[cairo] tablet input lags

Uli Schlachter psychon at znc.in
Tue Apr 23 12:10:51 PDT 2013


On 23.04.2013 05:59, Yale Zhang wrote:
> Hi, can someone take a look and fix the problem of laggy tablet input with
> Cairo 1.12 on Windows?

I fear that this someone would be you. Cairo's win32 backend is no one's
favorite backend and doesn't get much love.

> I have confirmed the problem exists in both Gimp
> and Inkscape (only x64 version, but another user says it happens in the 32
> builds too). I have also confirmed the lag doesn't happen in Cairo 1.10.
> https://bugzilla.gnome.org/show_bug.cgi?id=696148
> I've attempted to find out what's wrong, but haven't had much luck. I know
> that CPU usage doesn't seem to be the issue since even during rapid
> scribbling, only 1/2 the throughput of 1 core is used.

There were lots of changes between cairo 1.10 and cairo 1.12. If you are
building your own cairo DLL, could you try some of the intermediate versions?
Perhaps even do a git bisect to find the "evil change"?

"Do you know that books smell like nutmeg or some spice from a foreign land?"
                                                  -- Faber in Fahrenheit 451

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