如何使用反应钩子获取网络摄像头提要? [英] How to get webcam feed with react hooks?
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问题描述
我正在尝试使用 React 钩子获取要在我的应用程序上显示的网络摄像头提要.我还需要能够从提要中捕获最新的图像
I am trying to get a webcam feed to display on my app using react hooks. I also need to be able to capture the latest image from the feed
我相信我有基础,但缺少一些东西.
I believe I have the foundations but am missing something.
import React,{useState,useEffect} from "react"
export function VideoFeed(){
const[constraints] = useState({width:300,height:300})
useEffect(()=>{
navigator.mediaDevices.getUserMedia({video:true})
.then(stream=>{
let video = document.querySelector('video')
video.source = stream;
video.play();
})
.catch(e=>{
console.log(e)
})
})
return(
<video autoPlay ={true} id ="video"></video>
)
}
推荐答案
参见 如何在 React 中访问 DOM 元素? 而不是 document.querySelector
.
当使用 useRef
钩子和修复时useEffect
需要多久执行一次,它看起来像这样:
When applied with useRef
hook and fixing how often useEffect
needs to execute, it would look something like this:
export function VideoFeed() {
const videoEl = useRef(null)
useEffect(() => {
if (!videoEl) {
return
}
navigator.mediaDevices.getUserMedia({video:true})
.then(stream => {
let video = videoEl.current
video.srcObject = stream
video.play()
})
}, [videoEl])
return <video ref={videoEl} />
}
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