PHP自动裁剪图片输出来实现适应不同尺寸的显示

RewriteRule ^(.*\.(png|jpg))/(.*)$ image.php?url=$1&param=$3 [L]

<?php
define('EMLOG_ROOT', dirname(__FILE__));
$imgurl = EMLOG_ROOT.$_GET['url'];
$param = $_GET['param'];
if(file_exists($imgurl) || $param ==''){
	header("HTTP/1.1 404 Not Found");  
	header("Status: 404 Not Found");  
	exit;  
}
preg_match_all('#param=(.*)y(.*)#',$param,$info);
$width = $info[1][0];
$height = $info[2][0];
imagecropper($_GET['url'],$width,$height);
function imagecropper($source_path, $target_width, $target_height){
	$source_info = getimagesize($source_path);
	$source_width = $source_info[0];
	$source_height = $source_info[1];
	$source_mime = $source_info['mime'];
	$source_ratio = $source_height / $source_width;
	$target_ratio = $target_height / $target_width;
	// 源图过高
	if ($source_ratio > $target_ratio){
		$cropped_width = $source_width;
		$cropped_height = $source_width * $target_ratio;
		$source_x = 0;
		$source_y = ($source_height - $cropped_height) / 2;
	}
	// 源图过宽
	elseif ($source_ratio < $target_ratio)
	{
		$cropped_width = $source_height / $target_ratio;
		$cropped_height = $source_height;
		$source_x = ($source_width - $cropped_width) / 2;
		$source_y = 0;
	}// 源图适中
	else{
		$cropped_width = $source_width;
		$cropped_height = $source_height;
		$source_x = 0;
		$source_y = 0;
	}
	switch ($source_mime){
		case 'image/gif':
			$source_image = imagecreatefromgif($source_path);
		break;
			case 'image/jpeg':
			$source_image = imagecreatefromjpeg($source_path);
		break;
			case 'image/png':
			$source_image = imagecreatefrompng($source_path);
		break;
			default:
			return false;
		break;
	}
	$target_image = imagecreatetruecolor($target_width, $target_height);
	$cropped_image = imagecreatetruecolor($cropped_width, $cropped_height);
	// 裁剪
	imagecopy($cropped_image, $source_image, 0, 0, $source_x, $source_y, $cropped_width, $cropped_height);
	// 缩放
	imagecopyresampled($target_image, $cropped_image, 0, 0, 0, 0, $target_width, $target_height, $cropped_width, $cropped_height);
	//保存图片到本地(两者选一)
	//$randNumber = mt_rand(00000, 99999). mt_rand(000, 999);
	//$fileName = substr(md5($randNumber), 8, 16) .".png";
	//imagepng($target_image,'./'.$fileName);
	//imagedestroy($target_image);

	//直接在浏览器输出图片(两者选一)
	header('Content-Type: image/jpeg');
	imagepng($target_image);
	imagedestroy($target_image);
	imagejpeg($target_image);
	imagedestroy($source_image);
	imagedestroy($target_image);
	imagedestroy($cropped_image);
}
?>