feat: Adding autoResetTicker option to SpriteAnimationGroupComponent

packages/flame/lib/src/components/sprite_animation_group_component.dart

@@ -29,13 +29,18 @@ class SpriteAnimationGroupComponent<T> extends PositionComponent
   /// size of current animation sprite.
   bool _autoResize;
 
+  /// Whether the current animation's ticker should reset to the beginning
+  /// when it becomes current.
+  bool autoResetTicker;
+
   /// Creates a component with an empty animation which can be set later
   SpriteAnimationGroupComponent({
     Map<T, SpriteAnimation>? animations,
     T? current,
     bool? autoResize,
     this.playing = true,
     this.removeOnFinish = const {},
+    this.autoResetTicker = true,
     Paint? paint,
     super.position,
     super.size,
@@ -83,6 +88,7 @@ class SpriteAnimationGroupComponent<T> extends PositionComponent
     bool? autoResize,
     bool playing = true,
     Map<T, bool> removeOnFinish = const {},
+    bool autoResetTicker = true,
     Paint? paint,
     Vector2? position,
     Vector2? size,
@@ -104,6 +110,7 @@ class SpriteAnimationGroupComponent<T> extends PositionComponent
           current: current,
           autoResize: autoResize,
           removeOnFinish: removeOnFinish,
+          autoResetTicker: autoResetTicker,
           playing: playing,
           paint: paint,
           position: position,
@@ -125,8 +132,13 @@ class SpriteAnimationGroupComponent<T> extends PositionComponent
   ///
   /// Will update [size] if [autoResize] is true.
   set current(T? value) {
+    final changed = value != current;
     _current = value;
     _resizeToSprite();
+
+    if (changed && autoResetTicker) {
+      animationTicker?.reset();
+    }
   }
 
   /// Returns the map of animation state and their corresponding animations.

packages/flame/test/components/sprite_animation_group_component_test.dart

@@ -353,4 +353,64 @@ Future<void> main() async {
       expect(sizeChangeCounter, equals(4));
     });
   });
+
+  group('SpriteAnimationGroupComponent.autoResetTicker', () {
+    final sprite1 = Sprite(image, srcSize: Vector2.all(76));
+    final sprite2 = Sprite(image, srcSize: Vector2.all(15));
+    final animation1 = SpriteAnimation.spriteList(
+      List.filled(5, sprite1),
+      stepTime: 0.1,
+      loop: false,
+    );
+    final animation2 = SpriteAnimation.spriteList(
+      List.filled(5, sprite2),
+      stepTime: 0.1,
+      loop: false,
+    );
+
+    test('does reset ticker by default', () {
+      final component = SpriteAnimationGroupComponent<_AnimationState>(
+        animations: {
+          _AnimationState.idle: animation1,
+          _AnimationState.running: animation2,
+        },
+        current: _AnimationState.idle,
+      );
+      component.update(0.9);
+      expect(component.animationTicker!.currentIndex, 4);
+
+      component.current = _AnimationState.running;
+      component.update(0.1);
+      expect(component.animationTicker!.currentIndex, 1);
+
+      component.current = _AnimationState.idle;
+      expect(component.animationTicker!.currentIndex, 0);
+
+      component.current = _AnimationState.running;
+      expect(component.animationTicker!.currentIndex, 0);
+    });
+
+    test('resets the ticker when enabled', () {
+      final component = SpriteAnimationGroupComponent<_AnimationState>(
+        animations: {
+          _AnimationState.idle: animation1,
+          _AnimationState.running: animation2,
+        },
+        autoResetTicker: false,
+        current: _AnimationState.idle,
+      );
+      component.update(0.9);
+      expect(component.animationTicker!.currentIndex, 4);
+
+      component.current = _AnimationState.running;
+      component.update(0.1);
+      expect(component.animationTicker!.currentIndex, 1);
+
+      component.current = _AnimationState.idle;
+      expect(component.animationTicker!.currentIndex, 4);
+
+      component.current = _AnimationState.running;
+      expect(component.animationTicker!.currentIndex, 1);
+    });
+  });
 }