gui-video-clipper/chat-summaries/2026-09-22_10-37-extended-caption-styling-summary.md

Extended Caption Styling Implementation Summary

Date: 2026-09-22 10:37 Task: Implement extended caption styling (font selection, drop shadow, dimmed text color, background toggle)

Changes Made

Task 1: Data model (commit a4a1376)

• src/lib/stores/preferences.svelte.ts: Extended CaptionSettings interface with 8 new fields: fontFamily, backgroundEnabled, shadowEnabled, shadowDepth, shadowColor, dimmedColorMode, dimmedOpacity, dimmedColor
• src-tauri/src/models.rs: Extended CaptionStyle Rust struct with matching fields (snake_case, serde camelCase)
• src/lib/bindings/export.ts: Extended TS CaptionStyle binding interface
• src/lib/components/ExportDialog.svelte: Updated captionStyle passthrough to include all 17 fields

Task 2: System font detection (commit 1447071)

• src-tauri/src/commands/media_analysis.rs: Added list_system_fonts command using fc-list :lang=en family with hardcoded fallback (8 common fonts)
• src-tauri/src/lib.rs: Registered new command in generate_handler!
• src/lib/bindings/mediaAnalysis.ts: Added listSystemFonts() TS binding

Task 3: ASS generation wiring (commit 2cf8cdc)

• src-tauri/src/services/clip_exporter.rs: Rewrote style extraction block in vtt_to_ass_with_karaoke():
  • Uses font_family instead of hardcoded Arial
  • Dimmed color: auto mode derives from textColor + dimmedOpacity, custom mode uses dimmedColor directly
  • Background/shadow mutual exclusivity: background mode (BorderStyle 3/4 + BackColour for box), shadow mode (BorderStyle 1 + BackColour for shadow + Shadow depth), or neither (transparent BackColour)

Task 4: Preview caption rendering (commit bc39c2a)

• src/lib/components/VideoPlayer.svelte: Updated captionStyle derived to use $derived.by(), computing:
  • fontFamily, fontWeight from settings
  • Background conditional on backgroundEnabled with rgba() using hexToRgb helper
  • Shadow conditional on shadowEnabled with depth/color
  • Dimmed word colors: auto mode uses opacity, custom mode uses direct color

Task 5: Settings panel UI (commit 5c47e38)

• src/lib/components/CaptionSettingsPanel.svelte: Full rewrite with:
  • System font dropdown (loaded on mount via listSystemFonts(), each option styled in its own font)
  • Font size slider, bold checkbox
  • Text color picker
  • Dimmed text: auto/custom radio toggle with opacity slider or color picker
  • Outline: checkbox + color picker
  • Background: checkbox + color picker + opacity slider (disables shadow when enabled)
  • Drop shadow: checkbox + depth slider + color picker (disables background when enabled)
  • Position: bottom/top radio
  • Word highlight checkbox
  • Reset to defaults button
  • 320px width, scrollable, dark theme

Task 6: Verification

• cargo build: Clean (6 pre-existing warnings)
• cargo test --lib services::clip_exporter::tests: 23/23 passing
• npm run check: Only 4 pre-existing errors (node:path/process/url, overload)

Approach

• Used Subagent-Driven Development: fresh subagent per task + task reviewer per task
• 5 implementer dispatches + 5 reviewer dispatches + 1 verification pass
• All reviews approved on first pass (no fix cycles needed)

Minor Items for Future

• Font-family CSS quoting for multi-word names (e.g., Times New Roman) in dropdown options
• No defensive mutual exclusivity check in preview rendering (relies on settings panel enforcement)
• hexToRgb has no malformed-hex guard (UI-controlled values only)
• dimmedColorMode is string in Rust/TS binding vs 'auto' | 'custom' union in preferences
• No ASS Style-line unit tests for new field combinations

Follow-up Items

• Manual smoke test with cargo tauri dev recommended
• Test font selection with burn-in export
• Verify dimmed color auto vs custom modes in both preview and export