};
四、生成需要的结构
这个效果的原理就是：我们把图片复制到四个层里面，然后将这四个层相对定位，再把这个图拼起来，这样动画效果就能达到了。
that.generate = function(){
var w = that.node.width() / 2;
var h = that.node.height() / 2;
that.imga = [];
for (var i = 0; i < 4; i++) {
that.imga[i] = document.createElement(‘div’);
that.imga[i] = $(that.imga[i]);
that.imga[i].css({
‘position’: ‘absolute’,
‘z-index’: ‘2’,
‘width’: w,
‘height’: h,
‘background’: ‘url(“‘ + that.img.attr(“src”) + ‘”) no-repeat’
});
$(that.node).append(that.imga[i]);
}
that.imga[0].css({
‘left’: ‘0px’,
‘top’: ‘0px’
});
that.imga[1].css({
‘right’: ‘0px’,
‘top’: ‘0px’,
‘background-position’: ‘-‘ + w + ‘px’ + ‘ 0px’
});
that.imga[2].css({
‘left’: ‘0px’,
‘bottom’: ‘0px’,
‘background-position’: ‘0px’ + ‘ -‘ + h + ‘px’
});
that.imga[3].css({
‘right’: ‘0px’,
‘bottom’: ‘0px’,
‘background-position’: ‘-‘ + w + ‘px ‘ + ‘-‘ + h + ‘px’
});
that.img.remove();
};
这里的代码也比较简单，首先得到外面层的宽度和高度，然后计算，再生成四个层，给四个层写入相应的位置代码，需要注意的是，外面层的position属性要设置为relative，要么里面的层就无法准确定位了。这里其实可以直接写入相应的html代码，但是为了表现清晰，我们采用了比较明朗的写法，先生成一个div，然后赋给他一些css属性。
五、添加动画效果，注册事件处理程序
完成了结构的任务，下一步就是给他添加动画效果了，我们只需要将这四个图层在鼠标经过的时候移出外面的层，然鼠标离开的时候再复位就可以了，写起来也是非常的简单，看代码：
that.cutter = function(){
var w = that.node.width() / 2;
var h = that.node.height() / 2;
that.node.hover(function(){
that.imga[0].stop().animate({
‘left’: ‘-‘ + w,
‘top’: ‘-‘ + h
}, that.speedOut, that.easeOut);
that.imga[1].stop().animate({
‘right’: ‘-‘ + w,
‘top’: ‘-‘ + h
}, that.speedOut, that.easeOut);
that.imga[2].stop().animate({
‘left’: ‘-‘ + w,
‘bottom’: ‘-‘ + h
}, that.speedOut, that.easeOut);
that.imga[3].stop().animate({
