I am fairly new to React and I am developing an app which will take actual screenshots of a web page and the app can draw and add doodles on top of the screenshot taken. I initially used html2canvas and domToImage to take client-side screenshots but it doesn't render the image exactly as it is shown in the web page.
Reddit user /pamblam0 suggested I look into Google's Puppeteer. How it works is that it launches a headless chromium browser which goes to my react app on localhost then gets a screenshot of that whole page easily. My problem however, is that puppeteer doesn't play nice inside a react app. It gives me a ws error which, as explained on a google search can be fixed by simply installing ws (which doesn't work by the way).
What happens now my puppeteer script works out my react app. From what I understand it doesn't work with client side app (I might be wrong). What I want to happen is that whenever I click the button from my react app, puppeteer should execute and return a base64 string which will then be passed to a component in my react app.
Here is what I've done so far.
puppeteerApp.js
const puppeteer = require('puppeteer');
const takeScreenshot = async () => {
puppeteer.launch().then(async browser => {
const page = await browser.newPage();
const options = {
path: 'saved_images/webshot.png',
encoding: 'base64'
}
await page.goto('http://localhost:3000/', { waitUntil: 'networkidle2' });
const elem = await page.$('iframe').then(async (iframe) => {
return await iframe.screenshot(options)
});
await browser.close()
});
}
takeScreenshot();
Code from react app. App.js
import React, { Component } from 'react';
import ScreenshotsContainer from './containers/ScreenshotsContainer/ScreenshotsContainer'
import ImageContainer from './containers/ImageContainer/ImageContainer';
import html2canvas from 'html2canvas';
import domtoimage from 'dom-to-image';
import Button from './components/UI/Button/Button'
import classes from './App.module.css';
import { CSSTransition } from 'react-transition-group'
import { ToastContainer, toast } from 'react-toastify';
import 'react-toastify/dist/ReactToastify.css';
class App extends Component {
constructor(props) {
super(props);
this.state = {
imgURIArray: [],
img: null,
showImageContainer: false,
showScreenshotContainer: false,
selectedImageURI: null,
showSaveAnimation: false,
showNotify: false
}
}
storeImageToArrayHandler = (imgURI) => {
if (imgURI !== "") {
this.setState({ imgURIArray: [...this.state.imgURIArray, imgURI] }, () => {
this.setState({ showImageContainer: !this.state.showImageContainer })
})
}
}
getScreenshotHandler = () => {
//use puppeteer here!!!
}
getSelectedImageFromContainerHandler(selectedImageURI) {
this.setState({
selectedImageURI: selectedImageURI,
showImageContainer: !this.state.showImageContainer
})
}
showImageContainerHandler(showImageContainer) {
this.setState({ showImageContainer: showImageContainer })
}
showScreenshotContainerHandler = () => {
this.setState({ showScreenshotContainer: !this.state.showScreenshotContainer })
}
notify = (submitSuccessful, msg) => {
let message = msg ? msg : ""
submitSuccessful ?
toast.success(message, {
autoClose: 3000,
position: toast.POSITION.TOP_CENTER
})
:
toast.error(message, {
position: toast.POSITION.TOP_CENTER
});
}
render() {
let buttonOps = (
<CSSTransition
in={!this.state.showScreenshotContainer}
appear={true}
timeout={300}
classNames="fade"
>
<div className={classes.optionButtons}>
<Button icon={"fas fa-camera"} type={"button-success"} gridClass={""} buttonName={""} style={{ width: "100%", height: "70px" }} onClick={() => this.getScreenshotHandler} />
<Button icon={"fas fa-images"} type={"button-primary "} gridClass={""} buttonName={""} style={{ width: "100%", height: "70px" }} onClick={() => this.showScreenshotContainerHandler} />
</div>
</CSSTransition>
)
return (
<div>
{
this.state.showImageContainer ?
<div>
<ImageContainer
img={this.state.img}
showImageContainer={showImageContainer => this.showImageContainerHandler(showImageContainer)}
storeImageToArrayHandler={imgURI => this.storeImageToArrayHandler(imgURI)}
notify={(submitSuccessful, msg) => this.notify(submitSuccessful, msg)}
/>
</div>
: null
}
<CSSTransition
in={this.state.showScreenshotContainer}
appear={true}
timeout={300}
classNames="slide"
unmountOnExit
onExited={() => {
this.setState({ showScreenshotContainer: false })
}}
>
<ScreenshotsContainer
imgURIArray={this.state.imgURIArray}
getSelectedImageFromContainerHandler={imgURI => this.getSelectedImageFromContainerHandler(imgURI)}
showScreenshotContainerHandler={() => this.showScreenshotContainerHandler}
notify={(submitSuccessful, msg) => this.notify(submitSuccessful, msg)}
/>
</CSSTransition>
{this.state.showImageContainer ? null : buttonOps}
{/* <button onClick={this.notify}>Notify !</button> */}
<ToastContainer />
</div >
);
}
}
export default App;
Any help would be appreciated. Thanks!
Your React.js application runs on the client-side (in the browser). Puppeteer cannot run inside that environment as you cannot start a full browser inside the browser.
What you need is a server which does that for you. You could ether offer a HTTP endpoint (option 1) or expose your puppeteer Websocket (option 2):
Option 1: Provide a HTTP endpoint
For this option, you setup a server which handles the incoming request and runs the task (making a screenshot) for you:
server.js
const puppeteer = require('puppeteer');
const express = require('express');
const app = express();
app.get('/screenshot', async (req, res) => {
const browser = await puppeteer.launch();
const page = await browser.newPage();
await page.goto(req.query.url); // URL is given by the "user" (your client-side application)
const screenshotBuffer = await page.screenshot();
// Respond with the image
res.writeHead(200, {
'Content-Type': 'image/png',
'Content-Length': screenshotBuffer.length
});
res.end(screenshotBuffer);
await browser.close();
})
app.listen(4000);
Start the application with node server.js and you can now pass the URL to your server and get a screenshot back from your server: http://localhost:4000/screenshot?url=https://example.com/
The response from the server could then be used as as the source of an image element in your application.
Option 2: Exposing the puppeteer Websocket to the client
You could also control the browser (which runs on the server) from the client-side by by exposing the Websocket.
For that you need to expose the Websocket of your server like this:
server.js
const puppeteer = require('puppeteer');
(async () => {
const browser = await puppeteer.launch();
const browserWSEndpoint = browser.wsEndpoint();
browser.disconnect(); // Disconnect from the browser, but don't close it
console.log(browserWSEndpoint); // Communicate the Websocket URL to the client-side
// example output: ws://127.0.0.1:55620/devtools/browser/e62ec4c8-1f05-42a1-86ce-7b8dd3403f91
})();
Now you can control the browser (running on the server) form the client-side with a puppeteer bundle for the client. In this scenario you could now connect to the browser via puppeteer.connect and make a screenshot that way.
I would strongly recommend using option 1, as in option 2 you are fully exposing your running browser to the client. Even with option 1, you still need to handle user input validation, timeouts, navigation errors, etc.
来源：https://stackoverflow.com/questions/55031823/how-to-make-puppeteer-work-with-a-reactjs-application-on-the-client-side