Add template-aware text colors and code font auto-scaling#171
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jongalloway merged 3 commits intoMay 11, 2026
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- Build theme from template color scheme (lt1/dk1) to pick readable text color based on background luminance - Detect low-contrast placeholder text in layouts and override with scheme-appropriate color - Resolve scheme color references (bg1, tx1, dk1, lt1, etc.) through the template's color scheme - Scale code font to 75% of template body text size (capped at 32pt) - Scale code font to fill available frame height per line count - Supports solidFill backgrounds via both srgbClr and schemeClr
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Pull request overview
This PR improves template-driven rendering in MarpToPptx so output better matches (and remains readable with) dark PowerPoint templates, while also making code blocks scale more appropriately with template typography.
Changes:
- Derive effective text colors from the template theme color scheme (dk1/lt1) and slide background luminance when
--templatestyle rendering is enabled. - Detect low-contrast placeholder default text colors from layout
lstStyleand apply a per-run solid fill override when needed. - Auto-scale code font size based on template body text defaults and available frame height, with a maximum cap.
Show a summary per file
| File | Description |
|---|---|
| src/MarpToPptx.Pptx/Rendering/OpenXmlPptxRenderer.cs | Adds template-aware theme/color resolution and implements code font scaling logic for template-based rendering. |
Copilot's findings
- Files reviewed: 1/1 changed files
- Comments generated: 3
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| var bodyFontSizePt = bodySzAttr.Value / 100.0; // hundredths to points | ||
| var scaledCodeSize = Math.Round(bodyFontSizePt * 0.75, 1); | ||
| var clampedSize = Math.Clamp(scaledCodeSize, baseCode.FontSize, MaxCodeFontSize); | ||
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| return clampedSize > baseCode.FontSize |
| if (ph is null) continue; | ||
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| var matches = placeholder.Type is { } t | ||
| ? ph.Type?.Value == t |
| var optimalSize = availableHeight / (lineCount * lineHeight); | ||
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| // Clamp: never shrink below theme default, never exceed max. | ||
| var clampedSize = Math.Clamp(Math.Round(optimalSize, 1), style.FontSize, MaxCodeFontSize); |
jongalloway
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feature/template-aware-text-colors-and-code-scaling
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