# Function to calculate a shade or a tint of a color
# 'Shade or tint'
#' Shade or tint
#'
#' Shade or tint
#'
#' @param x (vector of) color(s) with no alpha
#' @param opt "tint" (lighten) or "shade" (darken)
#' @return altered (vector of) color(s)
#' @export
tint = function(colors=c('red','green','blue'), opt='shade', factor=0.5) {
if(!(opt %in% c('shade','tint'))){stop("Option must be either 'shade' or 'tint'")}
cols <- col2rgb(col=colors, alpha=FALSE)
if (opt=='shade'){
outcol = cols*(1-factor) / 255
}else if(opt=='tint'){
outcol = (cols+(255-cols)*factor) / 255
}
return(rgb(red=outcol[1,],green=outcol[2,],blue=outcol[3,]))
}
#' @rdname tint
#' @export
pkTintShade <- tint
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