IE浏览器不支持canvas toBlob()方法的Polyfill

2018-06-22 17:44

IE浏览器不支持canvas toBlob()方法的Polyfill，这里基于toDataURL()实现，直接粘贴在JS文件中即可。

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完整代码

if (!HTMLCanvasElement.prototype.toBlob) {
        Object.defineProperty(HTMLCanvasElement.prototype, 'toBlob', {
            value: function (callback, type, quality) {
                var canvas = this;
                setTimeout(function() {
                    var binStr = atob(canvas.toDataURL(type, quality).split(',')[1]);
                    var len = binStr.length, arr = new Uint8Array(len);

                    for (var i = 0; i < len; i++ ) {
                        arr[i] = binStr.charCodeAt(i);
                    }

                    callback(new Blob([arr], {type: type || 'image/png'}));
                });
            }
        });
    }

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