PHP 实现缩略图

PHP 实现缩略图

<?php
header("Content-type: image/png");

function resize_image($filename, $tmpname, $xmax, $ymax) 
{ 
$ext = explode(".", $filename); 
$ext = $ext[count($ext)-1]; 

//判断文件类型，获取不同的图像
if($ext == "jpg" || $ext == "jpeg") 
$im = imagecreatefromjpeg($tmpname); 
elseif($ext == "png") 
$im = imagecreatefrompng($tmpname); 
elseif($ext == "gif") 
$im = imagecreatefromgif($tmpname); 

//获取原图的高度和宽度
$x = imagesx($im); 
$y = imagesy($im); 

if($x <= $xmax && $y <= $ymax) 
return $im; 

//按比例缩放
if($x >= $y) { 
$newx = $xmax; 
$newy = $newx * $y / $x; 
    } 
else { 
$newy = $ymax; 
$newx = $x / $y * $newy; 
    } 
//创建新图像
$im2 = imagecreatetruecolor($newx, $newy); 
    imagecopyresized($im2, $im, 0, 0, 0, 0, floor($newx), floor($newy), $x, $y); 
return $im2;
} 
//输出资源
imagejpeg(resize_image('nriven.jpg','riven.jpg',300,300));
?>