php gd implements downloading pictures

Code reproduced from:

header("Content-type:text/html ; charset=utf-8");

if (!empty($_POST['submit'])){
 $url = $ _POST['url'];
 $pictureName = $_POST['pictureName'];
 $img = getPicture($url,$pictureName);
 echo '<img src="'.$img. '">';
 }
function getPicture($url,$pictureName){
 if ($url == "") return false;
 //Get the extension of the picture
 $info = getimagesize ($url);
 $mime = $info['mime'];
 $type = substr(strrchr($mime,'/'), 1);
 //Choose different image generation and saving for different image types Function
 switch($type){
 case 'jpeg':
 $img_create_func = 'imagecreatefromjpeg';
 $img_save_func = 'imagejpeg';
 $new_img_ext = 'jpg';
 break;
 case 'png':
 $img_create_func = 'imagecreatefrompng';
 $img_save_func = 'imagepng';
 $new_img_ext = 'png';
 break;
 case 'bmp':
 $img_create_func = 'imagecreatefrombmp';
 $img_save_func = 'imagebmp';
 $new_img_ext = 'bmp';
 break;
 case 'gif':
 $img_create_func = 'imagecreatefromgif';
 $img_save_func = 'imagegif';
 $new_img_ext = 'gif';
 break;
 case 'vnd.wap.wbmp':
 $img_create_func = 'imagecreatefromwbmp';
 $img_save_func = 'imagewbmp';
 $new_img_ext = 'bmp';
 break;
 case 'xbm':
 $img_create_func = 'imagecreatefromxbm';
 $img_save_func = 'imagexbm ';
 $new_img_ext = 'xbm';
 break;
 default:
 $img_create_func = 'imagecreatefromjpeg';
 $img_save_func = 'imagejpeg';
 $new_img_ext = 'jpg';
 }
 if ($pictureName == ""){
 $pictureName = time().".{$new_img_ext}";
 }else{
 $pictureName = $pictureName.".{$new_img_ext}";
 }
 $src_im = $img_create_func($url); // Create a new picture from url
 $img_save_func($src_im, $pictureName); //Output file to file
 return $pictureName;
}

?>

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