Mi aiutate con questa classe?

[mircov]

Salve. Ho trovato questa classe sul forum. Purtroppo permette solo di impostare l'altezza ma me serve che l'immagine generata stia in un quadrato di n lunghezza di lato. Ho preparato la funzione ed ho provato ad inserirla ma non funziona.
Posto sia la funzione che ho creato che la classe modificata e la classe non modificata così potete avere tutto a disposizione:

MIA FUNZIONE

function GetHeight ($height , $width, $side)
        {
           if ($height > $width)
             {
                return $side;
             }
           elseif ($height < $width)
		 {
		    $side = ($height*$side)/$width;
		    return $side;
	         }
        }

CLASSE MODIFICATA

class Image
     {
        var $src_filename;
        var $src_witdh;
        var $src_height;
        var $src_type;
        var $src_attr;
        var $src_image; 

        function Image($filename)
                {
                   $this->src_filename = $filename;
                   $this->GetImageInfo();
                }

        function GetImageInfo()
                {
                   list($this->src_width,$this->src_height, $this->src_type, $this->src_attr) =  getimagesize($this->src_filename);
                }

        function CreateSourceImage()
                {
                   switch ($this->src_type)
                         {
                            case 1:
                            $this->src_image =imagecreatefromgif($this->src_filename);
                            break;

                            case 2:
                            $this->src_image =imagecreatefromjpeg($this->src_filename);
                            break;

                            case 3:
                            $this->src_image =imagecreatefrompng($this->src_filename);
                            break;

                            default: return false;
                         }
                   return true;
                }

        function GetHeight ($side)
                {
                   if ($this->src_height > $this->src_width)
                     {
                        return $height;
                     }
		   elseif ($this->src_height < $this->src_width)
		         {
			    $height = ($this->src_height*$side)/$this->src_width;
			    return $height;
			 }
                }
		
		function SaveProportionateImage($filename, $quality, $this->height)
                {
                   $dest_height = $height;
                   $ratio = $this->src_height / $dest_height;
                   $dest_image = imagecreatetruecolor( $this->src_width / $ratio,$dest_height);

                   imagecopyresampled($dest_image, $this->src_image, 0, 0, 0, 0,$this->src_width / $ratio,$this->src_height / $ratio,$this->src_width,$this->src_height);
                   
                   imagejpeg($dest_image, $filename, $quality);

                   imagedestroy($dest_image);
                }

        function Free()
                {
                   imagedestroy($this->src_image);
                }
     }

CLASSE ORIGINALE

class Image
     {
        var $src_filename;
        var $src_witdh;
        var $src_height;
        var $src_type;
        var $src_attr;
        var $src_image; 

        function Image($filename)
                {
                   $this->src_filename = $filename;
                   $this->GetImageInfo();
                }

        function GetImageInfo()
                {
                   list($this->src_width,$this->src_height, $this->src_type, $this->src_attr) =  getimagesize($this->src_filename);
                }

        function CreateSourceImage()
                {
                   switch ($this->src_type)
                         {
                            case 1:
                            $this->src_image =imagecreatefromgif($this->src_filename);
                            break;

                            case 2:
                            $this->src_image =imagecreatefromjpeg($this->src_filename);
                            break;

                            case 3:
                            $this->src_image =imagecreatefrompng($this->src_filename);
                            break;

                            default: return false;
                         }
                   return true;
                }

        function SaveProportionateImage($filename, $quality, $height)
                {
                   $dest_height = $height;
                   $ratio = $this->src_height / $dest_height;
                   $dest_image = imagecreatetruecolor( $this->src_width / $ratio,$dest_height);

                   imagecopyresampled($dest_image, $this->src_image, 0, 0, 0, 0,$this->src_width / $ratio,$this->src_height / $ratio,$this->src_width,$this->src_height);
                   
                   imagejpeg($dest_image, $filename, $quality);

                   imagedestroy($dest_image);
                }

        function Free()
                {
                   imagedestroy($this->src_image);
                }
     }

Spero che qualcuno mi possa aiutare perchè io non ci sto capendo più niente!