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Draggable WinForms Controls

, 8 Apr 2011 CPOL 26.9K 32
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Extension method to make any WinForms control to be draggable at runtime

Sometimes, you need to make the control draggable during runtime. It can be a form with FormBorderStyle property set to None, or any other situation.

I want to propose a simple extension method that allows you to make this possible.
 

using System;
using System.Collections.Generic;
using System.Windows.Forms;
namespace DraggableControls
{
    public static class ControlExtension
    {
        // TKey is control to drag, TValue is a flag used while dragging
        private static Dictionary<Control, bool> draggables = 
                   new Dictionary<Control, bool>();
        private static System.Drawing.Size mouseOffset;
 
        /// <summary>
        /// Enabling/disabling dragging for control
        /// </summary>
        public static void Draggable(this Control control, bool Enable)
        {
            if (Enable)
            {
                // enable drag feature
                if (draggables.ContainsKey(control))
                {   // return if control is already draggable
                    return;
                }
                // 'false' - initial state is 'not dragging'
                draggables.Add(control, false);
 
                // assign required event handlersnnn
                control.MouseDown += new MouseEventHandler(control_MouseDown);
                control.MouseUp += new MouseEventHandler(control_MouseUp);
                control.MouseMove += new MouseEventHandler(control_MouseMove);
            }
            else
            {
                // disable drag feature
                if (!draggables.ContainsKey(control))
                {  // return if control is not draggable
                    return;
                }
                // remove event handlers
                control.MouseDown -= control_MouseDown;
                control.MouseUp -= control_MouseUp;
                control.MouseMove -= control_MouseMove;
                draggables.Remove(control);
            }
        }
        static void control_MouseDown(object sender, MouseEventArgs e)
        {
            mouseOffset = new System.Drawing.Size(e.Location);
            // turning on dragging
            draggables[(Control)sender] = true;
        }
        static void control_MouseUp(object sender, MouseEventArgs e)
        {
            // turning off dragging
            draggables[(Control)sender] = false;
        }
        static void control_MouseMove(object sender, MouseEventArgs e)
        {
            // only if dragging is turned on
            if (draggables[(Control)sender] == true)
            {
                // calculations of control's new position
                System.Drawing.Point newLocationOffset = e.Location - mouseOffset;
                ((Control)sender).Left += newLocationOffset.X;
                ((Control)sender).Top += newLocationOffset.Y;
            }
        }
    }
}

 

It's pretty simple to use this code. To make control draggable, you just need to write one line of code:
 

AnyControl.Draggable(true);

and to disable this feature:
 

AnyControl.Draggable(false);

For example, if your Form contains two checkboxes named checkBox_DragForm and checkBox_DragButton with CheckedChanged event handlers assigned, and button with name btnTest, you may use the following code to enable/disable drag feature on Form (represented by this) or/and button:

 
 

private void checkBox_DragForm_CheckedChanged(object sender, EventArgs e)
{
    this.Draggable(checkBox_DragForm.Checked);
}
private void checkBox_DragButton_CheckedChanged(object sender, EventArgs e)
{
    btnTest.Draggable(checkBox_DragButton.Checked);
}

 

The code sample is here (VS2010 solution).

Hope this would be helpful.

Update (2015-02-26): Extention is also available on Github and as a Nuget package

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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intrueder
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QuestionClick Event Pin
Manvendra Singh23-Feb-15 19:38
memberManvendra Singh23-Feb-15 19:38 
AnswerRe: Click Event Pin
intrueder25-Feb-15 23:10
memberintrueder25-Feb-15 23:10 
GeneralRe: Click Event Pin
Manvendra Singh25-Feb-15 23:57
memberManvendra Singh25-Feb-15 23:57 
AnswerRe: Click Event Pin
intrueder26-Feb-15 2:42
memberintrueder26-Feb-15 2:42 
GeneralRe: Click Event Pin
Manvendra Singh26-Feb-15 18:07
memberManvendra Singh26-Feb-15 18:07 
GeneralMy vote of 5 Pin
nirav raval13-Feb-15 1:09
membernirav raval13-Feb-15 1:09 
AnswerRe: My vote of 5 Pin
intrueder26-Feb-15 7:32
memberintrueder26-Feb-15 7:32 
GeneralMy vote of 5 Pin
Erik Norman9-Feb-15 3:20
memberErik Norman9-Feb-15 3:20 
GeneralMy vote of 5 Pin
Keyi Zhang12-Jul-13 23:12
memberKeyi Zhang12-Jul-13 23:12 
GeneralMy vote of 5 Pin
Horseman270323-Jan-13 22:18
memberHorseman270323-Jan-13 22:18 
AnswerRe: My vote of 5 Pin
InTRUEdeR23-Jan-13 23:55
memberInTRUEdeR23-Jan-13 23:55 
GeneralMy vote of 5 Pin
LeszekCode27025-Oct-12 21:24
memberLeszekCode27025-Oct-12 21:24 
GeneralMy vote of 5 Pin
truongvu_12324-Jun-12 23:20
membertruongvu_12324-Jun-12 23:20 
GeneralReason for my vote of 5 easy to use Pin
CalvinWang18-Dec-11 23:17
memberCalvinWang18-Dec-11 23:17 
GeneralReason for my vote of 5 Very nice. Thanks Pin
zenwalker198518-Dec-11 23:15
memberzenwalker198518-Dec-11 23:15 
GeneralReason for my vote of 5 Excellent!! thank you very much..it... Pin
jawed.ace27-Jun-11 23:01
memberjawed.ace27-Jun-11 23:01 
GeneralReason for my vote of 5 Nice one..thanks!! Pin
jawed.ace25-Jun-11 21:23
memberjawed.ace25-Jun-11 21:23 
Reason for my vote of 5
Nice one..thanks!!
GeneralRe: thanks for your vote! Pin
InTRUEdeR26-Jun-11 4:02
memberInTRUEdeR26-Jun-11 4:02 
Generalwow! I like it Pin
zhanghaocol1-May-11 22:44
memberzhanghaocol1-May-11 22:44 
GeneralReason for my vote of 5 Nice and usefull snippet Pin
DotNetMastermind12-Apr-11 0:15
memberDotNetMastermind12-Apr-11 0:15 
GeneralReason for my vote of 5 Simple, like it. Pin
Kim Togo11-Apr-11 22:16
memberKim Togo11-Apr-11 22:16 
GeneralReason for my vote of 5 Cool! Wish I needed to use this some... Pin
IGood11-Apr-11 13:54
memberIGood11-Apr-11 13:54 
GeneralMy vote 5 This was really nice. Pin
JAxelsson10-Apr-11 21:35
memberJAxelsson10-Apr-11 21:35 
GeneralReason for my vote of 5 Nice Pin
HiMik200310-Apr-11 20:57
memberHiMik200310-Apr-11 20:57 
GeneralReason for my vote of 5 Elegant and simple. Nice. Pin
Chris Trelawny-Ross8-Apr-11 7:32
memberChris Trelawny-Ross8-Apr-11 7:32 

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