Add beforeCapture for View Hierarchy (#2523)

Author: denrase

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## Unreleased
 
+### Features
+
+- Add `beforeCapture` for View Hierarchy ([#2523](https://github.com/getsentry/sentry-dart/pull/2523))
+  - View hierarchy calls are now debounced for 2 seconds.
+  
 ### Enhancements
 
 - Replay: improve performance of screenshot data to native recorder ([#2530](https://github.com/getsentry/sentry-dart/pull/2530))

flutter/lib/src/event_processor/screenshot_event_processor.dart

@@ -29,7 +29,7 @@ class ScreenshotEventProcessor implements EventProcessor {
     _debouncer = Debouncer(
       // ignore: invalid_use_of_internal_member
       _options.clock,
-      waitTimeMs: 2000,
+      waitTime: Duration(milliseconds: 2000),
     );
   }
 
@@ -50,7 +50,7 @@ class ScreenshotEventProcessor implements EventProcessor {
     }
 
     // skip capturing in case of debouncing (=too many frequent capture requests)
-    // the BeforeCaptureCallback may overrules the debouncing decision
+    // the BeforeCaptureCallback may overrule the debouncing decision
     final shouldDebounce = _debouncer.shouldDebounce();
 
     // ignore: deprecated_member_use_from_same_package
@@ -77,7 +77,7 @@ class ScreenshotEventProcessor implements EventProcessor {
       } else if (shouldDebounce) {
         _options.logger(
           SentryLevel.debug,
-          'Skipping screenshot capture due to debouncing (too many captures within ${_debouncer.waitTimeMs}ms)',
+          'Skipping screenshot capture due to debouncing (too many captures within ${_debouncer.waitTime.inMilliseconds}ms)',
         );
         takeScreenshot = false;
       }
@@ -88,7 +88,7 @@ class ScreenshotEventProcessor implements EventProcessor {
     } catch (exception, stackTrace) {
       _options.logger(
         SentryLevel.error,
-        'The beforeCapture/beforeScreenshot callback threw an exception',
+        'The beforeCaptureScreenshot/beforeScreenshot callback threw an exception',
         exception: exception,
         stackTrace: stackTrace,
       );

flutter/lib/src/sentry_flutter_options.dart

@@ -241,11 +241,17 @@ class SentryFlutterOptions extends SentryOptions {
 
   /// Enables the View Hierarchy feature.
   ///
-  /// Renders an ASCII represention of the entire view hierarchy of the
+  /// Renders an ASCII representation of the entire view hierarchy of the
   /// application when an error happens and includes it as an attachment.
   @meta.experimental
   bool attachViewHierarchy = false;
 
+  /// Sets a callback which is executed before capturing view hierarchy. Only
+  /// relevant if `attachViewHierarchy` is set to true. When false is returned
+  /// from the function, no view hierarchy will be attached.
+  @meta.experimental
+  BeforeCaptureCallback? beforeCaptureViewHierarchy;
+
   /// Enables collection of view hierarchy element identifiers.
   ///
   /// Identifiers are extracted from widget keys.

flutter/lib/src/utils/debouncer.dart

@@ -4,18 +4,19 @@ import 'package:sentry/sentry.dart';
 @internal
 class Debouncer {
   final ClockProvider clockProvider;
-  final int waitTimeMs;
+  final Duration waitTime;
   DateTime? _lastExecutionTime;
 
-  Debouncer(this.clockProvider, {this.waitTimeMs = 2000});
+  Debouncer(this.clockProvider,
+      {this.waitTime = const Duration(milliseconds: 2000)});
 
   bool shouldDebounce() {
     final currentTime = clockProvider();
     final lastExecutionTime = _lastExecutionTime;
     _lastExecutionTime = currentTime;
 
     if (lastExecutionTime != null &&
-        currentTime.difference(lastExecutionTime).inMilliseconds < waitTimeMs) {
+        currentTime.difference(lastExecutionTime) < waitTime) {
       return true;
     }
 

flutter/lib/src/view_hierarchy/view_hierarchy_event_processor.dart

@@ -1,16 +1,26 @@
+import 'dart:async';
+
 import '../../sentry_flutter.dart';
+import '../utils/debouncer.dart';
 import 'sentry_tree_walker.dart';
 
 /// A [EventProcessor] that renders an ASCII representation of the entire view
 /// hierarchy of the application when an error happens and includes it as an
 /// attachment to the [Hint].
 class SentryViewHierarchyEventProcessor implements EventProcessor {
-  SentryViewHierarchyEventProcessor(this._options);
-
   final SentryFlutterOptions _options;
+  late final Debouncer _debouncer;
+
+  SentryViewHierarchyEventProcessor(this._options) {
+    _debouncer = Debouncer(
+      // ignore: invalid_use_of_internal_member
+      _options.clock,
+      waitTime: Duration(milliseconds: 2000),
+    );
+  }
 
   @override
-  SentryEvent? apply(SentryEvent event, Hint hint) {
+  Future<SentryEvent?> apply(SentryEvent event, Hint hint) async {
     if (event is SentryTransaction) {
       return event;
     }
@@ -23,15 +33,56 @@ class SentryViewHierarchyEventProcessor implements EventProcessor {
     if (instance == null) {
       return event;
     }
-    final sentryViewHierarchy = walkWidgetTree(instance, _options);
 
+    // skip capturing in case of debouncing (=too many frequent capture requests)
+    // the BeforeCaptureCallback may overrule the debouncing decision
+    final shouldDebounce = _debouncer.shouldDebounce();
+
+    try {
+      final beforeCapture = _options.beforeCaptureViewHierarchy;
+      FutureOr<bool>? result;
+
+      if (beforeCapture != null) {
+        result = beforeCapture(event, hint, shouldDebounce);
+      }
+
+      bool captureViewHierarchy = true;
+
+      if (result != null) {
+        if (result is Future<bool>) {
+          captureViewHierarchy = await result;
+        } else {
+          captureViewHierarchy = result;
+        }
+      } else if (shouldDebounce) {
+        _options.logger(
+          SentryLevel.debug,
+          'Skipping view hierarchy capture due to debouncing (too many captures within ${_debouncer.waitTime.inMilliseconds}ms)',
+        );
+        captureViewHierarchy = false;
+      }
+
+      if (!captureViewHierarchy) {
+        return event;
+      }
+    } catch (exception, stackTrace) {
+      _options.logger(
+        SentryLevel.error,
+        'The beforeCaptureViewHierarchy callback threw an exception',
+        exception: exception,
+        stackTrace: stackTrace,
+      );
+      if (_options.automatedTestMode) {
+        rethrow;
+      }
+    }
+
+    final sentryViewHierarchy = walkWidgetTree(instance, _options);
     if (sentryViewHierarchy == null) {
       return event;
     }
-
-    final viewHierarchy =
+    hint.viewHierarchy =
         SentryAttachment.fromViewHierarchy(sentryViewHierarchy);
-    hint.viewHierarchy = viewHierarchy;
     return event;
   }
 }

flutter/test/utils/debouncer_test.dart

@@ -48,6 +48,6 @@ class Fixture {
   DateTime mockClock() => DateTime.fromMillisecondsSinceEpoch(currentTimeMs);
 
   Debouncer getSut({int waitTimeMs = 3000}) {
-    return Debouncer(mockClock, waitTimeMs: waitTimeMs);
+    return Debouncer(mockClock, waitTime: Duration(milliseconds: waitTimeMs));
   }
 }