PHP thumbnail implementation function code

array getimagesize ( string $filename [, array &$imageinfo ] ) Get the image size
resource imagecreatetruecolor ( int $x_size , int $y_size ) Create a new true color image
resource imagecreatefromjpeg ( string $filename ) Create a new one from a JPEG file or URL Image
bool imagecopyresized ( resource $dst_image , resource $src_image , int $dst_x , int $dst_y , int $src_x , int $src_y , int $dst_w , int $dst_h , int $src_w , int $src_h ) Copy part of the image and adjust it Size
bool imagejpeg ( resource $image [, string $filename [, int $quality ]] ) Output the image to the browser or file in JPEG format
The code is as follows:
/*
Created by */
// File and zoom size
//$imgfile = 'smp.jpg';
//$percent = 0.2;
header('Content -type: image/jpeg');
list($width, $height) = getimagesize($imgfile);
$newwidth = $width * $percent;
$newheight = $height * $percent;
$thumb = ImageCreateTrueColor ($newwidth,$newheight);
$source = imagecreatefromjpeg($imgfile);
imagecopyresized($thumb, $source, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
imagejpeg ($thumb);
?>