GOPAL YADAV GOPAL YADAV - 1 month ago 35
C# Question

Toggle Switch Control in Windows Forms

I am designing a Toggle Switch control using

CheckBox
, but currently my control only draws a circle. How can I draw round shapes like below image and how can I change the location of the circle based on value of the control like below image:

enter image description here

Here is my code:

public class MyCheckBox:CheckBox
{
public MyCheckBox()
{
this.Appearance = System.Windows.Forms.Appearance.Button;
this.BackColor = Color.Transparent;
this.TextAlign = ContentAlignment.MiddleCenter;
this.FlatStyle = System.Windows.Forms.FlatStyle.Flat;
this.FlatAppearance.BorderColor = Color.RoyalBlue;
this.FlatAppearance.BorderSize = 2;
}

protected override void OnPaint(PaintEventArgs e)
{
this.OnPaintBackground(e);
using (var path = new GraphicsPath())
{
var c = e.Graphics.ClipBounds;
var r = this.ClientRectangle;
r.Inflate(-FlatAppearance.BorderSize, -FlatAppearance.BorderSize);
path.AddEllipse(r);
e.Graphics.SetClip(path);
base.OnPaint(e);
e.Graphics.SetClip(c);
e.Graphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
if (this.Checked)
{
using (var p = new Pen(FlatAppearance.BorderColor,
FlatAppearance.BorderSize))
{
e.Graphics.DrawEllipse(p, r);
}
}
}
}
}


Please help me, thanks in advance.

Answer

I know this is a question. But you may want to take a look at Toggle Switches or read more about Universal Windows App Components. Anyway, here is an answer for Windows forms developers. It shows how we can customize rendering of a check box to have such appearance.

Currently you are drawing only an ellipse, it's quiet a toggle button. But if you want to show it like the below image, you should first draw a round shape for background, then based on Checked value draw the check circle. Using the codes in Example part of the answer you can have a CheckBox with such UI:

enter image description here

Example

The important thing about this sample is it's completely a CheckBox control and supports check using mouse and keyboard, also supports data-binding and all other standard features of CheckBox. The code is not perfect, but is a good start point to have a yes/no toggle switch:

using System.Drawing;
using System.Drawing.Drawing2D;
using System.Windows.Forms;
public class MyCheckBox : CheckBox
{
    public MyCheckBox()
    {
        SetStyle(ControlStyles.UserPaint | ControlStyles.AllPaintingInWmPaint, true);
        Padding = new Padding(6);
    }
    protected override void OnPaint(PaintEventArgs e)
    {
        this.OnPaintBackground(e);
        e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
        using (var path = new GraphicsPath())
        {
            var d = Padding.All;
            var r = this.Height - 2 * d;
            path.AddArc(d, d, r, r, 90, 180);
            path.AddArc(this.Width - r - d, d, r, r, -90, 180);
            path.CloseFigure();
            e.Graphics.FillPath(Checked ? Brushes.DarkGray : Brushes.LightGray, path);
            r = Height - 1;
            var rect = Checked ? new Rectangle(Width - r - 1, 0, r, r)
                               : new Rectangle(0, 0, r, r);
            e.Graphics.FillEllipse(Checked ? Brushes.Green : Brushes.WhiteSmoke, rect);
        }
    }
}