javascript 图片放大缩小功能实现代码

时间:2020-05-12 人气:2

看JS源码：

// 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()};

建议最好采用onload方式引用，可以准确读到初始图片的大小

<!doctype html> 
<html> 
<head> 
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" /> 
<meta name="auther" content="f7" /> 
<title>图片放大缩小</title> 
<script type="text/javascript"> 
// 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()}; 
</script> 
</head> 
<body> 
<input type="button" value="放大" onclick="PhotoSize.action(1);" /> <input type="button" value="缩小" onclick="PhotoSize.action(-1);" /> <input type="button" value="还原大小" onclick="PhotoSize.action(0);" /> <input type="button" value="查看当前倍数" onclick="alert(PhotoSize.cpu);" /><br> 
<img onerror="javascript:this.src='/skin1/img/error.jpg';" id="focusphoto" src="https://img.qb5200.com/download-x/20200512/26518.jpg" /> 
</body> 
</html>

[Ctrl+A 全选注:如需引入外部Js需刷新才能执行]

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