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Question

i have a problem with drag&drop. I have code:

      void labelWorker_MouseEvent(object sender, MouseEventArgs e)
    {
        Label labelWorker = (Label)sender;
        labelWorker.DoDragDrop(labelWorker, DragDropEffects.Move);
        labelWorker.MouseDown += new MouseEventHandler(labelWorker_MouseDown);
        labelWorker.MouseMove += new MouseEventHandler(labelWorker_MouseMove);
        labelWorker.MouseUp += new MouseEventHandler(labelWorker_MouseUp);
    }

        bool isDragged = false;
        Point ptOffset;
    void labelWorker_MouseDown(object sender, MouseEventArgs e)
    {
        if (e.Button == MouseButtons.Left)
        {
            Label labelWorker = (Label)sender;
            isDragged = true;
            Point ptStartPosition = labelWorker.PointToScreen(new Point(e.X, e.Y));

            ptOffset = new Point();
            ptOffset.X = labelWorker.Location.X - ptStartPosition.X;
            ptOffset.Y = labelWorker.Location.Y - ptStartPosition.Y;
        }
        else
        {
            isDragged = false;
        }
    }

    void labelWorker_MouseMove(object sender, MouseEventArgs e)
    {
        Label labelWorker = (Label)sender;
        if (isDragged)
        {
            Point newPoint = labelWorker.PointToScreen(new Point(e.X, e.Y));
            newPoint.Offset(ptOffset);
            labelWorker.Location = newPoint;
        }
    }

    void labelWorker_MouseUp(object sender, MouseEventArgs e)
    {
        Label labelWorker = (Label)sender;
        isDragged = false;            
    }

Label starts freaking out when I try to move it. I think the problem is in

  void labelWorker_MouseMove(object sender, MouseEventArgs e)
   {
       Label labelWorker = (Label)sender;
       if (isDragged)
         {
           Point newPoint = labelWorker.PointToScreen(new Point(e.X, e.Y));
           newPoint.Offset(ptOffset);
           labelWorker.Location = newPoint;
         }
   }

Answer 1

Ok. I just made it :)

    bool clicked = false;
    int iOldX;
    int iOldY;
    int iClickX;
    int iClickY;
    void labelWorker_MouseDown(object sender, MouseEventArgs e)
    {
        Label labelWorker = (Label)sender;
        if (e.Button == MouseButtons.Left)
        {
            Point p = ConvertFromChildToForm(e.X, e.Y, labelWorker);
            iOldX = p.X;
            iOldY = p.Y;
            iClickX = e.X;
            iClickY = e.Y;
            clicked = true;
        }
    }

    void labelWorker_MouseMove(object sender, MouseEventArgs e)
    {
        Label labelWorker = (Label)sender;
        if (clicked)
        {
            Point p = new Point(); // New Coordinate
            p.X = e.X + labelWorker.Left;
            p.Y = e.Y + labelWorker.Top;
            labelWorker.Left = p.X - iClickX;
            labelWorker.Top = p.Y - iClickY;
        }
    }

    void labelWorker_MouseUp(object sender, MouseEventArgs e)
    {
        clicked = false;
    }

    private Point ConvertFromChildToForm(int x, int y, Control control)
    {
        Point p = new Point(x, y);
        control.Location = p;
        return p;
    }