Hello,
how can I permanently clear the content of a PictureBox which has a
background colour set to white? I have tried to do it the same way as
I do the painting (create a Bitmap, clear it with white colour and
draw it onto a Graphics on the PictureBox), but it does not work as I
expect it would.

The PictureBox is on a TabPage of a TabControl. After I try to clear
the content of the PictureBox, it becomes white, but if I switch to
another TabPage and return back, the previous image is there again.
The same thing happens when I click a menu item. It rolls down, covers
the PictureBox partially, and after it rolls up, the part of the
PictureBox that was covered contains the previous content. What do I
do wrong?

Sample code supposed to permanently clear the contents of a
PictureBox:

Bitmap bm = new Bitmap(pictureBox.Width, pictureBox.Height);
Graphics g = Graphics.FromImage(bm);
g.Clear(System.Drawing.Color.White);
Graphics pbg = pictureBox.CreateGraphics();
pbg.DrawImageUnscaled(bm, new Point(0, 0));
g.Dispose();


Thanks for any help...

Best regards
nvx

SOLVED... There was one wrong declaration in the code.

nvx

A picture box displays images. You don't need to draw the image onto it, you 
just set the Picturebox's Image property to the image.

Bitmap bm=new Bitmap(...);
this.pictureBox1.Image=bm;

To clear the image from the picture box just simply set the Image parameter 
to null.


-- 
-- 
Bob Powell [MVP]
Visual C#, System.Drawing

Ramuseco Limited .NET consulting
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"nvx"  wrote in message 
news:1185885755.126623.52880@22g2000hsm.googlegroups.com...

> Hello,
> how can I permanently clear the content of a PictureBox which has a
> background colour set to white? I have tried to do it the same way as
> I do the painting (create a Bitmap, clear it with white colour and
> draw it onto a Graphics on the PictureBox), but it does not work as I
> expect it would.
>
> The PictureBox is on a TabPage of a TabControl. After I try to clear
> the content of the PictureBox, it becomes white, but if I switch to
> another TabPage and return back, the previous image is there again.
> The same thing happens when I click a menu item. It rolls down, covers
> the PictureBox partially, and after it rolls up, the part of the
> PictureBox that was covered contains the previous content. What do I
> do wrong?
>
> Sample code supposed to permanently clear the contents of a
> PictureBox:
>
> Bitmap bm = new Bitmap(pictureBox.Width, pictureBox.Height);
> Graphics g = Graphics.FromImage(bm);
> g.Clear(System.Drawing.Color.White);
> Graphics pbg = pictureBox.CreateGraphics();
> pbg.DrawImageUnscaled(bm, new Point(0, 0));
> g.Dispose();
>
>
> Thanks for any help...
>
> Best regards
> nvx
>