Android的多点触控：ACTION_UP并不总是叫什么名字？ [英] Android multitouch: ACTION_UP not always called?

问题描述

我已经开发了被处理的多点触控视图中的一个Android应用程序。我基本上跟踪可能发生的像ACTION_UP，ACTION_MOVE，...在View类我覆盖onTouch方法如下所示的几个MotionEvents：

I have developed an Android application that is handling multitouch in a view. I basically track the several MotionEvents that can occur like ACTION_UP, ACTION_MOVE, ... My overwritten onTouch method in the View class looks like this:

public boolean onTouch(View view, MotionEvent event) 
{
    int action = event.getAction() & MotionEvent.ACTION_MASK;

    if (action == MotionEvent.ACTION_DOWN) {
        float x = event.getX();
        handleTouchStart(view, x);
    } else if (action == MotionEvent.ACTION_UP) {
        float x = event.getX();
        handleTouchEnded(view, x);
    } else if (action == MotionEvent.ACTION_POINTER_DOWN) {
        int pointer = (event.getAction() & MotionEvent.ACTION_POINTER_ID_MASK) >> MotionEvent.ACTION_POINTER_ID_SHIFT;
        float x = event.getX(pointer);
        handleTouchStart(view, x);
    } else if (action == MotionEvent.ACTION_POINTER_UP) {
        int pointer = (event.getAction() & MotionEvent.ACTION_POINTER_ID_MASK) >> MotionEvent.ACTION_POINTER_ID_SHIFT;
        float x = event.getX(pointer);
        handleTouchEnded(view, x);
    } else if (action == MotionEvent.ACTION_MOVE) {
        int pointer = (event.getAction() & MotionEvent.ACTION_POINTER_ID_MASK) >> MotionEvent.ACTION_POINTER_ID_SHIFT;
        float x = event.getX(pointer);
        handleTouchMoved(view, x);
    }

    return true;
}

在我的手机（三星Galaxy S），这个完美的作品。对于每一个handleTouchStart（），适当的handleTouchEnded（）被调用。这是我的应用程序至关重要。它是一个二维的sidescroller有转向区域在屏幕的左下部。如果 - 因某种原因 - 当用户拿起从触摸屏手指的handleTouchEnded（）方法时不叫，玩家的角色将继续运行。

On my phone (Samsung Galaxy S), this works flawlessly. For every handleTouchStart(), the appropriate handleTouchEnded() is called. This is crucial for my app. It's a 2D sidescroller with a steering area in the left lower portion of the screen. If - for some reason - the handleTouchEnded() method is not called when the user lifts a finger from the touchscreen, the player's character continues running.

我收到了来自玩家在其他设备（如HTC Desire的），在极少数情况下，性格确实持续的方向运行，即使他们举起他们的手指从转向区域在屏幕上的报告。我认为，如果handleTouchEnded（）将不会调用这又意味着没有ACTION_UP（或ACTION_POINTER_UP）事件产生，这只能发生

I've received reports from players on other devices (like the HTC Desire) that in rare occasions, the character does indeed continue running in a direction even if they lifted their finger from the steering area on the screen. I concluded that this can only happen if handleTouchEnded() is not called which in turn means that no ACTION_UP (or ACTION_POINTER_UP) event is generated.

有没有对多点触摸的支持设备的具体实现？有没有保证每个ACTION_DOWN（或ACTION_POINTER_DOWN）MotionEvent，适当ACTION_UP（或ACTION_POINTER_UP）MotionEvent叫？还是我失去了一些东西？是我onTouch实现甚至是否正确？

Are there device specific implementations of multitouch support? Is there no guarantee that for each ACTION_DOWN (or ACTION_POINTER_DOWN) MotionEvent, an appropriate ACTION_UP (or ACTION_POINTER_UP) MotionEvent is called? Or am I missing something? Is my onTouch implementation even correct?

我的更广泛的问题是：是否有更好的方法来处理多点触控触摸屏输入的动作-games？我基本上模仿手柄的转向横的左边和右边的控制。我发现，Android的UI按钮都不能提供足够的灵活性，因为他们无法跟踪preSS和onRelease事件......或许他们？

My broader question would be: are there better ways to handle multitouch touchscreen input for "action"-games? I'm basically mimicking the left and right controls of a gamepad's steering cross. I've found that Android's UI buttons don't offer enough flexibility because they can't track onPress and onRelease events... or do they?

推荐答案

你失去了一些东西。 ;）还有就是你应该处理多一个操作类型： ACTION_CANCEL 。 ACTION_CANCEL 时，正在进行的手势中止在一些更高级别的发送 - 一些更高级别的组件可能截获手势，并采取过来，等

You're missing something. ;) There is one more action type that you should handle: ACTION_CANCEL. ACTION_CANCEL is sent when the gesture in progress is aborted at some higher level - some higher-level component may have intercepted the gesture and taken it over, etc.

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