Feat: Screenshots on reports

flutter/example/lib/main.dart

@@ -38,9 +38,11 @@ Future<void> main() async {
     },
     // Init your App.
     appRunner: () => runApp(
-      DefaultAssetBundle(
-        bundle: SentryAssetBundle(enableStructuredDataTracing: true),
-        child: MyApp(),
+      SentryScreenshot(child:
+        DefaultAssetBundle(
+          bundle: SentryAssetBundle(enableStructuredDataTracing: true),
+          child: MyApp(),
+        ),
       ),
     ),
   );

flutter/lib/sentry_flutter.dart

@@ -8,3 +8,4 @@ export 'src/sentry_flutter_options.dart';
 export 'src/flutter_sentry_attachment.dart';
 export 'src/sentry_asset_bundle.dart';
 export 'src/integrations/on_error_integration.dart';
+export 'src/screenshot/sentry_screenshot.dart' hide ScreenshotAttachment;

flutter/lib/src/screenshot/sentry_screenshot.dart

@@ -0,0 +1,118 @@
+import 'dart:async';
+import 'dart:typed_data';
+import 'dart:ui' as ui show ImageByteFormat;
+
+import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
+import 'package:flutter/scheduler.dart';
+import 'package:sentry/sentry.dart';
+
+/// Key which is used to identify the [RepaintBoundary] which gets captured
+final _gloablKey = GlobalKey(debugLabel: 'sentry_screenshot');
+
+/// You can add screenshots of [child] to crash reports by adding this widget.
+/// Ideally you are adding it around your app widget like in the following
+/// example.
+/// ```dart
+/// runApp(SentryScreenshot(child: App()));
+/// ```
+///
+/// Remarks:
+/// - Depending on the place where it's used, you might have a transparent
+///   background.
+/// - Platform Views currently can't be captured.
+/// - It only works on Flutters Canvas Kit Web renderer. For more information
+///   see https://flutter.dev/docs/development/tools/web-renderers
+/// - You can only have one [SentryScreenshot] widget in your widget tree at all
+///   times.
+class SentryScreenshot extends StatefulWidget {
+  const SentryScreenshot({Key? key, required this.child, this.hub})
+      : super(key: key);
+
+  final Widget child;
+  final Hub? hub;
+
+  @override
+  _SentryScreenshotState createState() => _SentryScreenshotState();
+}
+
+class _SentryScreenshotState extends State<SentryScreenshot> {
+  Hub get hub => widget.hub ?? HubAdapter();
+
+  @override
+  Widget build(BuildContext context) {
+    return RepaintBoundary(
+      key: _gloablKey,
+      child: widget.child,
+    );
+  }
+
+  @override
+  void initState() {
+    super.initState();
+    hub.configureScope((scope) {
+      scope.addAttachment(ScreenshotAttachment());
+    });
+  }
+
+  @override
+  void dispose() {
+    hub.configureScope((scope) {
+      // The following doesn't work
+      // scope.attachements.remove(ScreenshotAttachment());
+    });
+    super.dispose();
+  }
+}
+
+class ScreenshotAttachment implements SentryAttachment {
+  ScreenshotAttachment();
+
+  @override
+  String attachmentType = SentryAttachment.typeAttachmentDefault;
+
+  @override
+  String? contentType = 'image/png';
+
+  @override
+  String filename = 'screenshot.png';
+
+  @override
+  bool addToTransactions = true;
+
+  @override
+  FutureOr<Uint8List> get bytes async {
+    //return await createScreenshot() ?? Uint8List.fromList([]);
+    final instance = SchedulerBinding.instance;
+    if (instance == null) {
+      return Uint8List.fromList([]);
+    }
+
+    final _completer = Completer<Uint8List?>();
+    // We add an post frame callback because we aren't able to take a screenshot
+    // if there's currently a draw in process.
+    instance.addPostFrameCallback((timeStamp) async {
+      final image = await createScreenshot();
+      _completer.complete(image);
+    });
+    return await _completer.future ?? Uint8List.fromList([]);
+  }
+
+  @visibleForTesting
+  Future<Uint8List?> createScreenshot() async {
+    try {
+      final renderObject = _gloablKey.currentContext?.findRenderObject();
+
+      if (renderObject is RenderRepaintBoundary) {
+        final image = await renderObject.toImage(pixelRatio: 1);
+        // At the time of writing there's no other image format available which
+        // Sentry understands.
+        final bytes = await image.toByteData(format: ui.ImageByteFormat.png);
+        return bytes?.buffer.asUint8List();
+      }
+    } catch (_) {}
+    return null;
+  }
+
+
+}

flutter/test/screenshot/screenshot_test.dart

@@ -0,0 +1,37 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:sentry_flutter/sentry_flutter.dart';
+import 'package:sentry_flutter/src/screenshot/sentry_screenshot.dart';
+
+void main() {
+  setUp(() {
+    TestWidgetsFlutterBinding.ensureInitialized();
+  });
+
+  test('ScreenshotAttachment default values', () {
+    final attachment = ScreenshotAttachment();
+    expect(attachment.attachmentType, SentryAttachment.typeAttachmentDefault);
+    expect(attachment.contentType, 'image/png');
+    expect(attachment.filename, 'screenshot.png');
+  });
+
+  testWidgets('creates screenshot', (tester) async {
+    await tester.runAsync(() async {
+      final widget = SentryScreenshot(
+        child: MaterialApp(
+          home: Scaffold(
+            body: Center(
+              child: Text('Hello World'),
+            ),
+          ),
+        ),
+      );
+
+      await tester.pumpWidget(widget);
+
+      final screenshot = await ScreenshotAttachment().createScreenshot();
+
+      expect(screenshot, isNotNull);
+    });
+  });
+}