android - 如何检测向左、向右、向上和向下的运动

Question

我想知道是否可以使用下面的 onTouch 方法来检测用户是否在屏幕上向左、向右、向上或向下移动手指。我有一个包含对象的网格，我只希望用户能够在四个方向上移动其中一个对象。

我的想法是使用 Action_Down 事件获取 X 和 Y 位置，然后检查列表中的所有对象以查看哪个对象在 X 和 Y 值中。然后使用 Action_Move 开始沿其中一个方向移动它。

    @Override
public boolean onTouch(View v, MotionEvent event) {

    switch (event.getAction()) {

    case MotionEvent.ACTION_DOWN:
        Log.i("test","Down");
        break;

    case MotionEvent.ACTION_POINTER_UP:

        break;

    case MotionEvent.ACTION_MOVE:
        Log.i("test","Move");
        break;
    }

Answer 1

public class MainActivity extends Activity {
...
// This example shows an Activity, but you would use the same approach if
// you were subclassing a View.
@Override
public boolean onTouchEvent(MotionEvent event){ 

    int action = MotionEventCompat.getActionMasked(event);

    switch(action) {
        case (MotionEvent.ACTION_DOWN) :
            Log.d(DEBUG_TAG,"Action was DOWN");
            return true;
        case (MotionEvent.ACTION_MOVE) :
            Log.d(DEBUG_TAG,"Action was MOVE");
            return true;
        case (MotionEvent.ACTION_UP) :
            Log.d(DEBUG_TAG,"Action was UP");
            return true;
        case (MotionEvent.ACTION_CANCEL) :
            Log.d(DEBUG_TAG,"Action was CANCEL");
            return true;
        case (MotionEvent.ACTION_OUTSIDE) :
            Log.d(DEBUG_TAG,"Movement occurred outside bounds " +
                    "of current screen element");
            return true;      
        default : 
            return super.onTouchEvent(event);
    }      
}

有关详细信息，请参阅 this link ，您也可以使用(我会推荐)GestureDetector 的 OnFling() 作为访问的示例 this link ...