how-to draw rounded corner rectangle with perl and GD

# builds a rounded filled rectangle by the coordinates of the left upper , 

# righ down corner , radius and color object

sub AddRoundedRectangleToImg { 

   my $self = shift ; 

   my $refObjImg = shift ; 

   my $objImg = $$refObjImg ; 

   my $x1 = shift ; 

   my $y1 = shift ;    

   my $x2 = shift ; 

   my $y2 = shift ;    

   my $radius = shift ; 

   my $objColor = shift ; 

   #$objImg ->filledRectangle ( $x1 + 400, $y1, $x2 + 400, $y2, $colorBrown);

   $objImg->filledRectangle ( $x1 , $y1+ $radius , $x2 , $y2 - $radius , $objColor);

   $objImg->filledRectangle ( $x1 + $radius , $y1  , $x2 - $radius , $y2 , $objColor );

   my $diameter = $radius*2;

   # build the corners   

   $objImg ->filledArc( $x1+$radius, $y1+$radius, $diameter, $diameter, 0 , 360 ,  $objColor);

   $objImg ->filledArc( $x1+$radius, $y2-$radius, $diameter, $diameter, 0 , 360 , $objColor);

   $objImg ->filledArc( $x2-$radius, $y2-$radius, $diameter, $diameter, 0 , 360 , $objColor);

   $objImg ->filledArc( $x2-$radius, $y1+$radius, $diameter, $diameter, 0 , 360 , $objColor);

   return \$objImg ; 

}