/*common*/

/**

 * canvas图片压缩

 * @param  {[Object]} opt [配置参数]

 * @param  {[Function]} cbk [回调函数]

 * @return {[Void]}

 * example:

 * var opt = {

    'type' : 1,//为1为预览，建议不为1或后期进行改进

    'file' : "#loadFile"//文件上传控件

},_compress = require('app/compress');

_compress(opt,function (result) {

    console.log(result)

});

 */

function writeDom (opt,cbk) {

    var _opt = opt,

        _cbk = cbk;

    $('#img,#_canvas,#img-c').remove();

    $('body').append($('<canvas id="_canvas" style="display: none;"></canvas><img id="img-c" src="" style="display:none;"/><img id="img" src="" style="width:300px;"/>'));

    _image = new Image();

    _image.src = _opt.src || "";

    $('#img-c').attr('src',_opt.src)[0].onload = function(){

        var _this = $(this);

        var _canvas=document.getElementById('_canvas');

        _canvas.width = _this.width();

        _canvas.height = _this.height();

        var _context=_canvas.getContext('2d');

        _context.drawImage(_image,0,0);

        if (_opt.type) {$('#img').attr('src',_canvas.toDataURL('image/jpeg',_opt.scale));};

        _cbk(_canvas.toDataURL('image/jpeg',_opt.scale));

    };

}

var result = '';

return function(opt,cbk){

    var _opt = {

        'type' : opt.type || 0,

        'file' : opt.file ? $(opt.file) : $("#loadFile")

    },

    _file = _opt.file,

    _cbk = cbk || function(){};

    _file.change(function(){

        var file = $(this)[0].files[0];

        var fReader = new FileReader();

        fReader.readAsDataURL(file);

        fReader.onload = function (e){

            var _num = +prompt('请输入压缩比例');

            if (isNaN(_num)) {_num = 1};

            _opt.scale = _num;

            result = _opt.src = this.result;

            writeDom(_opt,_cbk);

        };

    });

}