拖放 - 在Winforms中移动标签

Question

我创建了一个标签覆盖,可以让我的新控件轻松地在屏幕上移动.

我已经附上了下面的代码,但是当我运行应用程序或尝试移动标签时,它总是关闭.它有时也会完全消失,留下痕迹或重置到0,0位置.看一下截图.

我曾经100%使用它,但经过最近的一些调整之后它再次出现在狗身上,我不知道如何让它发挥作用.

截图:

码:

internal sealed class DraggableLabel : Label
{

    private bool _dragging;
    private int _mouseX, _mouseY;

    public DraggableLabel()
    {
        DoubleBuffered = true;
    }

    protected override void OnMouseMove(MouseEventArgs e)
    {
      if (_dragging)
        {
            Point mposition = PointToClient(MousePosition);
            mposition.Offset(_mouseX, _mouseY);

            Location = mposition;
        }
        base.OnMouseMove(e);
    }

    protected override void OnMouseDown(MouseEventArgs e)
    {
       if (e.Button == MouseButtons.Left)
        {
           _dragging = true;
           _mouseX = -e.X;
           _mouseY = -e.Y;
           BringToFront();
           Invalidate();
        }
        base.OnMouseDown(e);
    }

    protected override void OnMouseUp(MouseEventArgs e)
    {
        if (_dragging)
        {
            _dragging = false;
            Cursor.Clip = new Rectangle();
            Invalidate();
        }

        base.OnMouseUp(e);
    }

}

Answer 1

OnMouseMove()代码很糟糕.这样做是这样的:

private Point lastPos;

protected override void OnMouseMove(MouseEventArgs e) {
    if (e.Button == MouseButtons.Left) {
        int dx = e.X - lastPos.X;
        int dy = e.Y - lastPos.Y;
        Location = new Point(Left + dx, Top + dy);
        // NOTE: do NOT update lastPos, the relative mouse position changed
    }
    base.OnMouseMove(e);
}

protected override void OnMouseDown(MouseEventArgs e) {
    if (e.Button == MouseButtons.Left) {
        lastPos = e.Location;
        BringToFront();
        this.Capture = true;
    }
    base.OnMouseDown(e);
}

protected override void OnMouseUp(MouseEventArgs e) {
    this.Capture = false;
    base.OnMouseUp(e);
}

屏幕截图还显示表格没有正确重绘的证据.你没有留下任何可能导致这种情况的线索.