Bug 63487 - Fix read_png with libpng 1.6
Summary: Fix read_png with libpng 1.6
Alias: None
Product: cairo
Classification: Unclassified
Component: png functions (show other bugs)
Version: 1.12.14
Hardware: x86-64 (AMD64) Linux (All)
: medium major
Assignee: Carl Worth
QA Contact: cairo-bugs mailing list
: 62779 (view as bug list)
Depends on:
Reported: 2013-04-12 20:53 UTC by Armin K
Modified: 2013-04-26 14:42 UTC (History)
3 users (show)

See Also:
i915 platform:
i915 features:

Fix read_png with libpng 1.6 (1.29 KB, text/plain)
2013-04-12 20:53 UTC, Armin K

Description Armin K 2013-04-12 20:53:11 UTC
Created attachment 77910 [details]
Fix read_png with libpng 1.6

With libpng 1.6, png_read_update_info() needs to be called after transformations.


The attached patch fixes it on my side.
Comment 1 Behdad Esfahbod 2013-04-12 22:27:07 UTC
The patch is wrong.

And the new requirement is really stupid, since to set the transform function we want to know what color type is going to be output by libpng, and to have that we have to call png_read_update_info().
Comment 2 Armin K 2013-04-12 22:40:34 UTC
Yeah, ickle pointed that out.

I've asked on libpng mailing list what would be the correct way to fix it since png_read_update_info() can't be used like this with libpng 1.6.
Comment 3 Behdad Esfahbod 2013-04-12 22:41:26 UTC
Thanks for following up with them.
Comment 4 Armin K 2013-04-12 23:19:45 UTC
-    png_read_update_info (png, info);
+    info = NULL;
+    png_read_info (png, info);

This appears to work, too. It doesn't work without unseting the info variable. If it's okay with you, I'll attach a new patch.
Comment 5 Armin K 2013-04-13 05:13:27 UTC
Someone responded at libpng mailing list and the response is here:


I admit that I don't really understand what he's saying - maybe someone here could figure it out?
Comment 7 Chris Wilson 2013-04-16 10:14:51 UTC
*** Bug 62779 has been marked as a duplicate of this bug. ***
Comment 8 Armin K 2013-04-26 14:42:05 UTC
Appears to work with libpng 1.6.2 which was released yesterday.

Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.