R/topright.R

In dankelley/imagedata: Digitize data in PNG files

#' A helper function to specify the stop region.
#'
#' topright invites the user to click the top-right corner of the plotting
#' area, and stores the x and y values (in plot units) as xstop and ystop.
#' These values are used by data().
#'
#' @return a list with x and y page coordinates
#' @export topright

topright <- function()
{
    idlocator(col="#F7819F", bell=FALSE, verbose=FALSE)[c("x", "y")]
}

showtopright <- function(xy)
{
    par <- par('usr')
    right <- par[2]
    top <- par[4]
    polygon(c(xy$x, right, right, xy$x), c(xy$y, xy$y, top, top), col='#F7819F')
    text(0.5*(xy$x + right), 0.5 * (xy$y + top), "STOP", cex=1/2, font=2)
}