Support trackpad gestures in framework (#89944)

* Implement trackpad gestures in framework

* Touch and Pan/Zoom pointers have separate IDs now

* Handle trackpad pointer device type

* Respect supportedDevices for pan/zoom events

* Update after rebase

* Fix check failures

* Avoid error with very short drags

* Address feedback

* Refactor drag event handler

* Address more feedback

* Add some missing punctuation

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

@@ -346,11 +346,11 @@ mixin GestureBinding on BindingBase implements HitTestable, HitTestDispatcher, H
 
   void _handlePointerEventImmediately(PointerEvent event) {
     HitTestResult? hitTestResult;
-    if (event is PointerDownEvent || event is PointerSignalEvent || event is PointerHoverEvent) {
+    if (event is PointerDownEvent || event is PointerSignalEvent || event is PointerHoverEvent || event is PointerPanZoomStartEvent) {
       assert(!_hitTests.containsKey(event.pointer));
       hitTestResult = HitTestResult();
       hitTest(hitTestResult, event.position);
-      if (event is PointerDownEvent) {
+      if (event is PointerDownEvent || event is PointerPanZoomStartEvent) {
         _hitTests[event.pointer] = hitTestResult;
       }
       assert(() {
@@ -358,9 +358,9 @@ mixin GestureBinding on BindingBase implements HitTestable, HitTestDispatcher, H
           debugPrint('$event: $hitTestResult');
         return true;
       }());
-    } else if (event is PointerUpEvent || event is PointerCancelEvent) {
+    } else if (event is PointerUpEvent || event is PointerCancelEvent || event is PointerPanZoomEndEvent) {
       hitTestResult = _hitTests.remove(event.pointer);
-    } else if (event.down) {
+    } else if (event.down || event is PointerPanZoomUpdateEvent) {
       // Because events that occur with the pointer down (like
       // [PointerMoveEvent]s) should be dispatched to the same place that their
       // initial PointerDownEvent was, we want to re-use the path we found when
@@ -443,9 +443,9 @@ mixin GestureBinding on BindingBase implements HitTestable, HitTestDispatcher, H
   @override // from HitTestTarget
   void handleEvent(PointerEvent event, HitTestEntry entry) {
     pointerRouter.route(event);
-    if (event is PointerDownEvent) {
+    if (event is PointerDownEvent || event is PointerPanZoomStartEvent) {
       gestureArena.close(event.pointer);
-    } else if (event is PointerUpEvent) {
+    } else if (event is PointerUpEvent || event is PointerPanZoomEndEvent) {
       gestureArena.sweep(event.pointer);
     } else if (event is PointerSignalEvent) {
       pointerSignalResolver.resolve(event);

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

@@ -15,14 +15,13 @@ import 'events.dart';
 int _synthesiseDownButtons(int buttons, PointerDeviceKind kind) {
   switch (kind) {
     case PointerDeviceKind.mouse:
+    case PointerDeviceKind.trackpad:
       return buttons;
     case PointerDeviceKind.touch:
     case PointerDeviceKind.stylus:
     case PointerDeviceKind.invertedStylus:
       return buttons == 0 ? kPrimaryButton : buttons;
     case PointerDeviceKind.unknown:
-    default: // ignore: no_default_cases, to allow adding new device types to [PointerDeviceKind]
-             // TODO(moffatman): Remove after landing https://github.com/flutter/flutter/issues/23604
       // We have no information about the device but we know we never want
       // buttons to be 0 when the pointer is down.
       return buttons == 0 ? kPrimaryButton : buttons;
@@ -209,9 +208,44 @@ class PointerEventConverter {
                     radiusMax: radiusMax,
                     embedderId: datum.embedderId,
                   );
-                default: // ignore: no_default_cases, to allow adding new pointer events to [ui.PointerChange]
-                         // TODO(moffatman): Remove after landing https://github.com/flutter/flutter/issues/23604
-                  throw StateError('Unreachable');
+                case ui.PointerChange.panZoomStart:
+                  return PointerPanZoomStartEvent(
+                    timeStamp: timeStamp,
+                    pointer: datum.pointerIdentifier,
+                    kind: kind,
+                    device: datum.device,
+                    position: position,
+                    embedderId: datum.embedderId,
+                    synthesized: datum.synthesized,
+                  );
+                case ui.PointerChange.panZoomUpdate:
+                  final Offset pan =
+                      Offset(datum.panX, datum.panY) / devicePixelRatio;
+                  final Offset panDelta =
+                      Offset(datum.panDeltaX, datum.panDeltaY) / devicePixelRatio;
+                  return PointerPanZoomUpdateEvent(
+                    timeStamp: timeStamp,
+                    pointer: datum.pointerIdentifier,
+                    kind: kind,
+                    device: datum.device,
+                    position: position,
+                    pan: pan,
+                    panDelta: panDelta,
+                    scale: datum.scale,
+                    rotation: datum.rotation,
+                    embedderId: datum.embedderId,
+                    synthesized: datum.synthesized,
+                  );
+                case ui.PointerChange.panZoomEnd:
+                  return PointerPanZoomEndEvent(
+                    timeStamp: timeStamp,
+                    pointer: datum.pointerIdentifier,
+                    kind: kind,
+                    device: datum.device,
+                    position: position,
+                    embedderId: datum.embedderId,
+                    synthesized: datum.synthesized,
+                  );
               }
             case ui.PointerSignalKind.scroll:
               final Offset scrollDelta =

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

@@ -1986,6 +1986,354 @@ class _TransformedPointerScrollEvent extends _TransformedPointerEvent with _Copy
   }
 }
 
+mixin _CopyPointerPanZoomStartEvent on PointerEvent {
+  @override
+  PointerPanZoomStartEvent copyWith({
+    Duration? timeStamp,
+    int? pointer,
+    PointerDeviceKind? kind,
+    int? device,
+    Offset? position,
+    Offset? delta,
+    int? buttons,
+    bool? obscured,
+    double? pressure,
+    double? pressureMin,
+    double? pressureMax,
+    double? distance,
+    double? distanceMax,
+    double? size,
+    double? radiusMajor,
+    double? radiusMinor,
+    double? radiusMin,
+    double? radiusMax,
+    double? orientation,
+    double? tilt,
+    bool? synthesized,
+    int? embedderId,
+  }) {
+    return PointerPanZoomStartEvent(
+      timeStamp: timeStamp ?? this.timeStamp,
+      kind: kind ?? this.kind,
+      device: device ?? this.device,
+      position: position ?? this.position,
+      embedderId: embedderId ?? this.embedderId,
+    ).transformed(transform);
+  }
+}
+
+/// A pan/zoom has begun on this pointer.
+///
+/// See also:
+///
+///  * [Listener.onPointerPanZoomStart], which allows callers to be notified of these
+///    events in a widget tree.
+class PointerPanZoomStartEvent extends PointerEvent with _PointerEventDescription, _CopyPointerPanZoomStartEvent {
+  /// Creates a pointer pan/zoom start event.
+  ///
+  /// All of the arguments must be non-null.
+  const PointerPanZoomStartEvent({
+    Duration timeStamp = Duration.zero,
+    PointerDeviceKind kind = PointerDeviceKind.mouse,
+    int device = 0,
+    int pointer = 0,
+    Offset position = Offset.zero,
+    int embedderId = 0,
+    bool synthesized = false,
+  }) : assert(timeStamp != null),
+       assert(kind != null),
+       assert(device != null),
+       assert(pointer != null),
+       assert(position != null),
+       assert(embedderId != null),
+       assert(synthesized != null),
+       super(
+         timeStamp: timeStamp,
+         kind: kind,
+         device: device,
+         pointer: pointer,
+         position: position,
+         embedderId: embedderId,
+         synthesized: synthesized,
+       );
+
+  @override
+  PointerPanZoomStartEvent transformed(Matrix4? transform) {
+    if (transform == null || transform == this.transform) {
+      return this;
+    }
+    return _TransformedPointerPanZoomStartEvent(original as PointerPanZoomStartEvent? ?? this, transform);
+  }
+}
+
+class _TransformedPointerPanZoomStartEvent extends _TransformedPointerEvent with _CopyPointerPanZoomStartEvent implements PointerPanZoomStartEvent {
+  _TransformedPointerPanZoomStartEvent(this.original, this.transform)
+    : assert(original != null), assert(transform != null);
+
+  @override
+  final PointerPanZoomStartEvent original;
+
+  @override
+  final Matrix4 transform;
+
+  @override
+  PointerPanZoomStartEvent transformed(Matrix4? transform) => original.transformed(transform);
+}
+
+mixin _CopyPointerPanZoomUpdateEvent on PointerEvent {
+  /// The total pan offset of the pan/zoom.
+  Offset get pan;
+  /// The total pan offset of the pan/zoom, transformed into local coordinates.
+  Offset get localPan;
+  /// The amount the pan offset changed since the last event.
+  Offset get panDelta;
+  /// The amount the pan offset changed since the last event, transformed into local coordinates.
+  Offset get localPanDelta;
+  /// The scale (zoom factor) of the pan/zoom.
+  double get scale;
+  /// The amount the pan/zoom has rotated in radians so far.
+  double get rotation;
+
+  @override
+  PointerPanZoomUpdateEvent copyWith({
+    Duration? timeStamp,
+    int? pointer,
+    PointerDeviceKind? kind,
+    int? device,
+    Offset? position,
+    Offset? delta,
+    int? buttons,
+    bool? obscured,
+    double? pressure,
+    double? pressureMin,
+    double? pressureMax,
+    double? distance,
+    double? distanceMax,
+    double? size,
+    double? radiusMajor,
+    double? radiusMinor,
+    double? radiusMin,
+    double? radiusMax,
+    double? orientation,
+    double? tilt,
+    bool? synthesized,
+    int? embedderId,
+    Offset? pan,
+    Offset? localPan,
+    Offset? panDelta,
+    Offset? localPanDelta,
+    double? scale,
+    double? rotation,
+  }) {
+    return PointerPanZoomUpdateEvent(
+      timeStamp: timeStamp ?? this.timeStamp,
+      kind: kind ?? this.kind,
+      device: device ?? this.device,
+      position: position ?? this.position,
+      embedderId: embedderId ?? this.embedderId,
+      pan: pan ?? this.pan,
+      panDelta: panDelta ?? this.panDelta,
+      scale: scale ?? this.scale,
+      rotation: rotation ?? this.rotation,
+    ).transformed(transform);
+  }
+}
+
+/// The active pan/zoom on this pointer has updated.
+///
+/// See also:
+///
+///  * [Listener.onPointerPanZoomUpdate], which allows callers to be notified of these
+///    events in a widget tree.
+class PointerPanZoomUpdateEvent extends PointerEvent with _PointerEventDescription, _CopyPointerPanZoomUpdateEvent {
+  /// Creates a pointer pan/zoom update event.
+  ///
+  /// All of the arguments must be non-null.
+  const PointerPanZoomUpdateEvent({
+    Duration timeStamp = Duration.zero,
+    PointerDeviceKind kind = PointerDeviceKind.mouse,
+    int device = 0,
+    int pointer = 0,
+    Offset position = Offset.zero,
+    int embedderId = 0,
+    this.pan = Offset.zero,
+    this.panDelta = Offset.zero,
+    this.scale = 1.0,
+    this.rotation = 0.0,
+    bool synthesized = false,
+  }) : assert(timeStamp != null),
+       assert(kind != null),
+       assert(device != null),
+       assert(pointer != null),
+       assert(position != null),
+       assert(embedderId != null),
+       assert(pan != null),
+       assert(panDelta != null),
+       assert(scale != null),
+       assert(rotation != null),
+       assert(synthesized != null),
+       super(
+         timeStamp: timeStamp,
+         kind: kind,
+         device: device,
+         pointer: pointer,
+         position: position,
+         embedderId: embedderId,
+         synthesized: synthesized,
+       );
+  @override
+  final Offset pan;
+  @override
+  Offset get localPan => pan;
+  @override
+  final Offset panDelta;
+  @override
+  Offset get localPanDelta => panDelta;
+  @override
+  final double scale;
+  @override
+  final double rotation;
+
+  @override
+  PointerPanZoomUpdateEvent transformed(Matrix4? transform) {
+    if (transform == null || transform == this.transform) {
+      return this;
+    }
+    return _TransformedPointerPanZoomUpdateEvent(original as PointerPanZoomUpdateEvent? ?? this, transform);
+  }
+}
+
+class _TransformedPointerPanZoomUpdateEvent extends _TransformedPointerEvent with _CopyPointerPanZoomUpdateEvent implements PointerPanZoomUpdateEvent {
+  _TransformedPointerPanZoomUpdateEvent(this.original, this.transform)
+    : assert(original != null), assert(transform != null);
+
+  @override
+  Offset get pan => original.pan;
+
+  @override
+  late final Offset localPan = PointerEvent.transformPosition(transform, pan);
+
+  @override
+  Offset get panDelta => original.panDelta;
+
+  @override
+  late final Offset localPanDelta = PointerEvent.transformDeltaViaPositions(
+    transform: transform,
+    untransformedDelta: panDelta,
+    untransformedEndPosition: pan,
+    transformedEndPosition: localPan,
+  );
+
+  @override
+  double get scale => original.scale;
+
+  @override
+  double get rotation => original.rotation;
+
+  @override
+  final PointerPanZoomUpdateEvent original;
+
+  @override
+  final Matrix4 transform;
+
+  @override
+  PointerPanZoomUpdateEvent transformed(Matrix4? transform) => original.transformed(transform);
+}
+
+mixin _CopyPointerPanZoomEndEvent on PointerEvent {
+  @override
+  PointerPanZoomEndEvent copyWith({
+    Duration? timeStamp,
+    int? pointer,
+    PointerDeviceKind? kind,
+    int? device,
+    Offset? position,
+    Offset? delta,
+    int? buttons,
+    bool? obscured,
+    double? pressure,
+    double? pressureMin,
+    double? pressureMax,
+    double? distance,
+    double? distanceMax,
+    double? size,
+    double? radiusMajor,
+    double? radiusMinor,
+    double? radiusMin,
+    double? radiusMax,
+    double? orientation,
+    double? tilt,
+    bool? synthesized,
+    int? embedderId,
+  }) {
+    return PointerPanZoomEndEvent(
+      timeStamp: timeStamp ?? this.timeStamp,
+      kind: kind ?? this.kind,
+      device: device ?? this.device,
+      position: position ?? this.position,
+      embedderId: embedderId ?? this.embedderId,
+    ).transformed(transform);
+  }
+}
+
+/// The pan/zoom on this pointer has ended.
+///
+/// See also:
+///
+///  * [Listener.onPointerPanZoomEnd], which allows callers to be notified of these
+///    events in a widget tree.
+class PointerPanZoomEndEvent extends PointerEvent with _PointerEventDescription, _CopyPointerPanZoomEndEvent {
+  /// Creates a pointer pan/zoom end event.
+  ///
+  /// All of the arguments must be non-null.
+  const PointerPanZoomEndEvent({
+    Duration timeStamp = Duration.zero,
+    PointerDeviceKind kind = PointerDeviceKind.mouse,
+    int device = 0,
+    int pointer = 0,
+    Offset position = Offset.zero,
+    int embedderId = 0,
+    bool synthesized = false,
+  }) : assert(timeStamp != null),
+       assert(kind != null),
+       assert(device != null),
+       assert(pointer != null),
+       assert(position != null),
+       assert(embedderId != null),
+       assert(synthesized != null),
+       super(
+         timeStamp: timeStamp,
+         kind: kind,
+         device: device,
+         pointer: pointer,
+         position: position,
+         embedderId: embedderId,
+         synthesized: synthesized,
+       );
+
+  @override
+  PointerPanZoomEndEvent transformed(Matrix4? transform) {
+    if (transform == null || transform == this.transform) {
+      return this;
+    }
+    return _TransformedPointerPanZoomEndEvent(original as PointerPanZoomEndEvent? ?? this, transform);
+  }
+}
+
+class _TransformedPointerPanZoomEndEvent extends _TransformedPointerEvent with _CopyPointerPanZoomEndEvent implements PointerPanZoomEndEvent {
+  _TransformedPointerPanZoomEndEvent(this.original, this.transform)
+    : assert(original != null), assert(transform != null);
+
+  @override
+  final PointerPanZoomEndEvent original;
+
+  @override
+  final Matrix4 transform;
+
+  @override
+  PointerPanZoomEndEvent transformed(Matrix4? transform) => original.transformed(transform);
+}
+
 mixin _CopyPointerCancelEvent on PointerEvent {
   @override
   PointerCancelEvent copyWith({
@@ -2108,8 +2456,7 @@ double computeHitSlop(PointerDeviceKind kind, DeviceGestureSettings? settings) {
     case PointerDeviceKind.invertedStylus:
     case PointerDeviceKind.unknown:
     case PointerDeviceKind.touch:
-    default: // ignore: no_default_cases, to allow adding new device types to [PointerDeviceKind]
-             // TODO(moffatman): Remove after landing https://github.com/flutter/flutter/issues/23604
+    case PointerDeviceKind.trackpad:
       return settings?.touchSlop ?? kTouchSlop;
   }
 }
@@ -2123,8 +2470,7 @@ double computePanSlop(PointerDeviceKind kind, DeviceGestureSettings? settings) {
     case PointerDeviceKind.invertedStylus:
     case PointerDeviceKind.unknown:
     case PointerDeviceKind.touch:
-    default: // ignore: no_default_cases, to allow adding new device types to [PointerDeviceKind]
-             // TODO(moffatman): Remove after landing https://github.com/flutter/flutter/issues/23604
+    case PointerDeviceKind.trackpad:
       return settings?.panSlop ?? kPanSlop;
   }
 }
@@ -2138,8 +2484,7 @@ double computeScaleSlop(PointerDeviceKind kind) {
     case PointerDeviceKind.invertedStylus:
     case PointerDeviceKind.unknown:
     case PointerDeviceKind.touch:
-    default: // ignore: no_default_cases, to allow adding new device types to [PointerDeviceKind]
-             // TODO(moffatman): Remove after landing https://github.com/flutter/flutter/issues/23604
+    case PointerDeviceKind.trackpad:
       return kScaleSlop;
   }
 }

