PHP缩放图片

缩放图片

function resize_image($filename, $tmpname, $xmax, $ymax) 
{ 
    $ext = explode(".", $filename); 
    $ext = $ext[count($ext)-1]; 
         
    if($ext == "jpg" || $ext == "jpeg") 
        $im = imagecreatefromjpeg($tmpname); 
    elseif($ext == "png") 
        $im = imagecreatefrompng($tmpname); 
    elseif($ext == "gif") 
        $im = imagecreatefromgif($tmpname); 
             
    $x = imagesx($im); 
    $y = imagesy($im); 
             
    if($x <= $xmax && $y <= $ymax) 
        return $im; 
         
    if($x >= $y) { 
        $newx = $xmax; 
        $newy = $newx * $y / $x; 
    } 
    else { 
        $newy = $ymax; 
        $newx = $x / $y * $newy; 
    } 
             
    $im2 = imagecreatetruecolor($newx, $newy); 
    imagecopyresized($im2, $im, 0, 0, 0, 0, floor($newx), floor($newy), $x, $y); 
    return $im2;  
}