java - Android 用手指拖动 imageview 行为很奇怪

Question

我正在为我的应用程序实现 imageview 拖动功能。我尝试过使用下面的代码，但它的行为很奇怪。当我尝试拖动图像时它会改变位置，并且在 move 过程中会显示类似缩放图像的效果。我想用手指平滑地 move 图像。

请帮我解决这个问题

@Override
    public boolean onTouch(View v, MotionEvent event) {
        final int X = (int) event.getRawX();
        final int Y = (int) event.getRawY();
        MarginLayoutParams marginParams = new MarginLayoutParams(mImagePreView.getLayoutParams());

        switch (event.getAction()) {

        case MotionEvent.ACTION_DOWN:
            _xDelta = X - marginParams.leftMargin;
            _yDelta = Y - marginParams.topMargin;
            break;
        case MotionEvent.ACTION_MOVE:
            marginParams.leftMargin = X-_xDelta;
            marginParams.topMargin = Y - _yDelta;
            marginParams.rightMargin = -250;
            marginParams.bottomMargin = -250;

            FrameLayout.LayoutParams layoutParams = new FrameLayout.LayoutParams(marginParams);
            mImagePreView.setLayoutParams(layoutParams);

            break;
        default:
            break;
        }
        return true;
    }

Answer 1

RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams) mImagePreView.getLayoutParams();
layoutParams.leftMargin += offsetX;
layoutParams.topMargin += offsetY;

并且有错误:

    _xDelta = X - marginParams.leftMargin;
    _yDelta = Y - marginParams.topMargin;

X - 绝对坐标中的事件，marginParams.leftMargin - 坐标相对于父布局