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

@@ -261,14 +261,11 @@ abstract class DragGestureRecognizer extends OneSequenceGestureRecognizer {
     return super.isPointerAllowed(event as PointerDownEvent);
   }
 
-  @override
-  void addAllowedPointer(PointerDownEvent event) {
-    super.addAllowedPointer(event);
+  void _addPointer(PointerEvent event) {
     _velocityTrackers[event.pointer] = velocityTrackerBuilder(event);
     if (_state == _DragState.ready) {
       _state = _DragState.possible;
       _initialPosition = OffsetPair(global: event.position, local: event.localPosition);
-      _initialButtons = event.buttons;
       _pendingDragOffset = OffsetPair.zero;
       _globalDistanceMoved = 0.0;
       _lastPendingEventTimestamp = event.timeStamp;
@@ -279,45 +276,76 @@ abstract class DragGestureRecognizer extends OneSequenceGestureRecognizer {
     }
   }
 
+  @override
+  void addAllowedPointer(PointerDownEvent event) {
+    super.addAllowedPointer(event);
+    if (_state == _DragState.ready) {
+      _initialButtons = event.buttons;
+    }
+    _addPointer(event);
+  }
+
+  @override
+  void addAllowedPointerPanZoom(PointerPanZoomStartEvent event) {
+    super.addAllowedPointerPanZoom(event);
+    startTrackingPointer(event.pointer, event.transform);
+    if (_state == _DragState.ready) {
+      _initialButtons = kPrimaryButton;
+    }
+    _addPointer(event);
+  }
+
   @override
   void handleEvent(PointerEvent event) {
     assert(_state != _DragState.ready);
-    if (!event.synthesized
-        && (event is PointerDownEvent || event is PointerMoveEvent)) {
+    if (!event.synthesized &&
+        (event is PointerDownEvent ||
+         event is PointerMoveEvent ||
+         event is PointerPanZoomStartEvent ||
+         event is PointerPanZoomUpdateEvent)) {
       final VelocityTracker tracker = _velocityTrackers[event.pointer]!;
       assert(tracker != null);
+      if (event is PointerPanZoomStartEvent) {
+        tracker.addPosition(event.timeStamp, Offset.zero);
+      } else if (event is PointerPanZoomUpdateEvent) {
+        tracker.addPosition(event.timeStamp, event.pan);
+      } else {
         tracker.addPosition(event.timeStamp, event.localPosition);
       }
-
-    if (event is PointerMoveEvent) {
-      if (event.buttons != _initialButtons) {
+    }
+    if (event is PointerMoveEvent && event.buttons != _initialButtons) {
       _giveUpPointer(event.pointer);
       return;
     }
+    if (event is PointerMoveEvent || event is PointerPanZoomUpdateEvent) {
+      final Offset delta = (event is PointerMoveEvent) ? event.delta : (event as PointerPanZoomUpdateEvent).panDelta;
+      final Offset localDelta = (event is PointerMoveEvent) ? event.localDelta : (event as PointerPanZoomUpdateEvent).localPanDelta;
+      final Offset position = (event is PointerMoveEvent) ? event.position : (event.position + (event as PointerPanZoomUpdateEvent).pan);
+      final Offset localPosition = (event is PointerMoveEvent) ? event.localPosition : (event.localPosition + (event as PointerPanZoomUpdateEvent).localPan);
       if (_state == _DragState.accepted) {
         _checkUpdate(
           sourceTimeStamp: event.timeStamp,
-          delta: _getDeltaForDetails(event.localDelta),
-          primaryDelta: _getPrimaryValueFromOffset(event.localDelta),
-          globalPosition: event.position,
-          localPosition: event.localPosition,
+          delta: _getDeltaForDetails(localDelta),
+          primaryDelta: _getPrimaryValueFromOffset(localDelta),
+          globalPosition: position,
+          localPosition: localPosition,
         );
       } else {
-        _pendingDragOffset += OffsetPair(local: event.localDelta, global: event.delta);
+        _pendingDragOffset += OffsetPair(local: localDelta, global: delta);
         _lastPendingEventTimestamp = event.timeStamp;
         _lastTransform = event.transform;
-        final Offset movedLocally = _getDeltaForDetails(event.localDelta);
+        final Offset movedLocally = _getDeltaForDetails(localDelta);
         final Matrix4? localToGlobalTransform = event.transform == null ? null : Matrix4.tryInvert(event.transform!);
         _globalDistanceMoved += PointerEvent.transformDeltaViaPositions(
           transform: localToGlobalTransform,
           untransformedDelta: movedLocally,
-          untransformedEndPosition: event.localPosition,
+          untransformedEndPosition: localPosition
         ).distance * (_getPrimaryValueFromOffset(movedLocally) ?? 1).sign;
         if (_hasSufficientGlobalDistanceToAccept(event.kind, gestureSettings?.touchSlop))
           resolve(GestureDisposition.accepted);
       }
     }
-    if (event is PointerUpEvent || event is PointerCancelEvent) {
+    if (event is PointerUpEvent || event is PointerCancelEvent || event is PointerPanZoomEndEvent) {
       _giveUpPointer(event.pointer);
     }
   }

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

@@ -96,6 +96,43 @@ abstract class GestureRecognizer extends GestureArenaMember with DiagnosticableT
   /// coming from.
   final Map<int, PointerDeviceKind> _pointerToKind = <int, PointerDeviceKind>{};
 
