Re: colormaps



Russell Shaw wrote:

Hi,

In an expose-event callback of a gtk_drawing_area this always paints
a black region even tho i have it set for white:

gdk_draw_rectangle(widget->window,
                   background_gc,
                   TRUE,
                   event->area.x,
                   event->area.y,
                   event->area.width,
                   event->area.height);


I set up the graphics context as:

    background_gc=gdk_gc_new(drawing_area->window);
    foreground.red=0;
    foreground.green=0;
    foreground.blue=0;
    background.red=0xffff;
    background.green=0xffff;
    background.blue=0xffff;
    gdk_gc_set_foreground(background_gc,&background);
    gdk_gc_set_background(background_gc,&background);
    gdk_gc_set_function(background_gc,GDK_COPY);


Would i need to do something with creating a new GdkColormap to make it work?

You should allocate colors before gdk_gc_set_*ground calls. You see the black color because of zero *pixel* field value in foreground/background structures. If you want to avoid color allocation - use gdk_gc_set_rgb_*_color functions:
http://developer.gnome.org/doc/API/2.0/gdk/gdk-Graphics-Contexts.html#gdk-gc-set-rgb-fg-color

   Olexiy




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