1 betto_pdfium

A monorepo for betto_pdfium — a pure Dart package wrapping the PDFium C++ library for PDF rendering, text extraction, search, annotations, and thumbnails via Dart FFI (native) and dart:js_interop (web) — plus its Flutter companion plugin for iOS.

No local C++ toolchain is required. Pre-built PDFium binaries are sourced from bblanchon/pdfium-binaries and downloaded automatically.

1.1 Platform support

1.2 Packages

packages/
  betto_pdfium/       # Pure Dart PDFium wrapper — the main package
  betto_pdfium_ios/   # Flutter iOS companion plugin (delivers the PDFium
                       # xcframework via Swift Package Manager)

betto_pdfium has no dependency on dart:ui or package:flutter and works in CLI tools, server-side Dart, and Flutter apps alike. betto_pdfium_ios is only needed by Flutter apps targeting iOS.

See packages/betto_pdfium/README.md for the full API guide (metadata, text/image/annotation extraction, rendering, search, table of contents, thumbnails), web (WASM) setup, and mobile setup.

The betto_pdf_widgets package provides Flutter widgets that use the betto_pdfium package for displaying PDF documents. The codebase includes a PDF viewer application as the example implementation.

1.3 Getting started

All commands are run from the repo root via the root Makefile, which composes per-package .mk fragments. This is a pure Dart package — never use flutter commands for betto_pdfium itself.

make test          # dart test — the native-assets hook downloads the
                    # platform PDFium binary automatically on first run
make analyze        # dart analyze (betto_pdfium) + flutter analyze (betto_pdfium_ios)
make format          # dart format
make coverage        # dart test --coverage + genhtml (site/coverage/)
make web_test        # dart test -p chrome (requires Chrome)
make pre_commit      # format_check + analyze + analyze_ios + license_check + test

Quick usage example:

import 'dart:io';
import 'package:betto_pdfium/betto_pdfium.dart';

final bytes = await File('document.pdf').readAsBytes();
final doc = await PdfDocument.fromBytes(bytes);
try {
  final meta = await doc.getMetadata();
  print(meta.title);
} finally {
  await doc.close();
}

1.4 Library development

Working on betto_pdfium itself (regenerating FFI bindings, bumping the PDFium version, running mobile/web tests) requires a few extra make targets:

make fetch_pdfium              # Download PDFium binary + headers for the
                                # current BBLANCHON_BUILD (only needed for
                                # FFI binding regeneration — make test works
                                # without it)
make check_pdfium_version      # Verify installed binary/headers match BBLANCHON_BUILD
make ffi_bindings               # Regenerate Dart FFI bindings from PDFium headers
make fetch_wasm_assets          # Download PDFium WASM + JS + Worker assets for web
make fetch_mobile_binaries       # Download Android .so (iOS xcframework is fetched by SPM)
make ios_test                    # Run the mobile integration suite on iOS
make android_test                # Run the mobile integration suite on Android

Bumping the PDFium version is a documented multi-step workflow — see packages/betto_pdfium/README.md and CLAUDE.md’s “Bumping the bblanchon version” section for the full single-commit workflow, and docs/spec/01_binary_distribution.md for the underlying distribution contract.

1.5 Developer CLI

Inspect a real-world PDF file at the command line:

cd packages/betto_pdfium
dart run bin/pdfinfo.dart path/to/document.pdf

Prints all Info dictionary fields, document version, and file identifiers. See packages/betto_pdfium/example/ for further usage examples.

1.6 Additional information

• Full package API guide: packages/betto_pdfium/README.md
• Implementation plans: docs/plans/
• Version roadmap: docs/roadmap/
• Full specification: docs/spec/
• Contributing: CONTRIBUTING.md