[cairo-bugs] [Bug 42421] New: It looks like Clipping of cairo doesn't work correctly.

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=42421

             Bug #: 42421
           Summary: It looks like Clipping of cairo doesn't work
                    correctly.
    Classification: Unclassified
           Product: cairo
           Version: 1.10.3
          Platform: x86 (IA32)
        OS/Version: Linux (All)
            Status: NEW
          Severity: critical
          Priority: medium
         Component: image backend
        AssignedTo: cworth at cworth.org
        ReportedBy: seongwon79 at hanafos.com
         QAContact: cairo-bugs at cairographics.org


Created attachment 52943
  --> https://bugs.freedesktop.org/attachment.cgi?id=52943
test code and result files

Hi,

I make test app which it contains 4 clips and 1 path and call cairo_fill() on
cairo 1.11.3 (upstream latest)
Each clips may have different AA option and path has CAIRO_ANTIALIAS_DEFAULT.
In this scenario clipping doesn't work correctly.
If I change the AA of path to CAIRO_ANTIALIAS_NONE clipping works well.

As I analysis of cairo clip_and_composite_boxes() in cairo-spans-compositor.c
has problem. 
Even I set clip on application, composite_needs_clip() in composite_boxes()
returns FALSE and call scan converter without clip information.

I attached test code with png files.

Thanks.

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