# Save and restore

#### Yang Tang

#### 2021-02-23

This vignette introduce the save and restore feature of the mouse-interaction functions.

## What can be save and restored?

The current state of a mouse-interaction enabled shiny ui element can be captured and loaded. See this table:

Interactions | State
--- | ---
draggable | The position of the draggable element
resizable | The dimension of the resizable element
selectable | The selected items inside the selectable element
sortable | The order of items inside the sortable element

## Save and restore within a shiny session (client-side)

This is the case when users want to temporarily save the current interaction state (e.g., position of element) and restore it later in the same shiny session (without closing the app or reloading the page). The `save` and `load` operations from the corresponding interaction functions can serve the purpose:

    ui <- fluidPage(
      actionButton("save", "Save position"),
      actionButton("restore", "Restore position"),
      # create a draggable textInput
      jqui_draggable(textInput("foo", "Textinput"))
    )

    server <- function(input, output) {
      # on save button clicked, save the current position of the textInput
      observeEvent(input$save, {
        jqui_draggable("#foo", operation = "save")
      })
      # on restore button clicked, move the textInput back to the last saved position
      observeEvent(input$restore, {
        jqui_draggable("#foo", operation = "load")
      })
    }

    shinyApp(ui, server)

This method also applies to interaction shortcuts like `orderInput()`, `selectableTableOutput()` and `sortableTabsetPanel()`. For example,

    ui <- fluidPage(
      actionButton("save", "Save order"),
      actionButton("restore", "Restore order"),
      orderInput("foo1", label = NULL, items = 1:3, connect = "foo2"),
      orderInput("foo2", label = NULL, items = NULL, placeholder = "empty")
    )

    server <- function(input, output) {
      observeEvent(input$save, {
        jqui_sortable("#foo1,#foo2", operation = "save")
      })
      observeEvent(input$restore, {
        jqui_sortable("#foo1,#foo2", operation = "load")
      })
    }

    shinyApp(ui, server)

The `load` operation also supports user-defined-state if a `state` exists in `options`.

    ui <- fluidPage(
      actionButton("s", "Small"),
      actionButton("m", "Medium"),
      actionButton("l", "Large"),
      jqui_resizable(plotOutput('gg', width = '200px', height = '200px'))
    )

    server <- function(input, output) {
      output$gg <- renderPlot({
        ggplot(mtcars, aes(x = cyl, y = mpg)) + geom_point()
      })
      observeEvent(input$s,
                   jqui_resizable(
                     ui        = "#gg",
                     operation = "load",
                     options   = list(state = list(width  = 100, height = 100))
                   )
      )
      observeEvent(input$m,
                   jqui_resizable(
                     ui        = "#gg",
                     operation = "load",
                     options   = list(state = list(width  = 200, height = 200))
                   )
      )
      observeEvent(input$l,
                   jqui_resizable(
                     ui        = "#gg",
                     operation = "load",
                     options   = list(state = list(width  = 400, height = 400))
                   )
      )
    }

    shinyApp(ui, server)

## Save and restore cross shiny sessions (shiny bookmarking)

In addition to the client-side mode, cross-session save/restore is also supported, which takes advantage of shiny bookmarking. In this case, users can save the interaction state alone with other shiny input values either by URL-encoding or by save-to-server, and restore them in another shiny session. The only thing needs to do is to include a `jqui_bookmarking()` call in server function. All the other operations are the same as the native shiny bookmarking:

    ui <- function(request) {
      fluidPage(
        bookmarkButton(),
        jqui_resizable(plotOutput('gg', width = '200px', height = '200px'))
      )
    }

    server <- function(input, output) {
      output$gg <- renderPlot({
        ggplot(mtcars, aes(x = cyl, y = mpg)) + geom_point()
      })
      # enable interaction state bookmarking
      jqui_bookmarking()
    }

    enableBookmarking(store = "url")

    shinyApp(ui, server)