fix: resolve FigureCanvasTkAgg clipping on Windows HiDPI by statxc · Pull Request #31133 · matplotlib/matplotlib

statxc · 2026-02-11T02:18:44Z

PR summary

Closes #31126

Why is this change necessary?

On HiDPI displays, FigureCanvasTkAgg embedded in layout-managed containers renders plots larger than the visible area, clipping axis labels and legends.

What problem does it solve?

When DPI changes, the canvas is configured to a larger size but layout managers constrain it, preventing the <Configure> event from firing and leaving figure.size_inches miscalculated, causing the render buffer to exceed the visible canvas size.

What is the reasoning for this implementation?

After configuring canvas size, explicitly check if the actual displayed size differs from the configured size and call resize() to recalculate figure.size_inches with the correct DPI, ensuring render size matches visible size.

PR checklist

"closes #0000" is in the body of the PR description to link the related issue
new and changed code is tested
Plotting related features are demonstrated in an example
New Features and API Changes are noted with a directive and release note
Documentation complies with general and docstring guidelines

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tacaswell · 2026-02-12T16:13:21Z

I think I understand how this works, but it feels like there should be a better way in tk for widgets to be notified that their size is changed. We should be using that mechanism (possibly re-working how we currently do it) instead#.

statxc · 2026-02-12T16:24:51Z

I think I understand how this works, but it feels like there should be a better way in tk for widgets to be notified that their size is changed. We should be using that mechanism (possibly re-working how we currently do it) instead#.

Thanks @tacaswell , I see what you mean. I’ll try to find a better Tk-native way for widgets to react to size changes and rework the current approach based on that.

… fix/issue-31126

…resizing with actual widget dimensions instead of computed ones after DPI changes

statxc · 2026-02-25T16:08:58Z

@tacaswell @sanrishi Please review the PR and let me know your feedback. Thanks!

statxc · 2026-03-06T00:12:33Z

please any update for me. thanks

tacaswell · 2026-03-11T02:03:14Z

Running the example code from #31126 on linux with X11 and hi-dpi I get

✔ 21:54:21 [belanna] @ python tk_bug.py
device_pixel_ratio: 1.6763463569165786
figure.dpi: 160.92925026399155 (original: 96)
figure.get_size_inches(): [23.86, 13.17]
Render size: 3840x2120
Canvas configured: 6437x3553
Canvas actual:     3840x2120

and it renders correctly.

vs the buggy case

✔ 21:54:33 [belanna] @ python tk_bug.py
device_pixel_ratio: 1.6763463569165786
figure.dpi: 160.92925026399155 (original: 96)
figure.get_size_inches(): [40.00, 22.08]
Render size: 6437x3553
Canvas configured: 6437x3553
Canvas actual:     3840x2120
BUG: render size (6437x3553) != actual size (3840x2120)

which renders clipped but on manually resizing fixes itself.

tacaswell

Manually verified that this fixes the problem and the fix makes sense.

Would like an explanation of the commit history before we merge.

statxc · 2026-03-11T02:11:59Z

Manually verified that this fixes the problem and the fix makes sense.

Would like an explanation of the commit history before we merge.

Thanks for approving. What should I do on my end? I don't understand your mention Would like an explanation of the commit history before we merge. What should I explain exactly?

tacaswell · 2026-03-11T02:14:54Z

There are commits from both @intelliking @statxc in the commit history. We are very much in favor of collaboration (it is the main thing we do here), but I also want to make sure everyone involved is aware they are involved etc. [I had a comment asking about this in another tab and failed to post it before my review]

statxc · 2026-03-11T02:17:48Z

@tacaswell Ah, I understand now. At first, my username was @intelliking. After that, I changed username to @statxc . @statxc and @intelliking are same - Me. Sorry for confusion. 🙏

timhoffm · 2026-03-11T10:47:35Z

lib/matplotlib/backends/_backend_tk.py

-        width, height = event.width, event.height
+        self._resize_canvas(event.width, event.height)
+
+    def _resize_canvas(self, width, height):


This should have a docstring

Suggested change

def _resize_canvas(self, width, height):

def _resize_canvas(self, width, height):

"""Update figure size and redraw based on a given canvas size."""

Also, the name _resize_canvas is a bit vague. Should this be _resize_figure_for_canvas_size?

timhoffm · 2026-03-11T10:50:37Z

lib/matplotlib/backends/_backend_tk.py

-            # canvas backing store on that event.
+            # The easiest way to resize the canvas is to emit a
+            # resize event since we implement all the logic for resizing
+            # the canvas backing store on that event.


Is the description correct? Isn't it primarily that we set the canvas size and then explicitly update the figure size using _resize_canvas (or possibly better named _resize_figure_for_canvas_size())? The event seems now an implementation detail of the called _resize_... method and seems to not be relevant here anymore.

…issue-31126

timhoffm · 2026-03-11T20:34:37Z

Thanks @statxc !

…matplotlib#31133)

fix: resolve FigureCanvasTkAgg clipping on Windows HiDPI

11a4f8f

github-actions bot added the GUI: tk label Feb 11, 2026

github-actions bot added the first-contribution label Feb 11, 2026

statxc added 2 commits February 11, 2026 02:28

Fix lint issues

538486b

Fix update_idletasks call in Tk backend

f13bb92

rcomer mentioned this pull request Feb 11, 2026

MAINT: Move to first-contribution action #31090

Merged

2 tasks

Check for update_idletasks existence before calling

61763bd

intelliking added 3 commits February 25, 2026 13:41

Merge branch 'main' of https://github.com/intelliking/matplotlib into…

7efbd0c

… fix/issue-31126

refactor: fix HiDPI clipping for layout-managed FigureCanvasTkAgg by …

6eed327

…resizing with actual widget dimensions instead of computed ones after DPI changes

fix: matplot error

2c0bf43

melissawm added this to First Time Contributors Mar 6, 2026

melissawm moved this to Needs review in First Time Contributors Mar 6, 2026

tacaswell approved these changes Mar 11, 2026

View reviewed changes

tacaswell added this to the v3.11.0 milestone Mar 11, 2026

tacaswell requested a review from richardsheridan March 11, 2026 02:08

timhoffm reviewed Mar 11, 2026

View reviewed changes

Ubuntu and others added 2 commits March 11, 2026 19:29

Merge branch 'main' of https://github.com/statxc/matplotlib into fix/…

d61cf1a

…issue-31126

update docstring

65cabc9

timhoffm approved these changes Mar 11, 2026

View reviewed changes

timhoffm merged commit 8095b72 into matplotlib:main Mar 11, 2026
34 of 37 checks passed

github-project-automation bot moved this from Needs review to Merged in First Time Contributors Mar 11, 2026

statxc deleted the fix/issue-31126 branch March 11, 2026 20:40

andreas16700 added a commit to andreas16700/matplotlib that referenced this pull request Mar 16, 2026

Run 8095b72: fix: resolve FigureCanvasTkAgg clipping on Windows HiDPI (…

39f2c8f

…matplotlib#31133)

andreas16700 added a commit to andreas16700/matplotlib that referenced this pull request Mar 16, 2026

Run 8095b72: fix: resolve FigureCanvasTkAgg clipping on Windows HiDPI (…

ac5c04d

…matplotlib#31133)

	def _resize_canvas(self, width, height):
	def _resize_canvas(self, width, height):
	"""Update figure size and redraw based on a given canvas size."""

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statxc commented Feb 11, 2026

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statxc commented Mar 11, 2026 •

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