Re: [Newbie] Despairence about Graphics Context.

[Gustavo Giráldez <gustavo giraldez gmx net>]

Hi,

On Sun, 2002-07-07 at 13:50, Jan Luehr wrote:
> Greetings,
> 
> I'm new to gtk, so please don't blame me.
> 
> I'm trying to paint a green square in an offscreen pixmap. My current  
> approach is:
> 
> GdkColor green; //Formulas
> GdkGC gc;
> GtkWidget *widget;
> Pixmap *pixmap;
> GdkColormap *map;
> GdkColor color_green;
> 
> map = gdk_colormap_get_system(); // Get the System's colormap
> gdk_color_parse("green",&color_green); //Get the color
> gdk_colormap_alloc_color(map,&color_green); //Allocate it
> gdk_draw_rectangle(pixmap,widget -> style -> black_gc,TRUE,30,30,20,20); 
> //Works fine.
> gdk_gc_copy(&gc, widget -> style -> white_gc); //Causes a segmentation fault; 
> get the new context

In GTK 2.0, GC are GObjects and as such cannot be allocated in the
stack.  You need to create one using gdk_gc_new() or
gdk_gc_new_with_values().  Of course the var will be of type GdkGC *. 
When you're finished with it don't forget to unref it with
g_object_unref().

HTH,
Gustavo

> 
> gdk_gc_set_foreground(&gc, &color_green); //Set the color
> 
> 
> gdk_draw_rectangle(pixmap,&gc,TRUE,1,1,20,20); //Draw the rectangle
> 
> What's wrong here?
> 
> Keep smiling
> yanosz
> 
> -- 
> GnuPG Key available at http://www.jluehr.de.vu/public_key.asc
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