---
title: "introduction"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{introduction}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r, include = FALSE}
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)
```

The waiter package comes with a few members of staff but the core one is the waiter which will let you show full page or partial loading screens in your shiny application.

It's fairly straightforward:

1. Place `useWaiter` anywhere in your UI.
2. Create a waiter with `Waiter$new()`
3. Show the waiter with `Waiter$show()`
4. Hide the waiter with `Waiter$hide()`

## Examples

A basic example could be like this, upon clicking a button we display a full page loading screen.

``` r
library(shiny)
library(waiter)
 
ui <- fluidPage(
  useWaiter(), # include dependencies
  actionButton("show", "Show loading for 3 seconds")
)

server <- function(input, output, session){
  # create a waiter
  w <- Waiter$new()

  # on button click
  observeEvent(input$show, {
    w$show()
    Sys.sleep(3)
    w$hide()
  })
}

shinyApp(ui, server)
```

> Make sure you include the dependencies with `useWaiter` or nothing will work.

By default the waiter will show a spinner, 1) you can choose from more than [100 spinners](https://shiny.john-coene.com/waiter/) 2) you are by no means limited to a spinner since the `html` argument takes any htmltools or shiny tag. Below we change the spinner, add some text and change the background color.

``` r
library(shiny)
library(waiter)

waiting_screen <- tagList(
  spin_flower(),
  h4("Cool stuff loading...")
) 

ui <- fluidPage(
  useWaiter(), # include dependencies
  actionButton("show", "Show loading for 3 seconds")
)

server <- function(input, output, session){
  observeEvent(input$show, {
    waiter_show(html = waiting_screen, color = "black")
    Sys.sleep(3) # do something that takes time
    waiter_hide()
  })
}

shinyApp(ui, server)
```

Visit the [full waiter documentation](https://shiny.john-coene.com/) to learn how to further customise your waiting screen, have it appear on parts of the application, show loading bars, and more.