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