153 lines
3.7 KiB
JavaScript
153 lines
3.7 KiB
JavaScript
import React from 'react';
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import PropTypes from 'prop-types';
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import classNames from 'classnames';
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export default class ImageLoader extends React.PureComponent {
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static propTypes = {
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alt: PropTypes.string,
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src: PropTypes.string.isRequired,
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previewSrc: PropTypes.string.isRequired,
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width: PropTypes.number,
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height: PropTypes.number,
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}
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static defaultProps = {
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alt: '',
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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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loading: true,
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error: false,
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}
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removers = [];
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get canvasContext() {
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if (!this.canvas) {
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return null;
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}
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this._canvasContext = this._canvasContext || this.canvas.getContext('2d');
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return this._canvasContext;
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}
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componentDidMount () {
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this.loadImage(this.props);
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}
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componentWillReceiveProps (nextProps) {
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if (this.props.src !== nextProps.src) {
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this.loadImage(nextProps);
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}
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}
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loadImage (props) {
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this.removeEventListeners();
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this.setState({ loading: true, error: false });
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Promise.all([
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this.loadPreviewCanvas(props),
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this.hasSize() && this.loadOriginalImage(props),
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].filter(Boolean))
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.then(() => {
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this.setState({ loading: false, error: false });
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this.clearPreviewCanvas();
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})
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.catch(() => this.setState({ loading: false, error: true }));
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}
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loadPreviewCanvas = ({ previewSrc, width, height }) => new Promise((resolve, reject) => {
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const image = new Image();
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const removeEventListeners = () => {
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image.removeEventListener('error', handleError);
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image.removeEventListener('load', handleLoad);
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};
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const handleError = () => {
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removeEventListeners();
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reject();
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};
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const handleLoad = () => {
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removeEventListeners();
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this.canvasContext.drawImage(image, 0, 0, width, height);
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resolve();
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};
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image.addEventListener('error', handleError);
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image.addEventListener('load', handleLoad);
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image.src = previewSrc;
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this.removers.push(removeEventListeners);
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})
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clearPreviewCanvas () {
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const { width, height } = this.canvas;
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this.canvasContext.clearRect(0, 0, width, height);
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}
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loadOriginalImage = ({ src }) => new Promise((resolve, reject) => {
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const image = new Image();
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const removeEventListeners = () => {
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image.removeEventListener('error', handleError);
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image.removeEventListener('load', handleLoad);
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};
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const handleError = () => {
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removeEventListeners();
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reject();
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};
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const handleLoad = () => {
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removeEventListeners();
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resolve();
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};
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image.addEventListener('error', handleError);
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image.addEventListener('load', handleLoad);
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image.src = src;
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this.removers.push(removeEventListeners);
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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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hasSize () {
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const { width, height } = this.props;
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return typeof width === 'number' && typeof height === 'number';
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}
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setCanvasRef = c => {
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this.canvas = c;
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}
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render () {
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const { alt, src, width, height } = this.props;
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const { loading } = this.state;
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const className = classNames('image-loader', {
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'image-loader--loading': loading,
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'image-loader--amorphous': !this.hasSize(),
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});
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return (
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<div className={className}>
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<canvas
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className='image-loader__preview-canvas'
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width={width}
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height={height}
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ref={this.setCanvasRef}
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style={{ opacity: loading ? 1 : 0 }}
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/>
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{!loading && (
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<img
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alt={alt}
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className='image-loader__img'
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src={src}
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width={width}
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height={height}
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/>
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)}
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</div>
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);
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}
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}
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