hi, On 17.08.2010 12:01, James Morris wrote: > Hi, > > I see that some GDK drawing functions and graphics contexts have been > deprecated in favour of using Cairo. > > Yesterday I spent a few hours *removing* Cairo code from my fledgling > GTK application and replacing it with gdk_draw_rectangle, > gdk_gc_set_rgb_fg_color, and gdk_gc_set_function. I did this for > performance reasons[1] > > I am wondering if my approach to drawing is wrong however and if a > better approach might yield less CPU usage? > > It begins with a 33ms timeout. The timeout callback calls > gtk_widget_queue_draw on the window and the drawing area. >
Would it be possible to isolate this into a standalone demo. Or could you point us to the actual code? Stefan > (Imagine rectangles appearing each time a note is played in a piece of > music and disappearing when that note ends.) > > In the expose event callback a linked-list of rectangles is > maintained. Rectangles are added to the list and removed from the list > as notes start and end (The application is an experimental MIDI > sequencer/arpeggiator operating in real time). > > Each and every time the expose event callback is called (every 33ms) > the background and the entire list of rectangles is drawn as well as > various maintenance functions performed on the list. > > The documentation of gdk_cairo_create seems to suggest this is the > only way of doing it when it says: > > "Note that due to double-buffering, Cairo contexts created in a GTK+ > expose event handler cannot be cached and reused between different > expose events." > > Is it possible to do this any other way? > Cheers, > James. > > [1]My machine is a 64bit 3.0ghz dual core desktop. Using GDK for > drawing, the CPU usage is at worst 5% on both cores. Using Cairo on > the other hand, the CPU usage can reach as much as 20% on both cores. > > The project is here: http://github.com/jwm-art-net/BoxySeq > Cairo routines is here: > http://github.com/jwm-art-net/BoxySeq/tree/97f6d674a2a182a143ef82b03bde11689fedcf18 > GDK routines is here: > http://github.com/jwm-art-net/BoxySeq/tree/29f412b41b2371ec136aa86da50d858f5892bfa0 > _______________________________________________ > gtk-app-devel-list mailing list > gtk-app-devel-list@gnome.org > http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list > _______________________________________________ gtk-app-devel-list mailing list gtk-app-devel-list@gnome.org http://mail.gnome.org/mailman/listinfo/gtk-app-devel-list
