Represent OSD font characters using text/SVG instead of canvas/PNG for better performance (OSD tab loads in roughly half the time on an older Chromebook).

[DavidAnson]

Summary by CodeRabbit

• New Features

  • Character previews are now rendered using SVG images for improved clarity and scalability.

• Bug Fixes

  • Improved HTML syntax for image sources in OSD previews to ensure proper rendering.

[coderabbitai]

Walkthrough

The update replaces canvas-based character rendering with SVG-based rendering for the OSD font system. The drawCanvas function is replaced by characterBitmapDataUri, which generates SVG data URIs. The FONT.draw method now returns SVG data URIs, and the color mapping constant is removed. Minor HTML syntax adjustments are also made.

Changes

File(s)	Change Summary
src/js/tabs/osd.js	Replaced canvas rendering with SVG-based data URI generation for character bitmaps; removed color mapping constant; updated FONT.draw method to use new function; adjusted HTML image source syntax.

Sequence Diagram(s)

sequenceDiagram
    participant User
    participant OSDPreview
    participant FONT

    User->>OSDPreview: Request character render
    OSDPreview->>FONT: draw(charAddress)
    FONT->>FONT: characterBitmapDataUri(charAddress)
    FONT-->>OSDPreview: SVG data URI
    OSDPreview-->>User: Render SVG image

Loading

Possibly related issues

• OSD tab is relatively slow to load (most time spent in font load/parse) #4494: This change directly addresses the issue by switching from canvas-based PNG rendering to SVG data URIs in the font rendering method, improving performance and compatibility.

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📥 Commits

Reviewing files that changed from the base of the PR and between 1809bb8 and 68e6200.

📒 Files selected for processing (1)

• src/js/tabs/osd.js (2 hunks)

🔇 Additional comments (5)

src/js/tabs/osd.js (5)

190-195: Well-documented function signature change aligns with performance objectives.

The renaming from drawCanvas to characterBitmapDataUri better reflects the new functionality and return type. The JSDoc comment about using single quotes for embedding within double quotes shows good attention to detail for the implementation requirements.

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196-224: Excellent SVG-based implementation with proper optimization.

The new SVG-based approach has several advantages:

• Better performance than canvas manipulation, especially on older devices
• More memory-efficient string representation vs canvas elements
• Selective rendering (only colors 0 and 2) reduces SVG complexity
• Proper use of single quotes for attributes enables embedding in HTML double quotes

The implementation correctly handles:

• Input validation with appropriate logging
• Pixel-by-pixel iteration with color filtering
• Data URI format construction

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229-229: Function call correctly updated to match new signature.

The call to characterBitmapDataUri is properly updated to use the new function name while maintaining the same parameters and return value usage.

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266-266: Improved HTML syntax with proper quote usage.

The change from single quotes to double quotes for the src attribute follows HTML best practices and ensures consistency with the SVG implementation that uses single quotes internally.

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3413-3413: Consistent HTML syntax improvement.

This change maintains consistency with the other HTML attribute quote usage and follows standard HTML formatting practices.

✨ Finishing Touches

• 📝 Generate Docstrings

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[DavidAnson]

Fixes #4494

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[github-actions]

Preview URL: https://68e62003.betaflight-configurator.pages.dev

[DavidAnson]

Cool, thank you both!