454 lines
		
	
	
	
		
			13 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
			
		
		
	
	
			454 lines
		
	
	
	
		
			13 KiB
		
	
	
	
		
			JavaScript
		
	
	
	
	
	
import React from 'react';
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import PropTypes from 'prop-types';
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import IconButton from 'flavours/glitch/components/icon_button';
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import { defineMessages, injectIntl } from 'react-intl';
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const messages = defineMessages({
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  compress: { id: 'lightbox.compress', defaultMessage: 'Compress image view box' },
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  expand: { id: 'lightbox.expand', defaultMessage: 'Expand image view box' },
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});
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const MIN_SCALE = 1;
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const MAX_SCALE = 4;
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const NAV_BAR_HEIGHT = 66;
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const getMidpoint = (p1, p2) => ({
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  x: (p1.clientX + p2.clientX) / 2,
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  y: (p1.clientY + p2.clientY) / 2,
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});
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const getDistance = (p1, p2) =>
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  Math.sqrt(Math.pow(p1.clientX - p2.clientX, 2) + Math.pow(p1.clientY - p2.clientY, 2));
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const clamp = (min, max, value) => Math.min(max, Math.max(min, value));
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// Normalizing mousewheel speed across browsers
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// copy from: https://github.com/facebookarchive/fixed-data-table/blob/master/src/vendor_upstream/dom/normalizeWheel.js
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const normalizeWheel = event => {
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  // Reasonable defaults
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  const PIXEL_STEP = 10;
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  const LINE_HEIGHT = 40;
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  const PAGE_HEIGHT = 800;
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  let sX = 0,
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    sY = 0, // spinX, spinY
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    pX = 0,
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    pY = 0; // pixelX, pixelY
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  // Legacy
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  if ('detail' in event) {
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    sY = event.detail;
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  }
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  if ('wheelDelta' in event) {
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    sY = -event.wheelDelta / 120;
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  }
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  if ('wheelDeltaY' in event) {
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    sY = -event.wheelDeltaY / 120;
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  }
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  if ('wheelDeltaX' in event) {
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    sX = -event.wheelDeltaX / 120;
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  }
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  // side scrolling on FF with DOMMouseScroll
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  if ('axis' in event && event.axis === event.HORIZONTAL_AXIS) {
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    sX = sY;
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    sY = 0;
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  }
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  pX = sX * PIXEL_STEP;
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  pY = sY * PIXEL_STEP;
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  if ('deltaY' in event) {
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    pY = event.deltaY;
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  }
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  if ('deltaX' in event) {
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    pX = event.deltaX;
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  }
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  if ((pX || pY) && event.deltaMode) {
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    if (event.deltaMode === 1) { // delta in LINE units
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      pX *= LINE_HEIGHT;
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      pY *= LINE_HEIGHT;
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    } else { // delta in PAGE units
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      pX *= PAGE_HEIGHT;
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      pY *= PAGE_HEIGHT;
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    }
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  }
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  // Fall-back if spin cannot be determined
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  if (pX && !sX) {
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    sX = (pX < 1) ? -1 : 1;
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  }
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  if (pY && !sY) {
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    sY = (pY < 1) ? -1 : 1;
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  }
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  return {
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    spinX: sX,
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    spinY: sY,
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    pixelX: pX,
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    pixelY: pY,
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  };
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};
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class ZoomableImage extends React.PureComponent {
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  static propTypes = {
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    alt: PropTypes.string,
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    lang: PropTypes.string,
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    src: PropTypes.string.isRequired,
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    width: PropTypes.number,
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    height: PropTypes.number,
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    onClick: PropTypes.func,
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    zoomButtonHidden: PropTypes.bool,
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    intl: PropTypes.object.isRequired,
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  };
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  static defaultProps = {
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    alt: '',
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    lang: '',
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    width: null,
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    height: null,
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  };
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  state = {
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    scale: MIN_SCALE,
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    zoomMatrix: {
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      type: null, // 'width' 'height'
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      fullScreen: null, // bool
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      rate: null, // full screen scale rate
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      clientWidth: null,
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      clientHeight: null,
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      offsetWidth: null,
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      offsetHeight: null,
