Add debounce to ScreenshotWidget

Author: denrase

flutter/lib/src/event_processor/screenshot_event_processor.dart

@@ -19,6 +19,14 @@ class ScreenshotEventProcessor implements EventProcessor {
   bool get _hasSentryScreenshotWidget =>
       sentryScreenshotWidgetGlobalKey.currentContext != null;
 
+  final _debounceDuration = Duration(milliseconds: 100);
+
+  /// Only apply this event processor every [debounceDuration] duration.
+  DateTime? _lastApplyCall;
+
+  /// The debounce duration for applying this event processor.
+  Duration get debounceDuration => _debounceDuration;
+
   @override
   Future<SentryEvent?> apply(SentryEvent event, Hint hint) async {
     if (event is SentryTransaction) {
@@ -30,6 +38,19 @@ class ScreenshotEventProcessor implements EventProcessor {
         _hasSentryScreenshotWidget) {
       return event;
     }
+
+    final now = DateTime.now();
+    final difference = _lastApplyCall?.difference(DateTime.now()).abs();
+    _lastApplyCall = now;
+
+    if (difference != null && difference < debounceDuration) {
+      _options.logger(
+        SentryLevel.warning,
+        'Skipping screenshot due to too many calls within a short time frame.',
+      );
+      return event; // Debounce
+    }
+
     final beforeScreenshot = _options.beforeScreenshot;
     if (beforeScreenshot != null) {
       try {

flutter/lib/src/integrations/screenshot_integration.dart

@@ -1,6 +1,7 @@
 import 'package:sentry/sentry.dart';
 import '../event_processor/screenshot_event_processor.dart';
 import '../sentry_flutter_options.dart';
+import '../utils/debouncer.dart';
 
 /// Adds [ScreenshotEventProcessor] to options event processors if
 /// [SentryFlutterOptions.attachScreenshot] is true

flutter/test/event_processor/screenshot_event_processor_test.dart

@@ -178,6 +178,60 @@ void main() {
       expect(beforeScreenshotHint, hint);
     });
   });
+
+  group("debounce", () {
+    testWidgets("limits added screenshots within debounce timeframe",
+        (tester) async {
+      // Run with real async https://stackoverflow.com/a/54021863
+      await tester.runAsync(() async {
+        final sut = fixture.getSut(FlutterRenderer.canvasKit, false);
+
+        await tester.pumpWidget(SentryScreenshotWidget(
+            child: Text('Catching Pokémon is a snap!',
+                textDirection: TextDirection.ltr)));
+
+        final throwable = Exception();
+
+        final firstEvent = SentryEvent(throwable: throwable);
+        final firstHint = Hint();
+
+        final secondEvent = SentryEvent(throwable: throwable);
+        final secondHint = Hint();
+
+        await sut.apply(firstEvent, firstHint);
+        await sut.apply(secondEvent, secondHint);
+
+        expect(firstHint.screenshot, isNotNull);
+        expect(secondHint.screenshot, isNull);
+      });
+    });
+
+    testWidgets("adds screenshots after debounce timeframe", (tester) async {
+      // Run with real async https://stackoverflow.com/a/54021863
+      await tester.runAsync(() async {
+        final sut = fixture.getSut(FlutterRenderer.canvasKit, false);
+
+        await tester.pumpWidget(SentryScreenshotWidget(
+            child: Text('Catching Pokémon is a snap!',
+                textDirection: TextDirection.ltr)));
+
+        final throwable = Exception();
+
+        final firstEvent = SentryEvent(throwable: throwable);
+        final firstHint = Hint();
+
+        final secondEvent = SentryEvent(throwable: throwable);
+        final secondHint = Hint();
+
+        await sut.apply(firstEvent, firstHint);
+        await Future<void>.delayed(sut.debounceDuration);
+        await sut.apply(secondEvent, secondHint);
+
+        expect(firstHint.screenshot, isNotNull);
+        expect(secondHint.screenshot, isNotNull);
+      });
+    });
+  });
 }
 
 class Fixture {