function base64ToqR(base64, callBack) {
                    var objCanvas = box.find('#qrChangeBase64Canvas')[0];
                    var ctx = objCanvas.getContext('2d'); // 返回值是CanvasRenderingContext2D类的对象实例。
                    var image = new window.Image();
                    image.src = base64;
                    image.onload = function() {
                        ctx.drawImage(image, 0, 0, image.width, image.height); // 绘图
                        var imageData = ctx.getImageData(0, 0, image.width, image.height);
                        callBack(imageData);
                    };
                }