/*
 *  call-seq:
 *     set_colorkey(color,flags=0)
 *
 *  Set the colorkey of the surface. See Surface#colorkey for a description
 *  of colorkeys.
 *
 *  This method takes these arguments:
 *  color:: color to use as the key, in the form [r,g,b]. Can be +nil+ to
 *          un-set the colorkey.
 *  flags:: 0 or Rubygame::SRC_COLORKEY (default) or 
 *          Rubygame::SRC_COLORKEY|Rubygame::SDL_RLEACCEL. Most people will 
 *          want the default, in which case this argument can be omitted. For
 *          advanced users: this flag affects the surface as described in the
 *          docs for the SDL C function, SDL_SetColorkey.
 */
VALUE rbgm_surface_set_colorkey( int argc, VALUE *argv, VALUE self)
{
        SDL_Surface *surf;
        Uint32 color;
        Uint32 flags;
        Uint8 r,g,b;
        VALUE vcolor, vflags;

        Data_Get_Struct(self, SDL_Surface, surf);

        rb_scan_args(argc, argv, "11", &vcolor, &vflags);

        if( !NIL_P(vflags) )
        {
                flags = NUM2UINT(vflags);
        }
        else
        {
                flags = SDL_SRCCOLORKEY;
        }


        if( RTEST(vcolor) )
        {
                vcolor = convert_color(vcolor);
                extract_rgb_u8_as_u8(vcolor, &r, &g, &b);
                color = SDL_MapRGB(surf->format, r,g,b);
        }
        else
        {
                flags = 0;
                color = 0;
        }

        if(SDL_SetColorKey(surf,flags,color)!=0)
                rb_raise(eSDLError,"could not set colorkey: %s",SDL_GetError());
        return self;
}