fix(display): draw text 1-bit, so glyphs stay crisp on the LED grid

[ChuckBuilds]

The bug

An LED panel has no partial brightness. PIL defaults ImageDraw's fontmode to "L", which anti-aliases TrueType glyphs into a grey fringe the panel can only round off — a 4px glyph arrives smeared into 3px.

DisplayManager creates its shared draw in six places and set fontmode at none of them, while _load_fonts loads extra_small_font as 4x6-font.ttf at size 6. Measured at draw time, that face at that size puts 74% of its lit pixels at partial coverage. Every plugin that draws small text through the shared draw inherited the blur.

The harness had the same gap, and that mattered more

src/plugin_system/testing/visual_display_manager.py creates its own draw in five places, also at the default. So the harness was recording anti-aliased goldens that production would never produce — it structurally could not have caught this.

That is not a theoretical point. After the production fix, geochron was still rendering anti-aliased under the harness; tracing the draw object's creation stack led to visual_display_manager.py:72. Fixing only production would have left the harness disagreeing with the panel.

Both are now "1", so the harness renders what the panel renders.

Verification

A probe hooked ImageDraw.text and recorded, for every real draw, the fontmode in effect, the font and size, the call site, and the Draw() object's creation site.

• before: 18 anti-aliased sites across 9 plugins
• after: 0, across 31 plugins × all 8 panel sizes

Companion plugin-side PR: ChuckBuilds/ledmatrix-plugins#417.

🤖 Generated with Claude Code

https://claude.ai/code/session_014RRtqXDCnvnY6EQwhT5CV9

Summary by CodeRabbit

• Bug Fixes
  • Standardized text rendering to use 1-bit, non-anti-aliased output across physical and visual displays.
  • Improved consistency between displayed text and visual test results.

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 0 complexity · 0 duplication

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Reviewing files that changed from the base of the PR and between 0730d95 and 1168c32.

📒 Files selected for processing (2)

• src/display_manager.py
• src/plugin_system/testing/visual_display_manager.py

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📝 Walkthrough

Walkthrough

The change sets ImageDraw.fontmode to "1" for all newly created production and visual test canvases. This applies during setup, resizing, clearing, resetting, and cleanup.

Changes

1-bit text rendering alignment

Layer / File(s)	Summary
Production canvas fontmode configuration src/display_manager.py	Production ImageDraw objects use fontmode = "1" across setup, resizing, clearing, and cleanup paths.
Visual test canvas fontmode configuration src/plugin_system/testing/visual_display_manager.py	Visual test ImageDraw objects use fontmode = "1" during initialization, clearing, resizing, resetting, and cleanup.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Merge Risk: ⚪ Minimal · up to 1168c

Text rendering now uses 1-bit glyphs in production and visual test canvases, eliminating partial-brightness text on LED panels while keeping visual test rendering aligned. The change is ready to merge.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	Docstring coverage is 90.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 10 functions across 2 files.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: configuring text rendering to 1-bit mode so glyphs remain crisp on the LED grid.

✨ Finishing Touches

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🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/crisp-text-shared-draw

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