force light mode

[sergey-yaroslavtsev]

Closes #1178

By forcing Light mode.
Actually it should probably also fix the issue related to use of different PySide6 version - because it force to use a standard them instead of implementing user windows settings (default windows behavior) - yes maybe it makes things to look more "old style" but fully visible and functional.

[woutdenolf]

I made some suggestions but I would prefer something better.

The idea is that the PyMca widgets don't show up well in dark mode.

So something like

from PyQt6.QtCore import Qt

def set_light_mode(app: QApplication):
    app.styleHints().setColorScheme(Qt.ColorScheme.Light)

or

from PyQt6.QtWidgets import QApplication
from PyQt6.QtGui import QPalette
from PyQt6.QtCore import Qt

def set_light_mode(app: QApplication):
    app.setStyle("Fusion")
    app.setPalette(app.style().standardPalette())

Of course we cannot use PyQt6 directly but you get the idea. Make a function that allows setting dark mode after instantiating the app. Perhaps this needs to be in silx.

Ping @t20100

[sergey-yaroslavtsev]

The problem is that

app.setStyle("Fusion")

will not work alone - setting "fusion" without disabling Dark mode still adapts to Dark mode and does not solve the issue of hardcoded colors. (I do not see why app.setPalette(app.style().standardPalette()) needed at all. Sorry if i am missing smthg.)

... Make a function that allows setting dark mode after instantiating the app. ...

the Dark mode should be disabled before starting the app thats the hole point unfortunately. Your first approach allows to bypass it but

app.styleHints().setColorScheme(qt.Qt.ColorScheme.Light)

do not exist in PySide6==6.7.3 and require higher version - which leads to another visual bugs #1182 #1179

[woutdenolf]

I do not see why app.setPalette(app.style().standardPalette()) needed at all. Sorry if i am missing smthg

I just dropped some code to help. I have no idea either. My point was: would it be possible to set the app to light-mode after instantiation and not use environment variables? I don't understand what this "fusion" business is either.

[t20100]

| would it be possible to set the app to light-mode after instantiation

Quick test with silx view & PySide 6.10.2 on Linux: app.styleHints().setColorScheme(qt.Qt.ColorScheme.Light) looks to work fine.

[sergey-yaroslavtsev]

I would assume this PR as a hot fix for Windows Dark mode. Since we probably need to release patch to fix MacOS issue #1181. I would suggest to implement it.

The proper solution is to fix hardcoded colors in the way suggested by @t20100 and then there will be no need neither for Pyside6==6.7.3 nor for forcing Light mode. But it is time consumable.

We can also decide that Dark mode issue is not worth to have a hot fix and forget about this PR completely. I fine with it.

[woutdenolf]

To summarize the patch:

• QT_QPA_PLATFORM="windows:darkmode=0": stop Windows from activating dark mode at the platform level.
• app.setStyle("Fusion"): control how widgets are drawn at the Qt style level.

[woutdenolf]

I still do not fully understand Qt's styles/palettes

Layer	Controlled By	What It Affects
Platform (QPA)	QT_QPA_PLATFORM	OS dark mode, title bars, palette defaults
Widget style	setStyle()	How widgets are drawn (e.g. layout)
Palette	setPalette()	Actual colors used

Mechanism	Layer	When Applied	What It Affects
QT_QPA_PLATFORM	Platform (QPA)	Before app creation	OS integration
setColorScheme()	Qt-level color preference	After app creation	Qt palette + style behavior

OS dark mode
        ↓
Platform plugin reports preference
        ↓
Qt styleHints() stores color scheme
        ↓
Qt builds default palette
        ↓
Style renders using palette

setColorScheme is Qt6-only. It does not affect Windows dark title bars at the OS level.

🤯

[woutdenolf]

Btw I was told VISA has dark-mode by default now.

[vasole]

It looks to me there are unresolved comments.

Ideally I would expect light mode forced unless the user has explicitly asked dark mode. I guess the comment of @woutdenolf was in that direction but not implemented. Could it be?

I am fine forcing light mode in the mean time too, but the comments should be resolved.

[woutdenolf]

The Platform/Style/Palette discussion is a complicated one. I agreed with Sergej that we can enforce light mode on Windows for the next patch release. There is no point in allowing dark mode anyway, the GUI would become basically unusable. Afterwards we can discuss a common approach to this in pymca and other tools like silx.

[sergey-yaroslavtsev]

i will merge after MacOS patch #1185