Move logic out of canvas

[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

What is the current behavior?

Item instances contain a reference to their Canvas

Issue Number: N/A

What is the new behavior?

• Item still has a canvas reference, but it's not exposed.
• Item.normalize() is gone.
• The update process is completely handled by the View.
• Segment now depends on a canvas, not on View.

Does this PR introduce a breaking change?

• Yes
• No

Other information

[sourcery-ai]

Sourcery Code Quality Report

❌  Merging this PR will decrease code quality in the affected files by 0.24%.

Quality metrics	Before	After	Change
Complexity	1.11 ⭐	1.11 ⭐	0.00
Method Length	44.39 ⭐	45.23 ⭐	0.84 👎
Working memory	5.46 ⭐	5.52 ⭐	0.06 👎
Quality	87.50% ⭐	87.26% ⭐	-0.24% 👎

Other metrics	Before	After	Change
Lines	4803	4582	-221

Changed files	Quality Before	Quality After	Quality Change
examples/demo.py	88.75% ⭐	88.75% ⭐	0.00%
gaphas/aspect.py	93.88% ⭐	94.02% ⭐	0.14% 👍
gaphas/canvas.py	93.38% ⭐	93.98% ⭐	0.60% 👍
gaphas/connections.py	84.12% ⭐	84.31% ⭐	0.19% 👍
gaphas/connector.py	93.52% ⭐	93.71% ⭐	0.19% 👍
gaphas/guide.py	84.61% ⭐	84.53% ⭐	-0.08% 👎
gaphas/item.py	90.37% ⭐	91.49% ⭐	1.12% 👍
gaphas/segment.py	76.27% ⭐	76.48% ⭐	0.21% 👍
gaphas/tool.py	83.91% ⭐	83.92% ⭐	0.01% 👍
gaphas/view/gtkview.py	80.61% ⭐	80.59% ⭐	-0.02% 👎
gaphas/view/view.py	90.39% ⭐	90.44% ⭐	0.05% 👍
tests/conftest.py	91.33% ⭐	91.34% ⭐	0.01% 👍
tests/test_canvas.py	81.63% ⭐	81.69% ⭐	0.06% 👍
tests/test_element.py	84.64% ⭐	83.81% ⭐	-0.83% 👎
tests/test_guide.py	82.09% ⭐	81.97% ⭐	-0.12% 👎
tests/test_line.py	87.22% ⭐	87.22% ⭐	0.00%
tests/test_segment.py	79.45% ⭐	79.44% ⭐	-0.01% 👎
tests/test_undo.py	77.72% ⭐	76.67% ⭐	-1.05% 👎
tests/test_view.py	88.62% ⭐	88.70% ⭐	0.08% 👍

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

File	Function	Complexity	Length	Working Memory	Quality	Recommendation
examples/demo.py	create_window	9 🙂	861 ⛔	15 😞	33.08% 😞	Try splitting into smaller methods. Extract out complex expressions
gaphas/view/gtkview.py	GtkView.update_back_buffer	14 🙂	224 ⛔	12 😞	39.89% 😞	Try splitting into smaller methods. Extract out complex expressions
gaphas/view/gtkview.py	GtkView.update_adjustments	6 ⭐	206 ⛔	15 😞	44.15% 😞	Try splitting into smaller methods. Extract out complex expressions
gaphas/view/gtkview.py	GtkView.get_handle_at_point	18 🙂	149 😞	9 🙂	48.65% 😞	Try splitting into smaller methods
gaphas/item.py	Line._update_orthogonal_constraints	11 🙂	142 😞	12 😞	49.54% 😞	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.