react-native-vision-camera/ANIMATED.md

README.md	ANIMATED.md	DEVICES.md	FORMATS.md	ERRORS.md

Animations

Often you'd want to animate specific props in the Camera. For example, if you'd want to create a custom zoom gesture, you can smoothly animate the Camera's zoom property.

The following example uses react-native-reanimated (v2) to animate the zoom property:

import Reanimated, {
  useAnimatedProps,
  useSharedValue,
  withSpring,
} from "react-native-reanimated";

const ReanimatedCamera = Reanimated.createAnimatedComponent(Camera);
Reanimated.addWhitelistedNativeProps({
  zoom: true,
});

export const App = () => {
  const zoom = useSharedValue(0);

  const onRandomZoomPress = useCallback(() => {
    zoom.value = withSpring(Math.random());
  }, []);

  const animatedProps = useAnimatedProps<Partial<CameraProps>>(
    () => ({ zoom: zoom.value }),
    [zoom]
  );

  return (
    <>
      <ReanimatedCamera
        style={StyleSheet.absoluteFill}
        device={device}
        isActive={true}
        {...{ animatedProps }}
      />
      <TouchableOpacity
        style={styles.zoomButton}
        onPress={onRandomZoomPress}>
        <Text>Zoom randomly!</Text>
      </TouchableOpacity>
    </>
  )
}

Implementation

1. The Camera is converted to a reanimated Camera using Reanimated.createAnimatedComponent
2. The zoom property is added to the whitelisted native props to make it animatable.

   Note that this might not be needed in the future, see: reanimated#1409

3. Using useSharedValue, we're creating a shared value that holds the zoom property.
4. Using the useAnimatedProps hook, we apply the shared value to the animated props.
5. We apply the animated props to the ReanimatedCamera component using the spread syntax.