[cairo] Handling invalid glyphs

Behdad Esfahbod behdad at behdad.org
Tue Sep 11 12:46:48 PDT 2007


Re bug 9846.  I want to commit the attached patch to cairo now, to get
it into a 1.4.12 soonish.  The issue at hand is real.  I've came across
many PDF files that fail to render any text because of this.

The patch is a bandaid, a really bad one.  The real fix is to:

  * for 1.4, fix all font backends to report 0x0 extents and render
nothing upon bad glyph indices and set no error at all.

  * for 1.6 propagate those errors up and return from the function call

In the mean time, the patch works, but I'm not sure exactly why.  That
is, I don't know what the contents of face->glyph are set to after a
failing FT_Load_Glyph call.  I can probably do a proper fix, but didn't
feel like it just yet.  Maybe David knows what exactly happens and can
offer a better fix.

Objections?  Brian, do you want to fix the Quartz backend?  No idea
what's the status of win32.


"Those who would give up Essential Liberty to purchase a little
 Temporary Safety, deserve neither Liberty nor Safety."
        -- Benjamin Franklin, 1759

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