R/gslider.R

In gWidgets2: Rewrite of gWidgets API for Simplified GUI Construction

##' @include methods.R
NULL

##' slider widget constructor
##'
##' A slider widgets allows a selection from a range of numeric
##' values. The widget presents the user with a quick to adjust, but
##' relatively difficult to adjust precisely way to to pick a number.
##' @param from If a number of length one then a starting point, in
##' which case to, by are passed to \code{seq}. Otherwise a sequence
##' of values for which sort(unique(from)) will order
##' @param to ending point when from is starting point
##' @param by step size if not specified by \code{from}
##' @param length.out in place of by
##' @param along.with in place of length.out
##' @param value initial value
##' @param horizontal Logical. Is separator drawn horizontally?
##' @inheritParams gwidget
##' @export
##' @seealso \code{\link{gspinbutton}}
##' @example inst/examples/ex-rangewidget.R
gslider <- function(
                    from = 0, to = 100, by = 1, length.out=NULL, along.with=NULL,
                    value = from[1], horizontal = TRUE,
                    handler = NULL, action = NULL, container = NULL, ... ,
                    toolkit=guiToolkit()) {
  
  ## mostly from seq.default
  ## Wanted to just call seq.default, but that didn't work with length.out bit
  if (!missing(along.with)) {
    length.out <- length(along.with)
  } else if(!missing(length.out)) {
    len <- length(length.out)
    if (!len) 
      stop("argument 'length.out' must be of length 1")
    if (len > 1L) {
      warning("first element used of 'length.out' argument")
      length.out <- length.out[1L]
    }
    length.out <- ceiling(length.out)
  }
  if(!is.null(length.out)) {
    ## set up by to be for length,out
    by <- (to - from)/(length.out[1] - 1)
  }

  obj <- .gslider(toolkit, from, to, by, value, horizontal, handler, action, container=container, ...)
  check_return_class(obj, "GSlider")
  obj
  
}
 
##' generic for toolkit dispatch
##'
##' @export
##' @rdname gslider
.gslider <- function(toolkit,
                     from = 0, to = 100, by = 1, value = from, horizontal = TRUE,
                     handler = NULL, action = NULL, container = NULL, ... ) UseMethod( '.gslider' )