[c#] no overload for matches delegate 'system.eventhandler'



Answers

Yes there is a problem with Click event handler (klik) - First argument must be an object type and second must be EventArgs.

public void klik(object sender, EventArgs e) {
  //
}

If you want to paint on a form or control then use CreateGraphics method.

public void klik(object sender, EventArgs e) {
    Bitmap c = this.DrawMandel();
    Graphics gr = CreateGraphics();  // Graphics gr=(sender as Button).CreateGraphics();
    gr.DrawImage(b, 150, 200);
}
Question

As I'm pretty new to C#, I struggle with the following piece of code. When I click to button 'knop', the method 'klik' has to be executed. The method has to draw the Bitmap 'b', generated by 'DrawMandel' on the form. But I constantly get the error 'no overload for matches delegate 'system.eventhandler'.

using System;
using System.Windows.Forms;
using System.Drawing;

class Mandelbrot : Form 
{
    public Bitmap b;
    public Mandelbrot() 
    {
        Button knop;
        knop = new Button();        
        knop.Location = new Point(370, 15);        
        knop.Size = new Size(50, 30);
        knop.Text = "OK";        

        this.Text = "Mandelbrot 1.0";
        this.ClientSize = new Size(800, 800);
        knop.Click += this.klik;
        this.Controls.Add(knop);        


    }
    public void klik(PaintEventArgs pea, EventArgs e) {
        Bitmap c = this.DrawMandel();
        Graphics gr = pea.Graphics;
        gr.DrawImage(b, 150, 200);
    }
    public Bitmap DrawMandel()
    {
        //function that creates the bitmap
        return b;
    }
    static void Main() {
        Application.Run(new Mandelbrot());
    }

}



Change the klik method as follows:

public void klik(object pea, EventArgs e)
{
    Bitmap c = this.DrawMandel();
    Button btn = pea as Button;
    Graphics gr = btn.CreateGraphics();
    gr.DrawImage(b, 150, 200);
}



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