用HTML5 可以实现二维码扫描识别的功能吗

恰好这几天在尝试，没有兼容所有浏览器。只在手机上试过firefox, 自带浏览器试过不行。以下是代码：

---------------------------------------------------------Html----------------------------------------------------------------

<form id="picForm" action="@Url.Action("scan")" method="post">

<input type="hidden" value="" id="code" name="code" />

<input type="hidden" value="" id="status" name="status" />

<section style="position: relative">

<video width="100%" id="video" autoplay="autoplay"></video>

<div id="result" style="position: absolutetop: 0left: 0width:100%height:100%text-align: centerborder:1px solid yellow" onclick="scanCode()">

<section class="smtwo" style="text-align:center">

<h3 ><a class="back" href="${ctx }/index/index.htm">

<img src="images/smtwo_1.png" style="border: none" alt=""></a>请将扫描框对准设备或包装上的二维码 </h3>

</section>

<div id="getCode" style="margin:autowidth:200pxheight:200pxborder:1px solid red"></div>

<canvas width="200" height="200" id="canvas"></canvas>

</div>

</section>

</form

--------------------------------------------------------------Js--------------------------------------------------------------------

<script>

var video, canvas, videoObj

window.addEventListener('DOMContentLoaded', function () {

'use strict'

//调取摄像头

navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia

window.URL = window.URL || window.webkitURL || window.mozURL || window.msURL

if (navigator.getUserMedia) {

videoObj = { video: true }

video = document.getElementById("video")// $("#video").get(0)

canvas = document.getElementById("canvas")// $("#canvas").get(0)

navigator.getUserMedia({

video: true

}, gotStream, noStream)

} else {

alert('Native web camera streaming (getUserMedia) not supported in this browser.')

}

//调取摄像头成功的回调函数

function gotStream(stream) {

if (video.mozSrcObject !== undefined) {

video.mozSrcObject = stream

} else {

video.src = (window.URL &&window.URL.createObjectURL(stream)) || stream

}

video.play()

//启动摄像头成功之后开始获取二维码

scanCode()

}

//调取摄像头失败的回调函数

function noStream(error) {

alert('An error occurred: [CODE ' + error.code + ']')

}

}, false)

//抓取video画面放入canvas

function photograph() {

var context = canvas.getContext("2d")

// 截取取景框范围（这里用canvas做取景框）

//var x = canvas.clientLeft

//var y = canvas.clientTop

//context.drawImage(video,x, y, canvas.width, canvas.height, 0, 0, canvas.width, canvas.height)

var box = getBox()

context.drawImage(video, box.X, box.Y, box.W, box.H, 0, 0, box.W , box.H)

//imageConvertToGray(context)

var imgData = canvas.toDataURL("image/png")

$("#code").val(imgData)

}

function getBox() {

var box = $("#getCode")

var position = { X: $(box).offset().top, Y: $(box).offset().left, W: $(box).width(), H: $(box).height() }

return position

}

//将图片处理成黑白的（二维码扫描需要处理黑白色图片，如果仅用于拍照这一步就省略了）

function imageConvertToGray(ctx) {

var length = canvas.width * canvas.height

imageData = ctx.getImageData(0, 0, canvas.width, canvas.height)

for (var i = 0i <length * 4i += 4) {

var myRed = imageData.data[i]

var myGreen = imageData.data[i + 1]

var myBlue = imageData.data[i + 2]

myGray = parseInt((myRed + myGreen + myBlue) / 3)

imageData.data[i] = myGray

imageData.data[i + 1] = myGray

imageData.data[i + 2] = myGray

}

ctx.putImageData(imageData, 0, 0)

}

function scanCode() {

//生成图片的base64码

photograph()

var data = { "code": $("#code").val() }

ajaxPostCompliate("@Url.Action("scan")", data, function (result) {

console.info("-----------result--------------" + result)

if (result != null) {//扫描出结果

var obj = JSON.parse(result)

if (obj.org != undefined) {

location.href = "@Url.Action("ScanResult")?org=" + obj.org + "&tp=" + obj.tp + "&ad=" + obj.ad

} else {

alert("该二维码非ME+授权编码")

}

} else {//继续扫描

setTimeout(function () {

scanCode()

}, 2000)

}

})

}

</script>

先简单的添加需要的控件

<video id="video" autoplay=""style='width:640pxheight:480px'></video>

<button id='picture'>PICTURE</button>

<canvas id="canvas" width="640" height="480"></canvas>

并在script中定义

var video = document.getElementById("video")

var context = canvas.getContext("2d")

var errocb = function () {

console.log('sth wrong!')

}

然后，简单的说就是利用html5的api navigator.getUserMedia来开启设备的摄像头，浏览器上会出现图示中的提示

if (navigator.getUserMedia) { // 标准的API

navigator.getUserMedia({ "video": true }, function (stream) {

video.src = stream

video.play()

}, errocb)

} else if (navigator.webkitGetUserMedia) { // WebKit 核心的API

navigator.webkitGetUserMedia({ "video": true }, function (stream) {

video.src = window.webkitURL.createObjectURL(stream)

video.play()

}, errocb)

}

网上有些例子中，navigator.getUserMedia第一个参数是‘video’，这可能是早期的版本，现在必须是obj

还有关于getUserMedia和webkitGetUserMedia 的判断，网上有这么写的

navigator.getUserMedia = (navigator.getUserMedia ||

navigator.webkitGetUserMedia ||

navigator.mozGetUserMedia ||

navigator.msGetUserMedia)

但要注意，他们绑定video.src的方法不一样，偶没有测过createObjectURL是否通用

拍照功能就是简单的调用canvas中的drawImage即可

document.getElementById("picture").addEventListener("click", function () {

context.drawImage(video, 0, 0, 640, 480)

})

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