Android 簡單的 左右上下手勢 判斷

private float startx;
    private float starty;
    private float upoffset;


@Override
public boolean onTouchEvent(MotionEvent event) {

    switch (event.getAction()) {
    case MotionEvent.ACTION_DOWN:
        startx = event.getX();
        starty = event.getY();
        break;
    case MotionEvent.ACTION_MOVE:
        offset = (int) (event.getX() - startx) / 3;
        // Log.e("TAST", offset + "offset");
        if (Math.abs(offset) > 10) {
            Log.e("TAG", "Left and Right");
        }
        upoffset = event.getY() - starty;
        if (Math.abs(upoffset) > 20) {
            Log.e("TAG", "UP and Down");
        }

        invalidate();

    default:
        break;
    }

    return true;
}</pre>