[GRASS-DEV] RGBA_Color struct revisited

[Hamish]

Hi,

I've changed the new RGBA_Color struct in gis.h to remove the "set"
flag, and in its place added some RGBA_COLOR_* defines. These defines
can be inserted to preset the alpha channel so it can be used as an
on/off switch by things that don't otherwise handle alpha support.
So now we have:

typedef struct
{
    unsigned char r, g, b, a;   /* red, green, blue, and alpha */
} RGBA_Color ;

typedef RGBA_Color RGB_Color;

/* RGBA_Color alpha presets */
#define RGBA_COLOR_OPAQUE     255
#define RGBA_COLOR_TRANSPARENT  0
#define RGBA_COLOR_NONE         0


see d.graph + D_symbol() for an example.

the RGB_Color struct can be used if you aren't interested in alpha or
having a color="none" option.

I hope all are happy with this and it will be useful for future coding.


Hamish