+  /// Registers a new pointer pan/zoom that might be relevant to this gesture
+  /// detector.
+  ///
+  /// A pointer pan/zoom is a stream of events that conveys data covering
+  /// pan, zoom, and rotate data from a multi-finger trackpad gesture.
+  ///
+  /// The owner of this gesture recognizer calls addPointerPanZoom() with the
+  /// PointerPanZoomStartEvent of each pointer that should be considered for
+  /// this gesture.
+  ///
+  /// It's the GestureRecognizer's responsibility to then add itself
+  /// to the global pointer router (see [PointerRouter]) to receive
+  /// subsequent events for this pointer, and to add the pointer to
+  /// the global gesture arena manager (see [GestureArenaManager]) to track
+  /// that pointer.
+  ///
+  /// This method is called for each and all pointers being added. In
+  /// most cases, you want to override [addAllowedPointerPanZoom] instead.
+  void addPointerPanZoom(PointerPanZoomStartEvent event) {
+    _pointerToKind[event.pointer] = event.kind;
+    if (isPointerPanZoomAllowed(event)) {
+      addAllowedPointerPanZoom(event);
+    } else {
+      handleNonAllowedPointerPanZoom(event);
+    }
+  }
+
+  /// Registers a new pointer pan/zoom that's been checked to be allowed by this
+  /// gesture recognizer.
+  ///
+  /// Subclasses of [GestureRecognizer] are supposed to override this method
+  /// instead of [addPointerPanZoom] because [addPointerPanZoom] will be called for each
+  /// pointer being added while [addAllowedPointerPanZoom] is only called for pointers
+  /// that are allowed by this recognizer.
+  @protected
+  void addAllowedPointerPanZoom(PointerPanZoomStartEvent event) { }
+
   /// Registers a new pointer that might be relevant to this gesture
   /// detector.
   ///
@@ -147,6 +184,18 @@ abstract class GestureRecognizer extends GestureArenaMember with DiagnosticableT
     return _supportedDevices == null || _supportedDevices!.contains(event.kind);
   }
 
+  /// Handles a pointer pan/zoom being added that's not allowed by this recognizer.
+  ///
+  /// Subclasses can override this method and reject the gesture.
+  @protected
+  void handleNonAllowedPointerPanZoom(PointerPanZoomStartEvent event) { }
+
+  /// Checks whether or not a pointer pan/zoom is allowed to be tracked by this recognizer.
+  @protected
+  bool isPointerPanZoomAllowed(PointerPanZoomStartEvent event) {
+    return _supportedDevices == null || _supportedDevices!.contains(event.kind);
+  }
+
   /// For a given pointer ID, returns the device kind associated with it.
   ///
   /// The pointer ID is expected to be a valid one i.e. an event was received
@@ -397,7 +446,7 @@ abstract class OneSequenceGestureRecognizer extends GestureRecognizer {
   /// a [PointerUpEvent] or a [PointerCancelEvent] event.
   @protected
   void stopTrackingIfPointerNoLongerDown(PointerEvent event) {
-    if (event is PointerUpEvent || event is PointerCancelEvent)
+    if (event is PointerUpEvent || event is PointerCancelEvent || event is PointerPanZoomEndEvent)
       stopTrackingPointer(event.pointer);
   }
 }

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

@@ -31,6 +31,20 @@ enum _ScaleState {
   started,
 }
 
+class _PointerPanZoomData {
+  _PointerPanZoomData({
+    required this.focalPoint,
+    required this.scale,
+    required this.rotation
+  });
+  Offset focalPoint;
+  double scale;
+  double rotation;
+
+  @override
+  String toString() => '_PointerPanZoomData(focalPoint: $focalPoint, scale: $scale, angle: $rotation)';
+}
+
 /// Details for [GestureScaleStartCallback].
 class ScaleStartDetails {
   /// Creates details for [GestureScaleStartCallback].
@@ -175,7 +189,7 @@ class ScaleUpdateDetails {
     ' verticalScale: $verticalScale,'
     ' rotation: $rotation,'
     ' pointerCount: $pointerCount,'
-    ' focalPointDelta: $localFocalPoint)';
+    ' focalPointDelta: $focalPointDelta)';
 }
 
 /// Details for [GestureScaleEndCallback].
@@ -329,21 +343,51 @@ class ScaleGestureRecognizer extends OneSequenceGestureRecognizer {
   late Offset _localFocalPoint;
   _LineBetweenPointers? _initialLine;
   _LineBetweenPointers? _currentLine;
-  late Map<int, Offset> _pointerLocations;
-  late List<int> _pointerQueue; // A queue to sort pointers in order of entrance
+  final Map<int, Offset> _pointerLocations = <int, Offset>{};
+  final List<int> _pointerQueue = <int>[]; // A queue to sort pointers in order of entrance
   final Map<int, VelocityTracker> _velocityTrackers = <int, VelocityTracker>{};
   late Offset _delta;
+  final Map<int, _PointerPanZoomData> _pointerPanZooms = <int, _PointerPanZoomData>{};
+  double _initialPanZoomScaleFactor = 1;
+  double _initialPanZoomRotationFactor = 0;
 
-  double get _scaleFactor => _initialSpan > 0.0 ? _currentSpan / _initialSpan : 1.0;
+  double get _pointerScaleFactor => _initialSpan > 0.0 ? _currentSpan / _initialSpan : 1.0;
 
-  double get _horizontalScaleFactor => _initialHorizontalSpan > 0.0 ? _currentHorizontalSpan / _initialHorizontalSpan : 1.0;
+  double get _pointerHorizontalScaleFactor => _initialHorizontalSpan > 0.0 ? _currentHorizontalSpan / _initialHorizontalSpan : 1.0;
 
-  double get _verticalScaleFactor => _initialVerticalSpan > 0.0 ? _currentVerticalSpan / _initialVerticalSpan : 1.0;
+  double get _pointerVerticalScaleFactor => _initialVerticalSpan > 0.0 ? _currentVerticalSpan / _initialVerticalSpan : 1.0;
 
-  double _computeRotationFactor() {
-    if (_initialLine == null || _currentLine == null) {
-      return 0.0;
+  double get _scaleFactor {
+    double scale = _pointerScaleFactor;
+    for (final _PointerPanZoomData p in _pointerPanZooms.values) {
+      scale *= p.scale / _initialPanZoomScaleFactor;
+    }
+    return scale;
+  }
+
+  double get _horizontalScaleFactor {
+    double scale = _pointerHorizontalScaleFactor;
+    for (final _PointerPanZoomData p in _pointerPanZooms.values) {
+      scale *= p.scale / _initialPanZoomScaleFactor;
+    }
+    return scale;
+  }
+
+  double get _verticalScaleFactor {
+    double scale = _pointerVerticalScaleFactor;
+    for (final _PointerPanZoomData p in _pointerPanZooms.values) {
+      scale *= p.scale / _initialPanZoomScaleFactor;
     }
+    return scale;
+  }
+
+  int get _pointerCount {
+    return _pointerPanZooms.length + _pointerQueue.length;
+  }
+
+  double _computeRotationFactor() {
+    double factor = 0.0;
+    if (_initialLine != null && _currentLine != null) {
       final double fx = _initialLine!.pointerStartLocation.dx;
       final double fy = _initialLine!.pointerStartLocation.dy;
       final double sx = _initialLine!.pointerEndLocation.dx;
@@ -357,7 +401,13 @@ class ScaleGestureRecognizer extends OneSequenceGestureRecognizer {
       final double angle1 = math.atan2(fy - sy, fx - sx);
       final double angle2 = math.atan2(nfy - nsy, nfx - nsx);
 
-    return angle2 - angle1;
+      factor = angle2 - angle1;
+    }
+    for (final _PointerPanZoomData p in _pointerPanZooms.values) {
+      factor += p.rotation;
+    }
+    factor -= _initialPanZoomRotationFactor;
+    return factor;
   }
 
   @override
@@ -372,8 +422,21 @@ class ScaleGestureRecognizer extends OneSequenceGestureRecognizer {
       _currentHorizontalSpan = 0.0;
       _initialVerticalSpan = 0.0;
       _currentVerticalSpan = 0.0;
-      _pointerLocations = <int, Offset>{};
-      _pointerQueue = <int>[];
+    }
+  }
+
+  @override
+  bool isPointerPanZoomAllowed(PointerPanZoomStartEvent event) => true;
+
+  @override
+  void addAllowedPointerPanZoom(PointerPanZoomStartEvent event) {
+    super.addAllowedPointerPanZoom(event);
+    startTrackingPointer(event.pointer, event.transform);
+    _velocityTrackers[event.pointer] = VelocityTracker.withKind(event.kind);
+    if (_state == _ScaleState.ready) {
+      _state = _ScaleState.possible;
+      _initialPanZoomScaleFactor = 1.0;
+      _initialPanZoomRotationFactor = 0.0;
     }
   }
 
@@ -400,6 +463,30 @@ class ScaleGestureRecognizer extends OneSequenceGestureRecognizer {
       _pointerQueue.remove(event.pointer);
       didChangeConfiguration = true;
       _lastTransform = event.transform;
+    } else if (event is PointerPanZoomStartEvent) {
+      assert(_pointerPanZooms[event.pointer] == null);
+      _pointerPanZooms[event.pointer] = _PointerPanZoomData(
+        focalPoint: event.position,
+        scale: 1,
+        rotation: 0
+      );
+      didChangeConfiguration = true;
+      shouldStartIfAccepted = true;
+    } else if (event is PointerPanZoomUpdateEvent) {
+      assert(_pointerPanZooms[event.pointer] != null);
+      if (!event.synthesized)
+        _velocityTrackers[event.pointer]!.addPosition(event.timeStamp, event.pan);
+      _pointerPanZooms[event.pointer] = _PointerPanZoomData(
+        focalPoint: event.position + event.pan,
+        scale: event.scale,
+        rotation: event.rotation
+      );
+      _lastTransform = event.transform;
+      shouldStartIfAccepted = true;
+    } else if (event is PointerPanZoomEndEvent) {
+      assert(_pointerPanZooms[event.pointer] != null);
+      _pointerPanZooms.remove(event.pointer);
+      didChangeConfiguration = true;
     }
 
     _updateLines();
@@ -411,15 +498,15 @@ class ScaleGestureRecognizer extends OneSequenceGestureRecognizer {
   }
 
   void _update() {
-    final int count = _pointerLocations.keys.length;
-
     final Offset? previousFocalPoint = _currentFocalPoint;
 
     // Compute the focal point
     Offset focalPoint = Offset.zero;
     for (final int pointer in _pointerLocations.keys)
       focalPoint += _pointerLocations[pointer]!;
-    _currentFocalPoint = count > 0 ? focalPoint / count.toDouble() : Offset.zero;
+    for (final _PointerPanZoomData p in _pointerPanZooms.values)
+      focalPoint += p.focalPoint;
+    _currentFocalPoint = _pointerCount > 0 ? focalPoint / _pointerCount.toDouble() : Offset.zero;
 
     if (previousFocalPoint == null) {
       _localFocalPoint = PointerEvent.transformPosition(
@@ -436,6 +523,14 @@ class ScaleGestureRecognizer extends OneSequenceGestureRecognizer {
       _delta = _localFocalPoint - localPreviousFocalPoint;
     }
 
