JS按比例缩放图片

1、JS代码

 1   <script type="text/javascript" language="javascript">
 2         var flag = false;
 3         function DrawImage3(iwidth,iheight,ImgD) {
 4             var image = new Image();
 5             image.src = ImgD.src;
 6             if (image.width > 0 && image.height > 0) {
 7                 flag = true;
 8                      //原图宽除高的值和定义宽除高的值的比较
 9                 if (image.width / image.height >= iwidth / iheight) {
10                     // 原图的宽大于定义的宽
11                     if (image.width > iwidth) {
12                         ImgD.width = iwidth;
13                         //定义的宽度和原图的宽度的比例，同比缩小高度
14                         ImgD.height = (image.height * iwidth) / image.width;
15                     } else {
16                         ImgD.width = image.width;
17                         ImgD.height = image.height;
18                     }
19                     ImgD.alt = image.width + "×" + image.height;
20                 }
21                 else {
22                     // 原图的高大于定义的高
23                     if (image.height > iheight) {
24                         ImgD.height = iheight;
25                         //定义的高度和原图的高度的比例，同比缩小宽度
26                         ImgD.width = (image.width * iheight) / image.height;
27                     } else {
28                         ImgD.width = image.width;
29                         ImgD.height = image.height;
30                     }
31                     ImgD.alt = image.width + "×" + image.height;
32                 }
33             }
34         }
35     </script>

2、前代代码

1 <img alt='' src="Image/wuqilong.jpg" onload="DrawImage3(200,150,this)" />

 

转载于:https://www.cnblogs.com/ElvisZhongShao/p/4505299.html