Plugin devs: Upcoming migration to Qt 6

[un_pogaz]

Okay, after some time, I just understood the compatibility of Qt.ItemFlag.
In fact, use the Qt.ItemFlags is a wrong usage, even in Qt5, the correcte usage and class is the 'simple' Qt.ItemFlag that actualy implemented.

Well,
All is done.
And congrat for the work kovidgoyal.

[DNSB]

I was modifying some of the conversion options and managed to get an error message when I tried to open the output options.

calibre, version 5.99.2
ERROR: Unhandled exception: <b>AttributeError</b>:'QPrinter' object has no attribute 'pageSize'

Spoiler:

calibre 5.99.2 Portable embedded-python: True
Windows-10-10.0.22000 Windows ('64bit', 'WindowsPE')
('Windows', '10', '10.0.22000')
Python 3.10.1
Windows: ('10', '10.0.22000', '', 'Multiprocessor Free')
Interface language: None
Successfully initialized third party plugins: DeDRM (10, 0, 2) && Annotations (1, 16, 0) && Calibre Power Search Plugin (2, 1, 1) && Count Pages (1, 11, 1) && Diaps Editing Toolbag (0, 3, 7) && EpubCheck (0, 2, 4) && EpubMerge (2, 11, 0) && EpubSplit (3, 1, 0) && FanFicFare (4, 8, 0) && Fantastic Fiction (1, 5, 1) && Find Duplicates (1, 8, 10) && Goodreads (1, 5, 3) && Goodreads Sync (1, 15, 1) && Hyphenate This! (0, 1, 3) && Job Spy (1, 0, 190) && KePub Output (3, 5, 3) && Kindle hi-res covers (0, 5, 0) && KindleUnpack - The Plugin (0, 83, 0) && Kobo Books (1, 8, 3) && Kobo Utilities (2, 15, 0) && KoboTouchExtended (3, 5, 4) && Modify ePub (1, 6, 3) && Obok DeDRM (10, 0, 0) && Open With (1, 5, 13) && Quality Check (1, 11, 4) && Resize Cover (1, 1, 0) && ScrambleEbook (0, 4, 5) && SmartEject (2, 3, 0) && Smashwords Metadata (1, 0, 2)
Traceback (most recent call last):
  File "calibre\gui2\preferences\main.py", line 319, in show_plugin
  File "calibre\gui2\preferences\conversion.py", line 99, in genesis
  File "calibre\gui2\preferences\conversion.py", line 96, in widget_factory
  File "calibre\gui2\convert\pdf_output.py", line 36, in __init__
  File "calibre\gui2\widgets.py", line 1271, in initialize
AttributeError: 'QPrinter' object has no attribute 'pageSize'

This happened after I set the Conversion => Common options => Page setup => Output Profile => tablet and all 4 margins to 0.0pt.

After this, if I clicked on any of the 3 Conversion options, I got a rather messy popup. See attached image for that.

[kovidgoyal]

@DNSB: Good catch. https://github.com/kovidgoyal/calibr...dc813a633f51ef

[theducks]

I just tried to use Review Download Metadata (results of using Ctrl-d)
Win10 x64 5.99.2

[DiapDealer]

I'm trying to get a handle on what all of my options are, here. So a few questions:

1) If I want to use the handy-dandy-

from qt.core import yada

-built-in compatibility approach, then the minimum calibre version needed for my plugin will now become 5.13, right? Basing this on:

Originally Posted by kovidgoyal

Indeed, from calibre 5.13 onwards you can simply do all Qt related imports as

from qt.core import whatever

It works on qt 5 and qt 6. This is what is used in calibre source code itself.

2) My hope for my plugins was to drop support for PtQt4 completely and use my own try/except imports for PyQt5/6 in order to support calibre 2.0+. This seems fairly trivial in my testing and, in fact, seems to work just fine... on systems where calibre is using its own embedded Python/Qt/PyQt. However, this fails miserably on my Arch machine using the pacman-supplied calibre 5.33 because my system has both PyQt5 and PyQt6 installed at the same time. So the initial import of PyQt6 in my plugin does not fail like I need it to with Calibre 5.33 on that system. Any way around this? I don't want to have to tell my users that they need to uninstall PyQt6 on Arch to get things working.

No criticism/judgement, here. I'm just making sure I understand all my options before making a decision about what to do.

The easiest thing to do would be to forget everything that came before calibre 5.13. I just don't know if I'm ready to do that. I was hoping to support calibre 2.0+ on all systems. Even those with debundled python/qt that might have multiple PyQt versions installed like my Arch machine.

[Leseratte_10]

Not sure how it works on Arch, but couldn't you just check the Calibre version, then import QT5 for <= 5.x, and QT6 for >= 6? Instead of using a try-catch-block to detect QT5 vs QT6? Surely there's some kind of Calibre API to get the Calibre version? (EDIT: Like described in the next post).

Or, do "from qt.core import yada" in a try-except-block, and if that fails, it's Calibre 5 or older and you can import QT5.

[thiago.eec]

Originally Posted by DiapDealer

2) My hope for my plugins was to drop support for PtQt4 completely and use my own try/except imports for PyQt5/6 in order to support calibre 2.0+. This seems fairly trivial in my testing and, in fact, seems to work just fine... on systems where calibre is using its own embedded Python/Qt/PyQt. However, this fails miserably on my Arch machine using the pacman-supplied calibre 5.33 because my system has both PyQt5 and PyQt6 installed at the same time. So the initial import of PyQt6 in my plugin does not fail like I need it to with Calibre 5.33 on that system. Any way around this? I don't want to have to tell my users that they need to uninstall PyQt6 on Arch to get things working.

Maybe you could check for calibre version instead of Qt:

from calibre.constants import numeric_version
if numeric_version < (6, 0, 0):
   PyQt5 imports
else:
   PyQt6 imports

EDIT: @Leseratte_10 beated me. =)

[DiapDealer]

All seems doable, thanks for the ideas! I may opt for something along the lines of:

from calibre.constants import numeric_version
if numeric_version < (5, 13, 0):
   PyQt5 imports
else:
   from qt.conf import yada

That should allow me to support Calibre 2.0+, with the advantage of being (somewhat) prepared for calibre PyQt7.

[DiapDealer]

Obviously meant "qt.core"

[nqk]

Dear Kovid,

I would like to report that the GUI texts are shown in low res or dpi (v5.99.2 on Windows 11)

[kovidgoyal]

@DiapDealer: You just need to do

try:
    from qt.core import whatever
except ImportError:
    from PyQt5.Qt import whatever

[kovidgoyal]

@nqk: DPI is now entirely controlled by Qt. You can check your env vars. See https://doc.qt.io/qt-6/portingguide.html#high-dpi

[kovidgoyal]

Originally Posted by theducks

I just tried to use Review Download Metadata (results of using Ctrl-d)
Win10 x64 5.99.2

https://github.com/kovidgoyal/calibr...34bc5982f91dca

[BeckyEbook]

Originally Posted by nqk

I would like to report that the GUI texts are shown in low res or dpi (v5.99.2 on Windows 11)

@nqk: IMHO, this is not a problem with low resolution, but with Segoe UI Light hinting in Windows 10/11 which makes the font look too delicate. Change the default font to Segoe UI Normal and you will see that everything looks perfectly sharp.

[thiago.eec]

Just noticed a bug on Configure Metadata Download dialog: checkboxes changes are not being saved. Other changes get saved.
This also happens configuring individual sources.