js实现google网站的小眼睛

时间：2011-03-08 来源：chemdemo

没看之前，觉得会挺难的，今天看了别人的思路，于是自己摸索着也整了一个出来。感觉这东西也不太实用，不过把它挂在博客上什么的装饰一下还可以，但主要是练习js，提高自己的编程能力啦~。写的时候，画张图，边分析边写，会容易些，另外就是一些初中数学知识的运用啦......

请先查看Demo

源码部分：

html：

<div id="googleEye">
        <h1>Google eye!</h1>
        <div id="leftEye"><img src="images/pupil.gif" /></div>
        <div id="rightEye"><img src="images/pupil.gif" /></div>
</div>

css：

body {background-color: #888;}
#googleEye {
        background-color: #FFF;
        width: 324px;
        margin: 1em auto;
        padding-bottom: 1em;
        border: 1px solid #E1ECFE;
        text-align: center;
        vertical-align: middle;
}
#googleEye h1 {
        line-
        background-color: #E1ECFE;
        font-size: 16px;
        text-align: center;
        margin: 0 0 1em;
        padding: 0;
}
#googleEye div {
        display: inline-block;
        _display: inline;
        _zoom: 1;
        width: 117px;
        
        position: relative;
}
#leftEye {background: url(images/eye-r.gif) no-repeat center;}
#rightEye {background: url(images/eye-y.gif) no-repeat center;}
#googleEye div img {
        position: absolute;
        left: 51px;
        top: 51px;
        width: auto;
}

js：

function $(id) {
        return document.getElementById(id);
}

function addEvent(obj, type, handler) {
        if(obj.addEventListener) {
                obj.addEventListener(type, handler, false);
        } else if(obj.attachEvent) {
                obj.attachEvent('on' + type, handler);
        } else {
                obj['on' + type] = handler;
        }
}

(function() {
        addEvent(window, 'load', initAll);

        addEvent(document, "mousemove", function(event) {
                GEye.init(event.clientX, event.clientY);
        });
        
        function initAll() {
                var gEye1 = new GEye($('leftEye'));
                var gEye2 = new GEye($('rightEye'));
        }

        function GEye(eye) {
                this.eye = eye;
                this.pupil = eye.getElementsByTagName('img')[0];
                GEye.eyes.push(this);
        }
        GEye.eyes = [];
        GEye.eyeRadius = 58;//眼睛半径
        GEye.pupilRadius = 7;//瞳孔半径
        GEye.pupilRange = 41;//瞳孔活动范围
        GEye.getHypotenuse = function(h, v) {//已知直角三角形的两直角边，求斜边长
                return Math.sqrt(Math.pow(h, 2) + Math.pow(v, 2));
        }

        GEye.init = function(x, y) {
                for(var i=0; i<this.eyes.length; i++) {
                        this.eyes[i].draw(x, y);
                };
        }

        GEye.prototype = {
                setPos: function(left, top) {
                        this.pupil.style.left = left + 'px';
                        this.pupil.style.top = top + 'px';
                },
                setAngle: function(sin, cos) {
                        var left = GEye.eyeRadius - cos*GEye.pupilRange - GEye.pupilRadius;
                        var top = GEye.eyeRadius - sin*GEye.pupilRange - GEye.pupilRadius;
                        this.setPos(left, top);
                },
                getCenter: function() {//求眼睛圆心坐标
                        return {
                                X: this.eye.offsetLeft + GEye.eyeRadius,
                                Y: this.eye.offsetTop + GEye.eyeRadius
                        };
                },
                draw: function(mouseX, mouseY) {        
                        var center = this.getCenter();
                        var len = GEye.getHypotenuse(center.X - mouseX, center.Y - mouseY);//鼠标顶点到眼睛圆心的距离
                        if(len > GEye.pupilRange) {//在眼睛外
                                var sin = (center.Y - mouseY)/len;
                                var cos = (center.X - mouseX)/len;
                                this.setAngle(sin, cos);
                        } else {//在眼睛里面
                                var left = mouseX - this.eye.offsetLeft - GEye.pupilRadius;
                                var top = mouseY - this.eye.offsetTop - GEye.pupilRadius;
                                this.setPos(left, top);
                        };
                }
        }
})();

最近一直学习js，也经常上cnblogs看园友们的文章，帮助挺大的，感谢大家的分享。