devtools/web/main.dart

// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'dart:async';
import 'dart:html';

import 'package:devtools/src/framework/framework_core.dart';
import 'package:devtools/src/main.dart';
import 'package:devtools/src/ui/analytics.dart' as ga;
import 'package:devtools/src/ui/analytics_platform.dart' as ga_platform;
import 'package:platform_detect/platform_detect.dart';

void main() {
  // Run in a zone in order to catch all Dart exceptions.
  runZoned(
    () {
      // Initialize the core framework.
      FrameworkCore.init();

      // Load the web app framework.
      final PerfToolFramework framework = PerfToolFramework();

      // Show the opt-in dialog for collection analytics?
      try {
        if (ga.isGtagsEnabled() &
            (!window.localStorage.containsKey(ga_platform.devToolsProperty()) ||
                window.localStorage[ga_platform.devToolsProperty()].isEmpty)) {
          framework.showAnalyticsDialog();
        }
      } catch (e) {
        // If there are errors setting up analytics, write them to the console
        // but do not prevent DevTools from loading.
        window.console.error(e);
      }

      if (!browser.isChrome) {
        final browserName =
            // Edge shows up as IE, so we replace it's name to avoid confusion.
            browser.isInternetExplorer || browser == Browser.UnknownBrowser
                ? 'an unsupported browser'
                : browser.name;
        framework.disableAppWithError(
          'ERROR: You are running DevTools on $browserName, '
              'but DevTools only runs on Chrome.',
          'Reopen this url in a Chrome browser to use DevTools.',
        );
        return;
      }

      FrameworkCore.initVmService(errorReporter: (String title, dynamic error) {
        framework.showError(title, error);
      }).then((bool connected) {
        if (!connected) {
          framework.showConnectionDialog();
          framework.showSnapshotMessage();
          // Clear the main element so it stops displaying "Loading..."
          // TODO(jacobr): display a message explaining how to launch a Flutter
          // application from the command line and connect to it with DevTools.
          framework.mainElement.clear();
        }
      });

      framework.loadScreenFromLocation();
    },
    zoneSpecification: const ZoneSpecification(
      handleUncaughtError: _handleUncaughtError,
    ),
  );
}

void _handleUncaughtError(
  Zone self,
  ZoneDelegate parent,
  Zone zone,
  Object error,
  StackTrace stackTrace,
) {
  // TODO(devoncarew): `stackTrace` always seems to be null.

  // Report exceptions with DevTools to GA; user's Flutter app exceptions are
  // not collected.
  ga.error('$error\n${stackTrace ?? ''}'.trim(), true);

  final Console console = window.console;

  // Also write them to the console to aid debugging.
  final errorLines = error.toString().split('\n');
  console.groupCollapsed(
      'DevTools exception: [${error.runtimeType}] ${errorLines.first}');
  console.log(errorLines.skip(1).join('\n'));

  if (stackTrace != null) {
    if (errorLines.length > 1) {
      console.log('\n');
    }
    console.log(stackTrace.toString().trim());
  }

  console.groupEnd();
}