React Native: How do you animate the rotation of an Image?

Question

Rotation is a style transform and in RN, you can rotate things like this

  render() {
    return (
      <View style={{transform:[{rotate: '10 deg'}]}}>
        <Image source={require('./logo.png')} />
      </View>
    );
  }

However, to animate things in RN, you have to use numbers, not strings. Can you still animate transforms in RN or do I have to come up with some kind of sprite sheet and change the Image src at some fps?

Answer 1

You can actually animate strings using the interpolate method. interpolate takes a range of values, typically 0 to 1 works well for most things, and interpolates them into a range of values (these could be strings, numbers, even functions that return a value).

What you would do is take an existing Animated value and pass it through the interpolate function like this:

spinValue = new Animated.Value(0);

// First set up animation 
Animated.timing(
    this.spinValue,
  {
    toValue: 1,
    duration: 3000,
    easing: Easing.linear, // Easing is an additional import from react-native
    useNativeDriver: true  // To make use of native driver for performance
  }
).start()

// Next, interpolate beginning and end values (in this case 0 and 1)
const spin = this.spinValue.interpolate({
  inputRange: [0, 1],
  outputRange: ['0deg', '360deg']
})

Then use it in your component like this:

<Animated.Image
  style={{transform: [{rotate: spin}] }}
  source={{uri: 'somesource.png'}} />

In case if you want to do the rotation in loop, then add the Animated.timing in the Animated.loop

Animated.loop(
 Animated.timing(
   this.spinValue,
   {
    toValue: 1,
    duration: 3000,
    easing: Easing.linear,
    useNativeDriver: true
   }
 )
).start();