js 控制图片大小


缩放图片脚本分享

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
 <head>
  <title> New Document </title>
  <meta name="Generator" content="EditPlus">
  <meta name="Author" content="">
  <meta name="Keywords" content="">
  <meta name="Description" content="">

  <script>
	
	function AutoResizeImage(maxWidth,maxHeight){
	var objImg = document.getElementById("operImg");
	var img = new Image();
	img.src = objImg.src;
	var hRatio;
	var wRatio;
	var Ratio = 1;
	var w = img.width;
	var h = img.height;
	wRatio = maxWidth / w;
	hRatio = maxHeight / h;
	if (maxWidth ==0 && maxHeight==0){
	Ratio = 1;
	}else if (maxWidth==0){//
	if (hRatio<1) Ratio = hRatio;
	}else if (maxHeight==0){
	if (wRatio<1) Ratio = wRatio;
	}else if (wRatio<1 || hRatio<1){
	Ratio = (wRatio<=hRatio?wRatio:hRatio);
	}
	if (Ratio<1){
	w = w * Ratio;
	h = h * Ratio;
	}
	objImg.height = h;
	objImg.width = w;
	}
  </script>

 </head>

 <body>

  <img src="1111.jpg" border="0"  alt="534 X 800" id="operImg"/>

  <input type="button" value="缩放至宽100px,等比例压缩" onclick="AutoResizeImage(100,0)"/>

  <input type="button" value="缩放至300px,等比例压缩" onclick="AutoResizeImage(300,0)"/>

  <input type="button" value="原图" onclick="AutoResizeImage(0,0)"/>
 </body>
</html>

重点js:

	function AutoResizeImage(maxWidth,maxHeight){
	var objImg = document.getElementById("operImg");
	var img = new Image();
	img.src = objImg.src;
	var hRatio;
	var wRatio;
	var Ratio = 1;
	var w = img.width;
	var h = img.height;
	wRatio = maxWidth / w;
	hRatio = maxHeight / h;
	if (maxWidth ==0 && maxHeight==0){
	Ratio = 1;
	}else if (maxWidth==0){//
	if (hRatio<1) Ratio = hRatio;
	}else if (maxHeight==0){
	if (wRatio<1) Ratio = wRatio;
	}else if (wRatio<1 || hRatio<1){
	Ratio = (wRatio<=hRatio?wRatio:hRatio);
	}
	if (Ratio<1){
	w = w * Ratio;
	h = h * Ratio;
	}
	objImg.height = h;
	objImg.width = w;
	}


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