Drawing Control

[sean.aulason]

hi there,

in Delphi, there is a control named TPaintBox which is similar to PictureBox but with a Canvas property that is very useful if we intend to do some drawing on it.

1. is there any control in C# like TPaintBox to draw something on it?

2. would you please write a simple code snippet in which a simple line is drawn on this control?

thanks for your time

[rliq]

You can use the:

// Create a Graphics object for the Control.
   Graphics g = pictureBox.CreateGraphics();

to get the Graphics object for the PictureBox control. Then use the members of the Graphics class to draw on it.

[sean.aulason]

thanks but how should i redraw the line?

it vanishes as soon as i scroll it or something covers it for a while!

EDIT:
ok,

i find a solution and it's using Bitmap instead.

so here is my code:

            Bitmap bm = new Bitmap(picturebox.Width, picturebox.Height);
            Graphics g = Graphics.FromImage(bm);
            System.Drawing.Pen p = new System.Drawing.Pen(Color.Red);
            
            g.DrawLine(p, 0, 0, 10, 10);
            picturebox.Image = bm;
            
            p.Dispose();
            g.Dispose();

but there's a problem. since i create PictureBoxes at runtime and i remove them by calling Controls.Clear(), when should i dispose this bitmap object?

[rliq]

In general, all drawing code should be placed in the forms Paint event handler. This is automatically called when part of your application needs to be drawn.