That's interesting.

I have used a copy of qcad installed to my home dir for years in all versions of Mageia so far. (it was a paid copy statically linked).
The icon now fails to render in exactly the same way as you describe.

I will attach the icon file here.

CC: (none) => zen25000

Created attachment 8104 [details]
qcad icon

This file is dated 2007 and has worked fine for me since Mandriva 2008.
Now it appears corrupted in all the image viewers that I have tested so far in Cauldron. It was working in Mageia 5 but I have yet to re-test there.

In that case, there must be a more general problem, but other png images are not affected.  goa-account.png is completely transparent in Cauldron.  I just installed qcad in Cauldron to test. The icon is showing up O.K. in the menu.  The IDAT system is explained at http://ubuntuforums.org/showthread.php?t=1402412

The link I gave was to a similar case.  The reply suggested a quirky bug in libpng.

This is what I was suspecting - some backward incompatibility in libpng.
Our packaged qcad is ok, (apart from other bugs) the icon changed some years back.
It is the icon in my old qcad pro version that I still use that shows this problem.
Just looking at pngcheck, but we don't have it - I will try to re-build SuSE's package to test.

OK I have a package for pngcheck now and it shows this for my old qcad icon:

[baz@localhost img]$ pngcheck -vtf qcadicon.png
File: qcadicon.png (701 bytes)
  chunk IHDR at offset 0x0000c, length 13
    32 x 32 image, 32-bit RGB+alpha, non-interlaced
  chunk bKGD at offset 0x00025, length 6
    red = 0x0000, green = 0x0000, blue = 0x0000
  chunk pHYs at offset 0x00037, length 9: 2835x2835 pixels/meter (72 dpi)
  chunk tIME at offset 0x0004c, length 7:  2 Aug 2005 10:44:18 UTC
  chunk IDAT at offset 0x0005f, length 586
    zlib: deflated, 1K window, maximum compression
  chunk IEND at offset 0x002b5, length 0
No errors detected in qcadicon.png (6 chunks, 82.9% compression).

If you would like to test your png with it, pngcheck for mga6 x86_64 is here:

http://mtf.no-ip.co.uk/pub/linux/barjac/distrib/cauldron/x86_64/media/extra/release/pngcheck-2.3.0-0.1.mga6.x86_64.rpm

So it does appear that the png is not faulty, but that libpng changed and broke it.

Created attachment 8105 [details]
old qcad icon in gimp in cauldron

\o/ got the fix!

In the pngcheck package are two other utilities:

    pngsplit - break a PNG, MNG or JNG image into constituent chunks (numbered for easy reassembly)
    png-fix-IDAT-windowsize - fix minor zlib-header breakage caused by libpng 1.2.6 

Out of curiosity I ran png-fix-IDAT-windowsize on my old qcad icon and now it is fine!

running:
png-fix-IDAT-windowsize qcadicon.png
produces:
qcadicon-fixed.png
...and leaves the original intact, so the original needs to be deleted and the new one re-named.

Strangely the file size is unchanged but it works ;)

@ Remi
Shall I push this tool (pngcheck) into Mageia? ..or will my build be enough to fix these few files?

Created attachment 8106 [details]
fillets-ng icon without fix

Quickly testing this on the fillets-ng icon in the package SOURCES works fine
this is the before.

Created attachment 8107 [details]
fillets-ng icon after fix

This is the fixed icon.

I will look more into the package later to check if there are other pngs affected and fix them before pushing to cauldron.

Pushed to Cauldron.

###############################
Update Advisory

Package fillets-ng-1.0.1-9.1.mga5 has been submitted to 5/updates_testing

###############################
Description

This update fixes a broken desktop icon in the package.
See https://bugs.mageia.org/show_bug.cgi?id=18837

###############################
Affected rpms

fillets-ng-1.0.1-11.mga6.src.rpm
fillets-ng-1.0.1-11.mga6.i586.rpm
fillets-ng-debuginfo-1.0.1-11.mga6.i586.rpm
fillets-ng-1.0.1-11.mga6.x86_64.rpm
fillets-ng-debuginfo-1.0.1-11.mga6.x86_64.rpm

##############################
Testing

Install the main package and check that the desktop icon does not appear corrupted.

Assignee: rverschelde => qa-bugs

(In reply to Doug Laidlaw from comment #3)
> In that case, there must be a more general problem, but other png images are
> not affected.  goa-account.png is completely transparent in Cauldron.  I
> just installed qcad in Cauldron to test. The icon is showing up O.K. in the
> menu.  The IDAT system is explained at
> http://ubuntuforums.org/showthread.php?t=1402412

Regarding the goa-account.png files it does look to me as though these files are in fact blank.
Looking at them with a hex editor I can see the IDAT text info but the main body of the file is all zeros.

New bug reported on the goa issue:
https://bugs.mageia.org/show_bug.cgi?id=18844

new icon for fillets-ng works in Cauldron. I copied it across to Official and it works there as well.

(In reply to Barry Jackson from comment #8)
> @ Remi
> Shall I push this tool (pngcheck) into Mageia? ..or will my build be enough
> to fix these few files?

Please do, yes, this sounds like it can be useful in various cases. Might run it on the png files of the open source games I develop, just in case :)

Thanks for handling the fix and update!

pngcheck is now in cauldron

Testing mga5 64

Before:
gwenview /usr/share/icons/hicolor/32x32/apps/fillets-ng.png

Shows half an icon as described.

After:
It shows the full icon. There is no icon in the menu for this game though. Is there one missing Barry?

$ find /usr/share/icons/ -name fillets-ng*
/usr/share/icons/hicolor/32x32/apps/fillets-ng.png

Game works fine.

Adding  feedback marker for now

Whiteboard: (none) => feedback

Created attachment 8193 [details]
plasma menu with fillets_ng icon

Strange, it works OK here ;)

Looking good.

I just realized that was Mga6, but it also works fine in Mga5 KDE4 - I just checked in a recent install with the package from updates_testing.
I tried to grab a screen shot, but the capture program seems missing from that install.

Created attachment 8194 [details]
Menu item in Mga5

Ah found it :)

yeah, it's there after a reboot. Thanks.

Validating.

Keywords: (none) => validated_update
Whiteboard: feedback => mga5-64-ok
CC: (none) => sysadmin-bugs

advisory uploaded.

Whiteboard: mga5-64-ok => advisory mga5-64-ok

An update for this issue has been pushed to the Mageia Updates repository.

http://advisories.mageia.org/MGAA-2016-0104.html

Status: NEW => RESOLVED
Resolution: (none) => FIXED