[JavaScript]Base64 ←→ 图像

1 Base64 → 图像

[demo1]

document.getElementById('img').setAttribute( 'src', 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0 DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg==' );

[demo2]
(HTML源码下)

展开HTML源码

效果：↓

2 JavaScript源码(base64图片编码 转 图片)

var dom = document.querySelector("div");
var tmpImgUrl = dom.style.background;
var base64Img = tmpImgUrl.substring(5,tmpImgUrl.length-2); // base64编码的图片数据
// base64Img = "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0 DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg=='";//形如←←←

var imgDom = document.querySelector("#img");
imgDom.setAttribute("src", base64Img);

效果：↓

3 Base64 ← 图像

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;  
}
  • demo1
var image = new Image();  
image.src = img;  
image.onload = function(){  
  var base64 = getBase64Image(image);  
  console.log(base64);  
}
  • demo2
var imageDom = document.querySelector("img");
var base64 = getBase64Image(imageDom);  
console.log(base64);

4 参考文献

posted @ 2020-05-04 00:21  千千寰宇  阅读(338)  评论(0)  编辑  收藏  举报