利用javascript實現圖片等比例縮放

learning_1發表於2008-10-10
JavaScript
下面方法可以實現等比例縮放：
1． 把Image的Width和Height屬性刪除。
2.　把下面js程式碼複製在Image[color=red]後面[/color]（注意：這裡假設你的Image名稱叫“Image1”如果不同請把它改過來，圖片按等比例縮放成200×200）。

<script language="javascript" type="text/javascript"> 
function DrawImage() 
{ 
	var FitWidth = 200,FitHeight = 200;
	var ImgD = document.getElementById('Image1');
	var image = new Image();
	image.src=ImgD.src;
	if(image.width>0 && image.height>0) 
	{ 
		if(image.width/image.height>= FitWidth/FitHeight) 
		{ 
			if(image.width>FitWidth) 
			{ 
				ImgD.width=FitWidth; 
				ImgD.height=(image.height*FitWidth)/image.width; 
			} 
			else 
			{ 
				ImgD.width=image.width; 
				ImgD.height=image.height; 
			} 
		} 
		else 
		{ 
			if(image.height>FitHeight) 
			{ 
				ImgD.height=FitHeight; 
				ImgD.width=(image.width*FitHeight)/image.height; 
			} 
			else 
			{ 
				ImgD.width=image.width; 
				ImgD.height=image.height; 
			} 
		} 
	} 
} 

DrawImage();
</script>

整個網頁的原始碼如下：

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>圖片等比例綻放</title>
</head>
<body>
<img src="Spring.jpg" id="Image1"/>
</body>
</html>
<script language="javascript" type="text/javascript"> 
function DrawImage() 
{ 
	var FitWidth = 200,FitHeight = 200;
	var ImgD = document.getElementById('Image1');
	var image = new Image();
	image.src=ImgD.src;
	if(image.width>0 && image.height>0) 
	{ 
		if(image.width/image.height>= FitWidth/FitHeight) 
		{ 
			if(image.width>FitWidth) 
			{ 
				ImgD.width=FitWidth; 
				ImgD.height=(image.height*FitWidth)/image.width; 
			} 
			else 
			{ 
				ImgD.width=image.width; 
				ImgD.height=image.height; 
			} 
		} 
		else 
		{ 
			if(image.height>FitHeight) 
			{ 
				ImgD.height=FitHeight; 
				ImgD.width=(image.width*FitHeight)/image.height; 
			} 
			else 
			{ 
				ImgD.width=image.width; 
				ImgD.height=image.height; 
			} 
		} 
	} 
} 

DrawImage();
</script>

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