`facet_wrap()` with `scales = "free_x"` squishes middle facets

Summary

When using facet_wrap() with scales = "free_x", the middle facets rows appear squished.

MWE

This bug is most apparent when working in Shiny contexts:

library(ggplot2)
library(shiny)
library(plotly)

ui <- fluidPage(
  plotlyOutput("p", height = "800px")
)

server <- function(input, output, session) {
  output$p <- renderPlotly({
    plt <- palmerpenguins::penguins |>
      ggplot(
        aes(x = sex)
      ) +
      geom_bar() +
      facet_wrap(
        ggplot2::vars(species, island, year),
        ncol = 2,
        axes = "all",
        scales = "free_x" # or "free"
      )

    plotly::ggplotly(plt)
  })
}

shinyApp(ui, server)

The result is an output where the first and last row of facets look correct, but all the middle facet rows are squished and there's a bunch of whitespace inbetween:

Interestingly, if you use scales = "free_y" or scales = "fixed", the bug is not triggered:

Potential Cause

I believe this is an issue with the responsivity / css of the resulting plot. You can get this to trigger outside of shiny, by doing the following:

1. Size your plot output window to result in a squished output, and run the following:

plt <- palmerpenguins::penguins |>
  ggplot(
    aes(x = sex)
  ) +
  geom_bar() +
  facet_wrap(
    ggplot2::vars(species, island, year),
    ncol = 2,
    axes = "all",
    scales = "free_x"
  )

plotly::ggplotly(plt)

Result:

2. Resize the plot window by increasing the height, and you get the weird result:

3. Key observation: if you now re-run the code from step 1, with the window height already tall, it renders correctly:

This is why I think there's responsivity / css thing going on here -- I imagine Shiny is rendering to a smaller height, then resizing to fill the space of the div. Responsivity is broken, triggering the weird result.

Thanks for looking in to this!

Bắt đầu bằng cách chạy MWE R/Shiny được cung cấp với ggplot2, plotly và facet_wrap(scales = "free_x"), sau đó tái hiện chuỗi thao tác thay đổi kích thước bên ngoài Shiny. Kiểm tra bố cục plot được tạo ra và hành vi responsive trong quá trình thay đổi kích thước; được xem là hoàn thành khi các hàng facet ở giữa vẫn giữ nguyên chiều cao như mong đợi và không xuất hiện khoảng trắng sau khi thay đổi kích thước.