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

import * as React from 'react';
import { useRef, useState, useCallback } from 'react';
import { StyleSheet, Text, View } from 'react-native';
import { PinchGestureHandler, PinchGestureHandlerGestureEvent, TapGestureHandler } from 'react-native-gesture-handler';
import { CameraRuntimeError, PhotoFile, useCameraDevice, useCameraFormat, useFrameProcessor, VideoFile } from 'react-native-vision-camera';
import { Camera } from 'react-native-vision-camera';
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 type { Routes } from './Routes';
import type { NativeStackScreenProps } from '@react-navigation/native-stack';
import { useIsFocused } from '@react-navigation/core';
import { examplePlugin } from './frame-processors/ExamplePlugin';

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

const SCALE_FULL_ZOOM = 3;
const BUTTON_SIZE = 40;

type Props = NativeStackScreenProps<Routes, 'CameraPage'>;
export function CameraPage({ navigation }: Props): React.ReactElement {
  const camera = useRef<Camera>(null);
  const [isCameraInitialized, setIsCameraInitialized] = useState(false);
  const [hasMicrophonePermission, setHasMicrophonePermission] = useState(false);
  const zoom = useSharedValue(0);
  const isPressingButton = useSharedValue(false);

  // check if camera page is active
  const isFocussed = useIsFocused();
  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 device = useCameraDevice(cameraPosition);
  const format = useCameraFormat(device, {
    fps: {
      target: 60,
      priority: 1,
    },
  });

  //#region Memos
  const [targetFps, setTargetFps] = useState(30);
  const fps = Math.min(format?.maxFps ?? 1, targetFps);

  const supportsFlash = device?.hasFlash ?? false;
  const supportsHdr = format?.supportsPhotoHDR;
  const supports60Fps = (format?.maxFps ?? 0) >= 60;
  const canToggleNightMode = device?.supportsLowLightBoost ?? false;
  //#endregion

  //#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 minZoom = device?.minZoom ?? 1;
  const maxZoom = Math.min(device?.maxZoom ?? 1, MAX_ZOOM_FACTOR);

  const cameraAnimatedProps = useAnimatedProps(() => {
    const z = Math.max(Math.min(zoom.value, maxZoom), minZoom);
    return {
      zoom: z,
    };
  }, [maxZoom, minZoom, 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(
    (media: PhotoFile | VideoFile, type: 'photo' | 'video') => {
      console.log(`Media captured! ${JSON.stringify(media)}`);
      navigation.navigate('MediaPage', {
        path: media.path,
        type: type,
      });
    },
    [navigation],
  );
  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
  const neutralZoom = device?.neutralZoom ?? 1;
  useEffect(() => {
    // Run everytime the neutralZoomScaled value changes. (reset zoom when device changes)
    zoom.value = neutralZoom;
  }, [neutralZoom, zoom]);

  useEffect(() => {
    Camera.getMicrophonePermissionStatus().then((status) => setHasMicrophonePermission(status === 'granted'));
  }, []);
  //#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], [minZoom, startZoom, maxZoom], 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} photo / ${format.videoWidth}x${format.videoHeight} video @ ${fps}fps)`,
    );
  } else {
    console.log('re-rendering camera page without active camera');
  }

  const frameProcessor = useFrameProcessor((frame) => {
    'worklet';

    console.log(`${frame.timestamp}: ${frame.width}x${frame.height} ${frame.pixelFormat} Frame (${frame.orientation})`);
    examplePlugin(frame);
  }, []);

  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}
                enableFpsGraph={true}
                orientation="portrait"
                photo={true}
                video={true}
                audio={hasMicrophonePermission}
                frameProcessor={frameProcessor}
              />
            </TapGestureHandler>
          </Reanimated.View>
        </PinchGestureHandler>
      )}

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

      <StatusBarBlurBackground />

      <View style={styles.rightButtonRow}>
        <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={() => setTargetFps((t) => (t === 30 ? 60 : 30))}>
            <Text style={styles.text}>{`${targetFps}\nFPS`}</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',
  },
});