###############################################################
#
# This function creates a simple B/W bitmap image
# to send back to the browser as a response.
#
# Usage: SpitBMP(width, height)
#
# Example: SpitBMP(4, 3) ---> Creates a black 4x3 BMP image
#

sub SpitBMP
{
  my $W = @_ ? shift : 1;
  my $H = @_ ? shift : 1;
  $|++;
  my $HEADERLEN = 62;
  my $DATASIZE = Ceil($W * $H / 8);
  my $FILESIZE = $DATASIZE + $HEADERLEN;
  my $BITS_PER_PIXEL = 1;
  my $HEADER = 'BM' . pack('VxxxxVVVV', $FILESIZE, $HEADERLEN, 40, $W, $H) . chr(1) . pack('xCxxxxxV', $BITS_PER_PIXEL, $DATASIZE) . "\0" x 20 . "\xFF\xFF\xFF\0";
  my $OUTPUT = $HEADER . "\0" x $DATASIZE;
  print "Content-Type: image/bmp\n" .
        'Content-Length: ' . length($OUTPUT) . "\n\n" . $OUTPUT;
}

###############################################################
#
# Rounds a number up to the nearest integer.
#
# Usage: INTEGER = Ceil(FLOAT)
#

sub Ceil
{
  my $DEC = shift;
  my $INT = int($DEC);
  return $INT if ($DEC - $INT == 0);
  return $INT + 1 if ($DEC > 0);
  return $INT - 1;
}