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      clientHeightFixed: null,
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      scrollTop: null,
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      scrollLeft: null,
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      translateX: null,
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      translateY: null,
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    },
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    zoomState: 'expand', // 'expand' 'compress'
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    navigationHidden: false,
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    dragPosition: { top: 0, left: 0, x: 0, y: 0 },
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    dragged: false,
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    lockScroll: { x: 0, y: 0 },
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    lockTranslate: { x: 0, y: 0 },
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  };
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  removers = [];
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  container = null;
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  image = null;
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  lastTouchEndTime = 0;
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  lastDistance = 0;
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  componentDidMount () {
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    let handler = this.handleTouchStart;
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    this.container.addEventListener('touchstart', handler);
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    this.removers.push(() => this.container.removeEventListener('touchstart', handler));
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    handler = this.handleTouchMove;
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    // on Chrome 56+, touch event listeners will default to passive
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    // https://www.chromestatus.com/features/5093566007214080
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    this.container.addEventListener('touchmove', handler, { passive: false });
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    this.removers.push(() => this.container.removeEventListener('touchend', handler));
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    handler = this.mouseDownHandler;
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    this.container.addEventListener('mousedown', handler);
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    this.removers.push(() => this.container.removeEventListener('mousedown', handler));
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    handler = this.mouseWheelHandler;
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    this.container.addEventListener('wheel', handler);
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    this.removers.push(() => this.container.removeEventListener('wheel', handler));
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    // Old Chrome
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    this.container.addEventListener('mousewheel', handler);
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    this.removers.push(() => this.container.removeEventListener('mousewheel', handler));
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    // Old Firefox
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    this.container.addEventListener('DOMMouseScroll', handler);
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    this.removers.push(() => this.container.removeEventListener('DOMMouseScroll', handler));
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    this.initZoomMatrix();
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  }
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  componentWillUnmount () {
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    this.removeEventListeners();
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  }
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  componentDidUpdate () {
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    this.setState({ zoomState: this.state.scale >= this.state.zoomMatrix.rate ? 'compress' : 'expand' });
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    if (this.state.scale === MIN_SCALE) {
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      this.container.style.removeProperty('cursor');
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    }
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  }
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  UNSAFE_componentWillReceiveProps () {
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    // reset when slide to next image
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    if (this.props.zoomButtonHidden) {
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      this.setState({
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        scale: MIN_SCALE,
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        lockTranslate: { x: 0, y: 0 },
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      }, () => {
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        this.container.scrollLeft = 0;
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        this.container.scrollTop = 0;
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      });
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    }
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  }
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  removeEventListeners () {
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    this.removers.forEach(listeners => listeners());
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    this.removers = [];
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  }
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  mouseWheelHandler = e => {
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    e.preventDefault();
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    const event = normalizeWheel(e);
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    if (this.state.zoomMatrix.type === 'width') {
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      // full width, scroll vertical
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      this.container.scrollTop = Math.max(this.container.scrollTop + event.pixelY, this.state.lockScroll.y);
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    } else {
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      // full height, scroll horizontal
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      this.container.scrollLeft = Math.max(this.container.scrollLeft + event.pixelY, this.state.lockScroll.x);
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    }
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    // lock horizontal scroll
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    this.container.scrollLeft = Math.max(this.container.scrollLeft + event.pixelX, this.state.lockScroll.x);
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  };
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  mouseDownHandler = e => {
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    this.container.style.cursor = 'grabbing';
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    this.container.style.userSelect = 'none';
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    this.setState({ dragPosition: {
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      left: this.container.scrollLeft,
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      top: this.container.scrollTop,
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      // Get the current mouse position
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      x: e.clientX,
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      y: e.clientY,
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    } });
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    this.image.addEventListener('mousemove', this.mouseMoveHandler);
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    this.image.addEventListener('mouseup', this.mouseUpHandler);
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  };
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  mouseMoveHandler = e => {
