finger was pressed down
        downXValue = e.getX();
        downYValue = e.getY();
        cancelLongPressEvent = true;
        eventInProgress = true;
        break;
    }

    case MotionEvent.ACTION_MOVE:
        // When having moved by too many x or y pixels, then
        // cancel any ongoing long klick events
        if (cancelLongPressEvent
                && Math.abs(e.getX() - downXValue)
                        + Math.abs(e.getY() - downYValue) > 40) {
            targetView.cancelLongPress();
            cancelLongPressEvent = false;
        }
        break;

    case MotionEvent.ACTION_UP: {
        if (eventInProgress) {
            // Get the X value when the user released his/her finger
            float deltaX = e.getX() - downXValue;
            float deltaY = e.getY() - downYValue;
            if (Math.abs(deltaX) > Math.abs(deltaY)
                    && Math.abs(deltaX) > 50) {
                // going backwards: pushing stuff to the right
                if (deltaX > 0) {
                    flipRight();
                    return (true);
                }
                // going forwards: pushing stuff to the left
                if (deltaX < 0) {
                    flipLeft();
                    return (true);
                }
                break;
            }
        }
    }
    }

    // If event was not handled here, then forward it to parent,
    // i. e. to view hierarchy
    return (super.dispatchTouchEvent(e));
}

[...]

@Override
public void onCreateContextMenu(ContextMenu menu, View v,
        ContextMenu.ContextMenuInfo menuInfo) {
    super.onCreateContextMenu(menu, v, menuInfo);
    MenuInflater mi = getMenuInflater();
    mi.inflate(R.menu.lztv_context_menu, menu);
    contextMenuTargetView = v;
    eventInProgress = false;
}

ScaleGestureDetector.onTouchEvent总是返回'true'

3 个答案: