Re: [gtk-list] Gdk_draw_rectangle

[José Miguel Rodríguez <jmiguel ceselsa es>]

Try drawing the rectangle after showing the windows. Even best, "catch" the expose event for the drawing area, and draw the rectangle whithin.



erwin.verhulst@philips.com wrote:

> Hoi,
>
> I'm trying to figure out this GTK stuff, but it's not getting anywhere. I'm trying to draw a simple rectangle in a window, but I keep getting the same error message everytime.
> Here below is the probably childies program, but aslong as I don't understand the functions it's as good as it gets.
>
> #include <glib.h>
> #include <gdk/gdk.h>
> #include <gtk/gtk.h>
>
> GtkWidget *drawingarea = NULL;
>
> gint main (gint argc, gchar *argv[])
> {
>         gint x,y;
>         GtkWidget *window;
>
>         gtk_init (&argc,&argv);
>
>         x = 51; y = 39;
>
>         window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
>         gtk_window_set_title (GTK_WINDOW(window), " PowerBar ");
>
>         gtk_signal_connect (GTK_OBJECT(window), "delete_event", (GtkSignalFunc) gtk_exit, NULL);
>         gtk_signal_connect (GTK_OBJECT(window), "destroy" , (GtkSignalFunc) gtk_exit, NULL);
>
>         drawingarea = gtk_drawing_area_new ();
>         gtk_drawing_area_size (GTK_DRAWING_AREA(drawingarea), 200, 200);
>
> -->     gdk_draw_rectangle (drawingarea->window,window->style->black_gc, 1,(gint)x ,(gint)y , 20, 5);
>
>         gtk_container_add (GTK_CONTAINER(window), drawingarea);
>
>         gtk_widget_show (drawingarea);
>         gtk_widget_show (window);
>
>         gtk_main ();
>
>         return (0);
> }
>
> When I run this program I get the following error message:
>
> Gdk-CRITICAL **: file gdkdraw.c: line 89 (gdk_draw_rectangle): assertion 'drawable != NULL' failed.
>
> What is wrong with my function call and can somebody explain the first two arguments, it would be all the help I need.
>
> Thanks,
>
> EV
>
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