Plugin devs: Upcoming migration to Qt 6

[thiago.eec]

I've just noticed that my plugin icons are being drawed with a lower quality then before. Also noticed a shadow on some checkboxes (why not all? ).

5.34 / 5.99(Beta)



There are also some separators missing on the beta, although using the same code (m.addSeparator()) for all of them.

[ownedbycats]

I'm not really a dev, but I do wonder what this will mean for some of DaltonST's plugins -- seeing as they've been absent for nearly a year, should the plugins be considered unmaintained at this point?

[kovidgoyal]

This will fix the drop/hover event errors: https://github.com/kovidgoyal/calibr...c60100810b09e5

@thiago.eec: No clue about your icons, most likely a DPI thing. Try using larger icons.

[thiago.eec]

Originally Posted by kovidgoyal

This will fix the drop/hover event errors: https://github.com/kovidgoyal/calibr...c60100810b09e5

@thiago.eec: No clue about your icons, most likely a DPI thing. Try using larger icons.

Strange, since it renders ok on calibre 5.34 and older versions.
Also, what about the missing separators?

[jackie_w]

I'm just going to raise problems as I find them, rather than save them up for a mega post ...

I'm having a few problems with QTextBrowser widgets. Simplifying the sample code to:

from qt.core import (QTextBrowser, QTextCursor, QTextEdit)
self.browser = QTextBrowser()

self.browser.setLineWrapMode(QTextEdit.NoWrap)
self.browser.setLineWrapMode(QTextEdit.WidgetWidth)
self.browser.moveCursor(QTextCursor.End)
self.browser.moveCursor(QTextCursor.StartOfLine)

I get AttributeError for missing QTextEdit/QTextCursor constants(???) when I try to use any of the last 4 lines. They all work OK in standard v5.34

[BeckyEbook]

I hope it will be useful to someone, so please don't hit me.

Easy quick and dirty fix for many plugins that use functions from common_utils.py). Of course, the following advice only makes sense for beta users before the plugin maintainers release new versions.

1. Edit file common_utils.py
2. Remove (twice) QRegExpValidator, QRegExp from imports
3. Delete this fragment* (if it exists):

Spoiler:

class NumericLineEdit(QLineEdit):
    '''
    Allows a numeric value up to two decimal places, or an integer
    '''
    def __init__(self, *args):
        QLineEdit.__init__(self, *args)
        self.setValidator(QRegExpValidator(QRegExp(r'(^\d*\.[\d]{1,2}$)|(^[1-9]\d*[\.]$)'), self))

[*] I haven't found a single plugin that uses this code, so it won't be a big deal.

In this way, I managed to modify about 90% of the plugins that I use and now work normally in the beta version.

The remaining plugins require minor or major changes, especially if they are to be backward compatible with previous versions of Calibre.

[jackie_w]

I think this may be similar to my post #20. This code for a general utility class used as part of creating a read-only table widget:

from qt.core import QTableWidgetItem
class ReadOnlyTableWidgetItem(QTableWidgetItem):
    def __init__(self, text): 
        if text is None:
            text = ''
        QTableWidgetItem.__init__(self, text, QTableWidgetItem.UserType)
        self.setFlags(Qt.ItemIsSelectable|Qt.ItemIsEnabled)

gives error

AttributeError: type object 'QTableWidgetItem' has no attribute 'UserType'

in v5.99

[thiago.eec]

Originally Posted by kovidgoyal

This will fix the drop/hover event errors: https://github.com/kovidgoyal/calibr...c60100810b09e5

@thiago.eec: No clue about your icons, most likely a DPI thing. Try using larger icons.

Found the solution on their porting guide.

Qt 6 changes the default scale factor rounding policy from Qt::HighDpiScaleFactorRoundingPolicy::Round to Qt::HighDpiScaleFactorRoundingPolicy::PassThrough in order to track operating system DPI settings accurately. Applications that use Qt Widgets may encounter graphical glitches at non-integer scale factors, for example on Windows with a display configured for 175%. In that case, set the rounding policy to Round to restore Qt 5 behavior.

