I would like to reload an image at a static URL indefinitely in React. Through some searching I arrived at the below less than ideal solution. It works, but I would like to remove the flickering of the image loading. I realize the issues is that the component is re-rendered, and then the image loads. I've seen a couple examples that use the two images one as a placeholder and the loading one hidden until it loads using onLoad
and setState
, but they all assume a finite number of images. How can I make this display the last image in the CardMedia
until the new one is loaded and then replaced without flicker every five seconds?
import React from 'react';
import ReactDOM from 'react-dom';
import { Card, CardMedia, CardTitle } from 'react-toolbox/lib/card';
const LIVE_IMAGE = 'https://cdn-images-1.medium.com/max/1600/1*oi8WLwC2u0EEI1j9uKmwWg.png';
class LiveImageCard extends React.Component {
constructor(props) {
super(props);
this.state = {
liveImage: null
};
}
componentDidMount() {
this.interval = setInterval(
() => this.setState({
liveImage: `${LIVE_IMAGE}?${new Date().getTime()}`,
}),
5000
);
}
componentWillUnmount() {
clearInterval(this.interval);
}
render() {
return (
<Card style={{width: '350px'}}>
<CardTitle title="Live Image" />
<CardMedia
aspectRatio="wide"
image={this.state.liveImage}
/>
</Card>
);
}
}
ReactDOM.render(
<LiveImageCard />,
document.getElementById('root'),
);
Not sure if this is the best solution, but I ended up with this and it works such that you don't see the flicker.
import React from 'react';
import ReactDOM from 'react-dom';
import { Card, CardMedia, CardTitle } from 'react-toolbox/lib/card';
const LIVE_IMAGE = 'https://cdn-images-1.medium.com/max/1600/1*oi8WLwC2u0EEI1j9uKmwWg.png';
class LiveImageCard extends React.Component {
constructor(props) {
super(props);
this.loadImage = () => {
const component = this;
const img = new Image();
img.crossOrigin = "Anonymous";
img.onload = function () {
var canvas = document.createElement("canvas");
canvas.width =this.width;
canvas.height =this.height;
var ctx = canvas.getContext("2d");
ctx.drawImage(this, 0, 0);
var dataURL = canvas.toDataURL("image/png");
component.setState({liveImage: dataURL});
};
img.src = `${LIVE_IMAGE}?${new Date().getTime()}`;
this.setState({ loadingImage: img });
}
this.state = {
loadingImage: null,
liveImage: null
};
}
componentDidMount() {
this.loadImage();
this.interval = setInterval(this.loadImage, 5000);
}
componentWillUnmount() {
clearInterval(this.interval);
}
render() {
return (
<Card style={{width: '350px'}}>
<CardTitle title="Live Image" />
<CardMedia
aspectRatio="wide"
image={this.state.liveImage}
/>
</Card>
);
}
}
ReactDOM.render(
<LiveImageCard />,
document.getElementById('root'),
);
Or as a standalone component without the React-Toolbox
class LiveImage extends React.Component {
constructor(props) {
super(props);
this.loadImage = () => {
const component = this;
const img = new Image();
img.crossOrigin = "Anonymous";
img.onload = function () {
var canvas = document.createElement("canvas");
canvas.width =this.width;
canvas.height =this.height;
var ctx = canvas.getContext("2d");
ctx.drawImage(this, 0, 0);
var dataURL = canvas.toDataURL("image/png");
component.setState({liveImage: dataURL});
};
img.src = `${this.props.image}?${new Date().getTime()}`;
this.setState({ loadingImage: img });
}
this.state = {
loadingImage: null,
liveImage: null
};
}
componentDidMount() {
this.loadImage();
this.interval = setInterval(this.loadImage, this.props.interval);
}
componentWillUnmount() {
clearInterval(this.interval);
}
render() {
return (
<img src={this.state.liveImage} {...this.props} />
);
}
}