Re: [newbie] How to plot to drawing_area

[Roland Smith <rsmith xs4all nl>]

On Sat, 1 Feb 2003 18:09:48 -0300
"Individual . ." <individual@mi.cl> wrote:

> I decided it would be great if I could learn how to plot an image to a 
> window, pixel by pixel. Getting the  image is no problem at all, since 
> I wrote a simple c++ class that uses libpng 
> (<http://pngwriter.sourceforge.net/>).
> The plotting part is what is holding me up.
> 
> I have looked at the scribble program that is given as an example, but 
> I must say that the lack of a chapter on drawing_area widgets in the 
> tutorial isn't helping me one bit!

Plotting pixel by pixel is _slow_. It's better to use GdkRGB, e.g. using
gdk_draw_rgb_image(). What you have to do is read from the png file to a buffer
containing an array of rgb values. This is then drawn to a drawable. See the
example in the GDK manual.

HTH, Roland
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