+    final int count = _pointerLocations.keys.length;
+
+    Offset pointerFocalPoint = Offset.zero;
+    for (final int pointer in _pointerLocations.keys)
+      pointerFocalPoint += _pointerLocations[pointer]!;
+    if (count > 0)
+      pointerFocalPoint = pointerFocalPoint / count.toDouble();
+
     // Span is the average deviation from focal point. Horizontal and vertical
     // spans are the average deviations from the focal point's horizontal and
     // vertical coordinates, respectively.
@@ -443,9 +538,9 @@ class ScaleGestureRecognizer extends OneSequenceGestureRecognizer {
     double totalHorizontalDeviation = 0.0;
     double totalVerticalDeviation = 0.0;
     for (final int pointer in _pointerLocations.keys) {
-      totalDeviation += (_currentFocalPoint! - _pointerLocations[pointer]!).distance;
-      totalHorizontalDeviation += (_currentFocalPoint!.dx - _pointerLocations[pointer]!.dx).abs();
-      totalVerticalDeviation += (_currentFocalPoint!.dy - _pointerLocations[pointer]!.dy).abs();
+      totalDeviation += (pointerFocalPoint - _pointerLocations[pointer]!).distance;
+      totalHorizontalDeviation += (pointerFocalPoint.dx - _pointerLocations[pointer]!.dx).abs();
+      totalVerticalDeviation += (pointerFocalPoint.dy - _pointerLocations[pointer]!.dy).abs();
     }
     _currentSpan = count > 0 ? totalDeviation / count : 0.0;
     _currentHorizontalSpan = count > 0 ? totalHorizontalDeviation / count : 0.0;
@@ -488,6 +583,13 @@ class ScaleGestureRecognizer extends OneSequenceGestureRecognizer {
     _initialLine = _currentLine;
     _initialHorizontalSpan = _currentHorizontalSpan;
     _initialVerticalSpan = _currentVerticalSpan;
+    if (_pointerPanZooms.isEmpty) {
+      _initialPanZoomScaleFactor = 1.0;
+      _initialPanZoomRotationFactor = 0.0;
+    } else {
+      _initialPanZoomScaleFactor = _scaleFactor / _pointerScaleFactor;
+      _initialPanZoomRotationFactor = _pointerPanZooms.values.map((_PointerPanZoomData x) => x.rotation).reduce((double a, double b) => a + b);
+    }
     if (_state == _ScaleState.started) {
       if (onEnd != null) {
         final VelocityTracker tracker = _velocityTrackers[pointer]!;
@@ -497,9 +599,9 @@ class ScaleGestureRecognizer extends OneSequenceGestureRecognizer {
           final Offset pixelsPerSecond = velocity.pixelsPerSecond;
           if (pixelsPerSecond.distanceSquared > kMaxFlingVelocity * kMaxFlingVelocity)
             velocity = Velocity(pixelsPerSecond: (pixelsPerSecond / pixelsPerSecond.distance) * kMaxFlingVelocity);
-          invokeCallback<void>('onEnd', () => onEnd!(ScaleEndDetails(velocity: velocity, pointerCount: _pointerQueue.length)));
+          invokeCallback<void>('onEnd', () => onEnd!(ScaleEndDetails(velocity: velocity, pointerCount: _pointerCount)));
         } else {
-          invokeCallback<void>('onEnd', () => onEnd!(ScaleEndDetails(pointerCount: _pointerQueue.length)));
+          invokeCallback<void>('onEnd', () => onEnd!(ScaleEndDetails(pointerCount: _pointerCount)));
         }
       }
       _state = _ScaleState.accepted;
@@ -515,7 +617,7 @@ class ScaleGestureRecognizer extends OneSequenceGestureRecognizer {
     if (_state == _ScaleState.possible) {
       final double spanDelta = (_currentSpan - _initialSpan).abs();
       final double focalPointDelta = (_currentFocalPoint! - _initialFocalPoint).distance;
-      if (spanDelta > computeScaleSlop(pointerDeviceKind) || focalPointDelta > computePanSlop(pointerDeviceKind, gestureSettings))
+      if (spanDelta > computeScaleSlop(pointerDeviceKind) || focalPointDelta > computePanSlop(pointerDeviceKind, gestureSettings) || math.max(_scaleFactor / _pointerScaleFactor, _pointerScaleFactor / _scaleFactor) > 1.05)
         resolve(GestureDisposition.accepted);
     } else if (_state.index >= _ScaleState.accepted.index) {
       resolve(GestureDisposition.accepted);
@@ -535,7 +637,7 @@ class ScaleGestureRecognizer extends OneSequenceGestureRecognizer {
           focalPoint: _currentFocalPoint!,
           localFocalPoint: _localFocalPoint,
           rotation: _computeRotationFactor(),
-          pointerCount: _pointerQueue.length,
+          pointerCount: _pointerCount,
           focalPointDelta: _delta,
         ));
       });
@@ -548,7 +650,7 @@ class ScaleGestureRecognizer extends OneSequenceGestureRecognizer {
         onStart!(ScaleStartDetails(
           focalPoint: _currentFocalPoint!,
           localFocalPoint: _localFocalPoint,
-          pointerCount: _pointerQueue.length,
+          pointerCount: _pointerCount,
         ));
       });
   }
@@ -564,12 +666,22 @@ class ScaleGestureRecognizer extends OneSequenceGestureRecognizer {
         _initialLine = _currentLine;
         _initialHorizontalSpan = _currentHorizontalSpan;
         _initialVerticalSpan = _currentVerticalSpan;
+        if (_pointerPanZooms.isEmpty) {
+          _initialPanZoomScaleFactor = 1.0;
+          _initialPanZoomRotationFactor = 0.0;
+        } else {
+          _initialPanZoomScaleFactor = _scaleFactor / _pointerScaleFactor;
+          _initialPanZoomRotationFactor = _pointerPanZooms.values.map((_PointerPanZoomData x) => x.rotation).reduce((double a, double b) => a + b);
+        }
       }
     }
   }
 
   @override
   void rejectGesture(int pointer) {
+    _pointerPanZooms.remove(pointer);
+    _pointerLocations.remove(pointer);
+    _pointerQueue.remove(pointer);
     stopTrackingPointer(pointer);
   }
 

packages/flutter/lib/src/rendering/proxy_box.dart

@@ -2858,6 +2858,21 @@ typedef PointerUpEventListener = void Function(PointerUpEvent event);
 /// Used by [Listener] and [RenderPointerListener].
 typedef PointerCancelEventListener = void Function(PointerCancelEvent event);
 
+/// Signature for listening to [PointerPanZoomStartEvent] events.
+///
+/// Used by [Listener] and [RenderPointerListener].
+typedef PointerPanZoomStartEventListener = void Function(PointerPanZoomStartEvent event);
+
+/// Signature for listening to [PointerPanZoomUpdateEvent] events.
+///
+/// Used by [Listener] and [RenderPointerListener].
+typedef PointerPanZoomUpdateEventListener = void Function(PointerPanZoomUpdateEvent event);
+
+/// Signature for listening to [PointerPanZoomEndEvent] events.
+///
+/// Used by [Listener] and [RenderPointerListener].
+typedef PointerPanZoomEndEventListener = void Function(PointerPanZoomEndEvent event);
+
 /// Signature for listening to [PointerSignalEvent] events.
 ///
 /// Used by [Listener] and [RenderPointerListener].
@@ -2885,6 +2900,9 @@ class RenderPointerListener extends RenderProxyBoxWithHitTestBehavior {
     this.onPointerUp,
     this.onPointerHover,
     this.onPointerCancel,
+    this.onPointerPanZoomStart,
+    this.onPointerPanZoomUpdate,
+    this.onPointerPanZoomEnd,
     this.onPointerSignal,
     HitTestBehavior behavior = HitTestBehavior.deferToChild,
     RenderBox? child,
@@ -2909,6 +2927,15 @@ class RenderPointerListener extends RenderProxyBoxWithHitTestBehavior {
   /// no longer directed towards this receiver.
   PointerCancelEventListener? onPointerCancel;
 
+  /// Called when a pan/zoom begins such as from a trackpad gesture.
+  PointerPanZoomStartEventListener? onPointerPanZoomStart;
+
+  /// Called when a pan/zoom is updated.
+  PointerPanZoomUpdateEventListener? onPointerPanZoomUpdate;
+
+  /// Called when a pan/zoom finishes.
+  PointerPanZoomEndEventListener? onPointerPanZoomEnd;
+
   /// Called when a pointer signal occurs over this object.
   PointerSignalEventListener? onPointerSignal;
 
@@ -2930,6 +2957,12 @@ class RenderPointerListener extends RenderProxyBoxWithHitTestBehavior {
       return onPointerHover?.call(event);
     if (event is PointerCancelEvent)
       return onPointerCancel?.call(event);
+    if (event is PointerPanZoomStartEvent)
+      return onPointerPanZoomStart?.call(event);
+    if (event is PointerPanZoomUpdateEvent)
+      return onPointerPanZoomUpdate?.call(event);
+    if (event is PointerPanZoomEndEvent)
+      return onPointerPanZoomEnd?.call(event);
     if (event is PointerSignalEvent)
       return onPointerSignal?.call(event);
   }
@@ -2945,6 +2978,9 @@ class RenderPointerListener extends RenderProxyBoxWithHitTestBehavior {
         'up': onPointerUp,
         'hover': onPointerHover,
         'cancel': onPointerCancel,
+        'panZoomStart': onPointerPanZoomStart,
+        'panZoomUpdate': onPointerPanZoomUpdate,
+        'panZoomEnd': onPointerPanZoomEnd,
         'signal': onPointerSignal,
       },
       ifEmpty: '<none>',

packages/flutter/lib/src/services/platform_views.dart

@@ -634,6 +634,7 @@ class _AndroidMotionEventConverter {
     int toolType = AndroidPointerProperties.kToolTypeUnknown;
     switch (event.kind) {
       case PointerDeviceKind.touch:
+      case PointerDeviceKind.trackpad:
         toolType = AndroidPointerProperties.kToolTypeFinger;
         break;
       case PointerDeviceKind.mouse:
@@ -646,8 +647,6 @@ class _AndroidMotionEventConverter {
         toolType = AndroidPointerProperties.kToolTypeEraser;
         break;
       case PointerDeviceKind.unknown:
-      default: // ignore: no_default_cases, to allow adding new device types to [PointerDeviceKind]
-               // TODO(moffatman): Remove after landing https://github.com/flutter/flutter/issues/23604
         toolType = AndroidPointerProperties.kToolTypeUnknown;
         break;
     }

packages/flutter/lib/src/widgets/basic.dart

@@ -6090,6 +6090,9 @@ class Listener extends SingleChildRenderObjectWidget {
     this.onPointerUp,
     this.onPointerHover,
     this.onPointerCancel,
+    this.onPointerPanZoomStart,
+    this.onPointerPanZoomUpdate,
+    this.onPointerPanZoomEnd,
     this.onPointerSignal,
     this.behavior = HitTestBehavior.deferToChild,
     Widget? child,
@@ -6119,6 +6122,15 @@ class Listener extends SingleChildRenderObjectWidget {
   /// no longer directed towards this receiver.
   final PointerCancelEventListener? onPointerCancel;
 
+  /// Called when a pan/zoom begins such as from a trackpad gesture.
+  final PointerPanZoomStartEventListener? onPointerPanZoomStart;
+
+  /// Called when a pan/zoom is updated.
+  final PointerPanZoomUpdateEventListener? onPointerPanZoomUpdate;
+
+  /// Called when a pan/zoom finishes.
+  final PointerPanZoomEndEventListener? onPointerPanZoomEnd;
+
   /// Called when a pointer signal occurs over this object.
   ///
   /// See also:
@@ -6138,6 +6150,9 @@ class Listener extends SingleChildRenderObjectWidget {
       onPointerUp: onPointerUp,
       onPointerHover: onPointerHover,
       onPointerCancel: onPointerCancel,
+      onPointerPanZoomStart: onPointerPanZoomStart,
+      onPointerPanZoomUpdate: onPointerPanZoomUpdate,
+      onPointerPanZoomEnd: onPointerPanZoomEnd,
       onPointerSignal: onPointerSignal,
       behavior: behavior,
     );
@@ -6151,6 +6166,9 @@ class Listener extends SingleChildRenderObjectWidget {
       ..onPointerUp = onPointerUp
       ..onPointerHover = onPointerHover
       ..onPointerCancel = onPointerCancel
+      ..onPointerPanZoomStart = onPointerPanZoomStart
+      ..onPointerPanZoomUpdate = onPointerPanZoomUpdate
+      ..onPointerPanZoomEnd = onPointerPanZoomEnd
       ..onPointerSignal = onPointerSignal
       ..behavior = behavior;
   }
@@ -6164,6 +6182,9 @@ class Listener extends SingleChildRenderObjectWidget {
       if (onPointerUp != null) 'up',
       if (onPointerHover != null) 'hover',
       if (onPointerCancel != null) 'cancel',
+      if (onPointerPanZoomStart != null) 'panZoomStart',
+      if (onPointerPanZoomUpdate != null) 'panZoomUpdate',
+      if (onPointerPanZoomEnd != null) 'panZoomEnd',
       if (onPointerSignal != null) 'signal',
     ];
     properties.add(IterableProperty<String>('listeners', listeners, ifEmpty: '<none>'));

packages/flutter/lib/src/widgets/focus_manager.dart

@@ -1648,9 +1648,8 @@ class FocusManager with DiagnosticableTreeMixin, ChangeNotifier {
         expectedMode = FocusHighlightMode.touch;
         break;
       case PointerDeviceKind.mouse:
+      case PointerDeviceKind.trackpad:
       case PointerDeviceKind.unknown:
-      default: // ignore: no_default_cases, to allow adding new device types to [PointerDeviceKind]
-               // TODO(moffatman): Remove after landing https://github.com/flutter/flutter/issues/23604
         _lastInteractionWasTouch = false;
         expectedMode = FocusHighlightMode.traditional;
         break;

packages/flutter/lib/src/widgets/gesture_detector.dart

@@ -1435,6 +1435,13 @@ class RawGestureDetectorState extends State<RawGestureDetector> {
       recognizer.addPointer(event);
   }
 
