[cairo-bugs] [Bug 4476] New: [pixman] non-projective transform optimization can result in wrongly scaled images

bugzilla-daemon at freedesktop.org bugzilla-daemon at freedesktop.org
Fri Sep 16 11:02:55 PDT 2005

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           Summary: [pixman] non-projective transform optimization can
                    result in wrongly scaled images
           Product: cairo
           Version: 1.1.1
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: minor
          Priority: P2
         Component: image backend
        AssignedTo: cworth at cworth.org
        ReportedBy: bertram.felgenhauer at googlemail.com
         QAContact: cairo-bugs at cairographics.org

In pixman/fbcompose.c, fbFetchTransformed(), Bool projective  is not set if the
transformation matrix is not projective but contains homogenous components that
are not 1; this will result in wrongly scaled images to be drawn.
The initialization should be done similar to the one in fbFetchSourcePict()
above. I'll attach a patch for this.

NB. I think 'projective' is a misnomer - maybe 'simple_transform' is better?
NB.2. I don't think this gets triggered by cairo's usage of the pixman code,
does it?          
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