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10 votes for this article.

Popularity: 3.95 Rating: 3.95 out of 5

Background

I was searching for a way to snap a form to the borders of the screen, like what Winamp does, and found one here. But my form was without border (FormBorderStyle = None) and the code I found here didn�t work great for the forms without border. It also seemed like a little complicated for the beginners (almost like me!) so I tried to write it myself and wrote a more simple and easy to understand code. This is also a very simple way to move forms without border.

Code

The following variables should be declared right after Public Class �.. so that other procedures can access them.

Dim X1 As Integer, Y1 As Integer, WR As Rectangle

Now put the following code in the MouseDown event of the form.

Private Sub Form1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Me.MouseDown
   X1 = e.X
   Y1 = e.Y
   WR = Screen.GetWorkingArea(Me)
End Sub

This piece of code records the point where mouse was clicked and also the working area of the desktop. Now the main part of the code should be put in the MouseMove event of the form.

Private Sub Form1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Me.MouseMove
   If Not e.Button = Windows.Forms.MouseButtons.Left Then Exit Sub
   Dim NewX As Integer = Me.Left + (e.X - X1)
   Dim NewY As Integer = Me.Top + (e.Y - Y1)
   Dim W As Integer = Me.Width
   Dim H As Integer = Me.Height
   If NewY >= WR.Top - 15 And NewY <= WR.Top + 15 Then
      Me.Top = WR.Top
   ElseIf NewY + H > WR.Bottom - 15 And NewY + H < WR.Bottom + 15 Then
      Me.Top = WR.Bottom - H
   Else
      Me.Top = NewY
   End If
   If NewX >= WR.Left - 15 And NewX <= WR.Left + 15 Then
      Me.Left = WR.Left
   ElseIf NewX + W > WR.Right - 15 And NewX + W < WR.Right + 15 Then
      Me.Left = WR.Right - W
   Else
      Me.Left = NewX
   End If
End Sub

This code calculates the new position of form when you move the mouse with left click pressed down and snaps it when it gets near the borders of the screen. The default distance is 15, but you can change it or replace it with a variable to change it dynamically during the runtime.

Significance

It is a very easy to understand code and has no complication. It also uses a very simple method to move a form which has no border.

License

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

About the Author

Hamed.M

Member

Occupation:	Other
Location:	Iran, Islamic Republic Of

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Thx for the port and thax for the original code

Mister03

9:25 29 Nov '08

As I have a couple of form in my project I did a class of it
Snap.cs

So I just add


SnapForm.SnapIt snap = new SnapForm.SnapIt(this,20);

Where you can see below is SnapIt(Form parent,int SnapDisatance)


using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;
using System.Drawing;

namespace SnapForm
{
    class SnapIt
    {

        private Form _parent;
        internal int iFormX;
        internal int iFormY;
        Rectangle rFormRect;
        internal int iScreenSnapDistance = 15;

        public SnapIt(Form parent,int SnapDisatance)
        { 
            this._parent = parent;
            this._parent.MouseDown += new MouseEventHandler(_parent_MouseDown);
            this._parent.MouseMove += new MouseEventHandler(_parent_MouseMove);
            iScreenSnapDistance = SnapDisatance;
        }

        internal void _parent_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button != MouseButtons.Left)
                return;
            rFormRect = Screen.FromControl(_parent).WorkingArea;
            int NewX = _parent.Left + (e.X - iFormX);
            int NewY = _parent.Top + (e.Y - iFormY);
            int w = _parent.Width;
            int h = _parent.Height;
            if (NewY >= rFormRect.Top - iScreenSnapDistance && NewY <= rFormRect.Top + iScreenSnapDistance)
                _parent.Top = rFormRect.Top;
            else if (NewY + h > rFormRect.Bottom - iScreenSnapDistance && NewY + h < rFormRect.Bottom + iScreenSnapDistance)
                _parent.Top = rFormRect.Bottom - h;
            else _parent.Top = NewY;

            if (NewX >= rFormRect.Left - iScreenSnapDistance && NewX <= rFormRect.Left + iScreenSnapDistance)
                _parent.Left = rFormRect.Left;
            else if (NewX + w > rFormRect.Right - iScreenSnapDistance && NewX + w < rFormRect.Right + iScreenSnapDistance)
                _parent.Left = rFormRect.Right - w;
            else
                _parent.Left = NewX;
        }

        internal void _parent_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                // Code for snap-to-screen-edge        
                iFormX = e.X;
                iFormY = e.Y;
            }
        }
    }
}

Thx again was realy hard to find as I was searchin all over for SticyWindows examples and there was only one..

Port to C#

hayes.adrian

13:53 18 Sep '08

Here is a port to C#. Enjoy!

Added as class-scope variables:

// Used to snap form to edge of the screen
int iFormX;
int iFormY;
Rectangle rFormRect;
// Set iScreenSnapDistance to 0 to disable screen edge snapping
int iScreenSnapDistance = 10;

Events:

private void Form1_MouseDown(object sender, MouseEventArgs e)
{
    if (e.Button == MouseButtons.Left)
    {
        // Code for snap-to-screen-edge
        iFormX = e.X;
        iFormY = e.Y;
        
    }

}

private void QPhoneBar_MouseMove(object sender, MouseEventArgs e)
{
    if (e.Button != MouseButtons.Left)
        return;
    rFormRect = Screen.FromControl(this).WorkingArea;

    int NewX = this.Left + (e.X - iFormX);
    int NewY = this.Top + (e.Y - iFormY);

    int w = this.Width;
    int h = this.Height;

    if (NewY >= rFormRect.Top - iScreenSnapDistance && 
        NewY <= rFormRect.Top + iScreenSnapDistance)
        this.Top = rFormRect.Top;
    else if (NewY + h > rFormRect.Bottom - iScreenSnapDistance && 
             NewY + h < rFormRect.Bottom + iScreenSnapDistance)
        this.Top = rFormRect.Bottom - h;
    else
        this.Top = NewY;

    if (NewX >= rFormRect.Left - iScreenSnapDistance && 
        NewX <= rFormRect.Left + iScreenSnapDistance)
        this.Left = rFormRect.Left;
    else if (NewX + w > rFormRect.Right - iScreenSnapDistance && 
             NewX + w < rFormRect.Right + iScreenSnapDistance)
        this.Left = rFormRect.Right - w;
    else
        this.Left = NewX;
}

Again, Thanks!

Change for Multiple Monitor screens and disabling Snap

hayes.adrian

13:35 18 Sep '08

This worked great! It is simple to use and works like a charm.

I did make two changes to how I implemented it in my form:

Multi-Monitor:
The original posting worked fine if run on a single-monitor system. However, in multi-monitor setups, it will only snap to the main screen.

I removed this line from the Form_MouseDown event and placed it in Form_MouseMove:

WR = Screen.GetWorkingArea(Me)

and I changed it to this:

WR = Screen.FromControl(this).WorkingArea

By using FromControl(), it uses the screen where the form is positioned as it's snap-to monitor. By placing it in the MouseMove event instead of MouseDown, it ensures that the form snaps to any monitor to which it is moved.

Disabling Snap:
I replaced your 15-pixel hard coded snap distance with a class-scope variable. By doing this, I could set the value to 0 to disable screen snapping. I could also include an option for the user to choose their level of "stickyness" by increasing or decreasing this variable.

Dim iScreenSnapDistance = 10;

In Form_MouseMove:
If NewX >= WR.Left - iScreenSnapDistance && ...

Thank you for posting this article. Good job!

Last Visit: 18:15 8 Nov '09 Last Update: 18:15 8 Nov '09

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