chuckya/app/javascript/mastodon/features/ui/components/zoomable_image.js

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