State Machines
Playing and changing inputs in state machines
For more information on designing and building state machines in Rive, please refer to the editor's state machine section.
Rive's state machines provide a way to combine a set of animations and manage the transition between them through a series of inputs that can be programmatically controlled. Once a state machine is instantiated and playing, transitioning states can be accomplished by changing
boolean or double-value inputs, or firing trigger inputs. The effects of these will be dependent on how the state machine has been configured in the editor.State machines are instantiated in much the same manner as animations: provide the state machine name to the Rive object when instantiated. Ensure that the Rive instance is set to auto-play on initialization to allow the state machine to start immediately.
Web
React
Angular
React Native
Flutter
iOS/macOS
Android
const r = new rive.Rive({
src: 'https://cdn.rive.app/animations/vehicles.riv',
canvas: document.getElementById('canvas'),
autoplay: true,
stateMachines: 'bumpy',
fit: rive.Fit.cover,
});
// State Machine require the useRive hook.
export default function Simple() {
const { RiveComponent } = useRive({
src: 'https://cdn.rive.app/animations/vehicles.riv',
stateMachines: "weather",
autoplay: true,
});
return <RiveComponent />;
}
<canvas riv="vehicles" width="500" height="500" fit="cover">
<riv-state-machine name="bumpy" play></riv-state-machine>
</canvas>
Set
stateMachineName on the Rive component to play a single state machine. <Rive
resourceName={'skills'}
autoplay={true}
stateMachineName="Designer's Test"
/>
To autoplay a state machine by default, simply set the
stateMachines property at instantiation:RiveAnimation.network(
'https://cdn.rive.app/animations/vehicles.riv',
fit: BoxFit.cover,
stateMachines: ['bumpy'],
);
In the above snippet, at instantiation time, the runtime will create a
StateMachineController reference implicitly and immediately play the state machine.
If you'd like further control over the state machine in cases where you may want to prevent autoplaying the state machine, you can instead pass your own reference to a
StateMachineController to the RiveAnimation widget at instantiation time with the isActive property set to false. Below is an example of what this might look like:class _ExampleState extends State<ExampleState> {
/// Controller for playback
late StateMachineController _controller;
void _onInit(Artboard art) {
var ctrl =
StateMachineController.fromArtboard(art, 'some-state-machine') as StateMachineController;
ctrl.isActive = false;
art.addController(ctrl);
setState(() {
_controller = ctrl;
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Play/Pause Example'),
),
body: Center(
child: RiveAnimation.asset('assets/example.riv', onInit: _onInit),
),
floatingActionButton: FloatingActionButton(
// Play/Pause the state machine
onPressed: () => {
_controller.isActive
? _controller.isActive = false
: _controller.isActive = true
},
tooltip: 'Play/Pause',
child: const Icon(Icons.arrow_upward),
),
);
}
}
As you change the
isActive property of the StateMachineController, you'll see that the current state may pause advancing through the render loop. This is useful in cases where you may want to load in your Rive on screen, but delay playing until a loading sequence occurs, or some data comes back for your application.
Specify a starting state machine by setting the name of the state machine via
stateMachineName when instantiating the RiveViewModel.var stateChanger = RiveViewModel(
fileName: "skills",
stateMachineName: "Designer's Test"
)
class StateMachineViewController: UIViewController {
var viewModel = RiveViewModel(
fileName: "skills",
stateMachineName: "Designer's Test"
)
override public func loadView() {
super.loadView()
guard let stateMachineView = view as? StateMachineView else {
fatalError("Could not find StateMachineView")
}
viewModel.setView(stateMachineView.riveView)
}
}
<app.rive.runtime.kotlin.RiveAnimationView
android:id="@+id/simple_state_machine"
android:layout_width="match_parent"
android:layout_height="400dp"
app:riveResource="@raw/skills"
app:riveStateMachine="Designer's Test" />
animationView.setRiveResource(
R.raw.simple_state_machine,
autoplay = true,
stateMachineName = "Designer's Test"
)
Additionally, you can use the same APIs from animation playback (i.e
play, pause, and stop) to control state machine playback, as long as you set the isStateMachine attribute to true.animationView.play(
"Designer's Test",
Loop.AUTO,
Direction.AUTO,
isStateMachine = true
)
animationView.pause(
"Designer's Test",
isStateMachine = true
)
animationView.stop(
"Designer's Test",
isStateMachine = true
)
Once the Rive file is loaded and instantiated, the state machine(s) can be queried for inputs, and these input values can be set, and in the case of triggers, fired, all programmatically.
