how to download/create pdf through webview in flutter

Question

I have created a webviewscaffold but can't download anything from it while browsing from the webview, I made but when I click the button it does nothing. I don't know where to start, like in other browsers that can download and preview, I'm trying to achieve the same thing in here.

class AppState extends State<App> {


  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Stack(
        children: <Widget>[
          Align(
            alignment: Alignment(1, 1),
            child: Container(
              child: Web(), // it is a statefulwidget that have WebviewScaffold, i have created it on a new page and imported/used here
            ),
          ),
          Column(
            mainAxisAlignment: MainAxisAlignment.end,
            children: <Widget>[
              Padding(
                padding: EdgeInsets.only(top: 20.0),
              )
            ],
          ),
          Align(
            alignment: Alignment(0.7, -0.93),
            child: FloatingActionButton(
                tooltip: "Share",
                child: Icon(
                  Icons.share,
                  color: Colors.amberAccent,
                ),
                onPressed: () {
                  _onShareTap();
                }),
          ),
        ],
      ),
    );
  }

I expect, when I click the print or download button within the webview it should work like any other browser.

@user10182490 did you find any solution? – demsey Jan 02 '20 at 20:54 — demsey, Jan 02 '20 at 20:54

score 5 · Answer 1 · answered May 31 '20 at 13:00

You can use my plugin flutter_inappwebview, which is a Flutter plugin that allows you to add inline WebViews or open an in-app browser window and has a lot of events, methods, and options to control WebViews.

To be able to recognize downloadable files, you need to set the useOnDownloadStart: true option, and then you can listen the onDownloadStart event!

Also, for example, on Android you need to add write permission inside your AndroidManifest.xml file:

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

Then, you need to ask permission using the permission_handler plugin. Instead, to effectively download your file, you can use the flutter_downloader plugin.

Here is a complete example using http://ovh.net/files/ (in particular, the http://ovh.net/files/1Mio.dat as URL) to test the download:

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter_inappwebview/flutter_inappwebview.dart';
import 'package:flutter_downloader/flutter_downloader.dart';
import 'package:path_provider/path_provider.dart';
import 'package:permission_handler/permission_handler.dart';

Future main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await FlutterDownloader.initialize(
      debug: true // optional: set false to disable printing logs to console
  );
  await Permission.storage.request();
  runApp(new MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => new _MyAppState();
}

class _MyAppState extends State<MyApp> {
  InAppWebViewController webView;

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

  @override
  void dispose() {
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('InAppWebView Example'),
        ),
        body: Container(
            child: Column(children: <Widget>[
          Expanded(
              child: InAppWebView(
            initialUrl: "http://ovh.net/files/1Mio.dat",
            initialHeaders: {},
            initialOptions: InAppWebViewGroupOptions(
              crossPlatform: InAppWebViewOptions(
                debuggingEnabled: true,
                useOnDownloadStart: true
              ),
            ),
            onWebViewCreated: (InAppWebViewController controller) {
              webView = controller;
            },
            onLoadStart: (InAppWebViewController controller, String url) {

            },
            onLoadStop: (InAppWebViewController controller, String url) {

            },
            onDownloadStart: (controller, url) async {
              print("onDownloadStart $url");
              final taskId = await FlutterDownloader.enqueue(
                url: url,
                savedDir: (await getExternalStorageDirectory()).path,
                showNotification: true, // show download progress in status bar (for Android)
                openFileFromNotification: true, // click on notification to open downloaded file (for Android)
              );
            },
          ))
        ])),
      ),
    );
  }
}

Here, as you can see, I'm using also the path_provider plugin to get the folder where I want to save the file.

score 2 · Answer 2 · answered Jan 24 '20 at 15:20

If you are the owner of html page, you can check workaround that works for me. In source of your html page add onclick function for specific resource links:

function downloadpdf() {
      var currentHref = window.location.href;
      window.history.pushState(null, null, '/app/somepdf.pdf');
      setTimeout(() => window.location.replace(currentHref), 1000);
}

In Flutter code add listener:

StreamSubscription<String> _onWebViewUrlChanged;
_onWebViewUrlChanged =
    FlutterWebviewPlugin().onUrlChanged.listen((String url) {
      if (url.contains('.pdf')) {
        launchURL(url);
      }
});

launchURL will open predefined url in external browser window. So you can download pdf/etc from flutter_webview_plugin.

You should add some your app-specific js/flutter magic

how to download/create pdf through webview in flutter

2 Answers2

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