js中图片二进制和base64的互转
2018-11-27 本文已影响0人
wy若只如初见
<html>
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<p>正常图片</p>
<p></p>
<img src="132.jpg" />
<p></p>
<p>base64</p>
<p></p>
<img src="" id="base64" alt="" />
<p></p>
<p></p>
<p>base64转为二进制</p>
<img src="" id="erjinz" alt="" />
</body>
<script src="jquery-2.1.0.js" type="text/javascript" charset="utf-8"></script>
<script type="text/javascript">
/**
* 网络图像文件转Base64
*/
function getBase64Image(img) {
var canvas = document.createElement("canvas");
canvas.width = img.width;
canvas.height = img.height;
var ctx = canvas.getContext("2d");
ctx.drawImage(img, 0, 0, img.width, img.height);
var ext = img.src.substring(img.src.lastIndexOf(".") + 1).toLowerCase();
var dataURL = canvas.toDataURL("image/" + ext);
return dataURL;
}
/**
*Base64字符串转二进制
*/
function dataURLtoBlob(dataurl) {
var arr = dataurl.split(','),
mime = arr[0].match(/:(.*?);/)[1],
bstr = atob(arr[1]),
n = bstr.length,
u8arr = new Uint8Array(n);
while(n--) {
u8arr[n] = bstr.charCodeAt(n);
}
return new Blob([u8arr], {
type: mime
});
}
//**blob to dataURL**
function blobToDataURL(blob, callback) {
var a = new FileReader();
a.onload = function(e) {
callback(e.target.result);
}
a.readAsDataURL(blob);
return a;
}
var result;
var img = "132.jpg";
var image = new Image();
image.src = img;
image.onload = function() {
//这样就获取到了文件的Base64字符串
var base64 = getBase64Image(image);
$("#base64").attr("src", base64);
//Base64字符串转二进制
var file = dataURLtoBlob(base64);
//二进制转base64
result = blobToDataURL(file, function(dataurl) {
console.log(dataurl);
});
setTimeout(function() {
$("#erjinz").attr("src", result.result);
}, 100);
}
</script>
</html>
