[cairo] GTK+, Cairo, XLib integration for fast 2D graphics drawing
chris at chris-wilson.co.uk
Tue Mar 20 02:32:17 PDT 2012
On Tue, 20 Mar 2012 09:42:19 +0200, Christos Sotiriou <csotiriou at gmail.com> wrote:
> On 19 March 2012 20:27, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > The truly puzzling part for me is that they seem viable candidates to
> > hit the fast-paths, yet end up in the general polygon code.
> > << /content //COLOR_ALPHA /width 500 /height 500 >> surface context
> > n 22.726562 22.726562 454.546875 454.546875 rectangle
> > 0 0.65 1 rgb set-source
> > 0.295602 0.913843 scale
> > 3.655372 set-line-width
> > stroke+
> > pop
> > Oh, I see. A non-uniform, non-integer scale factor. That would explain
> > it. Let's see if I can cook up something faster for you.
> I can round the scaling factor for the cairo_scale() function call; would
> that make a big performance difference?
I've already fixed the fast-path to catch this case as well. The other
thing worth asking about is that in the trace you use an image surface
for your rendering. Is this a deliberate change from earlier? For the
rendering you are performing, with a good driver, all the overhead will
be in cairo converting the strokes into geometry, though I suspect
the transfer of the image will be smaller than all the geometry. With
cairo-1.12, you may like to use cairo_surface_create_similar_image()
instead, as that opens up the possibilities of doing zero-copy uploads.
Chris Wilson, Intel Open Source Technology Centre
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