APNG bug

[guest2008]

XnView incorrectly displays this APNG file:



The file works fine in Firefox 3.

[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

[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.

[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.

[Danny]

Where did APNG come from? I was under the impression that animated PNGs are MNGs, and they've existed since 2001.

[guest2008]

Everything works fine in v1.93 Beta 2. Thank you!