+  void _handlePointerPanZoomStart(PointerPanZoomStartEvent event) {
+    assert(_recognizers != null);
+    for (final GestureRecognizer recognizer in _recognizers!.values) {
+      recognizer.addPointerPanZoom(event);
+    }
+  }
+
   HitTestBehavior get _defaultBehavior {
     return widget.child == null ? HitTestBehavior.translucent : HitTestBehavior.deferToChild;
   }
@@ -1449,6 +1456,7 @@ class RawGestureDetectorState extends State<RawGestureDetector> {
   Widget build(BuildContext context) {
     Widget result = Listener(
       onPointerDown: _handlePointerDown,
+      onPointerPanZoomStart: _handlePointerPanZoomStart,
       behavior: widget.behavior ?? _defaultBehavior,
       child: widget.child,
     );

packages/flutter/lib/src/widgets/scroll_configuration.dart

@@ -19,6 +19,7 @@ const Set<PointerDeviceKind> _kTouchLikeDeviceTypes = <PointerDeviceKind>{
   PointerDeviceKind.touch,
   PointerDeviceKind.stylus,
   PointerDeviceKind.invertedStylus,
+  PointerDeviceKind.trackpad,
   // The VoiceAccess sends pointer events with unknown type when scrolling
   // scrollables.
   PointerDeviceKind.unknown,

packages/flutter/lib/src/widgets/scrollbar.dart

@@ -682,13 +682,12 @@ class ScrollbarPainter extends ChangeNotifier implements CustomPainter {
 
     switch (kind) {
       case PointerDeviceKind.touch:
+      case PointerDeviceKind.trackpad:
         return paddedRect.contains(position);
       case PointerDeviceKind.mouse:
       case PointerDeviceKind.stylus:
       case PointerDeviceKind.invertedStylus:
       case PointerDeviceKind.unknown:
-      default: // ignore: no_default_cases, to allow adding new device types to [PointerDeviceKind]
-               // TODO(moffatman): Remove after landing https://github.com/flutter/flutter/issues/23604
         return interactiveRect.contains(position);
     }
   }
@@ -713,6 +712,7 @@ class ScrollbarPainter extends ChangeNotifier implements CustomPainter {
 
     switch (kind) {
       case PointerDeviceKind.touch:
+      case PointerDeviceKind.trackpad:
         final Rect touchThumbRect = _thumbRect!.expandToInclude(
           Rect.fromCircle(center: _thumbRect!.center, radius: _kMinInteractiveSize / 2),
         );
@@ -721,8 +721,6 @@ class ScrollbarPainter extends ChangeNotifier implements CustomPainter {
       case PointerDeviceKind.stylus:
       case PointerDeviceKind.invertedStylus:
       case PointerDeviceKind.unknown:
-      default: // ignore: no_default_cases, to allow adding new device types to [PointerDeviceKind]
-               // TODO(moffatman): Remove after landing https://github.com/flutter/flutter/issues/23604
         return _thumbRect!.contains(position);
     }
   }
@@ -1963,6 +1961,7 @@ class RawScrollbarState<T extends RawScrollbar> extends State<T> with TickerProv
               onExit: (PointerExitEvent event) {
                 switch(event.kind) {
                   case PointerDeviceKind.mouse:
+                  case PointerDeviceKind.trackpad:
                     if (enableGestures)
                       handleHoverExit(event);
                     break;
@@ -1970,14 +1969,13 @@ class RawScrollbarState<T extends RawScrollbar> extends State<T> with TickerProv
                   case PointerDeviceKind.invertedStylus:
                   case PointerDeviceKind.unknown:
                   case PointerDeviceKind.touch:
-                  default: // ignore: no_default_cases, to allow adding new device types to [PointerDeviceKind]
-                           // TODO(moffatman): Remove after landing https://github.com/flutter/flutter/issues/23604
                     break;
                 }
               },
               onHover: (PointerHoverEvent event) {
                 switch(event.kind) {
                   case PointerDeviceKind.mouse:
+                  case PointerDeviceKind.trackpad:
                     if (enableGestures)
                       handleHover(event);
                     break;
@@ -1985,8 +1983,6 @@ class RawScrollbarState<T extends RawScrollbar> extends State<T> with TickerProv
                   case PointerDeviceKind.invertedStylus:
                   case PointerDeviceKind.unknown:
                   case PointerDeviceKind.touch:
-                  default: // ignore: no_default_cases, to allow adding new device types to [PointerDeviceKind]
-                           // TODO(moffatman): Remove after landing https://github.com/flutter/flutter/issues/23604
                     break;
                 }
               },

packages/flutter/lib/src/widgets/text_selection.dart

@@ -1525,6 +1525,7 @@ class TextSelectionGestureDetectorBuilder {
         case TargetPlatform.macOS:
           switch (details.kind) {
             case PointerDeviceKind.mouse:
+            case PointerDeviceKind.trackpad:
             case PointerDeviceKind.stylus:
             case PointerDeviceKind.invertedStylus:
               // Precise devices should place the cursor at a precise position.
@@ -1532,8 +1533,6 @@ class TextSelectionGestureDetectorBuilder {
               break;
             case PointerDeviceKind.touch:
             case PointerDeviceKind.unknown:
-            default: // ignore: no_default_cases, to allow adding new device types to [PointerDeviceKind]
-                     // TODO(moffatman): Remove after landing https://github.com/flutter/flutter/issues/23604
               // On macOS/iOS/iPadOS a touch tap places the cursor at the edge
               // of the word.
               renderEditable.selectWordEdge(cause: SelectionChangedCause.tap);

packages/flutter/test/gestures/drag_test.dart

@@ -1484,4 +1484,219 @@ void main() {
 
     tap2.dispose();
   });
+
+  testGesture('Should recognize pan gestures from platform', (GestureTester tester) {
+    final PanGestureRecognizer pan = PanGestureRecognizer();
+    // We need a competing gesture recognizer so that the gesture is not immediately claimed.
+    final PanGestureRecognizer competingPan = PanGestureRecognizer();
+    addTearDown(pan.dispose);
+    addTearDown(competingPan.dispose);
+
+    bool didStartPan = false;
+    pan.onStart = (_) {
+      didStartPan = true;
+    };
+
+    Offset? updatedScrollDelta;
+    pan.onUpdate = (DragUpdateDetails details) {
+      updatedScrollDelta = details.delta;
+    };
+
+    bool didEndPan = false;
+    pan.onEnd = (DragEndDetails details) {
+      didEndPan = true;
+    };
+
+    final TestPointer pointer = TestPointer(2);
+    final PointerPanZoomStartEvent start = pointer.panZoomStart(const Offset(10.0, 10.0));
+    pan.addPointerPanZoom(start);
+    competingPan.addPointerPanZoom(start);
+    tester.closeArena(2);
+    expect(didStartPan, isFalse);
+    expect(updatedScrollDelta, isNull);
+    expect(didEndPan, isFalse);
+
+    tester.route(start);
+    expect(didStartPan, isFalse);
+    expect(updatedScrollDelta, isNull);
+    expect(didEndPan, isFalse);
+
+    // Gesture will be claimed when distance reaches kPanSlop, which was 36.0 when this test was last updated.
+    tester.route(pointer.panZoomUpdate(const Offset(10.0, 10.0), pan: const Offset(20.0, 20.0))); // moved 20 horizontally and 20 vertically which is 28 total
+    expect(didStartPan, isFalse); // 28 < 36
+    tester.route(pointer.panZoomUpdate(const Offset(10.0, 10.0), pan: const Offset(30.0, 30.0))); // moved 30 horizontally and 30 vertically which is 42 total
+    expect(didStartPan, isTrue); // 42 > 36
+    didStartPan = false;
+    expect(didEndPan, isFalse);
+
+    tester.route(pointer.panZoomUpdate(const Offset(10.0, 10.0), pan: const Offset(30.0, 25.0)));
+    expect(didStartPan, isFalse);
+    expect(updatedScrollDelta, const Offset(0.0, -5.0));
+    updatedScrollDelta = null;
+    expect(didEndPan, isFalse);
+
+    tester.route(pointer.panZoomEnd());
+    expect(didStartPan, isFalse);
+    expect(updatedScrollDelta, isNull);
+    expect(didEndPan, isTrue);
+    didEndPan = false;
+  });
+
+  testGesture('Pointer pan/zooms drags should allow touches to join them', (GestureTester tester) {
+    final PanGestureRecognizer pan = PanGestureRecognizer();
+    // We need a competing gesture recognizer so that the gesture is not immediately claimed.
+    final PanGestureRecognizer competingPan = PanGestureRecognizer();
+    addTearDown(pan.dispose);
+    addTearDown(competingPan.dispose);
+
+    bool didStartPan = false;
+    pan.onStart = (_) {
+      didStartPan = true;
+    };
+
+    Offset? updatedScrollDelta;
+    pan.onUpdate = (DragUpdateDetails details) {
+      updatedScrollDelta = details.delta;
+    };
+
+    bool didEndPan = false;
+    pan.onEnd = (DragEndDetails details) {
+      didEndPan = true;
+    };
+
+    final TestPointer panZoomPointer = TestPointer(2);
+    final TestPointer touchPointer = TestPointer(3);
+    final PointerPanZoomStartEvent start = panZoomPointer.panZoomStart(const Offset(10.0, 10.0));
+    pan.addPointerPanZoom(start);
+    competingPan.addPointerPanZoom(start);
+    tester.closeArena(2);
+    expect(didStartPan, isFalse);
+    expect(updatedScrollDelta, isNull);
+    expect(didEndPan, isFalse);
+
+    tester.route(start);
+    expect(didStartPan, isFalse);
+    expect(updatedScrollDelta, isNull);
+    expect(didEndPan, isFalse);
+
+    // Gesture will be claimed when distance reaches kPanSlop, which was 36.0 when this test was last updated.
+    tester.route(panZoomPointer.panZoomUpdate(const Offset(10.0, 10.0), pan: const Offset(20.0, 20.0))); // moved 20 horizontally and 20 vertically which is 28 total
+    expect(didStartPan, isFalse); // 28 < 36
+    tester.route(panZoomPointer.panZoomUpdate(const Offset(10.0, 10.0), pan: const Offset(30.0, 30.0))); // moved 30 horizontally and 30 vertically which is 42 total
+    expect(didStartPan, isTrue); // 42 > 36
+    didStartPan = false;
+    expect(didEndPan, isFalse);
+
+    tester.route(panZoomPointer.panZoomUpdate(const Offset(10.0, 10.0), pan: const Offset(30.0, 25.0)));
+    expect(didStartPan, isFalse);
+    expect(updatedScrollDelta, const Offset(0.0, -5.0));
+    updatedScrollDelta = null;
+    expect(didEndPan, isFalse);
+
+    final PointerDownEvent touchDown = touchPointer.down(const Offset(20.0, 20.0));
+    pan.addPointer(touchDown);
+    competingPan.addPointer(touchDown);
+    tester.closeArena(3);
+    expect(didStartPan, isFalse);
+    expect(updatedScrollDelta, isNull);
+    expect(didEndPan, isFalse);
+
+    tester.route(touchPointer.move(const Offset(25.0, 25.0)));
+    expect(didStartPan, isFalse);
+    expect(updatedScrollDelta, const Offset(5.0, 5.0));
+    updatedScrollDelta = null;
+    expect(didEndPan, isFalse);
+
+    tester.route(touchPointer.up());
+    expect(didStartPan, isFalse);
+    expect(updatedScrollDelta, isNull);
+    expect(didEndPan, isFalse);
+
+    tester.route(panZoomPointer.panZoomEnd());
+    expect(didStartPan, isFalse);
+    expect(updatedScrollDelta, isNull);
+    expect(didEndPan, isTrue);
+    didEndPan = false;
+  });
+
+testGesture('Touch drags should allow pointer pan/zooms to join them', (GestureTester tester) {
+    final PanGestureRecognizer pan = PanGestureRecognizer();
+    // We need a competing gesture recognizer so that the gesture is not immediately claimed.
+    final PanGestureRecognizer competingPan = PanGestureRecognizer();
+    addTearDown(pan.dispose);
+    addTearDown(competingPan.dispose);
+
+    bool didStartPan = false;
+    pan.onStart = (_) {
+      didStartPan = true;
+    };
+
+    Offset? updatedScrollDelta;
+    pan.onUpdate = (DragUpdateDetails details) {
+      updatedScrollDelta = details.delta;
+    };
+
+    bool didEndPan = false;
+    pan.onEnd = (DragEndDetails details) {
+      didEndPan = true;
+    };
+
+    final TestPointer panZoomPointer = TestPointer(2);
+    final TestPointer touchPointer = TestPointer(3);
+    final PointerDownEvent touchDown = touchPointer.down(const Offset(20.0, 20.0));
+    pan.addPointer(touchDown);
+    competingPan.addPointer(touchDown);
+    tester.closeArena(3);
+    expect(didStartPan, isFalse);
+    expect(updatedScrollDelta, isNull);
+    expect(didEndPan, isFalse);
+
+    tester.route(touchPointer.move(const Offset(60.0, 60.0)));
+    expect(didStartPan, isTrue);
+    didStartPan = false;
+    expect(updatedScrollDelta, isNull);
+    expect(didEndPan, isFalse);
+
+    tester.route(touchPointer.move(const Offset(70.0, 70.0)));
+    expect(didStartPan, isFalse);
+    expect(updatedScrollDelta, const Offset(10.0, 10.0));
+    updatedScrollDelta = null;
+    expect(didEndPan, isFalse);
+
+    final PointerPanZoomStartEvent start = panZoomPointer.panZoomStart(const Offset(10.0, 10.0));
+    pan.addPointerPanZoom(start);
+    competingPan.addPointerPanZoom(start);
+    tester.closeArena(2);
+    expect(didStartPan, isFalse);
+    expect(updatedScrollDelta, isNull);
+    expect(didEndPan, isFalse);
+
+    tester.route(start);
+    expect(didStartPan, isFalse);
+    expect(updatedScrollDelta, isNull);
+    expect(didEndPan, isFalse);
+
+    // Gesture will be claimed when distance reaches kPanSlop, which was 36.0 when this test was last updated.
+    tester.route(panZoomPointer.panZoomUpdate(const Offset(10.0, 10.0), pan: const Offset(20.0, 20.0))); // moved 20 horizontally and 20 vertically which is 28 total
+    expect(didStartPan, isFalse);
+    expect(updatedScrollDelta, const Offset(20.0, 20.0));
+    updatedScrollDelta = null;
+    expect(didEndPan, isFalse);
+    tester.route(panZoomPointer.panZoomUpdate(const Offset(10.0, 10.0), pan: const Offset(30.0, 30.0))); // moved 30 horizontally and 30 vertically which is 42 total
+    expect(didStartPan, isFalse);
+    expect(updatedScrollDelta, const Offset(10.0, 10.0));
+    updatedScrollDelta = null;
+    expect(didEndPan, isFalse);
+
+    tester.route(panZoomPointer.panZoomEnd());
+    expect(didStartPan, isFalse);
+    expect(updatedScrollDelta, isNull);
+    expect(didEndPan, isFalse);
+
+    tester.route(touchPointer.up());
+    expect(didStartPan, isFalse);
+    expect(updatedScrollDelta, isNull);
+    expect(didEndPan, isTrue);
+    didEndPan = false;
+  });
 }

