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Merged
merged 2 commits into from
Jul 24, 2025
Merged

Support fractional HiDPI in GTK4 backend #30344

merged 2 commits into from
Jul 24, 2025

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QuLogic
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@QuLogic QuLogic commented Jul 23, 2025

PR summary

Since GTK 4.12, fractional HiDPI is handled, but with a separate property on the backing surface due to it being a different type.

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timhoffm
timhoffm reviewed Jul 23, 2025
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lib/matplotlib/backends/backend_gtk4.py Outdated
scale = surface.get_scale()
else:
scale = self.get_scale_factor()
if scale is not None and self._set_device_pixel_ratio(scale):
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When can scale be None? I'd expect that this is rather a RuntimeError and should generally not happen.

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I suspect there is some funnyness with hidden / minimized / offscreen / not drawn yet windows in the _GTK_GE_4_12 branch where there may not be a defined scale yet (because they have not been put on the screen yet).

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Would it be better in that case to fall back to self.get_scale_factor() rather than doing nothing?

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I was trying to avoid issues if native or surface were not set yet, but it seems like this function only ends up being called after the widget is realized, so the window surface should always exist. The only other caller is the resize event, but that can obviously only happen with a window to resize...

So I guess I can just drop all the conditions, as I can't so far get it to fail.

@QuLogic
Support fractional HiDPI in GTK4 backend
f4d9f6c 
Since GTK 4.12, fractional HiDPI is handled, but with a separate
property on the backing surface due to it being a different type.
@github-actions github-actions bot added the Documentation: examples files in galleries/examples label Jul 24, 2025
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QuLogic commented Jul 24, 2025

Also pushed a fix for these warnings from the GTK4 examples:

matplotlib/galleries/examples/user_interfaces/embedding_in_gtk4_sgskip.py:42: DeprecationWarning: Gtk.Widget.show is deprecated
  win.show()

matplotlib/galleries/examples/user_interfaces/embedding_in_gtk4_panzoom_sgskip.py:47: DeprecationWarning: Gtk.Widget.show is deprecated
  win.show()

@tacaswell tacaswell added this to the v3.10.4 milestone Jul 24, 2025
@tacaswell tacaswell merged commit 3444f0f into matplotlib:main Jul 24, 2025
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meeseeksmachine pushed a commit to meeseeksmachine/matplotlib that referenced this pull request Jul 24, 2025
@tacaswell @meeseeksmachine
Backport PR matplotlib#30344: Support fractional HiDPI in GTK4 backend
d32fed7
@meeseeksmachine meeseeksmachine mentioned this pull request Jul 24, 2025
Merged
@QuLogic QuLogic deleted the gtk4-fractional branch July 24, 2025 18:37
ksunden added a commit that referenced this pull request Jul 25, 2025
@ksunden
Merge pull request #30350 from meeseeksmachine/auto-backport-of-pr-30…
e9c0239 
…344-on-v3.10.x

Backport PR #30344 on branch v3.10.x (Support fractional HiDPI in GTK4 backend)
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@tacaswell tacaswell tacaswell left review comments

@timhoffm timhoffm timhoffm approved these changes

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Documentation: examples files in galleries/examples GUI: gtk
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