react-native-vision-camera/example/src/CameraPage.tsx

import * as React from 'react';
import { useRef, useState, useMemo, useCallback } from 'react';
import { StyleSheet, Text, View } from 'react-native';
import { PinchGestureHandler, PinchGestureHandlerGestureEvent, TapGestureHandler } from 'react-native-gesture-handler';
import { Navigation, NavigationFunctionComponent } from 'react-native-navigation';
import {
  CameraDeviceFormat,
  CameraRuntimeError,
  PhotoFile,
  sortFormats,
  useCameraDevices,
  useFrameProcessor,
  VideoFile,
} from 'react-native-vision-camera';
import { Camera, frameRateIncluded } from 'react-native-vision-camera';
import { useIsScreenFocussed } from './hooks/useIsScreenFocused';
import { CONTENT_SPACING, MAX_ZOOM_FACTOR, SAFE_AREA_PADDING } from './Constants';
import Reanimated, { Extrapolate, interpolate, useAnimatedGestureHandler, useAnimatedProps, useSharedValue } from 'react-native-reanimated';
import { useEffect } from 'react';
import { useIsForeground } from './hooks/useIsForeground';
import { StatusBarBlurBackground } from './views/StatusBarBlurBackground';
import { CaptureButton } from './views/CaptureButton';
import { PressableOpacity } from 'react-native-pressable-opacity';
import MaterialIcon from 'react-native-vector-icons/MaterialCommunityIcons';
import IonIcon from 'react-native-vector-icons/Ionicons';
import { examplePlugin } from './frame-processors/ExamplePlugin';

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

const SCALE_FULL_ZOOM = 3;
const BUTTON_SIZE = 40;

export const CameraPage: NavigationFunctionComponent = ({ componentId }) => {
  const camera = useRef<Camera>(null);
  const [isCameraInitialized, setIsCameraInitialized] = useState(false);
  const zoom = useSharedValue(0);
  const isPressingButton = useSharedValue(false);

  // check if camera page is active
  const isFocussed = useIsScreenFocussed(componentId);
  const isForeground = useIsForeground();
  const isActive = isFocussed && isForeground;

  const [cameraPosition, setCameraPosition] = useState<'front' | 'back'>('back');
  const [enableHdr, setEnableHdr] = useState(false);
  const [flash, setFlash] = useState<'off' | 'on'>('off');
  const [enableNightMode, setEnableNightMode] = useState(false);

  // camera format settings
  const devices = useCameraDevices();
  const device = devices[cameraPosition];
  const formats = useMemo<CameraDeviceFormat[]>(() => {
    if (device?.formats == null) return [];
    return device.formats.sort(sortFormats);
  }, [device?.formats]);

  //#region Memos
  const [is60Fps, setIs60Fps] = useState(true);
  const fps = useMemo(() => {
    if (!is60Fps) return 30;

    if (enableNightMode && !device?.supportsLowLightBoost) {
      // User has enabled Night Mode, but Night Mode is not natively supported, so we simulate it by lowering the frame rate.
      return 30;
    }

    const supportsHdrAt60Fps = formats.some((f) => f.supportsVideoHDR && f.frameRateRanges.some((r) => frameRateIncluded(r, 60)));
    if (enableHdr && !supportsHdrAt60Fps) {
      // User has enabled HDR, but HDR is not supported at 60 FPS.
      return 30;
    }

    const supports60Fps = formats.some((f) => f.frameRateRanges.some((r) => frameRateIncluded(r, 60)));
    if (!supports60Fps) {
      // 60 FPS is not supported by any format.
      return 30;
    }
    // If nothing blocks us from using it, we default to 60 FPS.
    return 60;
  }, [device?.supportsLowLightBoost, enableHdr, enableNightMode, formats, is60Fps]);

  const supportsCameraFlipping = useMemo(() => devices.back != null && devices.front != null, [devices.back, devices.front]);
  const supportsFlash = device?.hasFlash ?? false;
  const supportsHdr = useMemo(() => formats.some((f) => f.supportsVideoHDR || f.supportsPhotoHDR), [formats]);
  const supports60Fps = useMemo(() => formats.some((f) => f.frameRateRanges.some((rate) => frameRateIncluded(rate, 60))), [formats]);
  const canToggleNightMode = enableNightMode
    ? true // it's enabled so you have to be able to turn it off again
    : (device?.supportsLowLightBoost ?? false) || fps > 30; // either we have native support, or we can lower the FPS
  //#endregion

  const format = useMemo(() => {
    let result = formats;
    if (enableHdr) {
      // We only filter by HDR capable formats if HDR is set to true.
      // Otherwise we ignore the `supportsVideoHDR` property and accept formats which support HDR `true` or `false`
      result = result.filter((f) => f.supportsVideoHDR || f.supportsPhotoHDR);
    }

