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Platform parity

The core layout, text, graphics, charts, QR / barcodes, and decorations render identically on every platform. Document-level navigation and security features differ because the native PDF backends expose different capabilities.

On Android, metadata, clickable links, internal links, and the outline are produced by a pure-Kotlin post-processor that applies an incremental update to the bytes android.graphics.pdf.PdfDocument produces (it has no API for any of them); the patcher returns the original bytes unchanged on any parse surprise.

On Web (Wasm), the pure-Kotlin kmpwriter backs the target — every vector feature plus links, named destinations, the outline, and the info dictionary work. It now embeds fonts: a PdfFont.Custom is embedded as a TrueType subset, and non-WinAnsi text falls back to a bundled-Inter subset (so Latin + Cyrillic render in the browser), with Flate-compressed content streams. See Web (Kotlin/Wasm).

Backends

Platform Backend
Android android.graphics.pdf.PdfDocument + Canvas
iOS UIGraphicsBeginPDFContextToData + Core Graphics
Desktop (JVM) Apache PDFBox — pure-Java
Web (Wasm) kmpwriter — PdfKmp's own pure-Kotlin PDF 1.7 writer

Feature matrix

Feature Android iOS Desktop (JVM) Web (Wasm)
Core layout / text / shapes / decorations ✅ ✅ ✅ ✅
Table colSpan / rowSpan merging ✅ ✅ ✅ ✅
Charts / QR / barcodes / Data Matrix / freeDraw ✅ ✅ ✅ ✅
Gradients ✅ ✅ ✅ ✅
Info dictionary (title / author / …) ✅ via post-processor ✅ ✅ ✅
Hyperlink annotations (link) ✅ via post-processor ✅ ✅ ✅
Internal links (anchor / linkToAnchor) ✅ via post-processor ✅ ✅ ✅ named destinations
Outline / bookmarks + TOC ✅ via post-processor ✅ ✅ ✅
Vector text embedding ✅ native ✅ native ✅ subset TrueType ✅ subset TrueType (Helvetica for plain Latin)
Non-Latin scripts (CJK / Arabic / Persian) ✅ via System* ✅ via System* ⚠️ custom font required ⚠️ custom font required (Cyrillic via bundled Inter)
Custom font embedding (registerFont) ✅ ✅ ✅ ✅ TrueType-outline (CFF/OTF → Helvetica)
Raster images ✅ PNG/JPEG (+ WebP/HEIF where the OS decodes them) ✅ PNG/JPEG (+ WebP/HEIF where the OS decodes them) ✅ PNG/JPEG ⚠️ JPEG + 8-bit RGB/gray PNG only
Encryption ❌ no-op ⚠️ passwords + print/copy (no "modify") ✅ AES-256 ❌
File attachments ❌ skipped ❌ skipped ✅ ❌
Forms interactivity (textField / checkBox) ⚠️ static visual ⚠️ static visual ✅ interactive ❌ static visual
PDF/A (best-effort) + image /Alt ❌ ignored ❌ ignored ⚠️ best-effort ❌
Digital signing (PdfSigner) ❌ ❌ ✅ ❌
PdfTools (merge / split / watermark / overlay) ❌ ❌ ✅ ❌
Factur-X / ZUGFeRD attach (attachFacturX) ❌ ❌ ✅ ❌
RTL bidi + Arabic shaping (+ kashida justify) ✅ native ✅ native ✅ own bidi + shaping pass ⚠️ embedded-font glyphs only

✅ supported · ⚠️ partial / best-effort · ❌ not supported on that platform.

The FacturXInvoice builder is common code (it produces the factur-x.xml string everywhere); only the PdfTools.attachFacturX attachment step is JVM-only. See Forms & security.

Viewer annotations

In the viewer, highlight annotations are overlay-only on Android and iOS (UI state via initialAnnotations / onAnnotationsChanged). On Desktop they can be written into the PDF as real Highlight annotations — the download action then exports the annotated bytes.

See also