Stirling-PDF/docs/pdf-text-editor-backlog.md

PDF Text Editor Backlog

• Type3 Font Support (Text Additions)

  • Parse Type3 charprocs to extract glyph outlines, build a synthetic TrueType/OpenType font (FontTools, Ghostscript ps2ttf, etc.), and store it in webProgram / pdfProgram for client use.
  • Preserve the original Type3 resources for round-trip fidelity; use the synthesized font only for edited elements while reusing the original stream elsewhere.
  • Extend conversion logic so fallback kicks in only when conversion fails, and track which elements rely on the synthetic font to avoid mixing source glyphs (PdfJsonConversionService.java:998-1090, 1840-2012).
  • Update the viewer/renderer to surface conversion errors and block editing when no faithful font can be produced.

• Lazy Fetch Endpoints

  • Provide separate endpoints to fetch:
    1. Raw COS dictionaries/font programs when the user opens advanced panels.
    2. Page-level raster/vector previews to avoid sending large imageData upfront.
  • Reuse the existing job cache (documentCache) to serve these on demand and clean up after timeouts (PdfJsonConversionService.java:3608-3687).

• Editor UX Safeguards

  • Mark groups using fallback glyphs so the UI can warn about possible appearance shifts. Font family matching is now implemented (Liberation fonts), but weight matching is still TODO, so bold/italic text using fallbacks may appear lighter than original.
  • Surface when Type3 conversion was downgraded (e.g., rasterized glyphs) and limit editing to operations that keep the PDF stable.
  • Reference: frontend/src/proprietary/components/tools/pdfTextEditor/PdfTextEditorView.tsx:1260-1287

• Canonical Font Sharing

  • Emit fonts once per unique embedded program. Add a canonicalFonts array containing the full payload (program, ToUnicode, metadata) and a compact fontAliases mapping {pageNumber, fontId, canonicalUid} so text elements can still reference per-page IDs.
  • Note: COS dictionaries are currently preserved for TrueType/Type0 fonts (needed for ToUnicode CMap). The canonical approach should maintain this preservation while deduplicating font programs.
  • Update buildFontMap to resolve aliases when recreating PDFBox fonts, and adjust the front end to load programs via the canonical UID.
  • Optional: expose a lazy endpoint for the original COS dictionary if the canonical record strips it, so export still reconstructs untouched fonts.

• Font Weight Matching for Fallback Fonts ✓ COMPLETED (January 2025)

  • Font family matching is now implemented:
    • Liberation fonts (metric-compatible with Microsoft core): Arial/Helvetica→LiberationSans, Times→LiberationSerif, Courier→LiberationMono
    • DejaVu fonts (widely used open source): DejaVu→DejaVuSans, DejaVuSerif, DejaVuMono
    • Noto fonts (Google universal font): Noto→NotoSans
  • Font weight/style matching is now implemented for multiple font families:
    • Liberation Sans/Serif/Mono: Regular, Bold, Italic, BoldItalic (full support)
    • Noto Sans: Regular, Bold, Italic, BoldItalic (full support)
    • DejaVu Sans/Serif/Mono: Regular, Bold, Italic/Oblique, BoldItalic/BoldOblique (full support)
  • All font variants registered in BUILT_IN_FALLBACK_FONTS map (PdfJsonFallbackFontService.java:63-267)
  • Weight/style detection implemented in resolveFallbackFontId():
    • detectBold(): Detects "bold", "heavy", "black", or numeric weights 600-900 (e.g., "700wght")
    • detectItalic(): Detects "italic" or "oblique"
    • applyWeightStyle(): Applies appropriate suffix (handles both "italic" and "oblique" naming)
  • All fonts consolidated from Type3 library into main fonts directory for unified fallback support
  • Benefits: Comprehensive visual consistency when editing text in bold/italic fonts across many font families

• Font Text Color Support

  • Add support for reading and preserving text color information from PDF content streams
  • Enable color editing in the editor UI
  • Ensure proper round-trip conversion maintains color fidelity

• Space Character Handling

  • Improve handling of space characters as proper text elements
  • Ensure spaces are correctly preserved during text extraction and reconstruction
  • Fix any issues with space positioning and width calculations

• Textbox Selection Enhancement

  • Improve textbox selection behavior in the editor
  • Enhance user experience for selecting and manipulating text boxes
  • Address any selection precision or interaction issues