[cairo] Text performance on windows?
damian.frank at gmail.com
Tue Aug 26 09:19:10 PDT 2008
Yes, I do wonder if I'm falling off of the slow path. Unfortunately the
whole rendering system is a bit .. sprawling, and impractical to show
everything. I'll try to show the relevant calls though.
For clipping, we are using cairo_rectangle/cairo_clip, with aligned
coordinates (although I need to verify that the alignment is working, I
suppose). When rendering the text, here's what the code looks like:
cairo_set_operator cr, CAIRO_OPERATOR_OVER);
cairo_set_source_rgba(cr, red, green, blue, alpha);
pixel_align_for_fill(cr, &x, &y);
cairo_move_to(cr, x, y);
For my testing, I haven't set any other text properties, so it's the default
font face & options. Alignment is handled by transforming to device,
rounding to integral values, and transforming back to user space.
(I wouldn't be surprised if my method of getting the results on-screen is
also a bottleneck, since the app is double-buffered and I haven't done any
performance testing of the copy yet. But right now I'm measuring the text
I really hope there's something I can do, because Cairo is, in all other
respects, awesome. It's the best 2D API I've ever used, easily.
Thanks for your time,
On Tue, Aug 26, 2008 at 5:23 AM, Gerdus van Zyl <gerdusvanzyl at gmail.com>wrote:
> Please see this discussing on the list:
> The reason I saw slow rendering was with the way I did double
> buffering and the type of surface I created. If you could show us your
> text rendering code it would be informative.
> On Tue, Aug 26, 2008 at 11:40 AM, Nicholas Allen <allen at ableton.com>
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> > I also experience serious performance problems with Cairo. I have only
> > run on Windows but it's performance is so bad as to make it completely
> > unusable for what we need. It's a shame because the API is really
> > clean and the output looks great. Hopefully, this will get fixed in
> > future releases...
> > Nick
> > Damian Frank wrote:
> >> I'm pretty new to Cairo, and I've been looking at using it for a
> >> codebase that currently uses, variously, Xlib, GDI, GDI+, and
> >> Quartz, among others. Performance is one of my chief concerns,
> >> though. At the moment I'm looking at text performance, and I have
> >> some serious concerns. For now, I am just benchmarking on Windows,
> >> and only for to-screen rendering (as opposed to printing or
> >> PS/PDF/etc).
> >> Can someone give me some pointers on staying on the fast code paths
> >> for text rendering on win32? My tests so far show image and DDB
> >> both taking about 15-20x as long as our GDI implementation, and
> >> 24-bit DIB taking about 5x as long.
> >> Thanks,
> >> Damian
> >> ----------------------------------------------------------------------
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> >> cairo at cairographics.org
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