php图片等比例放大与缩小的方法举例

<?php
/**
 * 图片等比例放大与缩小
 * @resizeimage
 * @param $srcfile 源文件尺寸
 * @param $mySize  要转换的尺寸
 * edit www.jb200.com
 * at 2013/6/7
*/
function resizeimage($srcfile,$mySize){
$size=getimagesize($srcfile);
switch($size[2]){
case 1:
$img=imagecreatefromgif($srcfile);
break;
case 2:
$img=imagecreatefromjpeg($srcfile);
break;
case 3:
$img=imagecreatefrompng($srcfile);
break;
}
//源图片的宽度和高度
$oldImg['w']=imagesx($img);
$oldImg['h']=imagesy($img);
if ($oldImg['w']<=$mySize['w'] && $oldImg['h']<156){
$rate=1;
}elseif ($oldImg['w']>$mySize['w'] && $oldImg['h']<$mySize['h']){
$rate=$mySize['w']/$oldImg['w'];
}elseif ($oldImg['w']<$mySize['w'] && $oldImg['h']>$mySize['h']){
$rate=$mySize['h']/$oldImg['h'];
}elseif ($oldImg['w']>$mySize['w'] && $oldImg['h']>$mySize['h']){
$rate1=$mySize['w']/$oldImg['w'];
$rate2=$mySize['h']/$oldImg['h'];
if ($rate1>$rate2){$rate=$rate2;}else{$rate=$rate1;}
}
$newImg['w']=$oldImg['w']*$rate;
$newImg['h']=$oldImg['h']*$rate;
return "width=".$newImg['w']." height=".$newImg['h'];
}

//调用示例：
$mySize=array('w'=>143,'h'=>156);
$imgSize=resizeimage("22.jpg",$mySize);
echo "<img src="22.jpg"".resizeimage("22.jpg",$mySize)."/>";
?>