fixes PointerEventConverter to handle malformed scrolling event (#118124)

* fixes PointerEventConverter to handle malformed scrolling event

* update

Author: chunhtai

packages/flutter/lib/src/gestures/converter.dart

@@ -52,7 +52,7 @@ class PointerEventConverter {
   static Iterable<PointerEvent> expand(Iterable<ui.PointerData> data, double devicePixelRatio) {
     return data
         .where((ui.PointerData datum) => datum.signalKind != ui.PointerSignalKind.unknown)
-        .map((ui.PointerData datum) {
+        .map<PointerEvent?>((ui.PointerData datum) {
           final Offset position = Offset(datum.physicalX, datum.physicalY) / devicePixelRatio;
           final Offset delta = Offset(datum.physicalDeltaX, datum.physicalDeltaY) / devicePixelRatio;
           final double radiusMinor = _toLogicalPixels(datum.radiusMinor, devicePixelRatio);
@@ -247,6 +247,9 @@ class PointerEventConverter {
                   );
               }
             case ui.PointerSignalKind.scroll:
+              if (!datum.scrollDeltaX.isFinite || !datum.scrollDeltaY.isFinite || devicePixelRatio <= 0) {
+                return null;
+              }
               final Offset scrollDelta =
                   Offset(datum.scrollDeltaX, datum.scrollDeltaY) / devicePixelRatio;
               return PointerScrollEvent(
@@ -280,7 +283,7 @@ class PointerEventConverter {
               // enumeration to PointerSignalKind.
               throw StateError('Unreachable');
           }
-        });
+        }).whereType<PointerEvent>();
   }
 
   static double _toLogicalPixels(double physicalPixels, double devicePixelRatio) => physicalPixels / devicePixelRatio;

packages/flutter/test/gestures/gesture_binding_test.dart

@@ -177,6 +177,47 @@ void main() {
     expect(events[4], isA<PointerHoverEvent>());
   });
 
+  test('Can handle malformed scrolling event.', () {
+    ui.PointerDataPacket packet = const ui.PointerDataPacket(
+      data: <ui.PointerData>[
+        ui.PointerData(change: ui.PointerChange.add, device: 24),
+      ],
+    );
+    List<PointerEvent> events = PointerEventConverter.expand(packet.data, GestureBinding.instance.window.devicePixelRatio).toList();
+
+    expect(events.length, 1);
+    expect(events[0], isA<PointerAddedEvent>());
+
+    // Send packet contains malformed scroll events.
+    packet = const ui.PointerDataPacket(
+      data: <ui.PointerData>[
+        ui.PointerData(signalKind: ui.PointerSignalKind.scroll, device: 24, scrollDeltaX: double.infinity, scrollDeltaY: 10),
+        ui.PointerData(signalKind: ui.PointerSignalKind.scroll, device: 24, scrollDeltaX: double.nan, scrollDeltaY: 10),
+        ui.PointerData(signalKind: ui.PointerSignalKind.scroll, device: 24, scrollDeltaX: double.negativeInfinity, scrollDeltaY: 10),
+        ui.PointerData(signalKind: ui.PointerSignalKind.scroll, device: 24, scrollDeltaY: double.infinity, scrollDeltaX: 10),
+        ui.PointerData(signalKind: ui.PointerSignalKind.scroll, device: 24, scrollDeltaY: double.nan, scrollDeltaX: 10),
+        ui.PointerData(signalKind: ui.PointerSignalKind.scroll, device: 24, scrollDeltaY: double.negativeInfinity, scrollDeltaX: 10),
+      ],
+    );
+    events = PointerEventConverter.expand(packet.data, GestureBinding.instance.window.devicePixelRatio).toList();
+    expect(events.length, 0);
+
+    // Send packet with a valid scroll event.
+    packet = const ui.PointerDataPacket(
+      data: <ui.PointerData>[
+        ui.PointerData(signalKind: ui.PointerSignalKind.scroll, device: 24, scrollDeltaX: 10, scrollDeltaY: 10),
+      ],
+    );
+    // Make sure PointerEventConverter can expand when device pixel ratio is valid.
+    events = PointerEventConverter.expand(packet.data, GestureBinding.instance.window.devicePixelRatio).toList();
+    expect(events.length, 1);
+    expect(events[0], isA<PointerScrollEvent>());
+
+    // Make sure PointerEventConverter returns none when device pixel ratio is invalid.
+    events = PointerEventConverter.expand(packet.data, 0).toList();
+    expect(events.length, 0);
+  });
+
   test('Can expand pointer scroll events', () {
     const ui.PointerDataPacket packet = ui.PointerDataPacket(
         data: <ui.PointerData>[