java - Android 屏幕操纵杆问题

Question

所以我正在尝试使用屏幕操纵杆构建一个游戏，该操纵杆可以在屏幕上移动位图。但是当我朝任何方向按住操纵杆并保持不动时，位图也会停止移动。只有当我移动操纵杆时，位图才会移动。基本上，我希望能够在左侧位置按住操纵杆并让位图向左移动，直到我松开为止。代码中的其他所有内容均有效。有什么建议吗？

public boolean onTouch(View v, MotionEvent event) { 
        if (event.getAction() == MotionEvent.ACTION_DOWN)
            _dragging = true;
        else if (event.getAction() == MotionEvent.ACTION_UP)
            _dragging = false;

        _touchingPoint = new Point();

        if (_dragging) {
            // get the pos
            int x = (int) event.getX();
            int y = (int) event.getY();
            _touchingPoint.x = x;
            _touchingPoint.y = y;

            double a = _touchingPoint.x - initx;
            double b = _touchingPoint.y - inity;
            controllerDistance = Math.sqrt((a * a) + (b * b));

            if (controllerDistance > 75) {
                a = (a / controllerDistance) * 75;
                b = (b / controllerDistance) * 75;
                _touchingPoint.x = (int) a + initx;
                _touchingPoint.y = (int) b + inity;
            }

            bitmapPoint.x += a * .05;
            bitmapPoint.y += b * .05;

        } else if (!_dragging) {
            // Snap back to center when the joystick is released
            _touchingPoint.x = initx;
            _touchingPoint.y = inity;
        }
}

Answer 1

尝试 this它是适用于 Android 的屏幕操纵杆的开源 API。