Web
React
Angular
React Native
Flutter
iOS/macOS
Android
The web runtime provides an
onLoad callback that's run when the Rive file is loaded and ready for use. We use this callback to ensure that the state machine is instantiated when we query for inputs.<div id="button">
<canvas id="canvas" width="1000" height="500"></canvas>
</div>
<script src="https://unpkg.com/@rive-app/[email protected]"></script>
<script>
const button = document.getElementById('button');
const r = new rive.Rive({
src: 'https://cdn.rive.app/animations/vehicles.riv',
canvas: document.getElementById('canvas'),
autoplay: true,
stateMachines: 'bumpy',
fit: rive.Fit.cover,
onLoad: (_) => {
// Get the inputs via the name of the state machine
const inputs = r.stateMachineInputs('bumpy');
// Find the input you want to set a value for, or trigger
const bumpTrigger = inputs.find(i => i.name === 'bump');
button.onclick = () => bumpTrigger.fire();
},
});
</script>
We use the
stateMachineInputs function on the Rive object to retrieve the inputs. Each input will have a name and type. There are three types:StateMachineInputType.Triggerwhich has afire()functionStateMachineInputType.Numberwhich has avaluenumber propertyStateMachineInputType.Booleanwhich has avalueboolean property
const inputs = r.stateMachineInputs('bumpy');
inputs.forEach(i => {
const inputName = i.name;
const inputType = i.type;
switch(inputType) {
case rive.StateMachineInputType.Trigger:
i.fire();
break;
case rive.StateMachineInputType.Number:
i.value = 42;
break;
case rive.StateMachineInputType.Boolean:
i.value = true;
break;
}
});
We can set a callback to determine when the state machine changes state.
onStateChange provides an event parameter that gives us the string name(s) of the current state(s):const r = new rive.Rive({
src: 'https://cdn.rive.app/animations/vehicles.riv',
canvas: document.getElementById('canvas'),
autoplay: true,
stateMachines: 'bumpy',
onStateChange: (event) => {
stateName.innerHTML = event.data[0];
},
});
The react runtime provides a
useStateMachineInput hook to make the process of retrieving a state machine input much simpler than that of the basic web runtime.import { useRive, useStateMachineInput } from "@rive-app/react-canvas";
export default function Simple() {
const { rive, RiveComponent } = useRive({
src: "https://cdn.rive.app/animations/vehicles.riv",
stateMachines: "bumpy",
autoplay: true,
});
const bumpInput = useStateMachineInput(rive, "bumpy", "bump");
return (
<RiveComponent
style={{ height: "1000px" }}
onClick={() => bumpInput && bumpInput.fire()}
/>
);
}
The above example shows the retrieval of a
Trigger input from a named state machine. The three types of inputs are:StateMachineInputType.Triggerwhich has afire()functionStateMachineInputType.Numberwhich has avaluenumber propertyStateMachineInputType.Booleanwhich has avalueboolean property
We can set a callback to determine when the state machine changes, just like in the web runtime.
import { useEffect } from 'react';
import { useRive, useStateMachineInput } from "@rive-app/react-canvas";
export default function Simple() {
const { rive, RiveComponent } = useRive({
src: "https://cdn.rive.app/animations/vehicles.riv",
stateMachines: "bumpy",
autoplay: true,
// We can pass the call back to the `useRive` hook
onStateChange: (event) => {
console.log(event.data[0]);
}
});
const bumpInput = useStateMachineInput(rive, "bumpy", "bump");
// We can also pass the callback to the rive object once it has loaded.
// NOTE: If you pass the callback to the rive object, you do not need to
// pass it to the useRive hook as well, and vice versa.