    // find the first format that includes the given FPS
    return result.find((f) => f.frameRateRanges.some((r) => frameRateIncluded(r, fps)));
  }, [formats, fps, enableHdr]);

  //#region Animated Zoom
  // This just maps the zoom factor to a percentage value.
  // so e.g. for [min, neutr., max] values [1, 2, 128] this would result in [0, 0.0081, 1]
  const minZoomFactor = device?.minZoom ?? 1;
  const neutralZoomFactor = device?.neutralZoom ?? 1;
  const maxZoomFactor = device?.maxZoom ?? 1;
  const maxZoomFactorClamped = Math.min(maxZoomFactor, MAX_ZOOM_FACTOR);

  const neutralZoomOut = (neutralZoomFactor - minZoomFactor) / (maxZoomFactor - minZoomFactor);
  const neutralZoomIn = (neutralZoomOut / maxZoomFactorClamped) * maxZoomFactor;
  const maxZoomOut = maxZoomFactorClamped / maxZoomFactor;

  const cameraAnimatedProps = useAnimatedProps(() => {
    const z = interpolate(zoom.value, [0, neutralZoomIn, 1], [0, neutralZoomOut, maxZoomOut], Extrapolate.CLAMP);
    return {
      zoom: isNaN(z) ? 0 : z,
    };
  }, [maxZoomOut, neutralZoomOut, neutralZoomIn, zoom]);
  //#endregion

  //#region Callbacks
  const setIsPressingButton = useCallback(
    (_isPressingButton: boolean) => {
      isPressingButton.value = _isPressingButton;
    },
    [isPressingButton],
  );
  // Camera callbacks
  const onError = useCallback((error: CameraRuntimeError) => {
    console.error(error);
  }, []);
  const onInitialized = useCallback(() => {
    console.log('Camera initialized!');
    setIsCameraInitialized(true);
  }, []);
  const onMediaCaptured = useCallback(async (media: PhotoFile | VideoFile, type: 'photo' | 'video') => {
    console.log(`Media captured! ${JSON.stringify(media)}`);
    await Navigation.showModal({
      component: {
        name: 'MediaPage',
        passProps: {
          type: type,
          path: media.path,
        },
      },
    });
  }, []);
  const onFlipCameraPressed = useCallback(() => {
    setCameraPosition((p) => (p === 'back' ? 'front' : 'back'));
  }, []);
  const onFlashPressed = useCallback(() => {
    setFlash((f) => (f === 'off' ? 'on' : 'off'));
  }, []);
  //#endregion

  //#region Tap Gesture
  const onDoubleTap = useCallback(() => {
    onFlipCameraPressed();
  }, [onFlipCameraPressed]);
  //#endregion

  //#region Effects
  useEffect(() => {
    // Run everytime the neutralZoomScaled value changes. (reset zoom when device changes)
    zoom.value = neutralZoomIn;
  }, [neutralZoomIn, zoom]);
  //#endregion

  //#region Pinch to Zoom Gesture
  // The gesture handler maps the linear pinch gesture (0 - 1) to an exponential curve since a camera's zoom
  // function does not appear linear to the user. (aka zoom 0.1 -> 0.2 does not look equal in difference as 0.8 -> 0.9)
  const onPinchGesture = useAnimatedGestureHandler<PinchGestureHandlerGestureEvent, { startZoom?: number }>({
    onStart: (_, context) => {
      context.startZoom = zoom.value;
    },
    onActive: (event, context) => {
      // we're trying to map the scale gesture to a linear zoom here
      const startZoom = context.startZoom ?? 0;
      const scale = interpolate(event.scale, [1 - 1 / SCALE_FULL_ZOOM, 1, SCALE_FULL_ZOOM], [-1, 0, 1], Extrapolate.CLAMP);
      zoom.value = interpolate(scale, [-1, 0, 1], [0, startZoom, 1], Extrapolate.CLAMP);
    },
  });
  //#endregion

