# 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
"image.plot.plt" <- function(x, add = FALSE, legend.shrink = 0.9, 
    legend.width = 1, horizontal = FALSE, legend.mar = NULL, 
    bigplot = NULL, smallplot = NULL, ...) {
    old.par <- par(no.readonly = TRUE)
    if (is.null(smallplot)) 
        stick <- TRUE
    else stick <- FALSE
    if (is.null(legend.mar)) {
        legend.mar <- ifelse(horizontal, 3.1, 5.1)
    }
    # compute how big a text character is
    char.size <- ifelse(horizontal, par()$cin[2]/par()$din[2], 
        par()$cin[1]/par()$din[1])
    # This is how much space to work with based on setting the margins in the
    # high level par command to leave between strip and big plot
    offset <- char.size * ifelse(horizontal, par()$mar[1], par()$mar[4])
    # this is the width of the legned strip itself.
    legend.width <- char.size * legend.width
    # this is room for legend axis labels
    legend.mar <- legend.mar * char.size
    # smallplot is the plotting region for the legend.
    if (is.null(smallplot)) {
        smallplot <- old.par$plt
        if (horizontal) {
            smallplot[3] <- legend.mar
            smallplot[4] <- legend.width + smallplot[3]
            pr <- (smallplot[2] - smallplot[1]) * ((1 - legend.shrink)/2)
            smallplot[1] <- smallplot[1] + pr
            smallplot[2] <- smallplot[2] - pr
        }
        else {
            smallplot[2] <- 1 - legend.mar
            smallplot[1] <- smallplot[2] - legend.width
            pr <- (smallplot[4] - smallplot[3]) * ((1 - legend.shrink)/2)
            smallplot[4] <- smallplot[4] - pr
            smallplot[3] <- smallplot[3] + pr
        }
    }
    if (is.null(bigplot)) {
        bigplot <- old.par$plt
        if (!horizontal) {
            bigplot[2] <- min(bigplot[2], smallplot[1] - offset)
        }
        else {
            bottom.space <- old.par$mar[1] * char.size
            bigplot[3] <- smallplot[4] + offset
        }
    }
    if (stick & (!horizontal)) {
        dp <- smallplot[2] - smallplot[1]
        smallplot[1] <- min(bigplot[2] + offset, smallplot[1])
        smallplot[2] <- smallplot[1] + dp
    }
    return(list(smallplot = smallplot, bigplot = bigplot))
}