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qt: Use better devicePixelRatio event to refresh scaling#30345
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tacaswell commentedJul 23, 2025
Confirmed that this Fixes#30218 |
| # Emitting this event is simply to trigger the DPI change handler | ||
| # in Matplotlib in the same manner that it would occur normally. | ||
| qt_canvas.eventFilter( |
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Is calling eventFilter() the standard way to emit a self-created event? This feels a bit hacky, which may be ok. But I'd rathe comment like this
| # Emitting this event is simply to trigger the DPI change handler | |
| # in Matplotlib in the same manner that it would occur normally. | |
| qt_canvas.eventFilter( | |
| # Create an event to explicitly trigger the DPI change handler. | |
| # We push the event into Qt's event handling system by injecting it into | |
| # the eventFilter | |
| qt_canvas.eventFilter( |
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I just copied the old form, but we can push an event normally.
97c3be7 toa23bb28CompareWith Qt 6.6, there is an event on the window that signals when thedevicePixelRatio has changed. This is better than before when we had torely on the underlying `QScreen`, which doesn't correctly refresh when afractional scale is used.Fixesmatplotlib#30218
QuLogic commentedJul 23, 2025
Note, I think we don't need the |
| ifcurrent_version>= (6,6): | ||
| window.installEventFilter(self) | ||
| else: | ||
| window.screenChanged.connect(self._update_screen) | ||
| self._update_screen(window.screen()) |
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I suspect that both cases are a bit sloppy in that they connect/install on every showEvent. We typically have one, but there may be cases where the window lives longer and is hidden/shown multiple times. At least forconnect() multiple calls result in multiple connections, i.e. firing multiple times.
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atleast for the event filter version
If filterObj has already been installed for this object, this function moves it so it acts as if it was installed last.
so it is OK to install it multiple times.
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I'm not sure if I could find a better event just yet, but I'll try to take a look again later.
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@QuLogic can self merge if he would like to deal with note about possible multiple connections in a follow on PR.
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cbrnr commentedJul 24, 2025
Thank you 🔥! So happy to get nice looking Matplotlib plots now! I haven't tested it though, when will this fix be available in a release? |
tacaswell commentedJul 24, 2025
We are going to do a 3.10.4 this week (mostly to the fix for py3.14 released) so this made it in under the wire. |
…345-on-v3.10.xBackport PR#30345 on branch v3.10.x (qt: Use better devicePixelRatio event to refresh scaling)
cgohlke commentedAug 3, 2025
This doesn't work for me on Windows 11, PyQt6 6.9.1, 4K display. The figures are very pixelated, especially noticeable on text. Reverting these changes, or downgrading to matplotlib 3.10.3, or using another backend resolves the issue. For example, matplotlib 3.10.5 matplotlib 3.10.3 |
cbrnr commentedAug 3, 2025
I will test this tomorrow on Wayland... |
PR summary
With Qt 6.6, there is an event on the window that signals when the devicePixelRatio has changed. This is better than before when we had to rely on the underlying
QScreen, which doesn't correctly refresh when a fractional scale is used.Fixes#30218
PR checklist