espresso3389/pdfrx

Purpose and Entry Points

This pub-workspace monorepo delivers PDF rendering, viewing, and manipulation for Dart and Flutter. Its public package entry points are:

• Flutter UI API: packages/pdfrx/lib/pdfrx.dart

• Platform-agnostic document API: packages/pdfrx_engine/lib/pdfrx_engine.dart

• Direct PDFium FFI: packages/pdfium_dart/lib/pdfium_dart.dart

• Flutter PDFium packaging: packages/pdfium_flutter/lib/pdfium_flutter.dart

• Experimental Apple CoreGraphics backend: packages/pdfrx_coregraphics/lib/pdfrx_coregraphics.dart

PDFium Binding and Deployment Layer

PDFium is the primary rendering/manipulation engine. pdfium_dart exposes generated C FFI bindings and resolves a usable PDFium library; build/link hooks acquire and package native assets. pdfium_flutter supplies Flutter-specific loading and Darwin framework integration.

• packages/pdfium_dart/lib/src/pdfium_bindings.dart

• packages/pdfium_dart/lib/src/pdfium_loader.dart

• packages/pdfium_dart/hook/build.dart

• packages/pdfium_flutter/darwin/pdfium_flutter/Sources/main/pdfium_flutter.swift

Native targets include Android, iOS, macOS, Windows, and Linux. iOS/macOS use a PDFium XCFramework through CocoaPods or Swift Package Manager; other native environments use Dart native assets.

Engine: Document and Rendering Domain

pdfrx_engine is the non-Flutter boundary over PDFium. It defines document/page abstractions plus PDF-domain values for text, images, annotations, links, outlines, permissions, destinations, and editing operations. This layer can support CLI or server-side Dart consumers without widget dependencies.

• packages/pdfrx_engine/lib/src/pdf_document.dart

• packages/pdfrx_engine/lib/src/pdf_page.dart

• packages/pdfrx_engine/lib/src/pdfrx.dart

The control flow is initialization → document open/create → page/text/image/link operations → render or write/export. Native PDFium adaptation, file access/write callbacks, caching, and worker handling live behind the engine boundary:

• packages/pdfrx_engine/lib/src/native/pdfrx_pdfium.dart

• packages/pdfrx_engine/lib/src/native/pdfium_file_access.dart

• packages/pdfrx_engine/lib/src/native/worker.dart

Flutter Viewer Composition

pdfrx builds the interactive Flutter presentation layer on the engine. The viewer owns document presentation, viewport/layout state, page rendering, gestures, keyboard handling, overlays, search, selection, links, and scroll feedback.

• packages/pdfrx/lib/src/widgets/pdf_viewer.dart

• packages/pdfrx/lib/src/widgets/interactive_viewer.dart

• packages/pdfrx/lib/src/widgets/pdf_viewer_params.dart

Viewer behavior is delegated rather than hard-coded: sizing, zoom steps, and scroll interaction have interchangeable strategies.

• packages/pdfrx/lib/src/widgets/sizing/pdf_viewer_size_delegate.dart

• packages/pdfrx/lib/src/widgets/zoom_steps/pdf_viewer_zoom_steps_delegate.dart

• packages/pdfrx/lib/src/widgets/scroll_interaction/pdf_viewer_scroll_interaction_delegate.dart

Web and Apple Backend Boundaries

Web uses bundled WebAssembly plus JavaScript client/worker assets, separated from native loading code.

• packages/pdfrx/assets/pdfium.wasm

• packages/pdfrx/assets/pdfium_client.js

• packages/pdfrx/lib/src/wasm/pdfrx_wasm.dart

On Apple platforms, an experimental plugin can substitute system PDFKit/CoreGraphics while preserving the pdfrx widget-facing API.

• packages/pdfrx_coregraphics/darwin/pdfrx_coregraphics/Sources/PdfrxCoregraphicsPlugin.swift

• packages/pdfrx_coregraphics/lib/pdfrx_coregraphics.dart

Consumer Applications and Delivery

The primary executable examples are Flutter applications: a full viewer and a PDF-combine/page-rearrangement tool.

• packages/pdfrx/example/viewer/lib/main.dart

• packages/pdfrx/example/pdf_combine/lib/main.dart

CI is GitHub Actions-based, including build/test, static analysis, Pages documentation, and Apple PDFium release automation.

• .github/workflows/build-test.yml

• .github/workflows/pdfium-apple-release.yml