Possible bug where keyword arguments don't work in PySide2 when they do in PyQt5

PeterH92

I made a resizable image class, and I'm using transformMode=QtCore.Qt.SmoothTransformation when scaling. It works fine in PyQt5, but it is ignored in PySide2. Instead you can only pass it in as a regular argument, which means you've got to specifically set everything before it too, such as aspectRatioMode, and that's not quite as pythonic.
I even tried using **{QtCore.Qt.TransformationMode: QtCore.Qt.SmoothTransformation}, as PySide2 says it internally uses that, but it was also ignored.

Here is what it is supposed to look like (PyQt5):

PyQt5

Here is what it looks like under PySide2:

PySide2

Btw, if anyone wants a quick try, the particular line is here, to run just clone the repo and run load_gui.py.

KazuoAsano

Hi @PeterH92 ,

I checked your Code.
I think that aspectMode arguments are probably missing at Qt for Python(PySide2).

See Document as below
https://doc-snapshots.qt.io/qtforpython/PySide2/QtGui/QPixmap.html#PySide2.QtGui.PySide2.QtGui.QPixmap.scaled

PeterH92

Thanks for the link, looks like PyQt's transformMode is just named mode in PySide2.

I think this is the first difference I've actually seen, at least in my opinion though, PyQt's version is what it should be.

KazuoAsano

@PeterH92,

PyQt's version is what it should be.

I'm not really familiar with PyQt5. Therefore, I don't know why it hasn't happened.
Because I can't generate the same environment.

Can you try the following?
Please add aspectMode = QtCore.Qt.IgnoreAspectRatio as 3rd argument.

-31: scaled_pixmap = self._pixmapOriginal.scaled(self._pixmapWidth * size_mult, self._pixmapHeight * size_mult, transformMode=QtCore.Qt.SmoothTransformation)

+31: scaled_pixmap = self._pixmapOriginal.scaled(self._pixmapWidth * size_mult, self._pixmapHeight * size_mult, aspectMode=QtCore.Qt.IgnoreAspectRatio, transformMode=QtCore.Qt.SmoothTransformation)

PeterH92

That still has the same problem, just did a quick test and it seems PySide 1 has the same behaviour.

Doesn't work: aspectMode=QtCore.Qt.IgnoreAspectRatio, transformMode=QtCore.Qt.SmoothTransformation
Works: aspectMode=QtCore.Qt.IgnoreAspectRatio, mode=QtCore.Qt.SmoothTransformation

It's not a huge issue, just seems a bit inconsistent, especially when it says it's a QtCore.Qt.TransformationMode parameter in tracebacks.

(I'm lucky I noticed this reply just now haha, turns out I'd accidentally deleted the UI code yesterday, fortunately was still in my undo history)