Re: Draw in a GdkPixbuf

[James Scott Jr <skoona verizon net>]

Take a look at the executable 'gtk-demo'.  It should have been installed
with gtk's development tools; i.e. already loaded on you machine.  Hint:
double click the sample for a live preview, then look at the source
code.

Additionally, here is a link to glinegraph, a simple line graph widget
written twice, once in gdk and again in cairo.

http://sourceforge.net/project/showfiles.php?group_id=157888&package_id=191712

James,




On Thu, 2008-05-29 at 03:18 +0200, Luis Menina wrote:
> Hi list!
> 
> I'm trying to find a way to draw in a GdkPixbuf (for example draw a 
> rectangle on the pixbuf) and save the result to a file afterwards.
> 
> I found in devhelp the gdk_draw_* functions, but to use them I need a 
> GdkPixmap. gdk_pixmap_new requires a GdkDrawable. The problem is that 
> I'm developping a command line application, so I don't use GTK, only 
> glib, gdk, and gdk-pixbuf. Even creating the GdkPixmap with a NULL 
> GdkDrawable, I can't workaround the problem, because the documentation 
> of gdk_draw_pixbuf tells me that "All windows have a colormap, however, 
> pixmaps only have colormap by default if they were created with a 
> non-NULL window argument. Otherwise a colormap must be set on them with 
> gdk_drawable_set_colormap()". Trying to get a colormap requires other 
> stuff, which requires other stuff, and so on...
> 
> As this seems to be quite old-fashioned way of doing things, I tried to 
> see if cairo could do the trick. But it seems there's no way to draw to 
> a GdkPixbuf with cairo (I'm unfamiliar with cairo).
> 
> So, does anyone have an hint on how to draw and save an image from a 
> GdkPixbuf, with gdk or cairo ?
> 
> Thanks for you help,
> 
> Luis
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