Integrate WebViewer into a Flutter App to Enable Cross-Platform Document Viewing

This sample demonstrates document viewing and targets Android and iOS mobile devices.

Apryse's WebViewer is integrated into a Flutter web project using Dart programming language to create the viewer. For more information, see this guide.

WebViewer provides a slick out-of-the-box responsive UI that enables you to view, annotate and manipulate PDFs and other document types inside any web project.

Click the button below to view the full project in GitHub.

Dart

main.dart

import 'package:flutter/material.dart';

import 'dart:ui_web' as ui;
import 'dart:html' as html;

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Apryse Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
        // This makes the visual density adapt to the platform that you run
        // the app on. For desktop platforms, the controls will be smaller and
        // closer together (more dense) than on mobile platforms.
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Apryse WebViewer for Flutter'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({wkey,required this.title}) : super(key: wkey);

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

String viewID = "webviewer-id"; 

class _MyHomePageState extends State<MyHomePage> {

  @override
  void initState() {
    super.initState();

    html.DivElement _element = html.DivElement();
    _element
      ..id = 'canvas'
      ..style.height = '100%'
      ..style.width = '100%'
      ..append(html.ScriptElement()
        ..text = """
        // Defines a ShadowRoot within DOM, and is set to 'Open'
        // Reference: https://developer.mozilla.org/en-US/docs/Web/API/ShadowRoot
        const shadowHost = document.querySelector("flt-platform-view").querySelector("#canvas");
        const shadowRoot = shadowHost.attachShadow({ mode: 'open' });

        WebViewer({
          path: 'WebViewer/lib',
          initialDoc: 'https://pdftron.s3.amazonaws.com/downloads/pl/demo.pdf'
        }, shadowRoot).then((instance) => {
            // call apis here
        });
        """);

    // ignore: undefined_prefixed_name
    ui.platformViewRegistry
        .registerViewFactory(viewID, (int viewId) => _element);
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
      body: FractionallySizedBox(
        widthFactor: 1,
        heightFactor: 1,
        child: Container(
          alignment: Alignment.center, 
          child: HtmlElementView(
            viewType: viewID,
          ),
        ),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

View the full sample on GitHub