Bound message snapshot raster size

Co-authored-by: Princess Donut <b238ea756dee4d98afa5883fc7f1de61eeabe65bf700e3a5a5a80db5e42e2c2b@buzz.block.builderlab.xyz>
Signed-off-by: Princess Donut <b238ea756dee4d98afa5883fc7f1de61eeabe65bf700e3a5a5a80db5e42e2c2b@buzz.block.builderlab.xyz>

mobile/lib/features/channels/message_long_press_region.dart

@@ -8,6 +8,13 @@ import 'package:flutter/rendering.dart';
 import 'package:flutter_hooks/flutter_hooks.dart';
 
 const _iosMessageLongPressDuration = Duration(milliseconds: 200);
+const _maxMessageSnapshotDimension = 2048.0;
+
+double _messageSnapshotPixelRatio(Size size, double devicePixelRatio) {
+  final longestSide = size.longestSide;
+  if (!longestSide.isFinite || longestSide <= 0) return devicePixelRatio;
+  return math.min(devicePixelRatio, _maxMessageSnapshotDimension / longestSide);
+}
 
 /// Geometry and snapshot controls for a completed message long press.
 class MessageLongPressDetails {
@@ -99,7 +106,7 @@ class _MessageLongPressRegion extends HookWidget {
         onLongPress?.call(anchorRect);
         return;
       }
-      final snapshotPixelRatio = math.min(
+      final maxSnapshotPixelRatio = math.min(
         MediaQuery.devicePixelRatioOf(context),
         2.0,
       );
@@ -113,6 +120,10 @@ class _MessageLongPressRegion extends HookWidget {
         if (boundary == null) {
           throw StateError('Message snapshot is unavailable');
         }
+        final snapshotPixelRatio = _messageSnapshotPixelRatio(
+          boundary.size,
+          maxSnapshotPixelRatio,
+        );
         try {
           return await boundary.toImage(pixelRatio: snapshotPixelRatio);
         } catch (_) {
@@ -123,10 +134,17 @@ class _MessageLongPressRegion extends HookWidget {
             rethrow;
           }
           try {
-            return await retryBoundary.toImage(pixelRatio: snapshotPixelRatio);
+            return await retryBoundary.toImage(
+              pixelRatio: _messageSnapshotPixelRatio(
+                retryBoundary.size,
+                maxSnapshotPixelRatio,
+              ),
+            );
           } catch (_) {
             if (snapshotPixelRatio <= 1) rethrow;
-            return retryBoundary.toImage(pixelRatio: 1);
+            return retryBoundary.toImage(
+              pixelRatio: _messageSnapshotPixelRatio(retryBoundary.size, 1),
+            );
           }
         }
       }

mobile/test/features/channels/message_actions_test.dart

@@ -441,6 +441,44 @@ void main() {
     },
   );
 
+  testWidgets('message snapshot bounds very tall raster dimensions', (
+    tester,
+  ) async {
+    tester.view.devicePixelRatio = 1;
+    tester.view.physicalSize = const Size(800, 5000);
+    addTearDown(tester.view.resetDevicePixelRatio);
+    addTearDown(tester.view.resetPhysicalSize);
+    MessageLongPressDetails? longPressDetails;
+    ui.Image? snapshot;
+    addTearDown(() => snapshot?.dispose());
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Scaffold(
+          body: Material(
+            child: MessageLongPressInkWell(
+              key: const ValueKey('tall-snapshot-gesture-target'),
+              onLongPressDetails: (details) => longPressDetails = details,
+              child: const SizedBox(width: 240, height: 4096),
+            ),
+          ),
+        ),
+      ),
+    );
+
+    await tester.longPress(
+      find.byKey(const ValueKey('tall-snapshot-gesture-target')),
+    );
+    expect(longPressDetails, isNotNull);
+
+    final capture = longPressDetails!.captureSnapshot();
+    await tester.pump();
+    snapshot = await capture;
+
+    expect(snapshot.width, 120);
+    expect(snapshot.height, 2048);
+  });
+
   testWidgets('message snapshot can exclude attached reaction content', (
     tester,
   ) async {