Re: Hi

[Olexiy Avramchenko <olexiy irtech cn ua>]

Zbigniew Wasik wrote:

> Already 4:33AM but I almost finished my small project (showing pictures)
> and do some drawings <- jut for me - to learn GTK / GDK
>
> Only one problem - How I can draw e.g. RED rectangles on drawingarea 
> I tried with GdkColor and GC but I all the time I get black rectangles.
>
> Also how to make double buffering for showing images and drawing lines
> on those images  
>  
Hello,
As for black rectangles - you should allocate color before use it in 
gdk_gc_set_[fore][back]ground():
http://developer.gnome.org/doc/API/2.0/gdk/gdk-Colormaps-and-Colors.html#gdk-colormap-alloc-color
you will see strange results with unallocated color because 
GdkColor::pixel value is not initialized.

Widgets in GTK2 are double-buffered by default, it can be turn off for 
particular widget with gtk_widget_set_double_buffered():
http://developer.gnome.org/doc/API/2.0/gtk/GtkWidget.html#gtk-widget-set-double-buffered
Also you can check whether widget is double buffered or not with 
GTK_WIDGET_DOUBLE_BUFFERED() macro:
http://developer.gnome.org/doc/API/2.0/gtk/GtkWidget.html#GTK-WIDGET-DOUBLE-BUFFERED-CAPS

   Olexiy