Fix initialization of time in repeat on AnimationController

flutter · Feb 20, 2024 · 115261c · 115261c
1 parent a2c7ed9
commit 115261c
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Showing 2 changed files with 44 additions and 3 deletions.
diff --git a/packages/flutter/lib/src/animation/animation_controller.dart b/packages/flutter/lib/src/animation/animation_controller.dart
@@ -919,7 +919,7 @@ typedef _DirectionSetter = void Function(_AnimationDirection direction);
 class _RepeatingSimulation extends Simulation {
   _RepeatingSimulation(double initialValue, this.min, this.max, this.reverse, Duration period, this.directionSetter)
       : _periodInSeconds = period.inMicroseconds / Duration.microsecondsPerSecond,
-        _initialT = (max == min) ? 0.0 : (initialValue / (max - min)) * (period.inMicroseconds / Duration.microsecondsPerSecond) {
+        _initialT = (max == min) ? 0.0 : ((clampDouble(initialValue, min, max) - min) / (max - min)) * (period.inMicroseconds / Duration.microsecondsPerSecond) {
     assert(_periodInSeconds > 0.0);
     assert(_initialT >= 0.0);
   }

diff --git a/packages/flutter/test/animation/animation_controller_test.dart b/packages/flutter/test/animation/animation_controller_test.dart
@@ -763,8 +763,8 @@ void main() {
   );
 
   test(
-    'calling repeat with specified min and max values makes the animation '
-    'alternate between min and max values on each repeat',
+    'calling repeat with specified min and max values between 0 and 1 makes '
+    'the animation alternate between min and max values on each repeat',
     () {
       final AnimationController controller = AnimationController(
         duration: const Duration(milliseconds: 100),
@@ -799,6 +799,47 @@ void main() {
       tick(Duration.zero);
       tick(const Duration(milliseconds: 125));
       expect(controller.value, 1.0);
+
+      controller.reset();
+      controller.value = 0.2;
+      expect(controller.value, 0.2);
+
+      controller.repeat(reverse: true, min: 0.2, max: 0.6);
+      tick(Duration.zero);
+      tick(const Duration(milliseconds: 50));
+      expect(controller.value, 0.4);
+      controller.dispose();
+    },
+  );
+
+  test(
+    'calling repeat with negative min value and positive max value makes the '
+    'animation alternate between min and max values on each repeat',
+    () {
+      final AnimationController controller = AnimationController(
+        duration: const Duration(milliseconds: 100),
+        value: 1.0,
+        lowerBound: -1,
+        upperBound: 3,
+        vsync: const TestVSync(),
+      );
+
+      expect(controller.value, 1.0);
+
+      controller.repeat(min: 1, max: 3);
+      tick(Duration.zero);
+      expect(controller.value, 1);
+      tick(const Duration(milliseconds: 50));
+      expect(controller.value, 2);
+
+      controller.reset();
+      controller.value = 0.0;
+
+      controller.repeat(min: -1, max: 3);
+      tick(Duration.zero);
+      expect(controller.value, 0);
+      tick(const Duration(milliseconds: 25));
+      expect(controller.value, 1);
       controller.dispose();
     },
   );