R/timer.R

In shinyDTC: Simple Dynamic Timer Control

#' timer
#'
#' A reactive function.
#'
#' @param inputId character: input slot for a timer
#' @param input an inpur object
#' @param session a session object
#' @param ... further parameters for [shiny::reactive()]
#'
#' @return a reactive function which returns a counter
#' @importFrom shiny reactive invalidateLater
#' @export
#'
#' @examples
#' if (interactive()) vignette("shinyDTC")
timer <- function(inputId, input, session, ...) {
  reactive({
    #browser()
    ret  <- NULL
    ival <- paste0(inputId, ".step")
    if (is.null(timerenv[[ival]])) stop(sprintf("timer '%s' does not exist", inputId))
    val  <- input[[ival]]
    if (val>timerenv[[ival]]) { # step pressed
      timerenv[[ival]]    <- timerenv[[ival]]+1
      timerenv[[inputId]] <- timerenv[[inputId]]+1
    }
    ival <- paste0(inputId, ".reset")
    val  <- input[[ival]]
    if (val>timerenv[[ival]]) { # reset pressed
      timerenv[[ival]]    <- timerenv[[ival]]+1
      timerenv[[inputId]] <- 0
    }
    val <- input[[paste0(inputId, ".speed")]]
    if (val>0) {
      #browser()
      max    <- timerenv[[paste0(inputId, '.max')]]
      millis <- 10+3000/val
      timerenv[[inputId]] <- timerenv[[inputId]]+1
      invalidateLater(millis, session)
    }
    timerenv[[inputId]]
  }, ...)
}