GTK 4 support

[amolenaar]

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Documentation content changes

The change

Gaphas works for GTK+ 3. This PR adds support for GTK 4 -- without breaking backwards compatibility.

Where there are incompatibilities between the GTK 3 and 4 api, a check for Gtk.get_major_version() == 3 is done.

Tests can be executed with GTK 4 by running TEST_GTK_VERSION=4.0 pytest.

Issue Number: gaphor/gaphor#618

Does this PR introduce a breaking change?

• Yes
• No

Other information

In GTK 4, the canvas is a lot more responsive, on macOS at least.

[danyeaw]

This looks really good!

I am getting a few warnings while running the demo:
Gtk-CRITICAL **: 21:27:25.049: gtk_event_controller_get_propagation_phase: assertion 'GTK_IS_EVENT_CONTROLLER (controller)' failed

I am not sure if it is a setup issue on my side, but the demo loads ok besides that.

Should we wait until a pygobject version with support is released?

[amolenaar]

I haven't seen that warning.

Should we wait until a pygobject version with support is released?

Although it works fine for both GTK+ 3 and GTK 4, I think we do not want to depend on a master branch of PyGObject. We'd better wait for an official release.

[sourcery-ai]

Sourcery Code Quality Report

❌  Merging this PR will decrease code quality in the affected files by 1.37%.

Quality metrics	Before	After	Change
Complexity	3.11 ⭐	3.58 ⭐	0.47 👎
Method Length	36.57 ⭐	38.29 ⭐	1.72 👎
Working memory	7.18 🙂	7.48 🙂	0.30 👎
Quality	77.39% ⭐	76.02% ⭐	-1.37% 👎

Other metrics	Before	After	Change
Lines	1768	1869	101

Changed files	Quality Before	Quality After	Quality Change
examples/simple-box.py	78.08% ⭐	78.08% ⭐	0.00%
gaphas/segment.py	67.45% 🙂	67.27% 🙂	-0.18% 👎
gaphas/aspect/handlemove.py	79.22% ⭐	77.28% ⭐	-1.94% 👎
gaphas/tool/hover.py	93.75% ⭐	90.61% ⭐	-3.14% 👎
gaphas/tool/itemtool.py	66.11% 🙂	65.55% 🙂	-0.56% 👎
gaphas/tool/placement.py	80.75% ⭐	79.12% ⭐	-1.63% 👎
gaphas/tool/rubberband.py	79.95% ⭐	78.85% ⭐	-1.10% 👎
gaphas/tool/scroll.py	88.48% ⭐	84.95% ⭐	-3.53% 👎
gaphas/tool/viewfocus.py	96.59% ⭐	92.75% ⭐	-3.84% 👎
gaphas/tool/zoom.py	78.11% ⭐	76.48% ⭐	-1.63% 👎
gaphas/view/gtkview.py	74.21% 🙂	71.50% 🙂	-2.71% 👎
gaphas/view/scrolling.py	65.98% 🙂	66.51% 🙂	0.53% 👍
tests/init.py	96.51% ⭐	92.38% ⭐	-4.13% 👎
tests/conftest.py	95.64% ⭐	92.73% ⭐	-2.91% 👎
tests/test_tool_hover.py	91.54% ⭐	91.05% ⭐	-0.49% 👎
tests/test_tool_item.py	88.09% ⭐	88.46% ⭐	0.37% 👍
tests/test_tool_placement.py	94.41% ⭐	93.72% ⭐	-0.69% 👎
tests/test_tool_scroll.py	93.10% ⭐	92.33% ⭐	-0.77% 👎
tests/test_tool_zoom.py	92.12% ⭐	91.52% ⭐	-0.60% 👎
tests/test_view.py	88.91% ⭐	82.57% ⭐	-6.34% 👎

Here are some functions in these files that still need a tune-up:

File	Function	Complexity	Length	Working Memory	Quality	Recommendation
gaphas/view/gtkview.py	GtkView.update_back_buffer	28 😞	265 ⛔	11 😞	29.80% 😞	Refactor to reduce nesting. Try splitting into smaller methods. Extract out complex expressions
gaphas/tool/itemtool.py	handle_at_point	18 🙂	151 😞	10 😞	46.38% 😞	Try splitting into smaller methods. Extract out complex expressions
gaphas/tool/itemtool.py	on_drag_begin	9 🙂	144 😞	15 😞	46.90% 😞	Try splitting into smaller methods. Extract out complex expressions
gaphas/view/gtkview.py	GtkView.__init__	4 ⭐	167 😞	15 😞	49.36% 😞	Try splitting into smaller methods. Extract out complex expressions
gaphas/segment.py	LineSegment.split_segment	6 ⭐	205 ⛔	11 😞	50.20% 🙂	Try splitting into smaller methods. Extract out complex expressions

Legend and Explanation

The emojis denote the absolute quality of the code:

• ⭐ excellent
• 🙂 good
• 😞 poor
• ⛔ very poor

The 👍 and 👎 indicate whether the quality has improved or gotten worse with this pull request.

---

Please see our documentation here for details on how these metrics are calculated.

We are actively working on this report - lots more documentation and extra metrics to come!

Let us know what you think of it by mentioning @sourcery-ai in a comment.

[amolenaar]

@danyeaw I changed the default PyGObject version back to stable. I added a separate job to test with GTK 4. It's using Fedora, since it already ships GTK 4. I think now it's safe to merge.

[danyeaw]

Nice one @amolenaar 👍