Adds one-shot animation controller

example/lib/main.dart

@@ -1,4 +1,5 @@
 import 'package:flutter/material.dart';
+import 'package:rive_example/play_one_shot_animation.dart';
 import 'package:rive_example/play_pause_animation.dart';
 import 'package:rive_example/example_state_machine.dart';
 import 'package:rive_example/liquid_download.dart';
@@ -50,6 +51,20 @@ class Home extends StatelessWidget {
             const SizedBox(
               height: 10,
             ),
+            ElevatedButton(
+              child: const Text('Play One-Shot Animation'),
+              onPressed: () {
+                Navigator.push(
+                  context,
+                  MaterialPageRoute<void>(
+                    builder: (context) => const PlayOneShotAnimation(),
+                  ),
+                );
+              },
+            ),
+            const SizedBox(
+              height: 10,
+            ),
             ElevatedButton(
               child: const Text('Button State Machine'),
               onPressed: () {

example/lib/play_one_shot_animation.dart

@@ -0,0 +1,52 @@
+/// Demonstrates play a one-shot animation on demand
+
+import 'package:flutter/material.dart';
+import 'package:rive/rive.dart';
+
+class PlayOneShotAnimation extends StatefulWidget {
+  const PlayOneShotAnimation({Key? key}) : super(key: key);
+
+  @override
+  _PlayOneShotAnimationState createState() => _PlayOneShotAnimationState();
+}
+
+class _PlayOneShotAnimationState extends State<PlayOneShotAnimation> {
+  /// Controller for playback
+  late RiveAnimationController _controller;
+
+  /// Is the animation currently playing?
+  bool _isPlaying = false;
+
+  @override
+  void initState() {
+    super.initState();
+    _controller = OnShotAnimation(
+      'bounce',
+      autoplay: false,
+      onStop: () => setState(() => _isPlaying = false),
+      onStart: () => setState(() => _isPlaying = true),
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(
+        title: const Text('One-Shot Example'),
+      ),
+      body: Center(
+        child: RiveAnimation.network(
+          'https://cdn.rive.app/vehicles.riv',
+          animations: const ['idle', 'curves'],
+          controllers: [_controller],
+        ),
+      ),
+      floatingActionButton: FloatingActionButton(
+        // disable the button while playing the animation
+        onPressed: () => _isPlaying ? null : _controller.isActive = true,
+        tooltip: 'Play',
+        child: const Icon(Icons.arrow_upward),
+      ),
+    );
+  }
+}

example/lib/play_pause_animation.dart

@@ -1,3 +1,5 @@
+/// Demonstrates how to play and pause a looping animation
+
 import 'package:flutter/material.dart';
 import 'package:rive/rive.dart';
 
@@ -9,10 +11,10 @@ class PlayPauseAnimation extends StatefulWidget {
 }
 
 class _PlayPauseAnimationState extends State<PlayPauseAnimation> {
-  // Controller for playback
+  /// Controller for playback
   late RiveAnimationController _controller;
 
-  // Toggles between play and pause animation states
+  /// Toggles between play and pause animation states
   void _togglePlay() =>
       setState(() => _controller.isActive = !_controller.isActive);
 

lib/rive.dart

@@ -1,6 +1,7 @@
 library rive;
 
 export 'package:rive/src/controllers/simple_controller.dart';
+export 'package:rive/src/controllers/one_shot_controller.dart';
 export 'package:rive/src/extensions.dart';
 export 'package:rive/src/extensions.dart';
 export 'package:rive/src/rive.dart';

lib/src/controllers/one_shot_controller.dart

@@ -0,0 +1,44 @@
+import 'dart:ui' show VoidCallback;
+
+import 'package:flutter/widgets.dart';
+import 'package:rive/src/controllers/simple_controller.dart';
+
+/// Controller tailered for managing one-shot animations
+class OnShotAnimation extends SimpleAnimation {
+  /// Fires when the animation stops being active
+  final VoidCallback? onStop;
+
+  /// Fires when the animation starts being active
+  final VoidCallback? onStart;
+
+  OnShotAnimation(
+    String animationName, {
+    double mix = 1,
+    bool autoplay = true,
+    this.onStop,
+    this.onStart,
+  }) : super(animationName, mix: mix, autoplay: autoplay) {
+    isActiveChanged.addListener(onActiveChanged);
+  }
+
+  /// Dispose of any callback listeners
+  @override
+  void dispose() {
+    super.dispose();
+    isActiveChanged.removeListener(onActiveChanged);
+  }
+
+  /// Perform tasks when the animation's active state changes
+  void onActiveChanged() {
+    // If the animation stops and it is at the end of the one-shot, reset the
+    // animation back to the starting time
+    if (!isActive) {
+      reset();
+    }
+    // Fire any callbacks
+    isActive
+        ? onStart?.call()
+        // onStop can fire while widgets are still drawing
+        : WidgetsBinding.instance?.addPostFrameCallback((_) => onStop?.call());
+  }
+}

lib/src/controllers/simple_controller.dart

@@ -21,7 +21,6 @@ class SimpleAnimation extends RiveAnimationController<RuntimeArtboard> {
   final String animationName;
 
   /// Stops the animation on the next apply
-  ///
   bool _stopOnNextApply = false;
 
   /// Pauses the animation when it's created
@@ -71,4 +70,9 @@ class SimpleAnimation extends RiveAnimationController<RuntimeArtboard> {
     // stop itself.
     _stopOnNextApply = false;
   }
+
+  /// Resets the animation back to it's starting time position
+  void reset() {
+    _instance?.reset();
+  }
 }