fix issue: #13911 'Double Click' bug on iPad with Magic Mouse (#14086)

* fix issue: #13911 'Double Click' bug on iPad with Magic Mouse

* remote_input.dart comments - gestures.dart organization and clean states of all interrupted gestures

flutter/lib/common/widgets/gestures.dart

@@ -25,6 +25,7 @@ class CustomTouchGestureRecognizer extends ScaleGestureRecognizer {
   GestureDragStartCallback? onOneFingerPanStart;
   GestureDragUpdateCallback? onOneFingerPanUpdate;
   GestureDragEndCallback? onOneFingerPanEnd;
+  GestureDragCancelCallback? onOneFingerPanCancel;
 
   // twoFingerScale : scale + pan event
   GestureScaleStartCallback? onTwoFingerScaleStart;
@@ -169,6 +170,27 @@ class CustomTouchGestureRecognizer extends ScaleGestureRecognizer {
 
   DragEndDetails _getDragEndDetails(ScaleEndDetails d) =>
       DragEndDetails(velocity: d.velocity);
+
+  @override
+  void rejectGesture(int pointer) {
+    super.rejectGesture(pointer);
+    switch (_currentState) {
+      case GestureState.oneFingerPan:
+        if (onOneFingerPanCancel != null) {
+          onOneFingerPanCancel!();
+        }
+        break;
+      case GestureState.twoFingerScale:
+        // Reset scale state if needed, currently self-contained
+        break;
+      case GestureState.threeFingerVerticalDrag:
+        // Reset drag state if needed, currently self-contained
+        break;
+      default:
+        break;
+    }
+    _currentState = GestureState.none;
+  }
 }
 
 class HoldTapMoveGestureRecognizer extends GestureRecognizer {
@@ -717,6 +739,7 @@ RawGestureDetector getMixinGestureDetector({
   GestureDragStartCallback? onOneFingerPanStart,
   GestureDragUpdateCallback? onOneFingerPanUpdate,
   GestureDragEndCallback? onOneFingerPanEnd,
+  GestureDragCancelCallback? onOneFingerPanCancel,
   GestureScaleUpdateCallback? onTwoFingerScaleUpdate,
   GestureScaleEndCallback? onTwoFingerScaleEnd,
   GestureDragUpdateCallback? onThreeFingerVerticalDragUpdate,
@@ -765,6 +788,7 @@ RawGestureDetector getMixinGestureDetector({
             ..onOneFingerPanStart = onOneFingerPanStart
             ..onOneFingerPanUpdate = onOneFingerPanUpdate
             ..onOneFingerPanEnd = onOneFingerPanEnd
+            ..onOneFingerPanCancel = onOneFingerPanCancel
             ..onTwoFingerScaleUpdate = onTwoFingerScaleUpdate
             ..onTwoFingerScaleEnd = onTwoFingerScaleEnd
             ..onThreeFingerVerticalDragUpdate = onThreeFingerVerticalDragUpdate;

flutter/lib/common/widgets/remote_input.dart

@@ -158,7 +158,8 @@ class _RawTouchGestureDetectorRegionState
       final isMoved =
           await ffi.cursorModel.move(d.localPosition.dx, d.localPosition.dy);
       if (isMoved) {
-        if (lastTapDownDetails != null) {
+        // If pan already handled 'down', don't send it again.
+        if (lastTapDownDetails != null && !_touchModePanStarted) {
           await inputModel.tapDown(MouseButtons.left);
         }
         await inputModel.tapUp(MouseButtons.left);
@@ -424,6 +425,14 @@ class _RawTouchGestureDetectorRegionState
     }
   }
 
+  // Reset `_touchModePanStarted` if the one-finger pan gesture is cancelled
+  // or rejected by the gesture arena. Without this, the flag can remain
+  // stuck in the "started" state and cause issues such as the Magic Mouse
+  // double-click problem on iPad with magic mouse.
+  onOneFingerPanCancel() {
+    _touchModePanStarted = false;
+  }
+
   // scale + pan event
   onTwoFingerScaleStart(ScaleStartDetails d) {
     _lastTapDownDetails = null;
@@ -557,6 +566,7 @@ class _RawTouchGestureDetectorRegionState
         instance
           ..onOneFingerPanUpdate = onOneFingerPanUpdate
           ..onOneFingerPanEnd = onOneFingerPanEnd
+          ..onOneFingerPanCancel = onOneFingerPanCancel
           ..onTwoFingerScaleStart = onTwoFingerScaleStart
           ..onTwoFingerScaleUpdate = onTwoFingerScaleUpdate
           ..onTwoFingerScaleEnd = onTwoFingerScaleEnd