GdkColor::red

Access: Read Write
Type: int

Returns the red part of the color in the range from 0 to 65536. If you convert it to hexadecimal via dechex, you will see that only the first 2 values are used, the last 2 are zero. So if you want to convert it to a nice html-like hexadecimal value like AF, you've got to shift it bitwise.

$orange = &new GdkColor('#FF8000');
echo dechex( $orange->red >> 8);

You can use the property to set the red part of the color as well.