Calibre and Qt5/GTK theming issues

[tempura]

I'm not sure if this is a Calibre issue or maybe a dependency issue. I recently upgraded to XUbuntu 17.10 which uses Qt 5.9. I have set the CALIBRE_USE_SYSTEM_THEME variable for calibre to use the Gtk/XFCE theme which in my case arc-theme. Note, all my other Qt5 applications including Qt5 Designer, work correctly while using the GTK theme.

A pure binary install from the script as provided on the website here: https://calibre-ebook.com/download_linux doesn't work. The theme is completely broken and there are parts of the menus which I can't access. I initially got this error on Calibre 3.0, and then I uninstalled that, and installed Calibre 3.12, both giving the same error on the system as:

QGtkStyle could not resolve GTK. Make sure you have installed the proper libraries.

Though, I tried a binary install from the Ubuntu repos for Calibre 3.7.0 which works perfectly fine, and adheres to the environment variable to use my GTK theme.

I hope this issue gets fixed sometime.

tempura

[kovidgoyal]

It's not possible to fix. Basically Qt themeing only reliably works if you use the system Qt, which the binary calibre acnnot use. So either use your distro provided calibre or use the official binary and no Qt themeing.

[tempura]

Originally Posted by kovidgoyal

It's not possible to fix. Basically Qt themeing only reliably works if you use the system Qt, which the binary calibre acnnot use. So either use your distro provided calibre or use the official binary and no Qt themeing.

Ugh, I was hoping it wasn't this. Oh well, at least my distro changes happens in 6 months, the same should persist over the next period of updates. Thanks for trying.

Just a minor note from my side, which leaves me puzzled is that how did it work with Qt 5.7 on Ubuntu 17.04. Just wondering is all, this probably does not require a answer.

[kovidgoyal]

It's complicated, the involved libraries are not just Qt but also glib, gobject, etc. Only if the Qt versions are compatible and the glib versions are compatible and the versions of a dozen other libraries are compatible will binary themeing work.

[tempura]

That makes sense, in a way. Thanks for answering, @kovid

[icq70610]

Hi all, kovid

not to necrobump - but that has been a topic that intruiged me for quite some time. just to roll a couple of Ideas here - no intend to ask for a dev change ..but some ideas.

1) if we use the binary version of calibre it will use the internal styling and as I can see from the previous post there is no way to change that except using the distro provided package, and i get the reason ... truly i get it ;-)

2) can we:

a) include at least the 2 major "styles" adwaita and breeze in a selection box - even on specific CALIBRE_QT_THEME variable in the binary release?

export CALIBRE_QT_THEME="awaita"
export CALIBRE_QT_THEME="breeze"

that would incorporate the style nicely with 80% (guess) of the desktops and still using the uptodate version of calibre

b) piggy back on the idea like the icon sets? something similar to "download" a QT style and apply?
so we could for a majority of themeing at the various distros solve that point.

since I dont have a win box I dont know how calibre currently loks on Win10 but I assume simlar behaviour there.

what you guys think?

\Pete

[Dan__]

Hi,
I'm on Fedora 30. Just installed calibre with the suggested wget.
When running calibre I too get the message:
QGtkStyle could not resolve GTK. Make sure you have installed the proper libraries.

I have no interest in themes.
It is suggested to run calibre with no QT themeing.

I am QT ignorant so please explain how to do that.

Thank you,
Dan

[kovidgoyal]

That message is harmless,it just means Qt fallsback to its native theme, fusion.

[Dan__]

Thank you