Re: color/colormap oddities

[Olexiy Avramchenko <olexiy irtech cn ua>]

Karl H. Beckers wrote:

> Hello,
>
> any pointers to a solution welcome, TIA ...
>
> I have this app which has one GtkWindow and a number of small GtkDialogs
> I'm abusing to mark an area on screen with an always-on-top rectangle.
>
> These GtkDialogs are painted red in an expose-event event handler.
>
> > //paint parts of frame on expose
> > static gint on_expose_paint(GtkWidget *w, GdkEventExpose *e) {
> >         GdkGC *gc;
> >         GdkColormap *colormap;
> >         GdkColor g_col;
> >         int n;
> >                                                                                                                             
> >         gc = w->style->fg_gc[GTK_WIDGET_STATE (w)];
> >         colormap = gtk_widget_get_colormap (w);
> >         if (gdk_color_parse("red", &g_col)){
> >                 if (gdk_colormap_alloc_color(colormap, &g_col, FALSE, 
> > TRUE)) {
> >                         gdk_gc_set_function ( gc, GDK_COPY );
> >                         gdk_gc_set_fill ( gc, GDK_SOLID );
> >                         gdk_gc_set_line_attributes ( gc, 3, 
> > GDK_LINE_SOLID, GDK_CAP_BUTT, GDK_JOIN_MITER );
> >                         gdk_gc_set_foreground ( gc, &g_col );
> >                         gdk_draw_rectangle (w->window, gc, TRUE, 0, 
> > 0, w->allocation.width, w->allocation.height);
> >                  }
> >         
> > }                                                                                                                            
> >
> > }
>
>
>
> If I do this, some widgets get painted red as well (even in other dialogs
> opened from the main window), e.g. the downward arrow in a spinbutton
> where you're already at the lowest value of the range.
>
> Looks to me like I'm messing up my colormap ... but how and why (on
> a TrueColor display).
>
> Any pointers and RTFMs welcom,

You've messed style's gc, not colormap. You have to create your own gc 
and use it for painting.

   Olexiy