[cairo-bugs] [Bug 15479] Unpredictable performance of cairo-xlib with non-integer translations of a source surface pattern

[bugzilla-daemon at freedesktop.org]

http://bugs.freedesktop.org/show_bug.cgi?id=15479


Chris Wilson <chris at chris-wilson.co.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED




--- Comment #4 from Chris Wilson <chris at chris-wilson.co.uk>  2008-10-13 15:37:18 PST ---
commit 3eb4bc37577e905d93a1935e7a9cd33ae8dbda15
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date:   Mon Oct 13 23:26:04 2008 +0100

    [pattern] Optimize away fractional translation for NEAREST patterns.

    As identified in bug 15479,
      Unpredictable performance of cairo-xlib with non-integer translations of
a
      source surface pattern
      (https://bugs.freedesktop.org/show_bug.cgi?id=15479),
    source surfaces with a fractional translation hit slow paths for some
    drivers, causing seemingly random performance variations. As a work-around
    Owen Taylor proposed that cairo could convert non-integer translations on
    NEAREST sources patterns to their integer equivalents.

    The messy detail involved here is replicating the rounding mode used by
    pixman for the sample offset, but otherwise the conversion is fairly
    trivial.


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