RE: drawing graphics
- From: Joerg Vogler <vogler panasonic de>
- To: Ian Britten <britten caris com>, gtk-list gnome org
- Subject: RE: drawing graphics
- Date: Fri, 20 Sep 2002 14:36:36 +0200
> Make a background pixmap the same size/depth
> bgPixmap = gdk_pixmap_new(drawArea->window,
> drawArea->allocation.height, -1);
> Set the background pixmap as the background of the drawing areas window
> gdk_window_set_back_pixmap(drawArea->window, bgPixmap, 0);
I've tried this piece of code. I have added it immediately after the
construction of the drawing area, i.e.
drawing_area = gtk_drawing_area_new ();
gtk_drawing_area_size (GTK_DRAWING_AREA (drawing_area),
gtk_box_pack_start (GTK_BOX (main_vbox), drawing_area, TRUE, TRUE, 0);
off_screen = gdk_pixmap_new (drawing_area->window,
gdk_window_set_back_pixmap (drawing_area->window, off_screen, 0);
When I run the application, the following messages are printed:
Gdk-CRITICAL **: file gdkpixmap.c: line 62 (gdk_pixmap_new): assertion
`(window != NULL) || (depth != -1)' failed.
Gdk-CRITICAL **: file gdkwindow.c: line 1249 (gdk_window_set_back_pixmap):
assertion `window != NULL' failed.
Why? At which time is drawing_area->window initialised? Is it necessary to
show the app window before initialising the pixmap?
(sorry for the newbie questions... it's my very first GTK app)
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