rive-react/examples/stories/StateMachineDocs.stories.mdx

<!-- RiveTestHook.stories.mdx -->

import { useState } from 'react';

import { Canvas, Meta, Story, ArgsTable } from '@storybook/addon-docs';

import RiveComponent, {useRive, useStateMachineInput} from '../../src';
import {Button} from './components/Button';
import './rive-overview.css';

<Meta title="React Runtime/State Machines" />

# State Machine Usage

Not familiar with Rive State Machines? Check out our [help docs](https://help.rive.app/editor/state-machine) on what these are first!

The `useStateMachineInput` hook is a helper that makes grabbing references to state machine inputs easier to setup. This hook should be used along with the `useRive` hook, as you need to pass in the `rive` instance returned from `useRive`. See each of the examples below to see usage of the hook creating instance of three types of inputs:
- Booleans
- Numbers
- Triggers

## Boolean inputs

Once you grab a reference to the state machine input, you can get/set the value of the input via the `.value` property.

**Note:** The input instance value itself is not a stateful React variable, therefore, any logic in the component dependent on an input value changing will not trigger a re-render like a React stateful variable change would. You can achieve this effect by keeping reference to the state machine input value inside a React state variable. See the example below for this pattern.

<Canvas withSource="open">
  <Story name="Boolean input">
    {() => {
      const STATE_MACHINE_NAME = 'State Machine 1';
      const ON_HOVER_INPUT_NAME = 'Hover';
      const ON_PRESSED_INPUT_NAME = 'Pressed';
      const { rive, RiveComponent: RiveComponentTouch } = useRive({
        src: 'like.riv',
        stateMachines: STATE_MACHINE_NAME,
        artboard: 'New Artboard',
        autoplay: true,
      });
      const [isHovered, setIsHovered] = useState(false);
      // Both onHoverInput and onPressedInput are boolean inputs. To transition
      // states we need to set the value property to true or false.
      const onPressedInput = useStateMachineInput(
        rive,
        STATE_MACHINE_NAME,
        ON_PRESSED_INPUT_NAME
      );
      const onHoverInput = useStateMachineInput(
        rive,
        STATE_MACHINE_NAME,
        ON_HOVER_INPUT_NAME
      );
      function onMouseDown() {
        onPressedInput.value = true;
      }
      function onMouseUp() {
        onPressedInput.value = false;
      }
      function onMouseEnter() {
        onHoverInput.value = true;
        setIsHovered(true);
      }
      function onMouseLeave() {
        onHoverInput.value = false;
        setIsHovered(false);
      }
      return (
        <>
          <div className="center">
            <RiveComponentTouch
              className="base-canvas-size"
              onMouseEnter={onMouseEnter}
              onMouseLeave={onMouseLeave}
              onMouseDown={onMouseDown}
              onMouseUp={onMouseUp}
            />
            <p>Hover and click on the canvas</p>
            <p>Is cursor hovering? {isHovered ? 'Yes' : 'No'}</p>
          </div>
        </>
      );
    }}
  </Story>
</Canvas>

## Number inputs

Once you grab a reference to the state machine input, you can get/set the value of the input via the `.value` property.

<Canvas withSource="open">
  <Story name="Number input">
    {() => {
      const STATE_MACHINE_NAME = 'State Machine ';
      const INPUT_NAME = 'Level';
      const { rive, RiveComponent: RiveComponentTouch } = useRive({
        src: 'skills.riv',
        stateMachines: STATE_MACHINE_NAME,
        artboard: 'New Artboard',
        autoplay: true,
      });
      // levelInput is a number state machine input. To transition the state machine,
      // we need to set the value to a number. For this state machine input, we need
      // to set to 0, 1 or 2 for a state transition to occur.
      const levelInput = useStateMachineInput(rive, STATE_MACHINE_NAME, INPUT_NAME);
      return (
        // The animation will fit to the parent element, so we set a large height
        // and width for this example.
        <div className="center">
          <RiveComponentTouch className="large-canvas-size" />
          <div className="btn-group">
            Choose a level:
            <Button onClick={() => (levelInput.value = 0)}>0</Button>
            <Button onClick={() => (levelInput.value = 1)}>1</Button>
            <Button onClick={() => (levelInput.value = 2)}>2</Button>
          </div>
        </div>
      );
    }}
  </Story>
</Canvas>

## Trigger inputs

Unlike the boolean and number inputs, you invoke the `.fire()` method on a trigger input.

<Canvas withSource="open">
  <Story name="Trigger input">
    {() => {
      const STATE_MACHINE_NAME = 'State Machine 1';
      const INPUT_NAME = 'Pressed';
      const { rive, RiveComponent: RiveComponentTouch } = useRive({
        src: 'piggy-bank.riv',
        stateMachines: STATE_MACHINE_NAME,
        artboard: 'New Artboard',
        autoplay: true,
      });
      // pressedInput in a trigger state machine input. To transition the state
      // we need to call the `fire()` method on the input.
      const pressedInput = useStateMachineInput(
        rive,
        STATE_MACHINE_NAME,
        INPUT_NAME
      );
      // The animation will fit to the parent element, so we set a large height
      // and width for this example.
      return (
        <div className="center">
          <RiveComponentTouch
            className="base-canvas-size"
            onClick={() => pressedInput.fire()}
          />
          <p>Click on the canvas</p>
        </div>
      );
    }}
  </Story>
</Canvas>