图片放大缩小功能

// 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()};