packages/flutter/test/gestures/events_test.dart

@@ -505,6 +505,39 @@ void main() {
       localPosition: localPosition,
     );
 
+    const PointerPanZoomStartEvent panZoomStart = PointerPanZoomStartEvent(
+      timeStamp: Duration(seconds: 2),
+      device: 1,
+      position: Offset(20, 30),
+    );
+    _expectTransformedEvent(
+      original: panZoomStart,
+      transform: transform,
+      localPosition: localPosition,
+    );
+
+    const PointerPanZoomUpdateEvent panZoomUpdate = PointerPanZoomUpdateEvent(
+      timeStamp: Duration(seconds: 2),
+      device: 1,
+      position: Offset(20, 30),
+    );
+    _expectTransformedEvent(
+      original: panZoomUpdate,
+      transform: transform,
+      localPosition: localPosition,
+    );
+
+    const PointerPanZoomEndEvent panZoomEnd = PointerPanZoomEndEvent(
+      timeStamp: Duration(seconds: 2),
+      device: 1,
+      position: Offset(20, 30),
+    );
+    _expectTransformedEvent(
+      original: panZoomEnd,
+      transform: transform,
+      localPosition: localPosition,
+    );
+
     const PointerUpEvent up = PointerUpEvent(
       timeStamp: Duration(seconds: 2),
       pointer: 45,

packages/flutter/test/gestures/gesture_binding_test.dart

@@ -335,4 +335,23 @@ void main() {
       expect(events[4].buttons, equals(0));
     }
   });
+
+  test('Pointer pan/zoom events', () {
+    const ui.PointerDataPacket packet = ui.PointerDataPacket(
+      data: <ui.PointerData>[
+        ui.PointerData(change: ui.PointerChange.panZoomStart),
+        ui.PointerData(change: ui.PointerChange.panZoomUpdate),
+        ui.PointerData(change: ui.PointerChange.panZoomEnd),
+      ],
+    );
+
+    final List<PointerEvent> events = <PointerEvent>[];
+    binding.callback = events.add;
+
+    ui.window.onPointerDataPacket?.call(packet);
+    expect(events.length, 3);
+    expect(events[0], isA<PointerPanZoomStartEvent>());
+    expect(events[1], isA<PointerPanZoomUpdateEvent>());
+    expect(events[2], isA<PointerPanZoomEndEvent>());
+  });
 }

packages/flutter/test/gestures/scale_test.dart

@@ -370,9 +370,9 @@ void main() {
     tester.route(down);
     expect(log, isEmpty);
 
-    // scale will win if focal point delta exceeds 18.0*2
+    // Scale will win if focal point delta exceeds 18.0*2.
 
-    tester.route(pointer1.move(const Offset(10.0, 50.0))); // delta of 40.0 exceeds 18.0*2
+    tester.route(pointer1.move(const Offset(10.0, 50.0))); // Delta of 40.0 exceeds 18.0*2.
     expect(log, equals(<String>['scale-start', 'scale-update']));
     log.clear();
 
@@ -704,6 +704,461 @@ void main() {
     scale.dispose();
   });
 
+  testGesture('Should recognize scale gestures from pointer pan/zoom events', (GestureTester tester) {
+    final ScaleGestureRecognizer scale = ScaleGestureRecognizer();
+    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer();
+
+    bool didStartScale = false;
+    Offset? updatedFocalPoint;
+    scale.onStart = (ScaleStartDetails details) {
+      didStartScale = true;
+      updatedFocalPoint = details.focalPoint;
+    };
+
+    double? updatedScale;
+    double? updatedHorizontalScale;
+    double? updatedVerticalScale;
+    Offset? updatedDelta;
+    scale.onUpdate = (ScaleUpdateDetails details) {
+      updatedScale = details.scale;
+      updatedHorizontalScale = details.horizontalScale;
+      updatedVerticalScale = details.verticalScale;
+      updatedFocalPoint = details.focalPoint;
+      updatedDelta = details.focalPointDelta;
+    };
+
+    bool didEndScale = false;
+    scale.onEnd = (ScaleEndDetails details) {
+      didEndScale = true;
+    };
+
+    final TestPointer pointer1 = TestPointer(2);
+
+    final PointerPanZoomStartEvent start = pointer1.panZoomStart(Offset.zero);
+    scale.addPointerPanZoom(start);
+    drag.addPointerPanZoom(start);
+
+    tester.closeArena(2);
+    expect(didStartScale, isFalse);
+    expect(updatedScale, isNull);
+    expect(updatedFocalPoint, isNull);
+    expect(updatedDelta, isNull);
+    expect(didEndScale, isFalse);
+
+    // Panning.
+    tester.route(start);
+    expect(didStartScale, isFalse);
+    expect(updatedScale, isNull);
+    expect(updatedFocalPoint, isNull);
+    expect(updatedDelta, isNull);
+    expect(didEndScale, isFalse);
+
+    tester.route(pointer1.panZoomUpdate(Offset.zero, pan: const Offset(20.0, 30.0)));
+    expect(didStartScale, isTrue);
+    didStartScale = false;
+    expect(updatedFocalPoint, const Offset(20.0, 30.0));
+    updatedFocalPoint = null;
+    expect(updatedScale, 1.0);
+    updatedScale = null;
+    expect(updatedDelta, const Offset(20.0, 30.0));
+    updatedDelta = null;
+    expect(didEndScale, isFalse);
+
+    // Zoom in.
+    tester.route(pointer1.panZoomUpdate(Offset.zero, pan: const Offset(20.0, 30.0), scale: 2.0));
+    expect(updatedFocalPoint, const Offset(20.0, 30.0));
+    updatedFocalPoint = null;
+    expect(updatedScale, 2.0);
+    expect(updatedHorizontalScale, 2.0);
+    expect(updatedVerticalScale, 2.0);
+    expect(updatedDelta, Offset.zero);
+    updatedScale = null;
+    updatedHorizontalScale = null;
+    updatedVerticalScale = null;
+    updatedDelta = null;
+    expect(didEndScale, isFalse);
+
+    // Zoom out.
+    tester.route(pointer1.panZoomUpdate(Offset.zero, pan: const Offset(20.0, 30.0)));
+    expect(updatedFocalPoint, const Offset(20.0, 30.0));
+    updatedFocalPoint = null;
+    expect(updatedScale, 1.0);
+    expect(updatedHorizontalScale, 1.0);
+    expect(updatedVerticalScale, 1.0);
+    expect(updatedDelta, Offset.zero);
+    updatedScale = null;
+    updatedHorizontalScale = null;
+    updatedVerticalScale = null;
+    updatedDelta = null;
+    expect(didEndScale, isFalse);
+
+    // We are done.
+    tester.route(pointer1.panZoomEnd());
+    expect(didStartScale, isFalse);
+    expect(updatedFocalPoint, isNull);
+    expect(updatedScale, isNull);
+    expect(updatedDelta, isNull);
+    expect(didEndScale, isTrue);
+    didEndScale = false;
+
+    scale.dispose();
+  });
+
+  testGesture('Pointer pan/zooms should work alongside touches', (GestureTester tester) {
+    final ScaleGestureRecognizer scale = ScaleGestureRecognizer();
+    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer();
+
+    bool didStartScale = false;
+    Offset? updatedFocalPoint;
+    scale.onStart = (ScaleStartDetails details) {
+      didStartScale = true;
+      updatedFocalPoint = details.focalPoint;
+    };
+
+    double? updatedScale;
+    double? updatedHorizontalScale;
+    double? updatedVerticalScale;
+    Offset? updatedDelta;
+    double? updatedRotation;
+    scale.onUpdate = (ScaleUpdateDetails details) {
+      updatedScale = details.scale;
+      updatedHorizontalScale = details.horizontalScale;
+      updatedVerticalScale = details.verticalScale;
+      updatedFocalPoint = details.focalPoint;
+      updatedDelta = details.focalPointDelta;
+      updatedRotation = details.rotation;
+    };
+
+    bool didEndScale = false;
+    scale.onEnd = (ScaleEndDetails details) {
+      didEndScale = true;
+    };
+
+    final TestPointer touchPointer1 = TestPointer(2);
+    final TestPointer touchPointer2 = TestPointer(3);
+    final TestPointer panZoomPointer = TestPointer(4);
+
+    final PointerPanZoomStartEvent panZoomStart = panZoomPointer.panZoomStart(Offset.zero);
+    scale.addPointerPanZoom(panZoomStart);
+    drag.addPointerPanZoom(panZoomStart);
+
+    tester.closeArena(4);
+    expect(didStartScale, isFalse);
+    expect(updatedScale, isNull);
+    expect(updatedFocalPoint, isNull);
+    expect(updatedDelta, isNull);
+    expect(didEndScale, isFalse);
+
+    // Panning starting with trackpad.
+    tester.route(panZoomStart);
+    expect(didStartScale, isFalse);
+    expect(updatedScale, isNull);
+    expect(updatedFocalPoint, isNull);
+    expect(updatedDelta, isNull);
+    expect(didEndScale, isFalse);
+
+    tester.route(panZoomPointer.panZoomUpdate(Offset.zero, pan: const Offset(40, 40)));
+    expect(didStartScale, isTrue);
+    didStartScale = false;
+    expect(updatedFocalPoint, const Offset(40.0, 40.0));
+    updatedFocalPoint = null;
+    expect(updatedScale, 1.0);
+    updatedScale = null;
+    expect(updatedDelta, const Offset(40.0, 40.0));
+    updatedDelta = null;
+    expect(didEndScale, isFalse);
+
+    // Add a touch pointer.
+    final PointerDownEvent touchStart1 = touchPointer1.down(const Offset(40, 40));
+    scale.addPointer(touchStart1);
+    drag.addPointer(touchStart1);
+    tester.closeArena(2);
+    tester.route(touchStart1);
+    expect(didEndScale, isTrue);
+    didEndScale = false;
+
+    tester.route(touchPointer1.move(const Offset(10, 10)));
+    expect(didStartScale, isTrue);
+    didStartScale = false;
+    expect(updatedFocalPoint, const Offset(25, 25));
+    updatedFocalPoint = null;
+    // 1 down pointer + pointer pan/zoom should not scale, only pan.
+    expect(updatedScale, 1.0);
+    updatedScale = null;
+    expect(updatedDelta, const Offset(-15, -15));
+    updatedDelta = null;
+    expect(didEndScale, isFalse);
+
+    // Add a second touch pointer.
+    final PointerDownEvent touchStart2 = touchPointer2.down(const Offset(10, 40));
+    scale.addPointer(touchStart2);
+    drag.addPointer(touchStart2);
+    tester.closeArena(3);
+    tester.route(touchStart2);
+    expect(didEndScale, isTrue);
+    didEndScale = false;
+
+    // Move the second pointer to cause pan, zoom, and rotation.
+    tester.route(touchPointer2.move(const Offset(40, 40)));
+    expect(didStartScale, isTrue);
+    didStartScale = false;
+    expect(updatedFocalPoint, const Offset(30, 30));
+    updatedFocalPoint = null;
+    expect(updatedScale, math.sqrt(2));
+    updatedScale = null;
+    expect(updatedHorizontalScale, 1.0);
+    updatedHorizontalScale = null;
+    expect(updatedVerticalScale, 1.0);
+    updatedVerticalScale = null;
+    expect(updatedDelta, const Offset(10, 0));
+    updatedDelta = null;
+    expect(updatedRotation, -math.pi / 4);
+    updatedRotation = null;
+    expect(didEndScale, isFalse);
+
+    // Change the scale and angle of the pan/zoom to test combining.
+    // Scale should be multiplied together.
+    // Rotation angle should be added together.
+    tester.route(panZoomPointer.panZoomUpdate(Offset.zero, pan: const Offset(40, 40), scale: math.sqrt(2), rotation: math.pi / 3));
+    expect(didStartScale, isFalse);
+    expect(updatedFocalPoint, const Offset(30, 30));
+    updatedFocalPoint = null;
+    expect(updatedScale, closeTo(2, 0.0001));
+    updatedScale = null;
+    expect(updatedHorizontalScale, math.sqrt(2));
+    updatedHorizontalScale = null;
+    expect(updatedVerticalScale, math.sqrt(2));
+    updatedVerticalScale = null;
+    expect(updatedDelta, Offset.zero);
+    updatedDelta = null;
+    expect(updatedRotation, closeTo(math.pi / 12, 0.0001));
+    updatedRotation = null;
+    expect(didEndScale, isFalse);
+
+    // Move the pan/zoom origin to test combining.
+    tester.route(panZoomPointer.panZoomUpdate(const Offset(15, 15), pan: const Offset(55, 55), scale: math.sqrt(2), rotation: math.pi / 3));
+    expect(didStartScale, isFalse);
+    expect(updatedFocalPoint, const Offset(40, 40));
+    updatedFocalPoint = null;
+    expect(updatedScale, closeTo(2, 0.0001));
+    updatedScale = null;
+    expect(updatedDelta, const Offset(10, 10));
+    updatedDelta = null;
+    expect(updatedRotation, closeTo(math.pi / 12, 0.0001));
+    updatedRotation = null;
+    expect(didEndScale, isFalse);
+
+    // We are done.
+    tester.route(panZoomPointer.panZoomEnd());
+    expect(updatedFocalPoint, isNull);
+    expect(didEndScale, isTrue);
+    didEndScale = false;
+    expect(updatedScale, isNull);
+    expect(updatedDelta, isNull);
+    expect(didStartScale, isFalse);
+    tester.route(touchPointer1.up());
+    expect(updatedFocalPoint, isNull);
+    expect(didEndScale, isFalse);
+    expect(updatedScale, isNull);
+    expect(updatedDelta, isNull);
+    expect(didStartScale, isFalse);
+    tester.route(touchPointer2.up());
+    expect(didEndScale, isFalse);
+    expect(updatedFocalPoint, isNull);
+    expect(updatedScale, isNull);
+    expect(updatedDelta, isNull);
+    expect(didStartScale, isFalse);
+
+    scale.dispose();
+  });
+
+  testGesture('Scale gesture competes with drag for trackpad gesture', (GestureTester tester) {
+    final ScaleGestureRecognizer scale = ScaleGestureRecognizer();
+    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer();
+
+    final List<String> log = <String>[];
+
+    scale.onStart = (ScaleStartDetails details) { log.add('scale-start'); };
+    scale.onUpdate = (ScaleUpdateDetails details) { log.add('scale-update'); };
+    scale.onEnd = (ScaleEndDetails details) { log.add('scale-end'); };
+
+    drag.onStart = (DragStartDetails details) { log.add('drag-start'); };
+    drag.onEnd = (DragEndDetails details) { log.add('drag-end'); };
+
+    final TestPointer pointer1 = TestPointer(2);
+
+    final PointerPanZoomStartEvent down = pointer1.panZoomStart(const Offset(10.0, 10.0));
+    scale.addPointerPanZoom(down);
+    drag.addPointerPanZoom(down);
+
+    tester.closeArena(2);
+    expect(log, isEmpty);
+
+    // Vertical moves are scales.
+    tester.route(down);
+    expect(log, isEmpty);
+
+    // Scale will win if focal point delta exceeds 18.0*2.
+
+    tester.route(pointer1.panZoomUpdate(const Offset(10.0, 10.0), pan: const Offset(10.0, 40.0))); // delta of 40.0 exceeds 18.0*2.
+    expect(log, equals(<String>['scale-start', 'scale-update']));
+    log.clear();
+
+    final TestPointer pointer2 = TestPointer(3);
+    final PointerPanZoomStartEvent down2 = pointer2.panZoomStart(const Offset(10.0, 20.0));
+    scale.addPointerPanZoom(down2);
+    drag.addPointerPanZoom(down2);
+
+    tester.closeArena(3);
+    expect(log, isEmpty);
+
+    // Second pointer joins scale even though it moves horizontally.
+    tester.route(down2);
+    expect(log, <String>['scale-end']);
+    log.clear();
+
+    tester.route(pointer2.panZoomUpdate(const Offset(10.0, 20.0), pan: const Offset(20.0, 0.0)));
+    expect(log, equals(<String>['scale-start', 'scale-update']));
+    log.clear();
+
+    tester.route(pointer1.panZoomEnd());
+    expect(log, equals(<String>['scale-end']));
+    log.clear();
+
+    tester.route(pointer2.panZoomEnd());
+    expect(log, isEmpty);
+    log.clear();
+
+    // Horizontal moves are either drags or scales, depending on which wins first.
+    // TODO(ianh): https://github.com/flutter/flutter/issues/11384
+    // In this case, we move fast, so that the scale wins. If we moved slowly,
+    // the horizontal drag would win, since it was added first.
+    final TestPointer pointer3 = TestPointer(4);
+    final PointerPanZoomStartEvent down3 = pointer3.panZoomStart(const Offset(30.0, 30.0));
+    scale.addPointerPanZoom(down3);
+    drag.addPointerPanZoom(down3);
+    tester.closeArena(4);
+    tester.route(down3);
+
+    expect(log, isEmpty);
+
+    tester.route(pointer3.panZoomUpdate(const Offset(30.0, 30.0), pan: const Offset(70.0, 0.0)));
+    expect(log, equals(<String>['scale-start', 'scale-update']));
+    log.clear();
+
+    tester.route(pointer3.panZoomEnd());
+    expect(log, equals(<String>['scale-end']));
+    log.clear();
+
+    scale.dispose();
+    drag.dispose();
+  });
+
+  testGesture('Scale gesture from pan/zoom events properly handles DragStartBehavior.start', (GestureTester tester) {
+    final ScaleGestureRecognizer scale = ScaleGestureRecognizer(dragStartBehavior: DragStartBehavior.start);
+    final HorizontalDragGestureRecognizer drag = HorizontalDragGestureRecognizer();
+
+    bool didStartScale = false;
+    Offset? updatedFocalPoint;
+    scale.onStart = (ScaleStartDetails details) {
+      didStartScale = true;
+      updatedFocalPoint = details.focalPoint;
+    };
+
+    double? updatedScale;
+    double? updatedHorizontalScale;
+    double? updatedVerticalScale;
+    double? updatedRotation;
+    Offset? updatedDelta;
+    scale.onUpdate = (ScaleUpdateDetails details) {
+      updatedScale = details.scale;
+      updatedHorizontalScale = details.horizontalScale;
+      updatedVerticalScale = details.verticalScale;
+      updatedFocalPoint = details.focalPoint;
+      updatedRotation = details.rotation;
+      updatedDelta = details.focalPointDelta;
+    };
+
+    bool didEndScale = false;
+    scale.onEnd = (ScaleEndDetails details) {
+      didEndScale = true;
+    };
+
+    final TestPointer pointer1 = TestPointer(2);
+
+    final PointerPanZoomStartEvent start = pointer1.panZoomStart(Offset.zero);
+    scale.addPointerPanZoom(start);
+    drag.addPointerPanZoom(start);
+
+    tester.closeArena(2);
+    expect(didStartScale, isFalse);
+    expect(updatedScale, isNull);
+    expect(updatedFocalPoint, isNull);
+    expect(updatedDelta, isNull);
+    expect(didEndScale, isFalse);
+
+    tester.route(start);
+    expect(didStartScale, isFalse);
+    expect(updatedScale, isNull);
+    expect(updatedFocalPoint, isNull);
+    expect(updatedDelta, isNull);
+    expect(didEndScale, isFalse);
+
+    // Zoom enough to win the gesture.
+    tester.route(pointer1.panZoomUpdate(Offset.zero, scale: 1.1, rotation: 1));
+    expect(didStartScale, isTrue);
+    didStartScale = false;
+    expect(updatedFocalPoint, Offset.zero);
+    updatedFocalPoint = null;
+    expect(updatedScale, 1.0);
+    updatedScale = null;
+    expect(updatedDelta, Offset.zero);
+    updatedDelta = null;
+    expect(didEndScale, isFalse);
+
+    // Zoom in - should be relative to 1.1.
+    tester.route(pointer1.panZoomUpdate(Offset.zero, scale: 1.21, rotation: 1.5));
+    expect(updatedFocalPoint, Offset.zero);
+    updatedFocalPoint = null;
+    expect(updatedScale, closeTo(1.1, 0.0001));
+    expect(updatedHorizontalScale, closeTo(1.1, 0.0001));
+    expect(updatedVerticalScale, closeTo(1.1, 0.0001));
+    expect(updatedRotation, 0.5);
+    expect(updatedDelta, Offset.zero);
+    updatedScale = null;
+    updatedHorizontalScale = null;
+    updatedVerticalScale = null;
+    updatedRotation = null;
+    updatedDelta = null;
+    expect(didEndScale, isFalse);
+
+    // Zoom out - should be relative to 1.1.
+    tester.route(pointer1.panZoomUpdate(Offset.zero, scale: 0.99, rotation: 1.0));
+    expect(updatedFocalPoint, Offset.zero);
+    updatedFocalPoint = null;
+    expect(updatedScale, closeTo(0.9, 0.0001));
+    expect(updatedHorizontalScale, closeTo(0.9, 0.0001));
+    expect(updatedVerticalScale, closeTo(0.9, 0.0001));
+    expect(updatedRotation, 0.0);
+    expect(updatedDelta, Offset.zero);
+    updatedScale = null;
+    updatedHorizontalScale = null;
+    updatedVerticalScale = null;
+    updatedDelta = null;
+    expect(didEndScale, isFalse);
+
+    // We are done.
+    tester.route(pointer1.panZoomEnd());
+    expect(didStartScale, isFalse);
+    expect(updatedFocalPoint, isNull);
+    expect(updatedScale, isNull);
+    expect(updatedDelta, isNull);
+    expect(didEndScale, isTrue);
+    didEndScale = false;
+
+    scale.dispose();
+  });
+
   testWidgets('ScaleGestureRecognizer asserts when kind and supportedDevices are both set', (WidgetTester tester) async {
     expect(
       () {

packages/flutter/test/widgets/keep_alive_test.dart

@@ -272,7 +272,7 @@ void main() {
       '               │ constraints: BoxConstraints(w=800.0, h=600.0)\n'
       '               │ size: Size(800.0, 600.0)\n'
       '               │ behavior: opaque\n'
-      '               │ listeners: down\n'
+      '               │ listeners: down, panZoomStart\n'
       '               │\n'
       '               └─child: RenderSemanticsAnnotations#00000\n'
       '                 │ needs compositing\n'
@@ -432,7 +432,7 @@ void main() {
       '               │ constraints: BoxConstraints(w=800.0, h=600.0)\n'
       '               │ size: Size(800.0, 600.0)\n'
       '               │ behavior: opaque\n'
-      '               │ listeners: down\n'
+      '               │ listeners: down, panZoomStart\n'
       '               │\n'
       '               └─child: RenderSemanticsAnnotations#00000\n'
       '                 │ needs compositing\n'

packages/flutter/test/widgets/scroll_behavior_test.dart

@@ -134,6 +134,7 @@ void main() {
         PointerDeviceKind.touch,
         PointerDeviceKind.stylus,
         PointerDeviceKind.invertedStylus,
+        PointerDeviceKind.trackpad,
         PointerDeviceKind.unknown,
       });
 

packages/flutter_test/lib/src/test_pointer.dart

@@ -33,9 +33,8 @@ class TestPointer {
       case PointerDeviceKind.stylus:
       case PointerDeviceKind.invertedStylus:
       case PointerDeviceKind.touch:
+      case PointerDeviceKind.trackpad:
       case PointerDeviceKind.unknown:
-      default: // ignore: no_default_cases, to allow adding new device types to [PointerDeviceKind]
-               // TODO(moffatman): Remove after landing https://github.com/flutter/flutter/issues/23604
         _device = device ?? 0;
         break;
     }
@@ -70,12 +69,27 @@ class TestPointer {
   bool get isDown => _isDown;
   bool _isDown = false;
 
+  /// Whether the pointer simulated by this object currently has
+  /// an active pan/zoom gesture.
+  ///
+  /// A pan/zoom gesture begins when [panZoomStart] is called, and
+  /// ends when [panZoomEnd] is called.
+  bool get isPanZoomActive => _isPanZoomActive;
+  bool _isPanZoomActive = false;
+
   /// The position of the last event sent by this object.
   ///
   /// If no event has ever been sent by this object, returns null.
   Offset? get location => _location;
   Offset? _location;
 
+
+  /// The pan offset of the last pointer pan/zoom event sent by this object.
+  ///
+  /// If no pan/zoom event has ever been sent by this object, returns null.
+  Offset? get pan => _pan;
+  Offset? _pan;
+
   /// If a custom event is created outside of this class, this function is used
   /// to set the [isDown].
   bool setDownInfo(
@@ -115,6 +129,7 @@ class TestPointer {
     int? buttons,
   }) {
     assert(!isDown);
+    assert(!isPanZoomActive);
     _isDown = true;
     _location = newLocation;
     if (buttons != null)
@@ -149,6 +164,7 @@ class TestPointer {
         'Move events can only be generated when the pointer is down. To '
         'create a movement event simulating a pointer move when the pointer is '
         'up, use hover() instead.');
+    assert(!isPanZoomActive);
     final Offset delta = newLocation - location!;
     _location = newLocation;
     if (buttons != null)
@@ -171,6 +187,7 @@ class TestPointer {
   ///
   /// The object is no longer usable after this method has been called.
   PointerUpEvent up({ Duration timeStamp = Duration.zero }) {
+    assert(!isPanZoomActive);
     assert(isDown);
     _isDown = false;
     return PointerUpEvent(
@@ -283,6 +300,79 @@ class TestPointer {
       scrollDelta: scrollDelta,
     );
   }
+
+  /// Create a [PointerPanZoomStartEvent] (e.g., trackpad scroll; not scroll wheel
+  /// or finger-drag scroll) with the given delta.
+  ///
+  /// By default, the time stamp on the event is [Duration.zero]. You can give a
+  /// specific time stamp by passing the `timeStamp` argument.
+  PointerPanZoomStartEvent panZoomStart(
+    Offset location, {
+    Duration timeStamp = Duration.zero
+  }) {
+    assert(!isPanZoomActive);
+    _location = location;
+    _pan = Offset.zero;
+    _isPanZoomActive = true;
+    return PointerPanZoomStartEvent(
+      timeStamp: timeStamp,
+      kind: kind,
+      device: _device,
+      pointer: pointer,
+      position: location,
+    );
+  }
+
+  /// Create a [PointerPanZoomUpdateEvent] to update the active pan/zoom sequence
+  /// on this pointer with updated pan, scale, and/or rotation values.
+  ///
+  /// [rotation] is in units of radians.
+  ///
+  /// By default, the time stamp on the event is [Duration.zero]. You can give a
+  /// specific time stamp by passing the `timeStamp` argument.
+  PointerPanZoomUpdateEvent panZoomUpdate(
+    Offset location, {
+    Offset pan = Offset.zero,
+    double scale = 1,
+    double rotation = 0,
+    Duration timeStamp = Duration.zero,
+  }) {
+    assert(isPanZoomActive);
+    _location = location;
+    final Offset panDelta = pan - _pan!;
+    _pan = pan;
+    return PointerPanZoomUpdateEvent(
+      timeStamp: timeStamp,
+      kind: kind,
+      device: _device,
+      pointer: pointer,
+      position: location,
+      pan: pan,
+      panDelta: panDelta,
+      scale: scale,
+      rotation: rotation,
+    );
+  }
+
+  /// Create a [PointerPanZoomEndEvent] to end the active pan/zoom sequence
+  /// on this pointer.
+  ///
+  /// By default, the time stamp on the event is [Duration.zero]. You can give a
+  /// specific time stamp by passing the `timeStamp` argument.
+  PointerPanZoomEndEvent panZoomEnd({
+    Duration timeStamp = Duration.zero
+  }) {
+    assert(isPanZoomActive);
+    _isPanZoomActive = false;
+    _pan = null;
+    return PointerPanZoomEndEvent(
+      timeStamp: timeStamp,
+      kind: kind,
+      device: _device,
+      pointer: pointer,
+      position: location!,
+    );
+  }
 }
 
 /// Signature for a callback that can dispatch events and returns a future that

packages/flutter_tools/templates/app_shared/ios.tmpl/Runner/Info.plist.tmpl

@@ -45,5 +45,7 @@
 	<false/>
 	<key>CADisableMinimumFrameDurationOnPhone</key>
 	<true/>
+	<key>UIApplicationSupportsIndirectInputEvents</key>
+	<true/>
 </dict>
 </plist>

packages/flutter_tools/templates/module/ios/host_app_ephemeral/Runner.tmpl/Info.plist.tmpl

@@ -45,5 +45,7 @@
 	<false/>
 	<key>CADisableMinimumFrameDurationOnPhone</key>
 	<true/>
+	<key>UIApplicationSupportsIndirectInputEvents</key>
+	<true/>
 </dict>
 </plist>

packages/flutter_tools/test/commands.shard/permeable/create_test.dart

@@ -1383,6 +1383,8 @@ void main() {
     expect(plistFile, exists);
     final bool disabled = _getBooleanValueFromPlist(plistFile: plistFile, key: 'CADisableMinimumFrameDurationOnPhone');
     expect(disabled, isTrue);
+    final bool indirectInput = _getBooleanValueFromPlist(plistFile: plistFile, key: 'UIApplicationSupportsIndirectInputEvents');
+    expect(indirectInput, isTrue);
     final String displayName = _getStringValueFromPlist(plistFile: plistFile, key: 'CFBundleDisplayName');
     expect(displayName, 'My Project');
   });
@@ -1400,6 +1402,8 @@ void main() {
     expect(plistFile, exists);
     final bool disabled = _getBooleanValueFromPlist(plistFile: plistFile, key: 'CADisableMinimumFrameDurationOnPhone');
     expect(disabled, isTrue);
+    final bool indirectInput = _getBooleanValueFromPlist(plistFile: plistFile, key: 'UIApplicationSupportsIndirectInputEvents');
+    expect(indirectInput, isTrue);
     final String displayName = _getStringValueFromPlist(plistFile: plistFile, key: 'CFBundleDisplayName');
     expect(displayName, 'My Project');
   });
@@ -1417,6 +1421,8 @@ void main() {
     expect(plistFile, exists);
     final bool disabled = _getBooleanValueFromPlist(plistFile: plistFile, key: 'CADisableMinimumFrameDurationOnPhone');
     expect(disabled, isTrue);
+    final bool indirectInput = _getBooleanValueFromPlist(plistFile: plistFile, key: 'UIApplicationSupportsIndirectInputEvents');
+    expect(indirectInput, isTrue);
     final String displayName = _getStringValueFromPlist(plistFile: plistFile, key: 'CFBundleDisplayName');
     expect(displayName, 'My Project');
   }, overrides: <Type, Generator>{
@@ -1443,6 +1449,8 @@ void main() {
     expect(plistFile, exists);
     final bool disabled = _getBooleanValueFromPlist(plistFile: plistFile, key: 'CADisableMinimumFrameDurationOnPhone');
     expect(disabled, isTrue);
+    final bool indirectInput = _getBooleanValueFromPlist(plistFile: plistFile, key: 'UIApplicationSupportsIndirectInputEvents');
+    expect(indirectInput, isTrue);
     final String displayName = _getStringValueFromPlist(plistFile: plistFile, key: 'CFBundleDisplayName');
     expect(displayName, 'My Project');
   }, overrides: <Type, Generator>{
@@ -1469,6 +1477,8 @@ void main() {
     expect(plistFile, exists);
     final bool disabled = _getBooleanValueFromPlist(plistFile: plistFile, key: 'CADisableMinimumFrameDurationOnPhone');
     expect(disabled, isTrue);
+    final bool indirectInput = _getBooleanValueFromPlist(plistFile: plistFile, key: 'UIApplicationSupportsIndirectInputEvents');
+    expect(indirectInput, isTrue);
     final String displayName = _getStringValueFromPlist(plistFile: plistFile, key: 'CFBundleDisplayName');
     expect(displayName, 'My Project');
   });
@@ -1486,6 +1496,8 @@ void main() {
     expect(plistFile, exists);
     final bool disabled = _getBooleanValueFromPlist(plistFile: plistFile, key: 'CADisableMinimumFrameDurationOnPhone');
     expect(disabled, isTrue);
+    final bool indirectInput = _getBooleanValueFromPlist(plistFile: plistFile, key: 'UIApplicationSupportsIndirectInputEvents');
+    expect(indirectInput, isTrue);
     final String displayName = _getStringValueFromPlist(plistFile: plistFile, key: 'CFBundleDisplayName');
     expect(displayName, 'My Project');
   });