将 base64 png 数据转换为 javascript 文件对象

I have two base64 encoded in PNG, and I need to compare them using Resemble.JS

我认为最好的方法是使用 fileReader 将 PNG 转换为文件对象.我该怎么做?

I think that the best way to do it is to convert the PNG's into file objects using fileReader. How can I do it?

推荐答案

你可以从你的base64数据创建一个Blob，然后读取它asDataURL:

You can create a Blob from your base64 data, and then read it asDataURL:

var img_b64 = canvas.toDataURL('image/png');
var png = img_b64.split(',')[1];

var the_file = new Blob([window.atob(png)],  {type: 'image/png', encoding: 'utf-8'});

var fr = new FileReader();
fr.onload = function ( oFREvent ) {
    var v = oFREvent.target.result.split(',')[1]; // encoding is messed up here, so we fix it
    v = atob(v);
    var good_b64 = btoa(decodeURIComponent(escape(v)));
    document.getElementById("uploadPreview").src = "data:image/png;base64," + good_b64;
};
fr.readAsDataURL(the_file);