Viết văn bản trên file ảnh! bó tay với file png và gif

class image {
var $imagesource = null;
var $widthimage = 0;
var $heightimage = 0;
var $error = array();
var $filename = "";
var $colorname = array();

function image($file)
{
if(empty($file)){
	$error[] = "No file found!";
	exit();
}

$this->imagesource = $this->Createimageresource($file);
$this->_Getimagesize();
$this->filename = $this->_Getfilename($file);
}
function _Getfilename($file)
{
	$pattern = "/([a-zA-Z0-9_@-]*\.[a-zA-Z0-9_@-]{2,4})$/";
	preg_match($pattern,$file,$match);
	return $match[1];
}
function Createcolor($colorname,$red = 0, $green = 0,$blue = 0)
{
	$this->colorname[$colorname] = imagecolorallocate($this->imagesource, $red, $green, $blue);
}
function Writetexttoimage($text='',$textsize = 12,$angeltext = 100,$x = 0,$y =0,$colorname="black",$font = "arial.ttf")
{
		putenv('GDFONTPATH=' . realpath('.')."/fonts");
		if($this->imagesource==null)
		{
		$this->error[] = "No image resource";
		return false;
		}
		else 
		imagettftext($this->imagesource,$textsize,$angeltext,$x,$y,$this->colorname[$colorname],$font,$text);
		//$this->Out();
}
function Createimageresource($file)
{
	$ext = $this->_Detectfileimage($file);
	switch ($ext) {
		case "jpg":
			$resourceimage = imagecreatefromjpeg($file);
			break;
		case "gif":
			$resourceimage = imagecreatefromgif($file);
			break;
		case "png":
			$resourceimage = imagecreatefrompng($file);
			break;
		default:
			$resourceimage = imagecreatefromjpeg($file);
			break;
	}
	
	return $resourceimage;
}
function _Detectfileimage($image)
{
	$pattern = "#.*\.([a-zA-Z0-9_]{2,4})$#";
	preg_match($pattern,$image,$match);
	return $match[1];
}
function _Getimagesize()
	{
		$imagesize = array();
		if (is_null($resource)) {
			$this->widthimage = imagesx($this->imagesource);
			$this->heightimage = imagesy($this->imagesource);
		}
		else 
		{
			$this->widthimage = imagesx($resource);
			$this->heightimage = imagesy($resource);
		}
	}
function Out()
{
	$imagetype = $this->_Detectfileimage($this->filename);
	header("Content-type: image/$imagetype");
	switch ($imagetype) {
		case "jpg":
			{
			imagejpeg($this->imagesource);
			}
			break;
		case "png":
			{
			imagepng($this->imagesource);
			}
		case "gif":
			{
			imagegif($this->imagesource);
			}
			break;
		default:
			{
			imagejpeg($this->imagesource);
			}
			break;
	}
}
function saveimage($save_dir = "download/")
{
			
		$imagetype = $this->_Detectfileimage($this->filename);
		switch ($imagetype) {
		case "jpg":
			{
			imagejpeg($this->imagesource,$save_dir.$this->filename);
			}
			break;
		case "png":
			{
			imagepng($this->imagesource,$save_dir.$this->filename);
			}
		case "gif":
			{
			imagegif($this->imagesource,$save_dir.$this->filename);
			}
			break;
			default:
			{
			imagejpeg($this->imagesource,$save_dir.$this->filename);
			}
			break;
		}

}
function imagemerge($fileimagedes,$des_x,$des_y,$source_x,$source_y,$source_w=0,$source_h=0,$pct)
{
	
	if($des_x<0)
	{
		$des_x = $this->widthimage+$des_x;
	}
	if($des_y <0)
	{
		$des_y = $this->heightimage+$des_y;
	}

	if($source_x<0)
	{
		$source_x = $this->widthimage+$source_x;
	}
	if($source_y<0)
	{
		$source_y = $this->heightimage+$source_y;
	}
	if($source_w==0)
	{
		$source_w=$this->widthimage;
	}
	if($source_h==0)
	{
		$source_h=$this->heightimage;
	}
	if($source_w<0)
	{
		$source_w=$this->widthimage+$source_w;
	}
	if($source_h<0)
	{
		$source_h=$this->heightimage+$source_h;
	}
	$des_image_source = $this->Createimageresource($fileimagedes);
	imagecopymerge($this->imagesource,$des_image_source,$des_x,$des_y,$source_x,$source_y,$source_w,$source_h,$pct);
}

function imagedestroy()
{
	imagedestroy($this->imagesource);
}
}