[Slackbuilds-users] qcomicbook link does not exist

[B Watson]

On 8/25/16, Thomas Morper <thomas at beingboiled.info> wrote:
>>   libpng warning: iCCP: known incorrect sRGB profile
>
> /usr/share/applications/qcomicbook.desktop: error: (will be fatal in the
> future): value "qcomicbook.png" for key "Icon" in group "Desktop Entry" is
> an icon name with an extension, but there should be no extension as
> described in the Icon Theme Specification if the value is not an absolute
> path

2 separate issues.

[note: everywhere you see me running qcomicbook from the $ prompt,
I closed the qcomicbook window right after it appeared]

$ qcomicbook
libpng warning: iCCP: known incorrect sRGB profile
$ sudo rm /usr/share/applications/qcomicbook.desktop
$ qcomicbook
libpng warning: iCCP: known incorrect sRGB profile

The libpng error isn't due to the .desktop file warning, in other words
(it happens even if I rm the desktop file).

Furthermore, it still happens without the icon:

$ sudo rm /usr/share/pixmaps/qcomicbook.png
$ qcomicbook
libpng warning: iCCP: known incorrect sRGB profile

...no surprise there actually, most applications don't bother to load
their own icon (it's there for the window manager or desktop env).

So I tried:

$ strace -f -ostrace.out qcomicbook
libpng warning: iCCP: known incorrect sRGB profile
$ grep png strace.out
10616 open("/usr/lib64/qt/lib/libpng16.so.16", O_RDONLY|O_CLOEXEC) =
-1 ENOENT (No such file or directory)
10616 open("/usr/lib64/libpng16.so.16", O_RDONLY|O_CLOEXEC) = 3
10616 write(2, "libpng warning: iCCP: known inco"..., 51) = 51

What does that mean? Means it's *not* loading a .png file from the disk.
If it were, there would have been a call like 'open("filename.png",
O_RDONLY) = 3'.

So what's going on here?

$ find /tmp/SBo/qcomicbook-0.9.0/ -name \*.png
/tmp/SBo/qcomicbook-0.9.0/data/nextframe.png
/tmp/SBo/qcomicbook-0.9.0/data/qcomicbook.png
/tmp/SBo/qcomicbook-0.9.0/data/fitwidth.png
... 27 more data/*.png files, not pasted here...

The icons for the GUI elements in the program are PNG files, and they're
most likely being compiled into the program somehow (since they don't
end up installed as part of the .tgz package). So I added this to
qcomicbook.SlackBuild, just before the 'cmake' command:

for i in data/*.png; do
  mv $i $i.old.png
  convert $i.old.png $i
  rm $i.old.png
done

...following the advice from the previously-mentioned stackexchange
thread, to use "convert old.png new.png" to get rid of the bogus sRGB
profile. After building & installing:

$ qcomicbook
$

Bingo, no more libpng warnings.

I dunno if the maintainer will consider this worth adding to his
SlackBuild, the libpng warnings are harmless anyway.