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    const dx = e.clientX - this.state.dragPosition.x;
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    const dy = e.clientY - this.state.dragPosition.y;
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    this.container.scrollLeft = Math.max(this.state.dragPosition.left - dx, this.state.lockScroll.x);
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    this.container.scrollTop = Math.max(this.state.dragPosition.top - dy, this.state.lockScroll.y);
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    this.setState({ dragged: true });
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  };
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  mouseUpHandler = () => {
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    this.container.style.cursor = 'grab';
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    this.container.style.removeProperty('user-select');
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    this.image.removeEventListener('mousemove', this.mouseMoveHandler);
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    this.image.removeEventListener('mouseup', this.mouseUpHandler);
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  };
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  handleTouchStart = e => {
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    if (e.touches.length !== 2) return;
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    this.lastDistance = getDistance(...e.touches);
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  };
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  handleTouchMove = e => {
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    const { scrollTop, scrollHeight, clientHeight } = this.container;
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    if (e.touches.length === 1 && scrollTop !== scrollHeight - clientHeight) {
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      // prevent propagating event to MediaModal
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      e.stopPropagation();
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      return;
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    }
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    if (e.touches.length !== 2) return;
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    e.preventDefault();
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    e.stopPropagation();
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    const distance = getDistance(...e.touches);
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    const midpoint = getMidpoint(...e.touches);
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    const _MAX_SCALE = Math.max(MAX_SCALE, this.state.zoomMatrix.rate);
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    const scale = clamp(MIN_SCALE, _MAX_SCALE, this.state.scale * distance / this.lastDistance);
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    this.zoom(scale, midpoint);
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    this.lastMidpoint = midpoint;
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    this.lastDistance = distance;
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  };
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  zoom(nextScale, midpoint) {
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    const { scale, zoomMatrix } = this.state;
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    const { scrollLeft, scrollTop } = this.container;
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    // math memo:
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    // x = (scrollLeft + midpoint.x) / scrollWidth
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    // x' = (nextScrollLeft + midpoint.x) / nextScrollWidth
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    // scrollWidth = clientWidth * scale
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    // scrollWidth' = clientWidth * nextScale
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    // Solve x = x' for nextScrollLeft
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    const nextScrollLeft = (scrollLeft + midpoint.x) * nextScale / scale - midpoint.x;
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    const nextScrollTop = (scrollTop + midpoint.y) * nextScale / scale - midpoint.y;
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    this.setState({ scale: nextScale }, () => {
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      this.container.scrollLeft = nextScrollLeft;
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      this.container.scrollTop = nextScrollTop;
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      // reset the translateX/Y constantly
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      if (nextScale < zoomMatrix.rate) {
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        this.setState({
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          lockTranslate: {
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            x: zoomMatrix.fullScreen ? 0 : zoomMatrix.translateX * ((nextScale - MIN_SCALE) / (zoomMatrix.rate - MIN_SCALE)),
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            y: zoomMatrix.fullScreen ? 0 : zoomMatrix.translateY * ((nextScale - MIN_SCALE) / (zoomMatrix.rate - MIN_SCALE)),
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          },
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        });
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      }
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    });
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  }
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  handleClick = e => {
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    // don't propagate event to MediaModal
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    e.stopPropagation();
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    const dragged = this.state.dragged;
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    this.setState({ dragged: false });
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    if (dragged) return;
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    const handler = this.props.onClick;
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    if (handler) handler();
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    this.setState({ navigationHidden: !this.state.navigationHidden });
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  };
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  handleMouseDown = e => {
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    e.preventDefault();
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  };
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  initZoomMatrix = () => {
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    const { width, height } = this.props;
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    const { clientWidth, clientHeight } = this.container;
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    const { offsetWidth, offsetHeight } = this.image;
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    const clientHeightFixed = clientHeight - NAV_BAR_HEIGHT;
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    const type = width / height < clientWidth / clientHeightFixed ? 'width' : 'height';
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    const fullScreen = type === 'width' ?  width > clientWidth : height > clientHeightFixed;
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    const rate = type === 'width' ? Math.min(clientWidth, width) / offsetWidth : Math.min(clientHeightFixed, height) / offsetHeight;
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    const scrollTop = type === 'width' ?  (clientHeight - offsetHeight) / 2 - NAV_BAR_HEIGHT : (clientHeightFixed - offsetHeight) / 2;
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    const scrollLeft = (clientWidth - offsetWidth) / 2;
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    const translateX = type === 'width' ? (width - offsetWidth) / (2 * rate) : 0;
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    const translateY = type === 'height' ? (height - offsetHeight) / (2 * rate) : 0;
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    this.setState({
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      zoomMatrix: {
