Re: Copying X pixmap.

[Owen Taylor <otaylor redhat com>]

On Sun, 2003-05-04 at 08:33, Fritz Ganter wrote:

> Am Son, 2003-05-04 um 03.32 schrieb Owen Taylor:
> 
> >  a) disable double buffering for that widget with
> 
> I'm porting gpsdrive (http://www.kraftvoll.at/software/index.shtml) from
> gtk-1.2 to gtk 2.2.
> But the performance is terrible, with gtk-1.2 I have around 4% CPU
> usage, with gtk-2.2 its about 30-40%
> I'm drawing ~ 600x500 big pixmaps 3 times a second to the screen. In
> gtk-1.2 I did doublebuffering myself (drawing all on a pixmap, then
> drawing it to the main window  gdk_draw_pixmap
> (drawing_area->window,..).
> I did now 
>   drawable = gdk_pixmap_new (mainwindow->window, SCREEN_X, SCREEN_Y,
> -1);
> 
> this added -> gtk_widget_set_double_buffered(drawable, FALSE);
> 
> But this doesn't give me the performance back.
> Another question: does a  gtk_label_set_markup (GTK_LABEL (altilabel),
> s3); have a bad perforcmance? I draw about 20 characters 3 times a
> second. This replaces my old gdk-style manipulation to draw in a bigger
> font.

Well, there is certainly overhead from parsing the markup; but for
3 times a second, it doesn't matter. 

Notes:

 - Drawing speed should not be significantly different with GTK+-1.2
   and GTK+-2.0 for lines/etc.
 - Pango is much slower than the old X bitmap fonts (the necessary
   cost of doing a lot more); but that "much slower" is on the order 
   0.5 million characters/second. Which doesn't sound like it should
   be an issue for your app.

I think you need to profile and see where your time is going; 
valgrind/kcachegrind is a very good combination for profiling.

Regards,
                                            Owen