javascript 图片放大缩小功能实现代码

// 放大缩小控制
var PhotoSize = {
zoom: 0, // 缩放率
count: 0, // 缩放次数
cpu: 0, // 当前缩放倍数值
elem: "", // 图片节点
photoWidth: 0, // 图片初始宽度记录
photoHeight: 0, // 图片初始高度记录

init: function(){
this.elem = document.getElementById("focusphoto");
this.photoWidth = this.elem.scrollWidth;
this.photoHeight = this.elem.scrollHeight;

this.zoom = 1.2; // 设置基本参数
this.count = 0;
this.cpu = 1;
},

action: function(x){
if(x === 0){
this.cpu = 1;
this.count = 0;
}else{
this.count += x; // 添加记录
this.cpu = Math.pow(this.zoom, this.count); // 任意次幂运算
};
this.elem.style.width = this.photoWidth * this.cpu +"px";
this.elem.style.height = this.photoHeight * this.cpu +"px";
}
};
// 启动放大缩小效果 用onload方式加载，防止第一次点击获取不到图片的宽高
window.onload = function(){PhotoSize.init()};