On Thu, 19 Sep 2002 12:00:10 +0300 Olexiy Avramchenko <[EMAIL PROTECTED]> wrote:
> >My app uses a GtkDrawingArea to display some data (lines & texts) drawn > >with gdk drawing primitives. > >the main drawing function is linked with the expose_event of my drawing area > > > > gtk_signal_connect (GTK_OBJECT (drawingarea1), "expose_event", > > GTK_SIGNAL_FUNC(DrawData),this); > > > >thus my system is not very effective and my function is called for each > >refresh request... > >what would be the most effective solution ? > > or where could i put the draw code so that it could be called only once ? > >maybe i should use something else rather than drawing area??? > >(btw: my drawing function reads a hard drive file that s why i would avoid > >to call it so much) > > > Hmm, in that case you have to use back buffer (usual GdkPixmap). You > have to paint all > graphics to that pixmap and draw pixmap on expose event. Look at > scribble-simple example, > coming with gtk. In addition to using a background pixmap (as suggested), I also 'attach' the pixmap to the window (using gdk_window_set_back_pixmap()). This way, you never have to deal with expose events (unless you are drawing stuff that isn't in your background pixmap). All in all, this give a very fast and pleasing application. No flicker, no waiting for expose events to be processed, the data is always visible (Even when stepping through the debugger! :-) etc, etc. (As you've discovered, trying to draw all your data within every expose event is really inefficient, and grinds your app to a standstill if you have much data to draw....) Ian _______________________________________________ gtk-list mailing list [EMAIL PROTECTED] http://mail.gnome.org/mailman/listinfo/gtk-list