  if (device != null && format != null) {
    console.log(
      `Re-rendering camera page with ${isActive ? 'active' : 'inactive'} camera. ` +
        `Device: "${device.name}" (${format.photoWidth}x${format.photoHeight} @ ${fps}fps)`,
    );
  } else {
    console.log('re-rendering camera page without active camera');
  }

  const frameProcessor = useFrameProcessor((frame) => {
    'worklet';
    const values = examplePlugin(frame);
    _log(`Return Values: ${JSON.stringify(values)}`);
  }, []);

  return (
    <View style={styles.container}>
      {device != null && (
        <PinchGestureHandler onGestureEvent={onPinchGesture} enabled={isActive}>
          <Reanimated.View style={StyleSheet.absoluteFill}>
            <TapGestureHandler onEnded={onDoubleTap} numberOfTaps={2}>
              <ReanimatedCamera
                ref={camera}
                style={StyleSheet.absoluteFill}
                device={device}
                format={format}
                fps={fps}
                hdr={enableHdr}
                lowLightBoost={device.supportsLowLightBoost && enableNightMode}
                isActive={isActive}
                onInitialized={onInitialized}
                onError={onError}
                enableZoomGesture={false}
                animatedProps={cameraAnimatedProps}
                photo={true}
                video={true}
                audio={true}
                frameProcessor={device.supportsParallelVideoProcessing ? frameProcessor : undefined}
                frameProcessorFps={1}
              />
            </TapGestureHandler>
          </Reanimated.View>
        </PinchGestureHandler>
      )}

      <CaptureButton
        style={styles.captureButton}
        camera={camera}
        onMediaCaptured={onMediaCaptured}
        cameraZoom={zoom}
        flash={supportsFlash ? flash : 'off'}
        enabled={isCameraInitialized && isActive}
        setIsPressingButton={setIsPressingButton}
      />

      <StatusBarBlurBackground />

      <View style={styles.rightButtonRow}>
        {supportsCameraFlipping && (
          <PressableOpacity style={styles.button} onPress={onFlipCameraPressed} disabledOpacity={0.4}>
            <IonIcon name="camera-reverse" color="white" size={24} />
          </PressableOpacity>
        )}
        {supportsFlash && (
          <PressableOpacity style={styles.button} onPress={onFlashPressed} disabledOpacity={0.4}>
            <IonIcon name={flash === 'on' ? 'flash' : 'flash-off'} color="white" size={24} />
          </PressableOpacity>
        )}
        {supports60Fps && (
          <PressableOpacity style={styles.button} onPress={() => setIs60Fps(!is60Fps)}>
            <Text style={styles.text}>
              {is60Fps ? '60' : '30'}
              {'\n'}FPS
            </Text>
          </PressableOpacity>
        )}
        {supportsHdr && (
          <PressableOpacity style={styles.button} onPress={() => setEnableHdr((h) => !h)}>
            <MaterialIcon name={enableHdr ? 'hdr' : 'hdr-off'} color="white" size={24} />
          </PressableOpacity>
        )}
        {canToggleNightMode && (
          <PressableOpacity style={styles.button} onPress={() => setEnableNightMode(!enableNightMode)} disabledOpacity={0.4}>
            <IonIcon name={enableNightMode ? 'moon' : 'moon-outline'} color="white" size={24} />
          </PressableOpacity>
        )}
      </View>
    </View>
  );
};

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: 'black',
  },
  captureButton: {
    position: 'absolute',
    alignSelf: 'center',
    bottom: SAFE_AREA_PADDING.paddingBottom,
  },
  button: {
    marginBottom: CONTENT_SPACING,
    width: BUTTON_SIZE,
    height: BUTTON_SIZE,
    borderRadius: BUTTON_SIZE / 2,
    backgroundColor: 'rgba(140, 140, 140, 0.3)',
    justifyContent: 'center',
    alignItems: 'center',
  },
  rightButtonRow: {
    position: 'absolute',
    right: SAFE_AREA_PADDING.paddingRight,
    top: SAFE_AREA_PADDING.paddingTop,
  },
  text: {
    color: 'white',
    fontSize: 11,
    fontWeight: 'bold',
    textAlign: 'center',
  },
});