Fix: BaseTapAndDragGestureRecognizer should reset drag state after losing gesture arena (#151989)
This PR properly resets the drag state when losing the gesture arena or when the recognizer stops tracking the current pointer. The _dragState enum was reset properly, but I had forgotten to also reset the `_start`, this caused an issue when the recognizer won the gesture arena the next time, as it tries to detect a drag given the old `_start` in `acceptGesture`, but the `_dragState` has been reset causing an assertion to trigger.
diff --git a/packages/flutter/lib/src/gestures/tap_and_drag.dart b/packages/flutter/lib/src/gestures/tap_and_drag.dart
index c847922..f1e06fe 100644
--- a/packages/flutter/lib/src/gestures/tap_and_drag.dart
+++ b/packages/flutter/lib/src/gestures/tap_and_drag.dart
@@ -1065,6 +1065,7 @@
}
_stopDeadlineTimer();
+ _start = null;
_dragState = _DragState.ready;
_pastSlopTolerance = false;
}
diff --git a/packages/flutter/test/gestures/tap_and_drag_test.dart b/packages/flutter/test/gestures/tap_and_drag_test.dart
index 9adc560..c06f399 100644
--- a/packages/flutter/test/gestures/tap_and_drag_test.dart
+++ b/packages/flutter/test/gestures/tap_and_drag_test.dart
@@ -45,9 +45,12 @@
addTearDown(tapAndDrag.dispose);
}
- void setUpTapAndHorizontalDragGestureRecognizer() {
+ void setUpTapAndHorizontalDragGestureRecognizer({
+ bool eagerVictoryOnDrag = true, // This is the default for [BaseTapAndDragGestureRecognizer].
+ }) {
tapAndDrag = TapAndHorizontalDragGestureRecognizer()
..dragStartBehavior = DragStartBehavior.down
+ ..eagerVictoryOnDrag = eagerVictoryOnDrag
..maxConsecutiveTap = 3
..onTapDown = (TapDragDownDetails details) {
events.add('down#${details.consecutiveTapCount}');
@@ -692,6 +695,74 @@
);
});
+ testGesture('Drag state is properly reset after losing GestureArena', (GestureTester tester) {
+ setUpTapAndHorizontalDragGestureRecognizer(eagerVictoryOnDrag: false);
+ final HorizontalDragGestureRecognizer horizontalDrag = HorizontalDragGestureRecognizer()
+ ..onStart = (DragStartDetails details) {
+ events.add('basichorizontalstart');
+ }
+ ..onUpdate = (DragUpdateDetails details) {
+ events.add('basichorizontalupdate');
+ }
+ ..onEnd = (DragEndDetails details) {
+ events.add('basichorizontalend');
+ }
+ ..onCancel = () {
+ events.add('basichorizontalcancel');
+ };
+ addTearDown(horizontalDrag.dispose);
+
+ final LongPressGestureRecognizer longpress = LongPressGestureRecognizer()
+ ..onLongPressStart = (LongPressStartDetails details) {
+ events.add('longpressstart');
+ }
+ ..onLongPressMoveUpdate = (LongPressMoveUpdateDetails details) {
+ events.add('longpressmoveupdate');
+ }
+ ..onLongPressEnd = (LongPressEndDetails details) {
+ events.add('longpressend');
+ }
+ ..onLongPressCancel = () {
+ events.add('longpresscancel');
+ };
+ addTearDown(longpress.dispose);
+
+ FlutterErrorDetails? errorDetails;
+ final FlutterExceptionHandler? oldHandler = FlutterError.onError;
+ FlutterError.onError = (FlutterErrorDetails details) {
+ errorDetails = details;
+ };
+
+ final TestPointer pointer = TestPointer(5);
+ final PointerDownEvent downB = pointer.down(const Offset(10.0, 10.0));
+ // When competing against another [DragGestureRecognizer], the [TapAndPanGestureRecognizer]
+ // will only win when it is the last recognizer in the arena.
+ tapAndDrag.addPointer(downB);
+ horizontalDrag.addPointer(downB);
+ longpress.addPointer(downB);
+ tester.closeArena(5);
+ tester.route(downB);
+ tester.route(pointer.move(const Offset(28.1, 10.0)));
+ tester.route(pointer.up());
+ expect(
+ events,
+ <String>[
+ 'basichorizontalstart',
+ 'basichorizontalend',
+ ],
+ );
+
+ final PointerDownEvent downC = pointer.down(const Offset(10.0, 10.0));
+ tapAndDrag.addPointer(downC);
+ horizontalDrag.addPointer(downC);
+ longpress.addPointer(downC);
+ tester.closeArena(5);
+ tester.route(downC);
+ tester.route(pointer.up());
+ FlutterError.onError = oldHandler;
+ expect(errorDetails, isNull);
+ });
+
testGesture('Beats LongPressGestureRecognizer on a consecutive tap greater than one', (GestureTester tester) {
setUpTapAndPanGestureRecognizer();
