Flutter auto resize webview based on its content

auto_resize_webview.dart

import 'dart:convert';

import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Code Sample',
      builder: (BuildContext context, Widget navigator) {
        return MyStatelessWidget();
      },
    );
  }
}

class MyStatelessWidget extends StatefulWidget {
  MyStatelessWidget({Key key}) : super(key: key);

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

class _MyStatelessWidgetState extends State<MyStatelessWidget> {
  List<WebViewController> _listController = List();

  List<double> _heights =
      List<double>.generate(htmlStrings.length, (int index) => 20.0);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: ListView.builder(
        shrinkWrap: true,
        itemCount: htmlStrings.length,
        itemBuilder: (context, index) {
          return Container(
            height: _heights[index] ?? 100.0,
            child: WebView(
              initialUrl:
                  'data:text/html;base64,${base64Encode(const Utf8Encoder().convert(htmlStrings[index]))}',
              onPageFinished: (some) async {
                double height = double.parse(await _listController[index]
                    .evaluateJavascript(
                        "document.documentElement.scrollHeight;"));
                setState(() {
                  _heights[index] = height;
                });
              },
              javascriptMode: JavascriptMode.unrestricted,
              onWebViewCreated: (controller) async {
                _listController.add(controller);
              },
            ),
          );
        },
      ),
    );
  }
}

final List<String> htmlStrings = [
  '''<p>Table shows some compounds and the name of their manufacturing process</p>
<table style="border-collapse: collapse; width: 100%; height: 85px;" border="1">
<tbody>
<tr style="height: 17px;">
<td style="width: 50%; text-align: center; height: 17px;">Compounds/Elements</td>
<td style="width: 50%; text-align: center; height: 17px;">Manufacture process</td>
</tr>
<tr style="height: 17px;">
<td style="width: 50%; height: 17px;">Nitric acid</td>
<td style="width: 50%; height: 17px;">Ostwald's process</td>
</tr>
<tr style="height: 17px;">
<td style="width: 50%; height: 17px;">Ammonia</td>
<td style="width: 50%; height: 17px;">Haber's process</td>
</tr>
<tr style="height: 17px;">
<td style="width: 50%; height: 17px;">Sulphuric acid</td>
<td style="width: 50%; height: 17px;">Contact process</td>
</tr>
<tr style="height: 17px;">
<td style="width: 50%; height: 17px;">Sodium</td>
<td style="width: 50%; height: 17px;">Down's process</td>
</tr>
</tbody>
</table>''',
  '''<p>\(L=[M{L }^{2 }{T }^{-2 }{A }^{-2 }]\)</p>
<p>\(C=[{M }^{-1 }{L }^{-2 }{T }^{4 }{A }^{2 }]\)</p>
<p>\(R=[M{L }^{2 }{T }^{-3 }{A }^{-2 }]\)</p>
<p>\(\therefore \frac {R}{L}=\frac{[M{L }^{2 }{T }^{-2 }{A }^{-2 }]}{[M{L }^{2 }{T }^{-3 }{A }^{-2 }]}=[T]\)</p>''',
  '''<p>Displacement(s)\(=\left(13.8\pm0.2\right)m\)</p>
<p>Time(t)\(=\left(4.0\pm0.3\right)s\)</p>
<p>Velocity(v)\(=\frac{13.8}{4.0}=3.45m{s}^{-1}\)</p>
<p>\(\frac{\delta v}{v}=\pm\left(\frac{\delta s}{s}+\frac{\delta t}{t}\right)=\pm\left(\frac{0.2}{13.8}+\frac{0.3}{4.0}\right)=\pm0.0895\)</p>
<p>\(\delta v =\pm0.0895*3.45=\pm0.3\)(rounding off to one place of decimal)</p>
<p>\(v=\left(3.45\pm0.3\right)m{s}^{-1}\)</p>''',
  '''<p>The only real numbers satisfying \(x^2=4\) are 2 and -2. But none of them satisfy the final condition, \(x+2=3\). So, there is no real number such that these conditions are met. Hence this is null set.</p>
<p>Note that, for \(x\) to be a memner of \(\{x:p(x),q(x)\}\),&nbsp;<em><strong>both</strong></em> \(p(x)\) and \(q(x)\) should be true.</p>''',
];