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APNG bug
Posted: Thu Feb 21, 2008 2:33 am
by guest2008
XnView incorrectly displays this APNG file:
The file works fine in Firefox 3.
Threads and …
Posted: Thu Feb 21, 2008 4:56 am
by Clo
guest 2008

Hello !
• There are already three main threads about APNG :
1.
http://newsgroup.xnview.com/viewtopic.p ... light=apng
2.
http://newsgroup.xnview.com/viewtopic.p ... light=apng
3.
http://newsgroup.xnview.com/viewtopic.p ... light=apng
• Your sample works partially in XnView, one frame is not displayed, but the ones working give a different colour
for each displayed character (red, blue…).
• The whole animation works in Firefox, but all characters have the same colour (Yellow-green).
- The animation seems optimized, it should be intersting to test that file as non-optimized…
- Finally, here I have Maxthon¦IE6 browser which doesn't support APNG, but the needed #1 frame
normally planned in such a case telling
“Your browser doesn't support APNG blah blah…” is missing…
… or not enabled.

KR
Claude
Clo
Posted: Thu Feb 21, 2008 9:21 am
by guest2008
Yes, it is optimized.
frame #1 is 192x72 (that's what you see in IE or old Firefox)
frames #2...#7 are 32x40 (highlighted letters)
I think the problem is that frames shift is calculated as 32x4 bytes, but it should be 32x3 bytes, because this image is 24 bit.
P.S. I don't think every APNG image should have “Your browser doesn't support APNG" message. It this case it's just "MATRIX" without animation.
Posted: Fri Feb 29, 2008 8:57 am
by guest2008
The colors are fine in 1.93.b1, thanks for fixing that!
But there is still a small problem. The letters should be highlighted one at a time, that's how Firefox displays it.
Maybe this instruction for frames 2-7 is processed incorrectly:
dispose_op = PNG_DISPOSE_OP_PREVIOUS
Also, I found this webpage with lots of APNG examples:
http://treebuilder.de/default.asp?file=89031.xml
I saved them all in one directory, and when I go from one image to another using PgUp/PgDn, sometimes they're displayed correctly, and sometimes they are not. It's somewhat unpredictable.
Posted: Fri Feb 29, 2008 3:12 pm
by Danny
Where did APNG come from? I was under the impression that animated PNGs are
MNGs, and they've existed since 2001.
Posted: Tue Mar 04, 2008 8:18 pm
by guest2008
Everything works fine in v1.93 Beta 2. Thank you!