function zoom(mask, bigimg, smallimg) {
    this.bigimg = bigimg;
    this.smallimg = smallimg;
    this.mask = mask
}

zoom.prototype = {
    init: function () {
        var that = this;
        this.smallimgClick();
        this.bigimgClick();
        this.maskClick();
        this.mouseWheel()
    },
    smallimgClick: function () {
        var that = this;
        $("." + that.smallimg).click(function (e) {
            var w,h;
            var naturalWidth = e.target.naturalWidth;
            var naturalHeight = e.target.naturalHeight;
            var rate = naturalHeight / naturalWidth;

            var baseWidth = e.target.naturalWidth * 1.5;
            var baseHeight = e.target.naturalHeight * 1.5;

            if (naturalWidth > naturalHeight) {
                if (naturalWidth > document.body.offsetWidth || baseWidth > document.body.offsetWidth) {
                    w = document.body.offsetWidth - 40;
                    h = rate * w;
                } else {
                    w = baseWidth;
                    h = baseHeight;
                }
            }

            if (naturalHeight > naturalWidth) {
                if (naturalHeight > document.body.clientHeight || baseHeight > document.body.clientHeight ) {
                    h = document.body.clientHeight - 130;
                    w = h / rate;
                } else {
                    w = baseWidth;
                    h = baseHeight;
                }
            }
            $("." + that.bigimg).css({
                width: 355.34,
                height:522.33,
            });
            $("." + that.mask).fadeIn();
            $("." + that.bigimg).attr("src", $(this).attr("src")).fadeIn()
        })
    },
    maskClick: function () {
        var that = this;
        $("." + that.mask).click(function () {
            $("." + that.bigimg).fadeOut();
            $("." + that.mask).fadeOut()
        })
    },
    bigimgClick: function () {
        var that = this;
        $("." + that.bigimg).click(function () {
            $("." + that.bigimg).fadeOut();
            $("." + that.mask).fadeOut()
        })
    },
    mouseWheel: function () {
        function mousewheel(obj, upfun, downfun) {
            if (document.attachEvent) {
                obj.attachEvent("onmousewheel", scrollFn)
            } else {
                if (document.addEventListener) {
                    obj.addEventListener("mousewheel", scrollFn, false);
                    obj.addEventListener("DOMMouseScroll", scrollFn, false)
                }
            }

            function scrollFn(e) {
                var ev = e || window.event;
                var dir = ev.wheelDelta || ev.detail;
                if (ev.preventDefault) {
                    ev.preventDefault()
                } else {
                    ev.returnValue = false
                }
                if (dir == -3 || dir == 120) {
                    upfun()
                } else {
                    downfun()
                }
            }
        }

        var that = this;
        mousewheel($("." + that.bigimg)[0], function () {
            if ($("." + that.bigimg).innerWidth() > $("body").width() + 20) {
                alert("不能再放大了");
                return
            }
            if ($("." + that.bigimg).innerHeight() > $("body").height() - 50) {
                alert("不能再放大");
                return
            }
            var zoomHeight = $("." + that.bigimg).innerHeight() * 1.03;
            var zoomWidth = $("." + that.bigimg).innerWidth() * 1.03;
            $("." + that.bigimg).css({
                height: zoomHeight + "px",
                width: zoomWidth + "px"
            })
        }, function () {
            if ($("." + that.bigimg).innerWidth() < 100) {
                alert("不能再缩小了哦！");
                return
            }
            if ($("." + that.bigimg).innerHeight() < 100) {
                alert("不能再缩小了哦！");
                return
            }
            var zoomHeight = $("." + that.bigimg).innerHeight() / 1.03;
            var zoomWidth = $("." + that.bigimg).innerWidth() / 1.03;
            $("." + that.bigimg).css({
                height: zoomHeight + "px",
                width: zoomWidth + "px"
            })
        })
    }
};