/**
     * 获得base64
     * @param {Object} obj
     * @param {Number} [obj.width] 图片需要压缩的宽度，高度会跟随调整
     * @param {Number} [obj.quality=0.8] 压缩质量，不压缩为1
     * @param {Function} [obj.before(this, blob, file)] 处理前函数,this指向的是input:file
     * @param {Function} obj.success(obj) 处理后函数
     * @example
     *
     */
    $.fn.localResizeIMG = function(obj) {
        this.on('change', function() {
            var file = this.files[0];
            if (file == null) return;
            if (file.size == 0) {
                var result = {
                    name: file.name,
                    filetype: "",
                    size: 0,
                    base64: "",
                    clearBase64: "",
                    error: "不能上传空文件"
                };
                // 执行后函数
                obj.success(result);
                this.value = ''; // 清空临时数据
                return;
            }
            if (obj.sizeLimit != 0) {
                var sizeLimit = 0;
                if (obj.sizeLimit.indexOf("kb") >= 0) {
                    sizeLimit = parseInt(obj.sizeLimit.substr(0, obj.sizeLimit.length - 2) * 1024);
                } else if (obj.sizeLimit.indexOf("mb") >= 0) {
                    sizeLimit = parseInt(obj.sizeLimit.substr(0, obj.sizeLimit.length - 2) * 1024 * 1024);
                } else {
                    sizeLimit = parseInt(obj.sizeLimit);
                }
                if (file.size > sizeLimit) {
                    var result = {
                        name: file.name,
                        filetype:"",
                        size: 0,
                        base64: "",
                        clearBase64: "",
                        error: "上传文件不能大于" + obj.sizeLimit
                    };
                    // 执行后函数
                    obj.success(result);
                    this.value = ''; // 清空临时数据
                    return;
                }
            }
            if (obj.fileTypeExts == "*") obj.fileTypeExts = "";
            var extStart = file.name.lastIndexOf(".") + 1;
            var ext = file.name.substring(extStart, file.name.length).toLowerCase();
            if (obj.fileTypeExts != "") {
                var ss = obj.fileTypeExts.split(",");
                var bk=false;
                for (var i = 0; i < ss.length; i++) {
                    var s = ss[i].substr(2, ss[i].length).toLowerCase();
                    if (ext == s) { bk = true; break;}
                }
                if (bk == false) {
                    var result = {
                        name: file.name,
                        filetype: "",
                        size: 0,
                        base64: "",
                        clearBase64: "",
                        error: "上传文件格式错误"
                    };
                    // 执行后函数
                    obj.success(result);
                    this.value = ''; // 清空临时数据
                    return;
                }   
            }

            if (ext != "bmp" && ext != "png" && ext != "gif" && ext != "jpg" && ext != "jpge") {
                var reader = new FileReader();
                reader.readAsDataURL(file);
                reader.onload = function (e) {
                    var base64 = e.target.result;
                    // 生成结果
                    var result = {
                        name: file.name,
                        filetype: ext,
                        size:file.size,
                        base64: base64,
                        clearBase64: base64.substr(base64.indexOf(',') + 1),
                        error: ""
                    };
                    // 执行后函数
                    obj.success(result);
                    this.value = ''; // 清空临时数据
                };
                return;
            } 
            var URL = window.URL || window.webkitURL;
            var blob = URL.createObjectURL(file);

            // 执行前函数
            if ($.isFunction(obj.before)) {
                obj.before(this, blob, file)
            };

            _create(blob, file,ext);
            this.value = ''; // 清空临时数据
        });

        /**
         * 生成base64
         * @param blob 通过file获得的二进制
         */
        function _create(blob, file, ext) {
            var Orientation = null;
            try {
                EXIF.getData(file, function () {
                    EXIF.getAllTags(this);
                    Orientation = EXIF.getTag(this, 'Orientation');
                });
            }
            catch (err)
            {

            }

            var img = new Image();
            img.src = blob;

            img.onload = function() {
                var that = this;

                //生成比例
                var w = that.width,
                    h = that.height,
                    scale = obj.width/ w;
                if (obj.width > 0 && obj.width < that.width) {

                    w = obj.width;
                    h = h*scale;
                    //h = obj.height || h;
                }

                //生成canvas
                var canvas = document.createElement('canvas');
                var ctx = canvas.getContext('2d');
                $(canvas).attr({
                    width: w,
                    height: h
                });
                ctx.drawImage(that, 0, 0, w, h);

                var base64 = "";
               // alert(Orientation);
                // 修复IOS
                if (Orientation != "" && Orientation != 1) {
                        switch (Orientation) {
                            case 6://需要顺时针（向左）90度旋转  
                                rotateImg(this, 'left', canvas);
                                break;
                            case 8://需要逆时针（向右）90度旋转  
                                rotateImg(this, 'right', canvas);
                                break;
                            case 3://需要180度旋转  
                                rotateImg(this, 'right', canvas);//转两次  
                                rotateImg(this, 'right', canvas);
                                break;
                        }
                }
                base64 = canvas.toDataURL('image/jpeg', obj.quality || 0.8);

                // 生成结果
                var result = {
                    name: file.name,
                    filetype: ext,
                    width: that.width,
                    height: that.height,
                    w: w,
                    h: h,
                    size: file.size,
                    base64: base64,
                    clearBase64: base64.substr(base64.indexOf(',') + 1),
                    error: ""
                };

                // 执行后函数
                obj.success(result);
            };
        }
};


function rotateImg(img, direction, canvas) {
    //alert(img);  
    //最小与最大旋转方向，图片旋转4次后回到原方向    
    var min_step = 0;
    var max_step = 3;
    //var img = document.getElementById(pid);    
    if (img == null) return;
    //img的高度和宽度不能在img元素隐藏后获取，否则会出错    
    var height = img.height;
    var width = img.width;
    //var step = img.getAttribute('step');    
    var step = 2;
    if (step == null) {
        step = min_step;
    }
    if (direction == 'right') {
        step++;
        //旋转到原位置，即超过最大值    
        step > max_step && (step = min_step);
    } else {
        step--;
        step < min_step && (step = max_step);
    }
    //img.setAttribute('step', step);    
    /*var canvas = document.getElementById('pic_' + pid);   
    if (canvas == null) {   
        img.style.display = 'none';   
        canvas = document.createElement('canvas');   
        canvas.setAttribute('id', 'pic_' + pid);   
        img.parentNode.appendChild(canvas);   
    }  */
    //旋转角度以弧度值为参数    
    var degree = step * 90 * Math.PI / 180;
    var ctx = canvas.getContext('2d');
    switch (step) {
        case 0:
            canvas.width = width;
            canvas.height = height;
            ctx.drawImage(img, 0, 0);
            break;
        case 1:
            canvas.width = height;
            canvas.height = width;
            ctx.rotate(degree);
            ctx.drawImage(img, 0, -height);
            break;
        case 2:
            canvas.width = width;
            canvas.height = height;
            ctx.rotate(degree);
            ctx.drawImage(img, -width, -height);
            break;
        case 3:
            canvas.width = height;
            canvas.height = width;
            ctx.rotate(degree);
            ctx.drawImage(img, -width, 0);
            break;
    }
} 



    // 例子
    /*
    $('input:file').localResizeIMG({
        width: 100,
        quality: 0.1,
        //before: function (that, blob) {},
        success: function (result) {
            var img = new Image();
            img.src = result.base64;

            $('body').append(img);
            console.log(result);
        }
    });
*/