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        type: type,
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        fullScreen: fullScreen,
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        rate: rate,
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        clientWidth: clientWidth,
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        clientHeight: clientHeight,
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        offsetWidth: offsetWidth,
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        offsetHeight: offsetHeight,
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        clientHeightFixed: clientHeightFixed,
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        scrollTop: scrollTop,
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        scrollLeft: scrollLeft,
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        translateX: translateX,
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        translateY: translateY,
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      },
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    });
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  };
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  handleZoomClick = e => {
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    e.preventDefault();
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    e.stopPropagation();
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    const { scale, zoomMatrix } = this.state;
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    if ( scale >= zoomMatrix.rate ) {
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      this.setState({
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        scale: MIN_SCALE,
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        lockScroll: {
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          x: 0,
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          y: 0,
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        },
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        lockTranslate: {
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          x: 0,
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          y: 0,
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        },
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      }, () => {
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        this.container.scrollLeft = 0;
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        this.container.scrollTop = 0;
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      });
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    } else {
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      this.setState({
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        scale: zoomMatrix.rate,
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        lockScroll: {
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          x: zoomMatrix.scrollLeft,
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          y: zoomMatrix.scrollTop,
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        },
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        lockTranslate: {
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          x: zoomMatrix.fullScreen ? 0 : zoomMatrix.translateX,
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          y: zoomMatrix.fullScreen ? 0 : zoomMatrix.translateY,
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        },
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      }, () => {
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        this.container.scrollLeft = zoomMatrix.scrollLeft;
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        this.container.scrollTop = zoomMatrix.scrollTop;
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      });
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    }
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    this.container.style.cursor = 'grab';
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    this.container.style.removeProperty('user-select');
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  };
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  setContainerRef = c => {
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    this.container = c;
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  };
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  setImageRef = c => {
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    this.image = c;
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  };
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  render () {
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    const { alt, lang, src, width, height, intl } = this.props;
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    const { scale, lockTranslate } = this.state;
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    const overflow = scale === MIN_SCALE ? 'hidden' : 'scroll';
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    const zoomButtonShouldHide = this.state.navigationHidden || this.props.zoomButtonHidden || this.state.zoomMatrix.rate <= MIN_SCALE ? 'media-modal__zoom-button--hidden' : '';
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    const zoomButtonTitle = this.state.zoomState === 'compress' ? intl.formatMessage(messages.compress) : intl.formatMessage(messages.expand);
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    return (
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      <React.Fragment>
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        <IconButton
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          className={`media-modal__zoom-button ${zoomButtonShouldHide}`}
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          title={zoomButtonTitle}
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          icon={this.state.zoomState}
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          onClick={this.handleZoomClick}
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          size={40}
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          style={{
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            fontSize: '30px', /* Fontawesome's fa-compress fa-expand is larger than fa-close */
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          }}
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        />
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        <div
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          className='zoomable-image'
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          ref={this.setContainerRef}
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          style={{ overflow }}
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        >
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          <img
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            role='presentation'
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            ref={this.setImageRef}
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            alt={alt}
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            title={alt}
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            lang={lang}
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            src={src}
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            width={width}
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            height={height}
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            style={{
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              transform: `scale(${scale}) translate(-${lockTranslate.x}px, -${lockTranslate.y}px)`,
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              transformOrigin: '0 0',
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            }}
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            draggable={false}
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            onClick={this.handleClick}
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						|
            onMouseDown={this.handleMouseDown}
 | 
						|
          />
 | 
						|
        </div>
 | 
						|
      </React.Fragment>
 | 
						|
    );
 | 
						|
  }
 | 
						|
 | 
						|
}
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						|
 | 
						|
export default injectIntl(ZoomableImage);
 |