Windows Form Drag Control

Question

Hi Everybody

I got a problem, I'm develop a Windows Form application that contain a panel and in the panel I'll add user controls that are be able to move with the mouse, that part is working perfect.

But when I put a background image to the panel then every time a move the control the image start to erase where the control is move, after stop moving the control then the image reload again

Is there a way to avoid that the image does that?

Thanks

 

Answer 1

If your movements is based on mouse events, then try calling the Update function for the form or just for panel during the MouseMove events.

Or show some details.

Answer 2

Hi I put the update for the panel and the erase effect is less but still hapen

here is the code for the move 

void control_MouseMove(object sender, MouseEventArgs e)
        {
            if (drag && e.Button == System.Windows.Forms.MouseButtons.Left)
            {
                Parent.Update();

                System.Drawing.Point newLocationOffset = e.Location - mouseOffset;

                #region X
                if (this.Left + newLocationOffset.X <= Parent.Location.X)
                {
                    this.Left = Parent.Location.X;
                }
                else if (this.Left + this.Width + newLocationOffset.X >= Parent.Width)
                {
                    this.Left = Parent.Width - this.Width;
                }
                else
                {
                    this.Left += newLocationOffset.X;
                }
                #endregion

                #region Y
                if (this.Top + newLocationOffset.Y <= 0)
                {
                    this.Top = 0;
                }
                else if (this.Top + this.Height + newLocationOffset.Y >= Parent.Height)
                {
                    this.Top = Parent.Height - this.Height;
                }
                else
                {
                    this.Top += newLocationOffset.Y;
                }
                #endregion
            }
        }

Answer 3

Those are details of how redrawing, caching and whatnot work. This really should be asked in teh WinForms subforum. It is way beyond a simple C# question.

A simple solution might be not to actually drag the Element around. Rather drag a primitive "shadow" around that helps users guessing the new layout and only move on mouse release.

Could it be you are looking for a Docking Control? That is the same type of layout used for Visual Studio itself. As far as I know for that you need 3rd party libraries. Not even WPF has a native Docking Layout Control.

http://www.telerik.com/help/winforms/dock-architecture-and-features-understanding-raddock.html

http://www.codeproject.com/Articles/18812/WPF-Docking-Library

Answer 4

Hi

Thanks for the replay

I found a solution, I just need to use double-buffering to reduce the amount of flickering when re-drawing

Thanks for your responses.