colors <- function() .Internal(colors())
colours <- colors
col2rgb <- function(col) .Internal(col2rgb(col))

gray <- function(level) .Internal(gray(level))
grey <- gray

rgb <- function(red, green, blue, names=NULL, maxColorValue = 1)
{
    ## in the first case, (r,g,b) are (coerced to) integer, otherwise
    ## double.
    if(maxColorValue == 255)
        .Internal(rgb256(red, green, blue, names))
    else .Internal(rgb(red, green, blue, maxColorValue, names))
}

hsv <- function(h=1,s=1,v=1,gamma=1)
    .Internal(hsv(h,s,v,gamma))

palette <- function(value)
{
    if(missing(value)) .Internal(palette(character()))
    else invisible(.Internal(palette(value)))
}

## A quick little ``rainbow'' function -- improved by MM
## doc in	../man/palettes.Rd
rainbow <-
    function (n, s = 1, v = 1, start = 0, end = max(1,n - 1)/n, gamma = 1)
{
    if ((n <- as.integer(n[1])) > 0) {
	if(start == end || any(c(start,end) < 0)|| any(c(start,end) > 1))
	    stop("`start' and `end' must be distinct and in [0,1].")
	hsv(h = seq(start, ifelse(start > end, 1, 0) + end, length= n) %% 1,
	    s, v, gamma)
    } else character(0)
}

topo.colors <- function (n)
{
    if ((n <- as.integer(n[1])) > 0) {
	j <- n %/% 3
	k <- n %/% 3
	i <- n - j - k
	c(if(i > 0) hsv(h= seq(from = 43/60, to = 31/60, length = i)),
	  if(j > 0) hsv(h= seq(from = 23/60, to = 11/60, length = j)),
	  if(k > 0) hsv(h= seq(from = 10/60, to =  6/60, length = k),
			s= seq(from = 1,     to = 0.3,	 length = k), v = 1))
    } else character(0)
}

terrain.colors <- function (n)
{
    if ((n <- as.integer(n[1])) > 0) {
	k <- n%/%2
	h <- c(4/12, 2/12, 0/12)
	s <- c(1, 1, 0)
	v <- c(0.65, 0.9, 0.95)
	c(hsv(h = seq(h[1], h[2], length = k),
	      s = seq(s[1], s[2], length = k),
	      v = seq(v[1], v[2], length = k)),
	  hsv(h = seq(h[2], h[3], length = n - k + 1)[-1],
	      s = seq(s[2], s[3], length = n - k + 1)[-1],
	      v = seq(v[2], v[3], length = n - k + 1)[-1]))
    } else character(0)
}

heat.colors <- function (n)
{
    if ((n <- as.integer(n[1])) > 0) {
	j <- n %/% 4
	i <- n - j
	c(rainbow(i, start = 0, end = 1/6),
	  if (j > 0)
	  hsv(h = 1/6, s = seq(from= 1-1/(2*j), to= 1/(2*j), length = j),
	      v = 1))
    } else character(0)
}

cm.colors <- function (n)
{
    if ((n <- as.integer(n[1])) > 0) {
	even.n <- n %% 2 == 0
	k <- n%/%2
	l1 <- k + 1 - even.n
	l2 <- n - k + even.n
	c(if(l1 > 0)
	  hsv(h =  6/12, s= seq(.5, ifelse(even.n,.5/k,0), length = l1), v = 1),
	  if(l2 > 1)
	  hsv(h = 10/12, s= seq(0, 0.5, length = l2)[-1], v = 1))
    } else character(0)
}