# fields, Tools for spatial data
# Copyright 2004-2011, Institute for Mathematics Applied Geosciences
# University Corporation for Atmospheric Research
# Licensed under the GPL -- www.gpl.org/licenses/gpl.html
fields.color.picker <- function() {
    c(mar = c(0, 0, 3, 0))
    # names of colors in default graphics options.
    clab <- colors()
    n <- length(clab)
    N <- ceiling(sqrt(n))
    M <- N
    temp <- rep(NA, M * N)
    temp[1:n] <- 1:n
    z <- matrix(temp, M, N)
    # matrix of all colors
    image(seq(0.5, M + 0.5, , M + 1), seq(0.5, N + 0.5, , N + 
        1), z, col = clab, axes = FALSE, xlab = "", ylab = "")
    cat("Use mouse to identify color", fill = TRUE)
    loc <- locator(1)
    i <- round(loc$x)
    j <- round(loc$y)
    ind <- z[i, j]
    points(i, j, col = clab[ind], cex = 4, pch = "O")
    points(i, j, pch = "+", col = "black", cex = 1)
    mtext(side = 3, text = clab[ind], col = clab[ind], line = 1, 
        cex = 2)
    # write out RGB values to console
    cat("ID ", ind, " name ", clab[ind], fill = TRUE)
    cat("RGB", col2rgb(clab[ind])/256, fill = TRUE)
    temp <- signif(col2rgb(clab[ind])/256, 3)
    # This line is  marginally in  LaTeX format to define color
    cat(clab[ind], " {rgb}{", temp[1], ",", temp[2], ",", temp[3], 
        "}", fill = TRUE)
}