bsky-social-app/src/view/com/lightbox/ImageViewing/components/ImageItem/ImageItem.android.tsx

/**
 * Copyright (c) JOB TODAY S.A. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 */

import React, {useCallback, useRef, useState} from 'react'

import {
  Animated,
  ScrollView,
  Dimensions,
  StyleSheet,
  NativeScrollEvent,
  NativeSyntheticEvent,
  NativeMethodsMixin,
} from 'react-native'
import {Image} from 'expo-image'

import useImageDimensions from '../../hooks/useImageDimensions'
import usePanResponder from '../../hooks/usePanResponder'

import {getImageStyles, getImageTransform} from '../../utils'
import {ImageSource} from '../../@types'
import {ImageLoading} from './ImageLoading'

const SWIPE_CLOSE_OFFSET = 75
const SWIPE_CLOSE_VELOCITY = 1.75
const SCREEN = Dimensions.get('window')
const SCREEN_WIDTH = SCREEN.width
const SCREEN_HEIGHT = SCREEN.height

type Props = {
  imageSrc: ImageSource
  onRequestClose: () => void
  onZoom: (isZoomed: boolean) => void
  swipeToCloseEnabled?: boolean
  doubleTapToZoomEnabled?: boolean
}

const AnimatedImage = Animated.createAnimatedComponent(Image)

const ImageItem = ({
  imageSrc,
  onZoom,
  onRequestClose,
  swipeToCloseEnabled = true,
  doubleTapToZoomEnabled = true,
}: Props) => {
  const imageContainer = useRef<ScrollView & NativeMethodsMixin>(null)
  const imageDimensions = useImageDimensions(imageSrc)
  const [translate, scale] = getImageTransform(imageDimensions, SCREEN)
  const scrollValueY = new Animated.Value(0)
  const [isLoaded, setLoadEnd] = useState(false)

  const onLoaded = useCallback(() => setLoadEnd(true), [])
  const onZoomPerformed = useCallback(
    (isZoomed: boolean) => {
      onZoom(isZoomed)
      if (imageContainer?.current) {
        imageContainer.current.setNativeProps({
          scrollEnabled: !isZoomed,
        })
      }
    },
    [onZoom],
  )

  const [panHandlers, scaleValue, translateValue] = usePanResponder({
    initialScale: scale || 1,
    initialTranslate: translate || {x: 0, y: 0},
    onZoom: onZoomPerformed,
    doubleTapToZoomEnabled,
  })

  const imagesStyles = getImageStyles(
    imageDimensions,
    translateValue,
    scaleValue,
  )
  const imageOpacity = scrollValueY.interpolate({
    inputRange: [-SWIPE_CLOSE_OFFSET, 0, SWIPE_CLOSE_OFFSET],
    outputRange: [0.7, 1, 0.7],
  })
  const imageStylesWithOpacity = {...imagesStyles, opacity: imageOpacity}

  const onScrollEndDrag = ({
    nativeEvent,
  }: NativeSyntheticEvent<NativeScrollEvent>) => {
    const velocityY = nativeEvent?.velocity?.y ?? 0
    const offsetY = nativeEvent?.contentOffset?.y ?? 0

    if (
      (Math.abs(velocityY) > SWIPE_CLOSE_VELOCITY &&
        offsetY > SWIPE_CLOSE_OFFSET) ||
      offsetY > SCREEN_HEIGHT / 2
    ) {
      onRequestClose()
    }
  }

  const onScroll = ({nativeEvent}: NativeSyntheticEvent<NativeScrollEvent>) => {
    const offsetY = nativeEvent?.contentOffset?.y ?? 0

    scrollValueY.setValue(offsetY)
  }

  return (
    <ScrollView
      ref={imageContainer}
      style={styles.listItem}
      pagingEnabled
      nestedScrollEnabled
      showsHorizontalScrollIndicator={false}
      showsVerticalScrollIndicator={false}
      contentContainerStyle={styles.imageScrollContainer}
      scrollEnabled={swipeToCloseEnabled}
      {...(swipeToCloseEnabled && {
        onScroll,
        onScrollEndDrag,
      })}>
      <AnimatedImage
        {...panHandlers}
        source={imageSrc}
        style={imageStylesWithOpacity}
        onLoad={onLoaded}
        accessibilityLabel={imageSrc.alt}
        accessibilityHint=""
      />
      {(!isLoaded || !imageDimensions) && <ImageLoading />}
    </ScrollView>
  )
}

const styles = StyleSheet.create({
  listItem: {
    width: SCREEN_WIDTH,
    height: SCREEN_HEIGHT,
  },
  imageScrollContainer: {
    height: SCREEN_HEIGHT * 2,
  },
})

export default React.memo(ImageItem)