[cairo] [SVG] a8-mask failure
Carl Worth
cworth at cworth.org
Thu Mar 20 16:32:03 PDT 2008
On Thu, 20 Mar 2008 18:50:43 +0100, Emmanuel Pacaud wrote:
> The libpng warning is "PNG warning = Ignoring attempt to write bKGD
> chunk out-of-range for bit_depth".
>
> I'm not sure to like the "upgrade" of the warning to a cairo error. And
> the suppression of the PNG warning makes the debugging harder than it
> should.
>
> Do we really want to hide them ? Is there a good reason to make cairo
> fail on something that the libpng developers consider a simple
> warning ?
Here's the commit that gave us the upgrade of libpng warnings into
errors:
commit c06d929325710c1a2cbecb8a64803ca8e1ffbec0
Author: Chris Wilson <chris at chris-wilson.co.uk>
Date: Thu Feb 28 16:07:57 2008 +0000
[cairo-png] Further hardening against malloc failures.
On some OOM paths, libpng raises a warning as opposed to an error,
these were not being propagated back to the caller. We were also not
checking that we did not overwrite a pre-existing error status when
raising an error whilst performing I/O.
That sounds like there are bugs in libpng where it's returning a
warning though it should be returning an error. And the workaround for
this is causing the problematic behavior for a8-mask with cairo-svg.
If nothing else, we've got a single commit to revert if really
necessary.
> And more important, does someone here know how to fix the warning ?
But yes, this is the most important part. Let's try to get this fixed
so we can avoid these warning-handling code paths entirely. (But no, I
don't have any idea yet what needs to be changed here.)
-Carl
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