useEffect(() => {
if (rive) {
rive.on('statechange', (event) => {
console.log(event.data[0]);
});
}
}, [rive]);
return (
<RiveComponent
style={{ height: "1000px" }}
onClick={() => bumpInput && bumpInput.fire()}
/>
);
}
You can listen on event & manipulate the state machine animation as any other animation:
<canvas riv="vehicles" width="500" height="500" fit="cover">
<riv-state-machine name="bumpy" play speed="2" (load)="onload($event)"></riv-state-machine>
</canvas>
If the input is a number or a boolean you can use the
value<canvas riv="vehicles" width="500" height="500" fit="cover">
<riv-state-machine name="bumpy" play (stateChange)="showStates($event)">
<riv-input name="level" [value]="value"><riv-input>
</riv-state-machine>
</canvas>
<input type="radio" formControl="level" value="0"> Car
<input type="radio" formControl="level" value="1"> Train
<input type="radio" formControl="level" value="2"> Airplane
The
stateChange output will display the list of state changed during the same frame.If the input is a trigger you can access it with the export as
rivInput:<canvas riv="vehicles">
<riv-state-machine name="bumpy" play>
<riv-input #trigger="rivInput" name="bump" (change)="showInput($event)"><riv-input>
</riv-state-machine>
</canvas>
<button (click)="trigger.fire()">Bump</button>
You can listen to the change in the input with the
change Ouput.With the React Native runtime, most methods/triggers are available on the ref of the
Rive component, including setting input values/triggering for state machines. In this case, there is no need to acquire an instance of an input. Simply set the input state from the Rive ref or fire an input state.export default function StateMachine() {
const riveRef = React.useRef<RiveRef>(null);
// Maintain the values of your state machine in React state
const [selectedLevel, setSelectedLevel] = useState('2');
const setLevel = (n: number) => {
setSelectedLevel(n.toString());
// No need to acquire an instance of a state machine input, just set the
// input state on the `riveRef` itself
riveRef.current?.setInputState("Designer's Test", 'Level', n);
};
return (
<SafeAreaView style={styles.safeAreaViewContainer}>
<ScrollView contentContainerStyle={styles.container}>
<Rive
resourceName={'skills'}
ref={riveRef}
autoplay={true}
stateMachineName="Designer's Test"
/>
<RadioButton.Group
onValueChange={(newValue) => setLevel(parseInt(newValue, 10))}
value={selectedLevel}
>
<View style={styles.radioButtonsWrapper}>
<View style={styles.radioButtonWrapper}>
<Text>{'Beginner'}</Text>
<RadioButton value={'0'} />
</View>
<View style={styles.radioButtonWrapper}>
<Text>{'Intermediate'}</Text>
<RadioButton value={'1'} />
</View>
<View style={styles.radioButtonWrapper}>
<Text>{'Expert'}</Text>
<RadioButton value={'2'} />
</View>
</View>
</RadioButton.Group>
</ScrollView>
</SafeAreaView>
);
}
We can set a callback to determine when the state machine changes.
<Rive
resourceName={'skills'}
autoplay={true}
stateMachineName="Designer's Test"
onStateChanged={(stateMachineName, stateName) => {
console.log(
'onStateChanged: ',
'stateMachineName: ',
stateMachineName,
'stateName: ',
stateName
);
}}
/>
State machine controllers are used to retrieve a state machine's inputs which can then be used to interact with, and drive the state of a state machine.
State machine controllers require a reference to an artboard when being instantiated. The
RiveAnimation widget provides a callback onInit(Artboard artboard) that is called when the Rive file has loaded and is initialized for playback:void _onRiveInit(Artboard artboard) {}
RiveAnimation.network(
'https://cdn.rive.app/animations/vehicles.riv',
fit: BoxFit.cover,
onInit: _onRiveInit,
);
In the
onInit callback, you can create an instance of a StateMachineController and then retrieve the inputs you're interested in by their name. Specific inputs can be retrieved using findInput() or all inputs with the inputs property.SMITrigger? _bump;
void _onRiveInit(Artboard artboard) {
// Get State Machine Controller for the state machine called "bumpy"
final controller = StateMachineController.fromArtboard(artboard, 'bumpy');
artboard.addController(controller!);
// Get a reference to the "bump" state machine input
_bump = controller.findInput<bool>('bump') as SMITrigger;
}
In the above snippet, the
bump input is retrieved, which is an SMITrigger. This type of input has a fire() method to activate the trigger.
class SimpleStateMachine extends StatefulWidget {
const SimpleStateMachine({Key? key}) : super(key: key);
@override
_SimpleStateMachineState createState() => _SimpleStateMachineState();
}
class _SimpleStateMachineState extends State<SimpleStateMachine> {
SMITrigger? _bump;
void _onRiveInit(Artboard artboard) {
final controller = StateMachineController.fromArtboard(artboard, 'bumpy');
artboard.addController(controller!);
_bump = controller.findInput<bool>('bump') as SMITrigger;
}
void _hitBump() => _bump?.fire();
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Simple Animation'),
),
body: Center(
child: GestureDetector(
child: RiveAnimation.network(
'https://cdn.rive.app/animations/vehicles.riv',
fit: BoxFit.cover,
onInit: _onRiveInit,
),
onTap: _hitBump,
),
),
);
}
}
In the complete example above, every time the
RiveAnimation is tapped, it fires the bump input trigger and the state machine reacts appropriately.Note: There are two other state machine input types to be aware of as well:
SMIBool and SMINumber. These both have a value property that can get and set the value.
// Example state machine input declarations
SMIInput<bool>? _boolExampleInput;
SMIInput<double>? _numberExampleInput;
...
