How to create a style without hook?

[dantenol]

Hi, I am using reanimated V2 on my project to build a carousel using FlatList. I need to scale the focused element on the carousel but the only way I fund to create the animated style is through useAnimatedStyle hook, which I can't put inside my function because of the rules of hook.

const _renderItem = ({ item, index }) => {
    const inputRange = [index - 2, index - 1, index];

    const itemStyle = useAnimatedStyle(() => ({ // <== can't do this
      transform: [
        {
          scaleY: interpolate(scrollX.value, inputRange, [0.2, 1, 0.2]),
        },
       ],
    }));


    return (
      <View style={{ width: ITEM_SIZE }}>
        <Animated.View
          style={[
            itemStyle,
            styles.itemDefaultStyle,
          ]}
        >
          <Text>{index - 1}</Text>
        </Animated.View>
      </View>
    );
  };

<AnimatedFlatList
  ...
  renderItem={_renderItem}
/>

I wonder if I can somehow create the animated style without using hooks so I can animate components on my renderItem function

[terrysahaidak]

Hi, you can achieve both: follow the rules of eslint and performance improvements if you move it to a component:

function ItemRenderer({ index, item, scrollY }) {
const inputRange = [index - 2, index - 1, index];
    const itemStyle = useAnimatedStyle(() => ({ // <== can't do this
      transform: [
        {
          scaleY: interpolate(scrollX.value, inputRange, [0.2, 1, 0.2]),
        },
       ],
    }));


    return (
      <View style={{ width: ITEM_SIZE }}>
        <Animated.View
          style={[
            itemStyle,
            styles.itemDefaultStyle,
          ]}
        >
          <Text>{index - 1}</Text>
        </Animated.View>
      </View>
    );
  };
}

But also use useCallback to create a function which you would pass to Flatlist:

const renderItem = useCallback(({ item, index }) => (
  <ItemRenderer item={item} index={index} scrollY={scrollY} />
), [scrollY]);