[cairo] Performance regression on Windows

[Chris Wilson]

On Sat, Nov 16, 2013 at 08:15:57AM +0000, Nicolas Dufour wrote:
> Hello,
> I'm currently updating some libraries for Inkscape on win32, and notice a serious UI slowdown when updating the Cairo libs. Everything works as expected with Cairo-1.11.2 (the dll we provide with the latest stable Inkscape version, 0.48.4), but the Inkscape UI becomes very slow when drawing or moving objects on canvas with a more recent Cairo version (tested with 1.12.8, 1.12.14, 1.12.16 and yesterdays git version). I've also updated Pixman to 0.32.2, but noticed no regression with the Pixman update as long as I don't update Cairo too. The compiler used to build Cairo and Pixman is TDM-GCC-4.6.1 (required to be consistent with the other libs in the Inkscape win32 repo.).
> 
> Other operating systems are not affected (tested on Debian stable with Cairo-1.12.2 and Pixman-0.26, but other Inkscape users confirmed it's ok with recent Ubuntu and OS-X versions).
> 
> Could you tell me if the performance issue we experience is a known bug?

It's not known, but it was an obvious risk with refactoring the code. It
probably needs more refinement on surface migration.
 
> Related question: I wanted to investigate with cairo-trace, but it doesn't output any trace file. Is cairo-trace expected to work on Windows too?

No. Window's doesn't use the same preload dynamic lib system, so it
won't work without some modifications. If you know what to do, that
would be very helpful.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre