Remove unnecessary null checks in flutter/gestures (#118926)

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

@@ -266,7 +266,6 @@ class GestureArenaManager {
 
   void _resolveInFavorOf(int pointer, _GestureArena state, GestureArenaMember member) {
     assert(state == _arenas[pointer]);
-    assert(state != null);
     assert(state.eagerWinner == null || state.eagerWinner == member);
     assert(!state.isOpen);
     _arenas.remove(pointer);

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

@@ -83,8 +83,6 @@ class _Resampler {
   // Add `event` for resampling or dispatch it directly if
   // not a touch event.
   void addOrDispatch(PointerEvent event) {
-    final SchedulerBinding scheduler = SchedulerBinding.instance;
-    assert(scheduler != null);
     // Add touch event to resampler or dispatch pointer event directly.
     if (event.kind == PointerDeviceKind.touch) {
       // Save last event time for debugPrint of resampling margin.
@@ -108,7 +106,6 @@ class _Resampler {
   // The `samplingClock` is the clock used to determine frame time age.
   void sample(Duration samplingOffset, SamplingClock clock) {
     final SchedulerBinding scheduler = SchedulerBinding.instance;
-    assert(scheduler != null);
 
     // Initialize `_frameTime` if needed. This will be used for periodic
     // sampling when frame callbacks are not received.
@@ -391,7 +388,6 @@ mixin GestureBinding on BindingBase implements HitTestable, HitTestDispatcher, H
     if (hitTestResult != null ||
         event is PointerAddedEvent ||
         event is PointerRemovedEvent) {
-      assert(event.position != null);
       dispatchEvent(event, hitTestResult);
     }
   }

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

@@ -54,7 +54,6 @@ class PointerEventConverter {
         .where((ui.PointerData datum) => datum.signalKind != ui.PointerSignalKind.unknown)
         .map((ui.PointerData datum) {
           final Offset position = Offset(datum.physicalX, datum.physicalY) / devicePixelRatio;
-          assert(position != null);
           final Offset delta = Offset(datum.physicalDeltaX, datum.physicalDeltaY) / devicePixelRatio;
           final double radiusMinor = _toLogicalPixels(datum.radiusMinor, devicePixelRatio);
           final double radiusMajor = _toLogicalPixels(datum.radiusMajor, devicePixelRatio);
@@ -62,7 +61,6 @@ class PointerEventConverter {
           final double radiusMax = _toLogicalPixels(datum.radiusMax, devicePixelRatio);
           final Duration timeStamp = datum.timeStamp;
           final PointerDeviceKind kind = datum.kind;
-          assert(datum.change != null);
           switch (datum.signalKind ?? ui.PointerSignalKind.none) {
             case ui.PointerSignalKind.none:
               switch (datum.change) {

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

@@ -25,8 +25,7 @@ class DragDownDetails {
   DragDownDetails({
     this.globalPosition = Offset.zero,
     Offset? localPosition,
-  }) : assert(globalPosition != null),
-       localPosition = localPosition ?? globalPosition;
+  }) : localPosition = localPosition ?? globalPosition;
 
   /// The global position at which the pointer contacted the screen.
   ///
@@ -73,8 +72,7 @@ class DragStartDetails {
     this.globalPosition = Offset.zero,
     Offset? localPosition,
     this.kind,
-  }) : assert(globalPosition != null),
-       localPosition = localPosition ?? globalPosition;
+  }) : localPosition = localPosition ?? globalPosition;
 
   /// Recorded timestamp of the source pointer event that triggered the drag
   /// event.
@@ -142,8 +140,7 @@ class DragUpdateDetails {
     this.primaryDelta,
     required this.globalPosition,
     Offset? localPosition,
-  }) : assert(delta != null),
-       assert(
+  }) : assert(
          primaryDelta == null
            || (primaryDelta == delta.dx && delta.dy == 0.0)
            || (primaryDelta == delta.dy && delta.dx == 0.0),
@@ -223,8 +220,7 @@ class DragEndDetails {
   DragEndDetails({
     this.velocity = Velocity.zero,
     this.primaryVelocity,
-  }) : assert(velocity != null),
-       assert(
+  }) : assert(
          primaryVelocity == null
            || primaryVelocity == velocity.pixelsPerSecond.dx
            || primaryVelocity == velocity.pixelsPerSecond.dy,

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

@@ -843,8 +843,7 @@ class PointerAddedEvent extends PointerEvent with _PointerEventDescription, _Cop
 }
 
 class _TransformedPointerAddedEvent extends _TransformedPointerEvent with _CopyPointerAddedEvent implements PointerAddedEvent {
-  _TransformedPointerAddedEvent(this.original, this.transform)
-    : assert(original != null), assert(transform != null);
+  _TransformedPointerAddedEvent(this.original, this.transform);
 
   @override
   final PointerAddedEvent original;
@@ -934,8 +933,7 @@ class PointerRemovedEvent extends PointerEvent with _PointerEventDescription, _C
 }
 
 class _TransformedPointerRemovedEvent extends _TransformedPointerEvent with _CopyPointerRemovedEvent implements PointerRemovedEvent {
-  _TransformedPointerRemovedEvent(this.original, this.transform)
-    : assert(original != null), assert(transform != null);
+  _TransformedPointerRemovedEvent(this.original, this.transform);
 
   @override
   final PointerRemovedEvent original;
@@ -1051,8 +1049,7 @@ class PointerHoverEvent extends PointerEvent with _PointerEventDescription, _Cop
 }
 
 class _TransformedPointerHoverEvent extends _TransformedPointerEvent with _CopyPointerHoverEvent implements PointerHoverEvent {
-  _TransformedPointerHoverEvent(this.original, this.transform)
-    : assert(original != null), assert(transform != null);
+  _TransformedPointerHoverEvent(this.original, this.transform);
 
   @override
   final PointerHoverEvent original;
@@ -1198,8 +1195,7 @@ class PointerEnterEvent extends PointerEvent with _PointerEventDescription, _Cop
 }
 
 class _TransformedPointerEnterEvent extends _TransformedPointerEvent with _CopyPointerEnterEvent implements PointerEnterEvent {
-  _TransformedPointerEnterEvent(this.original, this.transform)
-    : assert(original != null), assert(transform != null);
+  _TransformedPointerEnterEvent(this.original, this.transform);
 
   @override
   final PointerEnterEvent original;
@@ -1344,8 +1340,7 @@ class PointerExitEvent extends PointerEvent with _PointerEventDescription, _Copy
 }
 
 class _TransformedPointerExitEvent extends _TransformedPointerEvent with _CopyPointerExitEvent implements PointerExitEvent {
-  _TransformedPointerExitEvent(this.original, this.transform)
-    : assert(original != null), assert(transform != null);
+  _TransformedPointerExitEvent(this.original, this.transform);
 
   @override
   final PointerExitEvent original;
@@ -1453,8 +1448,7 @@ class PointerDownEvent extends PointerEvent with _PointerEventDescription, _Copy
 }
 
 class _TransformedPointerDownEvent extends _TransformedPointerEvent with _CopyPointerDownEvent implements PointerDownEvent {
-  _TransformedPointerDownEvent(this.original, this.transform)
-    : assert(original != null), assert(transform != null);
+  _TransformedPointerDownEvent(this.original, this.transform);
 
   @override
   final PointerDownEvent original;
@@ -1571,8 +1565,7 @@ class PointerMoveEvent extends PointerEvent with _PointerEventDescription, _Copy
 }
 
 class _TransformedPointerMoveEvent extends _TransformedPointerEvent with _CopyPointerMoveEvent implements PointerMoveEvent {
-  _TransformedPointerMoveEvent(this.original, this.transform)
-    : assert(original != null), assert(transform != null);
+  _TransformedPointerMoveEvent(this.original, this.transform);
 
   @override
   final PointerMoveEvent original;
@@ -1684,8 +1677,7 @@ class PointerUpEvent extends PointerEvent with _PointerEventDescription, _CopyPo
 }
 
 class _TransformedPointerUpEvent extends _TransformedPointerEvent with _CopyPointerUpEvent implements PointerUpEvent {
-  _TransformedPointerUpEvent(this.original, this.transform)
-    : assert(original != null), assert(transform != null);
+  _TransformedPointerUpEvent(this.original, this.transform);
 
   @override
   final PointerUpEvent original;
@@ -1784,11 +1776,7 @@ class PointerScrollEvent extends PointerSignalEvent with _PointerEventDescriptio
     super.position,
     this.scrollDelta = Offset.zero,
     super.embedderId,
-  }) : assert(timeStamp != null),
-       assert(kind != null),
-       assert(device != null),
-       assert(position != null),
-       assert(scrollDelta != null);
+  });
 
   @override
   final Offset scrollDelta;
@@ -1809,8 +1797,7 @@ class PointerScrollEvent extends PointerSignalEvent with _PointerEventDescriptio
 }
 
 class _TransformedPointerScrollEvent extends _TransformedPointerEvent with _CopyPointerScrollEvent implements PointerScrollEvent {
-  _TransformedPointerScrollEvent(this.original, this.transform)
-    : assert(original != null), assert(transform != null);
+  _TransformedPointerScrollEvent(this.original, this.transform);
 
   @override
   final PointerScrollEvent original;
@@ -1888,10 +1875,7 @@ class PointerScrollInertiaCancelEvent extends PointerSignalEvent with _PointerEv
     super.device,
     super.position,
     super.embedderId,
-  }) : assert(timeStamp != null),
-       assert(kind != null),
-       assert(device != null),
-       assert(position != null);
+  });
 
   @override
   PointerScrollInertiaCancelEvent transformed(Matrix4? transform) {
@@ -1903,8 +1887,7 @@ class PointerScrollInertiaCancelEvent extends PointerSignalEvent with _PointerEv
 }
 
 class _TransformedPointerScrollInertiaCancelEvent extends _TransformedPointerEvent with _CopyPointerScrollInertiaCancelEvent implements PointerScrollInertiaCancelEvent {
-  _TransformedPointerScrollInertiaCancelEvent(this.original, this.transform)
-    : assert(original != null), assert(transform != null);
+  _TransformedPointerScrollInertiaCancelEvent(this.original, this.transform);
 
   @override
   final PointerScrollInertiaCancelEvent original;
@@ -1979,12 +1962,7 @@ class PointerScaleEvent extends PointerSignalEvent with _PointerEventDescription
     super.position,
     super.embedderId,
     this.scale = 1.0,
-  }) : assert(timeStamp != null),
-       assert(kind != null),
-       assert(device != null),
-       assert(position != null),
-       assert(embedderId != null),
-       assert(scale != null);
+  });
 
   @override
   final double scale;
@@ -1999,8 +1977,7 @@ class PointerScaleEvent extends PointerSignalEvent with _PointerEventDescription
 }
 
 class _TransformedPointerScaleEvent extends _TransformedPointerEvent with _CopyPointerScaleEvent implements PointerScaleEvent {
-  _TransformedPointerScaleEvent(this.original, this.transform)
-    : assert(original != null), assert(transform != null);
+  _TransformedPointerScaleEvent(this.original, this.transform);
 
   @override
   final PointerScaleEvent original;
@@ -2068,13 +2045,7 @@ class PointerPanZoomStartEvent extends PointerEvent with _PointerEventDescriptio
     super.position,
     super.embedderId,
     super.synthesized,
-  }) : assert(timeStamp != null),
-       assert(device != null),
-       assert(pointer != null),
-       assert(position != null),
-       assert(embedderId != null),
-       assert(synthesized != null),
-       super(kind: PointerDeviceKind.trackpad);
+  }) : super(kind: PointerDeviceKind.trackpad);
 
   @override
   PointerPanZoomStartEvent transformed(Matrix4? transform) {
@@ -2086,8 +2057,7 @@ class PointerPanZoomStartEvent extends PointerEvent with _PointerEventDescriptio
 }
 
 class _TransformedPointerPanZoomStartEvent extends _TransformedPointerEvent with _CopyPointerPanZoomStartEvent implements PointerPanZoomStartEvent {
-  _TransformedPointerPanZoomStartEvent(this.original, this.transform)
-    : assert(original != null), assert(transform != null);
+  _TransformedPointerPanZoomStartEvent(this.original, this.transform);
 
   @override
   final PointerPanZoomStartEvent original;
@@ -2179,17 +2149,7 @@ class PointerPanZoomUpdateEvent extends PointerEvent with _PointerEventDescripti
     this.scale = 1.0,
     this.rotation = 0.0,
     super.synthesized,
-  }) : assert(timeStamp != 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(kind: PointerDeviceKind.trackpad);
+  }) : super(kind: PointerDeviceKind.trackpad);
 
   @override
   final Offset pan;
@@ -2214,8 +2174,7 @@ class PointerPanZoomUpdateEvent extends PointerEvent with _PointerEventDescripti
 }
 
 class _TransformedPointerPanZoomUpdateEvent extends _TransformedPointerEvent with _CopyPointerPanZoomUpdateEvent implements PointerPanZoomUpdateEvent {
-  _TransformedPointerPanZoomUpdateEvent(this.original, this.transform)
-    : assert(original != null), assert(transform != null);
+  _TransformedPointerPanZoomUpdateEvent(this.original, this.transform);
 
   @override
   Offset get pan => original.pan;
@@ -2303,13 +2262,7 @@ class PointerPanZoomEndEvent extends PointerEvent with _PointerEventDescription,
     super.position,
     super.embedderId,
     super.synthesized,
-  }) : assert(timeStamp != null),
-       assert(device != null),
-       assert(pointer != null),
-       assert(position != null),
-       assert(embedderId != null),
-       assert(synthesized != null),
-       super(kind: PointerDeviceKind.trackpad);
+  }) : super(kind: PointerDeviceKind.trackpad);
 
   @override
   PointerPanZoomEndEvent transformed(Matrix4? transform) {
@@ -2321,8 +2274,7 @@ class PointerPanZoomEndEvent extends PointerEvent with _PointerEventDescription,
 }
 
 class _TransformedPointerPanZoomEndEvent extends _TransformedPointerEvent with _CopyPointerPanZoomEndEvent implements PointerPanZoomEndEvent {
-  _TransformedPointerPanZoomEndEvent(this.original, this.transform)
-    : assert(original != null), assert(transform != null);
+  _TransformedPointerPanZoomEndEvent(this.original, this.transform);
 
   @override
   final PointerPanZoomEndEvent original;
@@ -2472,8 +2424,7 @@ double computeScaleSlop(PointerDeviceKind kind) {
 }
 
 class _TransformedPointerCancelEvent extends _TransformedPointerEvent with _CopyPointerCancelEvent implements PointerCancelEvent {
-  _TransformedPointerCancelEvent(this.original, this.transform)
-    : assert(original != null), assert(transform != null);
+  _TransformedPointerCancelEvent(this.original, this.transform);
 
   @override
   final PointerCancelEvent original;

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

@@ -52,9 +52,7 @@ class ForcePressDetails {
     required this.globalPosition,
     Offset? localPosition,
     required this.pressure,
-  }) : assert(globalPosition != null),
-       assert(pressure != null),
-       localPosition = localPosition ?? globalPosition;
+  }) : localPosition = localPosition ?? globalPosition;
 
   /// The global position at which the function was called.
   final Offset globalPosition;
@@ -134,10 +132,7 @@ class ForcePressGestureRecognizer extends OneSequenceGestureRecognizer {
     super.kind,
     super.supportedDevices,
     super.allowedButtonsFilter,
-  }) : assert(startPressure != null),
-       assert(peakPressure != null),
-       assert(interpolation != null),
-       assert(peakPressure > startPressure);
+  }) : assert(peakPressure > startPressure);
 
   /// A pointer is in contact with the screen and has just pressed with a force
   /// exceeding the [startPressure]. Consequently, if there were other gesture

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

@@ -215,7 +215,6 @@ class HitTestResult {
   ///    around this function for hit testing on [RenderBox]s.
   @protected
   void pushTransform(Matrix4 transform) {
-    assert(transform != null);
     assert(
       _debugVectorMoreOrLessEquals(transform.getRow(2), Vector4(0, 0, 1, 0)) &&
       _debugVectorMoreOrLessEquals(transform.getColumn(2), Vector4(0, 0, 1, 0)),
@@ -255,7 +254,6 @@ class HitTestResult {
   ///    around this function for hit testing on [RenderSliver]s.
   @protected
   void pushOffset(Offset offset) {
-    assert(offset != null);
     _localTransforms.add(_OffsetTransformPart(offset));
   }
 

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

@@ -115,8 +115,7 @@ class LongPressDownDetails {
     this.globalPosition = Offset.zero,
     Offset? localPosition,
     this.kind,
-  }) : assert(globalPosition != null),
-       localPosition = localPosition ?? globalPosition;
+  }) : localPosition = localPosition ?? globalPosition;
 
   /// The global position at which the pointer contacted the screen.
   final Offset globalPosition;
@@ -142,8 +141,7 @@ class LongPressStartDetails {
   const LongPressStartDetails({
     this.globalPosition = Offset.zero,
     Offset? localPosition,
-  }) : assert(globalPosition != null),
-       localPosition = localPosition ?? globalPosition;
+  }) : localPosition = localPosition ?? globalPosition;
 
   /// The global position at which the pointer initially contacted the screen.
   final Offset globalPosition;
@@ -168,9 +166,7 @@ class LongPressMoveUpdateDetails {
     Offset? localPosition,
     this.offsetFromOrigin = Offset.zero,
     Offset? localOffsetFromOrigin,
-  }) : assert(globalPosition != null),
-       assert(offsetFromOrigin != null),
-       localPosition = localPosition ?? globalPosition,
+  }) : localPosition = localPosition ?? globalPosition,
        localOffsetFromOrigin = localOffsetFromOrigin ?? offsetFromOrigin;
 
   /// The global position of the pointer when it triggered this update.
@@ -205,8 +201,7 @@ class LongPressEndDetails {
     this.globalPosition = Offset.zero,
     Offset? localPosition,
     this.velocity = Velocity.zero,
-  }) : assert(globalPosition != null),
-       localPosition = localPosition ?? globalPosition;
+  }) : localPosition = localPosition ?? globalPosition;
 
   /// The global position at which the pointer lifted from the screen.
   final Offset globalPosition;

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

@@ -84,7 +84,7 @@ abstract class DragGestureRecognizer extends OneSequenceGestureRecognizer {
     this.velocityTrackerBuilder = _defaultBuilder,
     super.supportedDevices,
     super.allowedButtonsFilter = _defaultButtonAcceptBehavior,
-  }) : assert(dragStartBehavior != null);
+  });
 
   static VelocityTracker _defaultBuilder(PointerEvent event) => VelocityTracker.withKind(event.kind);
 
@@ -313,7 +313,6 @@ abstract class DragGestureRecognizer extends OneSequenceGestureRecognizer {
          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) {
@@ -492,7 +491,6 @@ abstract class DragGestureRecognizer extends OneSequenceGestureRecognizer {
     }
 
     final VelocityTracker tracker = _velocityTrackers[pointer]!;
-    assert(tracker != null);
 
     final DragEndDetails details;
     final String Function() debugReport;

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

@@ -35,8 +35,7 @@ abstract class MultiDragPointerState {
   ///
   /// The [initialPosition] argument must not be null.
   MultiDragPointerState(this.initialPosition, this.kind, this.gestureSettings)
-    : assert(initialPosition != null),
-      _velocityTracker = VelocityTracker.withKind(kind);
+    : _velocityTracker = VelocityTracker.withKind(kind);
 
   /// Device specific gesture configuration that should be preferred over
   /// framework constants.
@@ -133,7 +132,6 @@ abstract class MultiDragPointerState {
   void _startDrag(Drag client) {
     assert(_arenaEntry != null);
     assert(_client == null);
-    assert(client != null);
     assert(pendingDelta != null);
     _client = client;
     final DragUpdateDetails details = DragUpdateDetails(
@@ -240,8 +238,6 @@ abstract class MultiDragGestureRecognizer extends GestureRecognizer {
   @override
   void addAllowedPointer(PointerDownEvent event) {
     assert(_pointers != null);
-    assert(event.pointer != null);
-    assert(event.position != null);
     assert(!_pointers!.containsKey(event.pointer));
     final MultiDragPointerState state = createNewPointerState(event);
     _pointers![event.pointer] = state;
@@ -257,9 +253,6 @@ abstract class MultiDragGestureRecognizer extends GestureRecognizer {
 
   void _handleEvent(PointerEvent event) {
     assert(_pointers != null);
-    assert(event.pointer != null);
-    assert(event.timeStamp != null);
-    assert(event.position != null);
     assert(_pointers!.containsKey(event.pointer));
     final MultiDragPointerState state = _pointers![event.pointer]!;
     if (event is PointerMoveEvent) {
@@ -296,7 +289,6 @@ abstract class MultiDragGestureRecognizer extends GestureRecognizer {
   Drag? _startDrag(Offset initialPosition, int pointer) {
     assert(_pointers != null);
     final MultiDragPointerState state = _pointers![pointer]!;
-    assert(state != null);
     assert(state._pendingDelta != null);
     Drag? drag;
     if (onStart != null) {
@@ -315,7 +307,6 @@ abstract class MultiDragGestureRecognizer extends GestureRecognizer {
     assert(_pointers != null);
     if (_pointers!.containsKey(pointer)) {
       final MultiDragPointerState state = _pointers![pointer]!;
-      assert(state != null);
       state.rejected();
       _removeState(pointer);
     } // else we already preemptively forgot about it (e.g. we got an up event)
@@ -515,8 +506,7 @@ class VerticalMultiDragGestureRecognizer extends MultiDragGestureRecognizer {
 }
 
 class _DelayedPointerState extends MultiDragPointerState {
-  _DelayedPointerState(super.initialPosition, Duration delay, super.kind, super.deviceGestureSettings)
-      : assert(delay != null) {
+  _DelayedPointerState(super.initialPosition, Duration delay, super.kind, super.deviceGestureSettings) {
     _timer = Timer(delay, _delayPassed);
   }
 
@@ -614,7 +604,7 @@ class DelayedMultiDragGestureRecognizer extends MultiDragGestureRecognizer {
     super.kind,
     super.supportedDevices,
     super.allowedButtonsFilter,
-  }) : assert(delay != null);
+  });
 
   /// The amount of time the pointer must remain in the same place for the drag
   /// to be recognized.

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

@@ -43,8 +43,7 @@ typedef GestureMultiTapCancelCallback = void Function(int pointer);
 /// CountdownZoned tracks whether the specified duration has elapsed since
 /// creation, honoring [Zone].
 class _CountdownZoned {
-  _CountdownZoned({ required Duration duration })
-       : assert(duration != null) {
+  _CountdownZoned({ required Duration duration }) {
     Timer(duration, _onTimeout);
   }
 
@@ -65,10 +64,7 @@ class _TapTracker {
     required this.entry,
     required Duration doubleTapMinTime,
     required this.gestureSettings,
-  }) : assert(doubleTapMinTime != null),
-       assert(event != null),
-       assert(event.buttons != null),
-       pointer = event.pointer,
+  }) : pointer = event.pointer,
        _initialGlobalPosition = event.position,
        initialButtons = event.buttons,
        _doubleTapMinTimeCountdown = _CountdownZoned(duration: doubleTapMinTime);
@@ -684,8 +680,7 @@ class SerialTapCancelDetails {
   /// The `count` argument must be greater than zero.
   SerialTapCancelDetails({
     this.count = 1,
-  }) : assert(count != null),
-       assert(count > 0);
+  }) : assert(count > 0);
 
   /// The number of consecutive taps that were in progress when the gesture was
   /// interrupted.

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

@@ -64,8 +64,6 @@ class PointerSignalResolver {
   /// See the documentation for the [PointerSignalResolver] class on when and
   /// how this method should be used.
   void register(PointerSignalEvent event, PointerSignalResolvedCallback callback) {
-    assert(event != null);
-    assert(callback != null);
     assert(_currentEvent == null || _isSameEvent(_currentEvent!, event));
     if (_firstRegisteredCallback != null) {
       return;

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

@@ -267,7 +267,6 @@ abstract class GestureRecognizer extends GestureArenaMember with DiagnosticableT
   @protected
   @pragma('vm:notify-debugger-on-exception')
   T? invokeCallback<T>(String name, RecognizerCallback<T> callback, { String Function()? debugReport }) {
-    assert(callback != null);
     T? result;
     try {
       assert(() {

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

@@ -102,7 +102,7 @@ class ScaleStartDetails {
     this.focalPoint = Offset.zero,
     Offset? localFocalPoint,
     this.pointerCount = 0,
-  }) : assert(focalPoint != null), localFocalPoint = localFocalPoint ?? focalPoint;
+  }) : localFocalPoint = localFocalPoint ?? focalPoint;
 
   /// The initial focal point of the pointers in contact with the screen.
   ///
@@ -151,12 +151,9 @@ class ScaleUpdateDetails {
     this.rotation = 0.0,
     this.pointerCount = 0,
     this.focalPointDelta = Offset.zero,
-  }) : assert(focalPoint != null),
-       assert(focalPointDelta != null),
-       assert(scale != null && scale >= 0.0),
-       assert(horizontalScale != null && horizontalScale >= 0.0),
-       assert(verticalScale != null && verticalScale >= 0.0),
-       assert(rotation != null),
+  }) : assert(scale >= 0.0),
+       assert(horizontalScale >= 0.0),
+       assert(verticalScale >= 0.0),
        localFocalPoint = localFocalPoint ?? focalPoint;
 
   /// The amount the gesture's focal point has moved in the coordinate space of
@@ -248,8 +245,7 @@ class ScaleEndDetails {
   /// Creates details for [GestureScaleEndCallback].
   ///
   /// The [velocity] argument must not be null.
-  ScaleEndDetails({ this.velocity = Velocity.zero, this.scaleVelocity = 0, this.pointerCount = 0 })
-    : assert(velocity != null);
+  ScaleEndDetails({ this.velocity = Velocity.zero, this.scaleVelocity = 0, this.pointerCount = 0 });
 
   /// The velocity of the last pointer to be lifted off of the screen.
   final Velocity velocity;
@@ -279,7 +275,6 @@ typedef GestureScaleUpdateCallback = void Function(ScaleUpdateDetails details);
 typedef GestureScaleEndCallback = void Function(ScaleEndDetails details);
 
 bool _isFlingGesture(Velocity velocity) {
-  assert(velocity != null);
   final double speedSquared = velocity.pixelsPerSecond.distanceSquared;
   return speedSquared > kMinFlingVelocity * kMinFlingVelocity;
 }
@@ -299,9 +294,7 @@ class _LineBetweenPointers {
     this.pointerStartId = 0,
     this.pointerEndLocation = Offset.zero,
     this.pointerEndId = 1,
-  }) : assert(pointerStartLocation != null && pointerEndLocation != null),
-       assert(pointerStartId != null && pointerEndId != null),
-       assert(pointerStartId != pointerEndId);
+  }) : assert(pointerStartId != pointerEndId);
 
   // The location and the id of the pointer that marks the start of the line.
   final Offset pointerStartLocation;
@@ -338,7 +331,7 @@ class ScaleGestureRecognizer extends OneSequenceGestureRecognizer {
     this.dragStartBehavior = DragStartBehavior.down,
     this.trackpadScrollCausesScale = false,
     this.trackpadScrollToScaleFactor = kDefaultTrackpadScrollToScaleFactor,
-  }) : assert(dragStartBehavior != null);
+  });
 
   /// Determines what point is used as the starting point in all calculations
   /// involving this gesture.

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

@@ -32,8 +32,7 @@ class TapDownDetails {
     this.globalPosition = Offset.zero,
     Offset? localPosition,
     this.kind,
-  }) : assert(globalPosition != null),
-       localPosition = localPosition ?? globalPosition;
+  }) : localPosition = localPosition ?? globalPosition;
 
   /// The global position at which the pointer contacted the screen.
   final Offset globalPosition;
@@ -71,8 +70,7 @@ class TapUpDetails {
     required this.kind,
     this.globalPosition = Offset.zero,
     Offset? localPosition,
-  }) : assert(globalPosition != null),
-       localPosition = localPosition ?? globalPosition;
+  }) : localPosition = localPosition ?? globalPosition;
 
   /// The global position at which the pointer contacted the screen.
   final Offset globalPosition;
@@ -206,7 +204,6 @@ abstract class BaseTapGestureRecognizer extends PrimaryPointerGestureRecognizer
 
   @override
   void addAllowedPointer(PointerDownEvent event) {
-    assert(event != null);
     if (state == GestureRecognizerState.ready) {
       // If there is no result in the previous gesture arena,
       // we ignore them and prepare to accept a new pointer.

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

@@ -18,7 +18,7 @@ class Velocity {
   /// The [pixelsPerSecond] argument must not be null.
   const Velocity({
     required this.pixelsPerSecond,
-  }) : assert(pixelsPerSecond != null);
+  });
 
   /// A velocity that isn't moving at all.
   static const Velocity zero = Velocity(pixelsPerSecond: Offset.zero);
@@ -50,8 +50,8 @@ class Velocity {
   /// If the magnitude of this Velocity is within the specified bounds then
   /// just return this.
   Velocity clampMagnitude(double minValue, double maxValue) {
-    assert(minValue != null && minValue >= 0.0);
-    assert(maxValue != null && maxValue >= 0.0 && maxValue >= minValue);
+    assert(minValue >= 0.0);
+    assert(maxValue >= 0.0 && maxValue >= minValue);
     final double valueSquared = pixelsPerSecond.distanceSquared;
     if (valueSquared > maxValue * maxValue) {
       return Velocity(pixelsPerSecond: (pixelsPerSecond / pixelsPerSecond.distance) * maxValue);
@@ -97,10 +97,7 @@ class VelocityEstimate {
     required this.confidence,
     required this.duration,
     required this.offset,
-  }) : assert(pixelsPerSecond != null),
-       assert(confidence != null),
-       assert(duration != null),
-       assert(offset != null);
+  });
 
   /// The number of pixels per second of velocity in the x and y directions.
   final Offset pixelsPerSecond;
@@ -124,9 +121,7 @@ class VelocityEstimate {
 }
 
 class _PointAtTime {
-  const _PointAtTime(this.point, this.time)
-    : assert(point != null),
-      assert(time != null);
+  const _PointAtTime(this.point, this.time);
 
   final Duration time;
   final Offset point;