native_pdf_engine

A minimal, high-performance Flutter package for generating PDFs from HTML or URLs using native OS webview capabilities.

This package uses dart:ffi and package:jni to invoke native APIs directly, ensuring:

• Zero bloat: No bundled browser engines (uses pre-installed OS webviews).
• High performance: Direct native calls, low overhead.
• Native fidelity: PDFs look exactly as they would when printing from Safari (iOS/macOS) or Chrome (Android).

Platforms Supported

Platform	Tech Stack	Status	Testing Note
Android	Android WebView	✅	Tested on Real Device
iOS	WKWebView	✅	Tested on Real Device
macOS	WKWebView	✅	Tested on Real Device
Windows	WebView2 (Chromium)	✅	Tested via Integration Tests
Linux	WebKitGTK	✅	Tested via Integration Tests

Note: Windows and Linux support has been verified using automated integration tests. If you encounter any issues on specific distributions or setups, please open an issue with the full error log and sample code.

Features

• Convert HTML String to PDF: Render raw HTML content directly to a PDF file or data.
• Convert URL to PDF: Capture a full webpage and save it as a PDF file or data.
• Background Execution: Most operations run efficiently without blocking the main UI thread (Android uses runOnUiThread for safety).

Installation

Add native_pdf_engine to your pubspec.yaml:

dependencies:
  native_pdf_engine: ^0.0.1

Setup

Android

1. Internet Permission: If you are converting URLs, ensure your android/app/src/main/AndroidManifest.xml includes:

   <uses-permission android:name="android.permission.INTERNET" />
   

2. Cleartext Traffic: If you need to support HTTP URLs (not recommended), allow cleartext traffic in your manifest or network security config.

iOS / macOS

No special setup is usually required. App Sandbox/Hardened Runtime on macOS may require allowing outgoing network connections (com.apple.security.network.client) if fetching URLs.

Usage

import 'package:native_pdf_engine/native_pdf_engine.dart';

void main() async {
  // 1. Convert HTML String
  try {
     await NativePdf.convert(
       '<h1>Hello World</h1><p>This is a native PDF!</p>',
       'output/path/document.pdf',
     );
     print('PDF Generated!');
  } catch (e) {
     print('Error: $e');
  }

  // 2. Convert URL
  try {
     await NativePdf.convertUrl(
       'https://flutter.dev',
       'output/path/flutter_website.pdf',
     );
     print('URL Captured!');
  } catch (e) {
     print('Error: $e');
  }

  // 3. Get PDF Data directly (HTML)
  try {
     final pdfData = await NativePdf.convertToData('<h1>Direct Data</h1>');
     print('Got PDF Data: ${pdfData.length} bytes');
  } catch (e) {
     print('Error: $e');
  }

  // 4. Get PDF Data directly (URL)
  try {
     final pdfData = await NativePdf.convertUrlToData('https://dart.dev');
     print('Got PDF Data: ${pdfData.length} bytes');
  } catch (e) {
     print('Error: $e');
  }
}

How It Works

This package avoids the complexity of flutter_inappwebview or printing when you just need a simple, headless PDF generation:

• Android: It spins up a headless WebView, loads the content, waits for completion (via polling), and draws the view hierarchy onto a android.graphics.pdf.PdfDocument Canvas.
• iOS/macOS: It creates a headless WKWebView, loads the content, and uses the native createPDF configuration API available in WebKit.

License

MIT