openpdf-renderer: support Tr text rendering mode (fixes invisible OCR text layers rendering as visible) - #1603
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Previously the renderer always filled text regardless of the active PDF §9.3.3 text rendering mode, so invisible text (Tr 3), which scanned-PDF / OCR pipelines rely on to lay a searchable text layer over a page-image XObject, would incorrectly render as visible glyphs on top of the image. Add Tr parsing plus fill/stroke/invisible handling (modes 4-7, which also add glyphs to the clip path, degrade to their 0-2 fill/stroke behavior since text clipping isn't implemented). Update the README operator tables and docs to match.
Up to standards ✅🟢 Issues
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| Metric | Results |
|---|---|
| Complexity | 7 |
| Duplication | 6 |
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Consolidated into LibrePDF#1607 along with the README updates for LibrePDF#1604, LibrePDF#1605, and LibrePDF#1606, so these four independent PRs (all based on master) don't each carry their own overlapping README.md diff and risk merge conflicts with each other depending on merge order.
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Consolidated into LibrePDF#1607 along with the README updates for LibrePDF#1603, LibrePDF#1605, and LibrePDF#1606, so these four independent PRs (all based on master) don't each carry their own overlapping README.md diff and risk merge conflicts with each other depending on merge order.
andreasrosdalw
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Jul 28, 2026
Consolidated into LibrePDF#1607 along with the README updates for LibrePDF#1603, LibrePDF#1604, and LibrePDF#1606, so these four independent PRs (all based on master) don't each carry their own overlapping README.md diff and risk merge conflicts with each other depending on merge order.
andreasrosdalw
added a commit
to andreasrosdalw/OpenPDF
that referenced
this pull request
Jul 28, 2026
Consolidated into LibrePDF#1607 along with the README updates for LibrePDF#1603, LibrePDF#1604, and LibrePDF#1605, so these four independent PRs (all based on master) don't each carry their own overlapping README.md diff and risk merge conflicts with each other depending on merge order.
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Summary
OpenPdfCorePageRenderer(theopenpdf-core-backed Java2D rasterizer used byOpenPdfCoreRenderer) never parsed theTroperator, so text was always filled regardless of the active PDF §9.3.3 text rendering mode.Tr 3) searchable text layer directly on top of a page-image XObject. Without honoringTr, that invisible text was incorrectly rendered as visible black glyphs on top of the scanned image.Trhandling: mode 0 fill (previous/default behavior), mode 1 stroke (viaFont.createGlyphVector+BasicStrokeusing the current stroke color/width/dash/join), mode 2 fill+stroke, and modes 3/7 invisible (skip painting entirely). Modes 4-6 (which additionally add glyphs to the clipping path) fall back to their 0-2 fill/stroke behavior — text clipping isn't implemented, called out explicitly in code and README.openpdf-renderer/README.md's operator-support tables and text-rendering section to documentTrsupport and the clip-mode caveat.