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# Color utilities
#
# Author: Renaud Gaujoux
# Created: 30 Nov 2012
###############################################################################
#' Colour utilities
#'
#' \code{alphacol} adds an alpha value to a colour specification and convert to
#' a hexadecimal colour string.
#'
#' @inheritParams grDevices::col2rgb
#'
#' @return a character vector of color specifications.
#' @export
#' @examples
#'
#' # Alphas
#' alphacol('red') # do nothing
#' alphacol('red', 10)
#' alphacol('#aabbcc', 5)
#' alphacol(4, 5)
#'
alphacol <- function(col, alpha = FALSE){
col <- as.hexmode(col2rgb(col, alpha))
storage.mode(col) <- "character"
if( !is.logical(alpha) ){
if( alpha < 1 ) alpha <- alpha * 255
alpha <- round(alpha)
col['alpha', ] <- as.character(as.hexmode(alpha))
}
apply(col, 2, function(x) paste("#", paste(x, collapse=''), sep=''))
}
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