// Extracting inputs from the StateMachineController
void _onRiveInit(Artboard artboard) {
final controller = StateMachineController.fromArtboard(artboard, 'example');
artboard.addController(controller!);
_boolExampleInput = controller.findInput<bool>('exampleBool') as SMIBool;
_numberExampleInput = controller.findInput<double>('exampleNum') as SMINumber;
}
...
// Getting/setting state machine input values
if (_boolExampleInput.value == false) {
_boolExampleInput.value = true;
}
if (_numberExampleInput.value >= 100) {
_numberExampleInput.value = 0;
}
If you'd like to know which state a state machine is in, or when a state machine transitions to another state, you can provide a callback to
StateMachineController. The callback has the name of the state machine and the name of the animation associated with the state transitioned to: void _onRiveInit(Artboard artboard) {
final controller = StateMachineController.fromArtboard(
artboard,
'bumpy',
onStateChange: _onStateChange,
);
artboard.addController(controller!);
_bump = controller.findInput<bool>('bump') as SMITrigger;
}
void _onStateChange(
String stateMachineName,
String stateName,
) =>
setState(
() => message = 'State Changed in $stateMachineName to $stateName',
);
Just like with animation playback controls, setting input values for state machines goes through the
RiveViewModel instantiated in the View class..setInput()inputName(String) - Name of the input on a state machine to set a value forvalue(Bool, Float, or Double) - value to set for the associatedinputName
triggerInput()inputName(String) - Name of the input on a state machine to trigger
// Example of a number input
starsVM.setInput("Rating Changed", value: 5)
// Example of a boolean input
toggleVM.setInput("Switch Flipped", value: true)
// Example of a trigger input
confettiVM.triggerInput("Celebrate")
This runtime allows for delegates that can be set on the
RiveViewModel. If provided, these delegate functions will be fired whenever a matching event is triggered to be able to hook into and listen for certain events in the Rive animation cycle.
Currently, there exist the following delegates:
RivePlayerDelegate- Hook into animation and state machine lifecycle eventsplayer:(loopedWithModel riveModel: RiveModel?, type: Int) {}player:(playedWithModel riveModel: RiveModel?) {}player:(pausedWithModel riveModel: RiveModel?) {}player:(stoppedWithModel riveModel: RiveModel?) {}
RiveStateMachineDelegate- Hook into state changes on a state machine lifecyclestateMachine:(_ stateMachine: RiveStateMachineInstance, didStateChange stateName: String) {}
You can create your own delegate or mix in with the
RiveViewModel, implementing as many protocols as are needed. Below is an example of how to customize a RiveViewModel's implementation of the RivePlayerDelegate:class SimpleAnimation: RiveViewModel {
init() {
let model = RiveModel(fileName: "truck_v7", stateMachineName: "Drive")
super.init(model)
}
override func setView(rview view: RiveView) {
super.setView(view)
rview?.playerDelegate = self
rview?.stateMachineDelegate = self
}
override func player(playedWithModel riveModel: RiveModel?) {
if let stateMachineName = riveModel?.stateMachine?.name() {...}
}
override func player(pausedWithModel riveModel: RiveModel?) {
if let stateMachineName = riveModel?.stateMachine?.name() {...}
}
override func player(stoppedWithModel riveModel: RiveModel?) {
if let stateMachineName = riveModel?.stateMachine?.name() {...}
}
@objc func stateMachine(_ stateMachine: RiveStateMachineInstance, didChangeState stateName: String) {
var stateMachineNames: [String] = []
var stateMachineStates: [String] = []
stateMachineNames.append(stateMachine.name())
stateMachineStates.append(stateName)
...
}
}
Just like other methods within the
rive-android runtime, use the view to set values on a state machine input. In this case, there is no need to grab references to state machine input instances to set values.
There are 3 different methods to set input values or trigger inputs for number, boolean, and trigger inputs respectively:
.setNumberState(stateMachineName: String, inputName: String, value: Float).setBooleanState(stateMachineName: String, inputName: String, value: Boolean).fireState(stateMachineName: String, inputName: String)
// i.e Set input state on a number input
animationView.setNumberState("Designer's Test", "Level", 0f)
// i.e Set boolean state on a boolean input
animationView.setBooleanState("Boolean test", "foo", true)
// i.e Fire a trigger input
animationView.fireState("Trigger test", "fireInput");
To listen for state changes, when creating a
Listener to register on your animation view, you can add the following callback, where you'll receive the name of the state machine, and the state it transitions to:
val listener = object : Listener {
override fun notifyStateChanged(stateMachineName: String, stateName: String) {
// Do something
}
}
animationView.registerListener(listener)
Last modified 1mo ago