GetMap =
function (center, size = c(640, 640), destfile = "MyTile.png", 
    zoom = 12, markers, path = "", span, frame, hl="ja", sensor = "true", 
    maptype = c("roadmap", "mobile", "satellite", "terrain", 
        "hybrid", "mapmaker-roadmap", "mapmaker-hybrid")[4], 
    format = c("gif", "jpg", "jpg-baseline", "png8", "png32")[5], 
    RETURNIMAGE = TRUE, GRAYSCALE = FALSE, NEWMAP = TRUE, verbose = 1) 
{
    stopifnot(all(size <= 640))
    fileBase <- substring(destfile, 1, nchar(destfile) - 4)
    fileExt <- substring(destfile, nchar(destfile) - 2, nchar(destfile))
    if (missing(center)) {
        print("Note that when center and zoom are not specified, no meta information on the map tile can be stored. This basically means that R cannot compute proper coordinates. You can still download the map tile and view it in R but overlays are not possible. Do you want to proceed ? (y/n)")
        ans <- readLines(n = 1)
        if (ans != "y") 
            return()
    }
    else if (is.numeric(center) & !missing(zoom)) {
        if (is.null(names(center))) {
            names(center) = c("lat", "lon")
        }
        else stopifnot(all(names(center) %in% c("lat", "lon")))
        center = center[c("lat", "lon")]
        MyMap <- list(lat.center = center[1], lon.center = center[2], 
            zoom = zoom)
        BBOX <- list(ll = XY2LatLon(MyMap, -size[1]/2 + 0.5, 
            -size[2]/2 - 0.5), ur = XY2LatLon(MyMap, size[1]/2 + 
            0.5, size[2]/2 - 0.5))
        MetaInfo <- list(lat.center = center[1], lon.center = center[2], 
            zoom = zoom, url = "google", BBOX = BBOX, size = size)
        save(MetaInfo, file = paste(destfile, "rda", sep = "."))
    }
    if (length(size) < 2) {
        s <- paste(size, size, sep = "x")
    }
    else {
        s <- paste(size, collapse = "x")
    }
    if (!missing(center)) 
        center <- paste(center, collapse = ",")
    if (missing(format)) {
        if (fileExt == "png") 
            format <- "png32"
    }
    googleurl <- "http://maps.google.com/maps/api/staticmap?"
    if (!missing(span)) {
        span <- paste(span, collapse = ",")
        url <- paste(googleurl, "center=", center, "&span=", 
            span, "&size=", s, "&maptype=", maptype, "&format=", 
            format, "&sensor=", sensor, "&language=", hl, sep = "")
    }
    else if (missing(center) & missing(zoom)) {
        stopifnot(!missing(markers) | path != "")
        url <- paste(googleurl, "size=", s, "&maptype=", maptype, 
            "&format=", format, "&sensor=", sensor, "&language=", hl, sep = "")
    }
    else {
        stopifnot(!missing(center), !missing(zoom))
        url <- paste(googleurl, "center=", center, "&zoom=", 
            zoom, "&size=", s, "&maptype=", maptype, "&format=", 
            format, "&sensor=", sensor, "&language=", hl, sep = "")
    }
    url <- paste(url, path, sep = "")
    if (!missing(markers)) {
        if (is.data.frame(markers)) 
            markers <- as.matrix(markers)
        if (is.matrix(markers)) {
            stopifnot(all(c("lat", "lon") %in% colnames(markers)))
            latlon = which(colnames(markers) %in% c("lat", "lon"))
            for (i in 1:nrow(markers)) {
                m1 <- paste(markers[i, c("lat", "lon")], collapse = ",")
                if (any(c("size", "color", "label") %in% colnames(markers))) {
                  m2 <- paste(colnames(markers)[-latlon], markers[i, 
                    -latlon], collapse = "|", sep = ":")
                  m <- paste(m2, m1, sep = "|")
                }
                else {
                  m <- m1
                }
                if (i == 1) {
                  markers.string <- m
                }
                else {
                  markers.string <- paste(markers.string, m, 
                    sep = "|")
                }
            }
            markers.string <- paste("&markers=", markers.string, 
                sep = "")
        }
        else if (is.character(markers)) {
            markers.string <- markers
        }
        url <- paste(url, markers.string, sep = "")
    }
    if (verbose) 
        print(url)
    if (verbose == -1) 
        browser()
    if (verbose < 2) 
        download.file(url, destfile, mode = "wb", quiet = TRUE)
    if (GRAYSCALE) {
        myTile <- readPNG(destfile, native = FALSE)
        myTile <- RGB2GRAY(myTile)
        writePNG(myTile, destfile)
    }
    if (RETURNIMAGE) {
        myMap <- ReadMapTile(destfile)
        return(myMap)
    }
    invisible(url)
}