Dynamically created roundbutton bakgroundcolor is not changing

Question

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Hi all,

can anybody tell me the reason why the dynamically created roundbutton doesn't change its background color when initiated to do so.. The sample code is showwn below:

C#

using System.Windows.Forms;  
using System.Drawing;  
namespace MyNamespace  
{  
    public class RoundButton : UserControl  
    {  
        public Color backgroundColor = Color.LimeGreen;  
        protected override void OnPaint(PaintEventArgs e)  
        {  
            Graphics graphics = e.Graphics;  
            int penWidth = 4;  
            Pen pen = new Pen(Color.Black, 4);  
            int fontHeight = 10;  
            Font font = new Font("Arial", fontHeight);  
            SolidBrush brush = new SolidBrush(backgroundColor);  
            graphics.FillEllipse(brush, 0, 0, Width, Height);  
            SolidBrush textBrush = new SolidBrush(Color.Black);  
            graphics.DrawEllipse(pen, (int)penWidth / 2,  
            (int)penWidth / 2, Width - penWidth, Height - penWidth);  
            graphics.DrawString(Text, font, textBrush, penWidth,  
            Height / 2 - fontHeight);  
        }  
    }  
}  
  
//Usage:  
  
public class MyForm : Form  
{  
    public MyForm()  
    {  
        RoundButton roundButton = new RoundButton();  
        EventHandler handler = new EventHandler(roundButton_Click);  
        //roundButton.Click += handler;  
        roundButton.Text = "Click Here!";  
        roundButton.backgroundColor = System.Drawing.Color.LimeGreen;  
        roundButton.Size = new System.Drawing.Size(80, 80);  
        roundButton.Location = new System.Drawing.Point(100, 30);  
        this.Controls.Add(roundButton);  
    }  
}

public void button1_click(object sender, EventArgs e)
{
timer1.Start();
}
private void timer1_Tick(object sender, EventArgs e)
       {
          if (roundButton[1].backgroundColor == System.Drawing.Color.LimeGreen)
            {
                roundButton[1].backgroundColor = System.Drawing.Color.Red;
            }
          else if(roundButton[1].backgroundColor == System.Drawing.Color.Red)
            {
                roundButton[1].backgroundColor = System.Drawing.Color.LimeGreen;
            }

        }

Thanks in advance...

Posted 15-May-13 0:55am

Jagadisha_Ingenious

Updated 19-May-13 20:25pm

v3

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Comments

toATwork 15-May-13 7:33am

does it stay LimeGreen all the time? If so try to Refresh your control.

Jagadisha_Ingenious 15-May-13 10:45am

@toATwork: Yes it remains Limegreen all the time. When debugging it enters the 1st instruction but it doesn't change. How to refresh the control...?

toATwork 15-May-13 10:46am

Either call Invalidate() or Refresh() on the control
if (roundButton[1].backgroundColor == System.Drawing.Color.LimeGreen)
{
roundButton[1].backgroundColor = System.Drawing.Color.Red;
roundButton[1].Refresh(); // that should do the trick
}

Jagadisha_Ingenious 15-May-13 10:53am

@toATwork: Thanks sir it worked with that instruction. But i want to know why such things happen...? What exactly is the cause for this..?

toATwork 15-May-13 10:54am

I will post an answer with some explanation

Jagadisha_Ingenious 15-May-13 10:56am

@toAtwork: Thank you for that sir..

toATwork 15-May-13 11:24am

You are welcome. Please accept the solution.

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toATwork · Accepted Answer · 2013-05-15T04:59:00

You need to Refresh the control because it does not know that repainting is necessary.

C#

if (roundButton[1].backgroundColor == System.Drawing.Color.LimeGreen)
{
  roundButton[1].backgroundColor = System.Drawing.Color.Red;
  roundButton[1].Refresh(); // that should do the trick
}

When you change the BackColor of a standard control, the system takes care of all that stuff for you (invalidating and repainting). But you have defined a separate property with the containing backcolor - if you change it, the control must be informed.

If you use the default BackColor propery, it should work without calling Refresh manually.