Basic types
-----------
Coordinates and Size and Length
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Most of the drawing functions use typedefed 'gp_coord' and 'gp_size' integer
types for parameters.

'gp_coord' is a signed integer type which is used for coordinates and
'gp_size' is an unsigned integer type used for object size, length and
so on.

Pixel
~~~~~

A Pixel value in 'GFXprim' is an integer wide enough to hold the actual pixel
values. The default typedef for 'gp_pixel' is set to a 32 bit integer. This may
be changed at compile time to support colors with more than 10 bits per
channel. 'gp_pixel' is thus used as an opaque value big enough to hold any
supported pixel value.
