feat: ensure min/max height args on value_box() and column layouts

[gadenbuie]

Fixes #973 #974

• Adds min_height to value_box()
• Adds min_height and max_height to layout_columns() and layout_column_wrap()

Example

Example App

library(shiny)
library(bslib)
library(ggplot2)

data(penguins, package = "palmerpenguins")

# Calculate column means for the value boxes
means <- colMeans(
  penguins[c("bill_length_mm", "bill_length_mm", "body_mass_g")],
  na.rm = TRUE
)

ui <- page_sidebar(
  title = "Penguins dashboard",
  sidebar = sidebar(
    varSelectInput(
      "color_by", "Color by",
      penguins[c("species", "island", "sex")],
      selected = "species"
    )
  ),
  layout_columns(
    fill = FALSE,
    value_box(
      title = "Average bill length",
      value = scales::unit_format(unit = "mm")(means[[1]]),
      showcase = bsicons::bs_icon("align-bottom")
    ),
    value_box(
      title = "Average bill depth",
      value = scales::unit_format(unit = "mm")(means[[2]]),
      showcase = bsicons::bs_icon("align-center"),
      theme_color = "dark"
    ),
    value_box(
      title = "Average body mass",
      value = scales::unit_format(unit = "g", big.mark = ",")(means[[3]]),
      showcase = bsicons::bs_icon("handbag"),
      theme_color = "secondary"
    )
  ),
  layout_columns(
    min_height = 300, #<<
    max_height = 400, #<<
    card(
      full_screen = TRUE,
      card_header("Bill Length"),
      plotOutput("bill_length")
    ),
    card(
      full_screen = TRUE,
      card_header("Bill depth"),
      plotOutput("bill_depth")
    )
  ),
  card(
    min_height = 400, #<<
    full_screen = TRUE,
    card_header("Body Mass"),
    plotOutput("body_mass")
  )
)

server <- function(input, output) {
  gg_plot <- reactive({
    ggplot(penguins) +
      geom_density(aes(fill = !!input$color_by), alpha = 0.2) +
      theme_bw(base_size = 16) +
      theme(axis.title = element_blank())
  })

  output$bill_length <- renderPlot(gg_plot() + aes(bill_length_mm))
  output$bill_depth <- renderPlot(gg_plot() + aes(bill_depth_mm))
  output$body_mass <- renderPlot(gg_plot() + aes(body_mass_g))
}

shinyApp(ui, server)

The example app above has three rows of elements in a fillable page_sidebar() container. Without adding min_height anywhere in the UI, at small screen heights the app looks like this:

Adding min_height = 300 to the layout_columns() with the two plots and min_height = 400 to the final card, we now have a layout that scrolls at small screen heights.