html5扫描二维码

早先用html5写了一个扫描二维码的小应用，但是镜头是反的。
找了半天没有解决，看着反的二维码也扫出来了，就没管了。

今天要做过拍照的功能，发现静态分明是正常的，排除法发现罪魁祸首。竟然解决了，也算是完整的案例了，先标记一下。（还没有做浏览器兼容，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: absolute; top: 0; left: 0;width:100%;height:100%;text-align: center;border: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:auto;width:200px;height:200px;border: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 = 0; i < length * 4; i += 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>

------------------------------------------------------ZXing后台解析----------------------------------------------------------

[HttpPost]

public ActionResult Scan(string code) {

BarcodeReader reader = new BarcodeReader();

MemoryStream stream = new MemoryStream(Convert.FromBase64String(code));

Bitmap img = new Bitmap(stream);

Result result = reader.Decode(img);

return Json(result.Text);

}