PCX not supported by QImageReader, should not be listed in .desktop file about lximage-qt

[tsujan]

BTW, a funny comparison:

Qt5 supports "3fr", "ani", "arq", "arw", "avif", "avifs", "bay", "bmp", "bmq", "bw", "cap", "cine", "cr2", "cr3", "crw", "cs1", "cur", "dc2", "dcr", "dcs", "dng", "drf", "dxo", "eip", "eps", "epsf", "epsi", "erf", "exr", "fff", "gif", "hdr", "heic", "heif", "icns", "ico", "iiq", "jp2", "jpeg", "jpg", "jxl", "k25", "kc2", "kdc", "kra", "mdc", "mef", "mfw", "mng", "mos", "mrw", "nef", "nrw", "obm", "ora", "orf", "ori", "pbm", "pcx", "pdd", "pdf", "pef", "pgm", "pic", "png", "ppm", "psb", "psd", "psdt", "ptx", "pxn", "qtk", "r3d", "raf", "ras", "raw", "rdc", "rgb", "rgba", "rw2", "rwl", "rwz", "sgi", "sr2", "srf", "srw", "sti", "svg", "svgz", "tga", "tif", "tiff", "wbmp", "webp", "x3f", "xbm", "xcf", "xpm".

While, here, Qt6 supports "bmp", "cur", "gif", "icns", "ico", "jp2", "jpeg", "jpg", "mng", "pbm", "pdf", "pgm", "png", "ppm", "svg", "svgz", "tga", "tif", "tiff", "wbmp", "webp", "xbm", "xpm".

[tsujan]

OK, will add a note to README.

BTW, I logged into LXQt+kwin_x11 and opened the image. This time, it's a black rectangle. Why it's transparent under Wayland and black under X11+compositing, I don't know.

KDE's gwenview has exactly the same behavior. I added the info to your report (https://bugs.kde.org/show_bug.cgi?id=463951).

[tsujan]

"pcx" is among the formats supported by Qt5, on which lximage-qt is based currently.

But you're right: (1) Qt5 can't handle it (correctly), and (2) Qt6 doesn't support it. It will be removed when lximage-qt is ported to Qt6.

[fenugrec]

"pcx" is among the formats supported by Qt5

Ok, where is that documented ? A quick look at https://doc.qt.io/qt-5/qimagereader.html#supportedImageFormats doesn't show it...

[EDIT] - ah, could it be you have KDE kimageformats installed ? looks like a Qt plugin for extra formats

I think ::supportedImageFormats() doesn't return PCX, at least on my system, because File->Open dialog doesn't even list PCX.

[tsujan]

Ok, where is that documented ?

Qt didn't give a list in its doc the last time I checked. Just see QImageReader::supportedImageFormats().

Anyway, PCX (and many other formats) will be removed soon.

EDIT:

ah, could it be you have KDE kimageformats installed

Yes, I have it here. If it's a Qt plugin, it explains the difference between Qt5 and Qt6; then Qt6 might give the same list when kimageformats is ported to Qt6.

[fenugrec]

Yes, I have it here. If it's a Qt plugin,

So that would be the explanation : https://api.kde.org/frameworks/kimageformats/html/index.html

• I will test that -> it's showing up as a black rectangle here
• , and (possibly) submit an upstream bug if my PCX file can't be loaded. -> https://bugs.kde.org/show_bug.cgi?id=463951
• I will also work on my distro side to add kimagereader as an optional dependency. -> https://bugs.archlinux.org/task/77027

Thanks for looking at this.

[edit - FYI, the attached PCX file opens fine in gimp which has its own image parser.]

[tsujan]

So that would be the explanation : https://api.kde.org/frameworks/kimageformats/html/index.html

You're right. Thanks for finding it!

I'm under LXQt+Wayfire now. Your attached PCX image is shown as a completely transparent rectangle by both lxmage-qt and another Qt-based viewer of mine. Will test it under X11 later.

[fenugrec]

I would still suggest adding a note about kimagereader as an optional dependency somewhere in the README ?

[tsujan]

Let's reopen this. My question is more general: Shouldn't we include only those formats in the desktop file that Qt supports without any plugin?

[fenugrec]

Shouldn't we include only those formats in the desktop file that Qt supports without any plugin?

You will have guessed that my quick answer would be "yes", because it's a safe default, and I'm not sure if it's realistic to

• modify .desktop file at the distro end to add extra entries depending on installed plugins
• modify .desktop.in file here with some equivalent cmake magic to detect a few common plugins , or to call supportedImageFormats ? seems like a lot of complexity

[tsujan]

You will have guessed that my quick answer would be "yes"...

And I agree with you. But some users might kill us ;)

What about keeping the current formats and adding a note about kimageformats?

[fenugrec]

And I agree with you. But some users might kill us ;)

Any non-trivial change always has a risk of upsetting a certain group of users, that's true. I'm not well placed to judge.

What about keeping the current formats and adding a note about kimageformats?

That would be an improvement, yes.

[stefonarch]

Just tried to open the image here: it opens fine with PhotoQt imageviewer (appimage) which apparently is the default for this type on my installation.

[tsujan]

It can be opened by GIMP too. The problem was that kimageformats should enable all Qt image viewers to open it, but it didn't.

[tsujan]

Oh, we forgot about qt5-imageformats. Added it to #593 too.