javascript - 如何从 dataURL 创建图像文件？

Question

我正在尝试将图片上传到 Parse.com，我没有文件，但是有 dataURL(因为我调整了图片的大小)，但需要上传图片文件。

欢迎任何提示。

这里是更多细节的代码:

// First want to resize the image, where the result is a dataURL
var dataURL;
function resizePicture(file) {    // This file is the original image
    var reader = new FileReader();
    reader.onloadend = function() {
        var tempImg = new Image();
        tempImg.src = reader.result;
        tempImg.onload = function() {
            var MAX_WIDTH = 100;
            var MAX_HEIGHT = 150;
            var tempW = tempImg.width;
            var tempH = tempImg.height;
            if (tempW > tempH) {
                if (tempW > MAX_WIDTH) {
                    tempH *= MAX_WIDTH / tempW;
                    tempW = MAX_WIDTH;
                }
            } else {
                if (tempH > MAX_HEIGHT) {
                    tempW *= MAX_HEIGHT / tempH;
                    tempH = MAX_HEIGHT;
                }
            }
            var canvas = document.createElement('canvas');
            canvas.width = tempW;
            canvas.height = tempH;
            var ctx = canvas.getContext("2d");
            ctx.drawImage(this, 0, 0, tempW, tempH);
            dataURL = canvas.toDataURL("image/jpeg"); // How can I convert this dataURL to an image file?
        }
    }
    reader.readAsDataURL(file);
}

// Then,  want to upload the image to Parse.com. 
function savePicture() {
    var name = "productPicture.jpg";
    var parseFile = new Parse.File(name, dataURL); // Here instead of dataURL, I need an image file.
    parseFile.save().then(function() {
            // successful save
        }, function(error) {
            alert("The file either could not be read, or could not be saved to Parse.");
    });
}

Answer 1

根据 API Documentation对于 Parse.File(name, data, type):

data

The data for the file, as either:

1. an Array of byte value Numbers, or
2. an Object like { base64: "..." } with a base64-encoded String.
3. a File object selected with a file upload control.

(3) only works in Firefox 3.6+, Safari 6.0.2+, Chrome 7+, and IE 10+.

理论上这应该可行:

// get everything after "base64,"
var base64 = dataURL.split('base64,')[1];
var parseFile = new Parse.File(name, { base64: base64 });