[英]On Android, how can I tell the location of a second finger that isn't moving but is touching the screen when the first finger releases from the screen
[英]how to detect the secondary finger on touching the screen not at same time in android touchlistener?
如何检测屏幕上的其他手指? 例如,我用一根手指触摸屏幕,一段时间后我将第一根手指放在屏幕上,然后用另一根手指触摸屏幕,同时保持第一根手指的原样? 如何在Touch Listener中检测秒针触摸?
从第二个手指开始发送MotionEvent.ACTION_POINTER_DOWN and MotionEvent.ACTION_POINTER_UP
。 对于第一个手指MotionEvent.ACTION_DOWN and MotionEvent.ACTION_UP
使用MotionEvent.ACTION_DOWN and MotionEvent.ACTION_UP
。
在getPointerCount()方法MotionEvent允许您确定在装置上的指针的数目。 所有事件和指针的位置都包含在您在onTouch()
方法中收到的onTouch()
实例中。
要跟踪来自多个指针的触摸事件,您必须使用MotionEvent.getActionIndex()
和MotionEvent.getActionMasked()
方法来标识指针的索引和此指针发生的触摸事件。
int action = MotionEventCompat.getActionMasked(event);
// Get the index of the pointer associated with the action.
int index = MotionEventCompat.getActionIndex(event);
int xPos = -1;
int yPos = -1;
Log.d(DEBUG_TAG,"The action is " + actionToString(action));
if (event.getPointerCount() > 1) {
Log.d(DEBUG_TAG,"Multitouch event");
// The coordinates of the current screen contact, relative to
// the responding View or Activity.
xPos = (int)MotionEventCompat.getX(event, index);
yPos = (int)MotionEventCompat.getY(event, index);
} else {
// Single touch event
Log.d(DEBUG_TAG,"Single touch event");
xPos = (int)MotionEventCompat.getX(event, index);
yPos = (int)MotionEventCompat.getY(event, index);
}
...
// Given an action int, returns a string description
public static String actionToString(int action) {
switch (action) {
case MotionEvent.ACTION_DOWN: return "Down";
case MotionEvent.ACTION_MOVE: return "Move";
case MotionEvent.ACTION_POINTER_DOWN: return "Pointer Down";
case MotionEvent.ACTION_UP: return "Up";
case MotionEvent.ACTION_POINTER_UP: return "Pointer Up";
case MotionEvent.ACTION_OUTSIDE: return "Outside";
case MotionEvent.ACTION_CANCEL: return "Cancel";
}
return "";
}
有关详细信息,请访问Google 处理多点触控手势 。
如果您需要处理多点触控事件,请检查PointerCount。
public boolean onTouchEvent(MotionEvent event) {
if (event.getPointerCount() > 1) {
Log.d(DEBUG_TAG,"Multitouch event");
// The coordinates of the current screen contact, relative to
// the responding View or Activity.
xPos = (int)MotionEventCompat.getX(event, index);
yPos = (int)MotionEventCompat.getY(event, index);
} else {
// Single touch event
Log.d(DEBUG_TAG,"Single touch event");
xPos = (int)MotionEventCompat.getX(event, index);
yPos = (int)MotionEventCompat.getY(event, index);
}
...
}
您可以在此处找到更多信息: https : //developer.android.com/training/gestures/multi.html
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