[Windows Forms] Automatically drag and drop controls (DragMove)

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Here’s a piece of code I wrote a while ago, I just thought it could be useful for WinForms developers…

In WPF, there is a very handy method to move a window with no borders : Window.DragMove. It can be used like that :

        private void Window_MouseDown(object sender, MouseButtonEventArgs e)
        {
            this.DragMove();
        }

When you call this method, the window is moved with the mouse until the button is released. It could hardly be simpler ;)

Unfortunately, this method only exists in WPF, and a majority of developers are still working with Windows Forms. So I came up with a solution to use a similar technique in Windows Forms, with a few improvements :

  • Usable on any control, not only a window
  • No need to explicitly handle the MouseDown event
  • Form designer integration, using a IExtenderProvider

My solution consists of the following items :

  • a static DragMoveExtensions class which provides extension methods for the Control class (easily convertible to regular static methods for use with C# 2)
  • a DragMoveProvider component, which implements IExtenderProvider to add a new EnableDragMove property to controls

There are several ways to use this solution, pick the one that best suits your needs :

  • The simplest, which requires no coding at all : in design mode, drop a DragMoveProvider on the Form, and set the EnableDragMove property to true on the Form or control
  • DragMoveProvider

    DragMoveProvider

  • The closest to WPF’s DragMove : in the handler of the MouseDown event, call the DragMove extension method on the Form or control to move
  •         private void label2_MouseDown(object sender, MouseEventArgs e)
            {
                label2.DragMove();
            }
    
  • The most flexible : call the EnableDragMove extension method on the Form or control to move (no event handling needed).
  •         private void checkBox1_CheckedChanged(object sender, EventArgs e)
            {
                this.EnableDragMove(checkBox1.Checked);
            }
    

The attached Visual Studio solution contains the WinFormsDragMove library, and a test project to demonstrate the various ways to use this library. A C#2-compatible version of these projects is also included.

Download source

3 Comments

  1. Fred. says:

    Excellent Article on using Drag & Drop, with a disposable extension.

    Thx!

  2. Josh says:

    I copied provider.cs and extensions.cs into my project, dragged a provider onto my GUI, enabled the property on the controls I wanted and had good movement!

    My use for this is re-arranging the “dominos” in a user”s “hand” for a Trains game.

  3. Joel says:

    I have tried to add this to my program and i get nothing but errors. I have tried adding the project and I have tried just adding the files themselves and I have tried copy/paste. I am writing a simple game called knights tour. where the user moves the knight around from square to square.

    Your code works perfectly when I just run your supplied project, but any which way I try to add it into my own project, nothing but errors.

    I am new to c# and have learned a lot, but i seriously don”t know why i can”t add this bit to my code so my game will work better when the knight moves around.

    InitializeComponent(); throws an error cause it says the function isn”t there when I add just the code as 2 more classes. As far as custom controls, I have two others in play already. This is the other reason this doesn”t make sense.

    Can you please help?

    I am a student that will be returning to college soon and just wanting to get a leg up on the stuff before i get there. ill happily email you my little project so you can help me figure this out. i can move the knight, but it is bad ugly and i believe this code is just what i need. I am just not sure how to implement it. :(

    Thank you.

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