(function(){
    var watermark = function(self){
        this.elem = self;
    };
    watermark.prototype = {
        defaults : {
            path : '',//ˮӡͼƬ��ַ
            width : 30, //��
            height : 30, //��
            textRotate : -30 , //��ת�Ƕ� -90 ~ 90
            opacity: 1,//͸����
            type: 'Tile',//Tile Ϊƽ�� ����Ϊ�Զ���λ��
            scaleVal: 1, //���ű���
            margin: 5,//�Զ���λ��ʱ �߾�
            gravity:'ne',//�Զ���λ��  nw | n | ne | w | c | e | sw | s | se
            fullOverlay: false//�Զ���ʱ ����ˮӡͼƬ
        },
        options : {
            canvas : []
        },
        init : function(options){
            $.extend(this.options, this.defaults, options);
            var $body = $('body');
            var settings = this.options;
            var canOne = this.__createCanvas($body), canAll = this.__createCanvas($body);
            settings.deg = settings.textRotate * Math.PI / 180; //����
            this.__calcTextSize($body);
            var ctxOne = this.__setCanvasStyle(canOne, settings.canvasWidth, settings.canvasHeight);
            this.__drawImgOne(ctxOne);
            var ctx = this.__setCanvasStyle(canAll, settings.canvasMaxWidth, settings.canvasMaxHeight, true);
            this.__drawImgAll(ctx, canOne);
            var dataURL = canAll.toDataURL("image/png");
            $(this.elem).css('backgroundImage', "url(" + dataURL + ")");
            this.__destory();
            try{if(settings.callback) settings.callback();}catch(e){}
        },
        __createCanvas : function($container){
            var canvas = document.createElement('canvas');
            $container.append(canvas);
            this.options.canvas.push(canvas); 
            return canvas;
        },
        __calcTextSize : function($container){
            var canvasWidth = 0,
                canvasHeight = 0,
                settings = this.options,
                tWidth = settings.imgObj.width,
                tHeight = settings.imgObj.height,
                absdeg = Math.abs(settings.deg);
            //�ж�ͼƬ�������� ע�� �����г�������
            /*if(tWidth > $(this.elem).width() || tHeight > $(this.elem).height()){
                settings.scaleVal = Math.max(Math.ceil(tWidth / $(this.elem).width()), Math.ceil(tHeight / $(this.elem).height())) + 1;
            }*/
            canvasWidth = (Math.sin(absdeg) * tHeight + Math.cos(absdeg) * tWidth) / settings.scaleVal;
            canvasHeight = (Math.sin(absdeg) * tWidth + Math.cos(absdeg) * tHeight) / settings.scaleVal;
            //�и� �и�
            canvasWidth += settings.type == 'Tile' ? settings.width : 0;
            canvasHeight += settings.type == 'Tile' ? settings.height : 0;
            //
            var xRepeatTimes = 0, canvasMaxWidth = 0, yRepeatTimes = 0, canvasMaxHeight = 0;
            xRepeatTimes = Math.ceil($(this.elem).width() / canvasWidth);
            canvasMaxWidth = settings.type == 'Tile' ? canvasWidth * xRepeatTimes : $(this.elem).width();
            yRepeatTimes = Math.ceil($(this.elem).height() / canvasHeight);
            canvasMaxHeight = settings.type == 'Tile' ? canvasHeight * yRepeatTimes : $(this.elem).height();
            //
            settings.xRepeatTimes = xRepeatTimes;
            settings.canvasMaxWidth = canvasMaxWidth;
            settings.yRepeatTimes = yRepeatTimes;
            settings.canvasMaxHeight = canvasMaxHeight;
            settings.absdeg = absdeg;
            settings.canvasWidth = canvasWidth;
            settings.canvasHeight = canvasHeight;
        },
        __setCanvasStyle : function(canvas, width, height, nostyle){
            canvas.width = width;
            canvas.height = height;
            canvas.style.display='none';
            var ctx = canvas.getContext('2d');
            var settings = this.options;
            if(!nostyle) {
                var nx = Math.sin(settings.absdeg) * settings.imgObj.height / settings.scaleVal;
                var ny = Math.sin(settings.absdeg) * settings.imgObj.width / settings.scaleVal;
                nx = settings.textRotate < 0 ? 0 : nx;
                ny = settings.textRotate > 0 ? 0 : ny;
                ctx.translate(nx, ny);
                ctx.rotate(settings.deg);
                //͸����
                var op = settings.opacity;
                if (op > 0 && op < 1) {
                    ctx.globalAlpha = op;
                }
            }
            return ctx;
        },
        __drawImgOne: function(ctx){
            var settings = this.options;
            ctx.drawImage(settings.imgObj, 0, 0, settings.imgObj.width / settings.scaleVal, settings.imgObj.height / settings.scaleVal);
        },
        __drawImgAll: function(ctx, canvas){
            var settings = this.options;
            if(settings.type == 'Tile') {//ƽ��
                /*ctx.clearRect(0, 0, settings.canvasMaxWidth, settings.canvasMaxHeight); 
                var pat = ctx.createPattern(canvas, 'repeat');
                ctx.rect(0, 0, settings.canvasMaxWidth, settings.canvasMaxHeight);
                ctx.fillStyle = pat;
                ctx.fill();*/
                for(var J = 0; J < settings.yRepeatTimes; J++){
                    for(var i = 0; i < settings.xRepeatTimes; i++){
                        ctx.drawImage(canvas, settings.canvasWidth * i, settings.canvasHeight * J);
                    }
                }
            }else{
                //�Զ���λ��
                var w = settings.canvasMaxWidth,
                    h = settings.canvasMaxHeight,
                    wmW = settings.fullOverlay ? w : canvas.width,
                    wmH = settings.fullOverlay ? h : canvas.height,
                    pos = settings.margin || 0,
                    gLeft = 0, gTop = 0;
                switch (settings.gravity) { // nw | n | ne | w | c | e | sw | s | se
                    case 'nw': // ����
                        gLeft = pos;
                        gTop = pos;
                        break;
                    case 'n': // ��
                        gLeft = w / 2 - wmW / 2;
                        gTop = pos;
                        break;
                    case 'ne': // ����
                        gLeft = w - wmW - pos;
                        gTop = pos;
                        break;
                    case 'w': // ��
                        gLeft = pos;
                        gTop = h / 2 - wmH / 2;
                        break;
                    case 'c': // ��
                        gLeft = w / 2 - wmW / 2;
                        gTop = h / 2 - wmH / 2;
                        break;
                    case 'e': // ��
                        gLeft = w - wmW - pos;
                        gTop = h / 2 - wmH / 2;
                        break;
                    case 'sw': // ����
                        gLeft = pos;
                        gTop = h - wmH - pos;
                        break;
                    case 's': // ��
                        gLeft = w / 2 - wmW / 2;
                        gTop = h - wmH - pos;
                        break;
                    default: // ����
                        gLeft = w - wmW - pos;
                        gTop = h - wmH - pos;
                }
                ctx.drawImage(canvas, gLeft, gTop, wmW, wmH);
            }
        },
        __destory : function(){
            try{
                $.each(this.options.canvas, function(i, canvas){
                    canvas.remove();
                    canvas = null;
                });
            }catch(e){}
        }
    };
   
    $.fn.watermark = function(options){
        try{
            var _this = this;
            if(options.path != ''){
                var imgObj = new Image();
                //imgObj.src = options.path + "?rnd=" + Math.random();
                imgObj.src = options.path;
                imgObj.onload = function () {
                    options.imgObj = imgObj;
                    new watermark(_this).init(options);
                };
            }
        }catch(e){}
    }
})(jQuery);