[cairo-bugs] [Bug 4705] New: crash at XRenderAddGlyphs

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https://bugs.freedesktop.org/show_bug.cgi?id=4705          
     
           Summary: crash at XRenderAddGlyphs
           Product: cairo
           Version: 1.1.1
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: xlib backend
        AssignedTo: cworth at cworth.org
        ReportedBy: sunmoon1997 at gmail.com
         QAContact: cairo-bugs at cairographics.org


while running some apps against cairo-1.1.0, app crashed and i got 
something like follow.
fcitx: BadLength (poly request too large or internal Xlib length error)
X Error of failed request:  BadLength (poly request too large or
internal Xlib length error)
  Major opcode of failed request:  150 (RENDER)
  Minor opcode of failed request:  20 (RenderAddGlyphs)
  Serial number of failed request:  721
  Current serial number in output stream:  722.
the problem is:
currenty cairo xlib backend assume that the depth of glyphs from a font
face are the same, but this is not true for some embedded bitmap fonts.
The may have two different depth glyphs, from my attached file, you can
see the fist eight glyphs are 1-bit depth bitmap, but latter ones' depth
become 8-bit. Cairo only extracts the format information from the fisrt
glyph, if glyph's depth changed, cairo'll still use the old formation info,
and send the glyph to X server, then X will complain cairo sended too much
bits to it and reply an error (bad length) that will crash a lot of apps.

This only happens with cairo-1.1.1, cairo-1.0.x works fine.          
     
     
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