Since I use a non-integer scale factor on my windows machine, this was causing the problem. So, to correct it, i restored Qt 5 behavior setting the policy to Round:

QApplication.setHighDpiScaleFactorRoundingPolicy(QtCore.Qt.HighDpiScaleFactorRoundingPolicy.Round)

[thiago.eec]

Originally Posted by jackie_w

        QTableWidgetItem.__init__(self, text, QTableWidgetItem.UserType)
        self.setFlags(Qt.ItemIsSelectable|Qt.ItemIsEnabled)

Not tested, but a suggestion based on the problems I found porting my plugins... maybe you should use:

QTableWidgetItem.ItemType.UserType

https://doc.qt.io/qt-6/qtablewidgeti...#ItemType-enum

I noticed this change on setting flags, maybe this is the same case.
For example, on Qt 5, you could use this:

QApplication.processEvents(QtCore.QEventLoop.ExcludeUserInputEvents)

On Qt 6, you need to be more explicit:

QApplication.processEvents(QtCore.QEventLoop.ProcessEventsFlag.ExcludeUserInputEvents)

[kovidgoyal]

@jackie_w You need to use fully qualified names for enums in PyQt6, as thiago pointed out. I have added compatibility layers for the most common enums in calibre so they can continue to be used as before, but not for all of them.

[kovidgoyal]

Originally Posted by thiago.eec

Found the solution on their porting guide.



Since I use a non-integer scale factor on my windows machine, this was causing the problem. So, to correct it, i restored Qt 5 behavior setting the policy to Round:

QApplication.setHighDpiScaleFactorRoundingPolicy(QtCore.Qt.HighDpiScaleFactorRoundingPolicy.Round)

That doesnt explain why it affects only plugin icons though. Is it because they are too small?

[kovidgoyal]

@BeckyEbook: A better fix is to use

QRegularExpressionValidator(QRegularExpression(r'(^\d*\.[\d]{1,2}$)|(^[1-9]\d*[\.]$)'))

[thiago.eec]

Originally Posted by kovidgoyal

That doesnt explain why it affects only plugin icons though. Is it because they are too small?

I'm guessing* this is it.

Anyway, my fix backfired, since it sets the Policy for QApplication, messing with whole calibre. I guess I'll have to change all my icons for larger versions.

P.S.: The shadow on checkboxes borders happens on main calibre either.

* Confirmed. Using larger images fixes the problem.

[jackie_w]

An error message from the Editor ...

calibre, version 5.99.0
ERROR: Unhandled exception: <b>TypeError</b>:int() argument must be a string, a bytes-like object or a real number, not 'KeyboardModifier'

calibre 5.99 Portable embedded-python: True
Windows-10-10.0.19042 Windows ('64bit', 'WindowsPE')
('Windows', '10', '10.0.19042')
Python 3.10.1
Windows: ('10', '10.0.19042', '', 'Multiprocessor Free')
Interface language: en_GB
Successfully initialized third party plugins: EpubCheck (0, 2, 3) && EpubMetadata (0, 0, 6) && EpubXCustomMetadata (0, 0, 7) && JS_Editor_Tools (0, 3, 16) && JS_Editor_Utils (0, 0, 9) && JS_Modify_Epub (0, 0, 22) && KoboTouchExtended (3, 5, 4) && ScrambleEbook (0, 5, 0) && Smart_Device_App_CSSAdd (0, 0, 12) && TTS to MP3 (0, 5, 10)
Traceback (most recent call last):
  File "calibre\gui2\tweak_book\editor\text.py", line 950, in keyPressEvent
  File "calibre\gui2\tweak_book\editor\smarts\html.py", line 738, in handle_key_press
TypeError: int() argument must be a string, a bytes-like object or a real number, not 'KeyboardModifier'

I'm not 100% sure of the rules to make this happen but here's an example where it did.

If the html is:

<p class="noindent">First paragraph.</p>
<p class="indent">Second paragraph.</p>

To trigger the error, double-click noindent to select it, then try to manually type indent. The error happens as I try to type the last 't'.

Changing classname via copy/paste doesn't trigger the error. Neither does changing noindent to indent by manually deleting the first 2 chars with the [Delete] key or the [Backspace] key.

[jackie_w]

Originally Posted by kovidgoyal

@jackie_w You need to use fully qualified names for enums in PyQt6, as thiago pointed out. I have added compatibility layers for the most common enums in calibre so they can continue to be used as before, but not for all of them.

and @thiago.eec

Thanks for the info and examples about needing fully qualifed names.