能否直接将Shiny应用源码嵌入Bookdown文档而非使用knitr::include_app？

Hey there, let's tackle this Bookdown + embedded Shiny app issue you're facing! It's totally possible to embed Shiny app source code directly in your Bookdown docs—let's break down why you're hitting those errors and how to fix them.

Why the Errors Happen #

Bookdown has a slightly different rendering pipeline than regular R Markdown, especially when it comes to handling HTML dependencies (like Shiny's JS/CSS files). When you try to drop a raw shinyApp() call into Bookdown, it often fails to locate those critical dependencies, leading to either the "path for html_dependency not provided" error or a blank frame.

Fix 1: Manually Declare Shiny's HTML Dependencies #

This method ensures Bookdown can find Shiny's core assets by explicitly defining the dependency. Here's a working example:

---
title: "Bookdown with Embedded Shiny"
output: bookdown::gitbook
---

# My Embedded Shiny App

```{r, echo=FALSE, message=FALSE}
library(shiny)
library(htmltools)

# Build your Shiny app as usual
my_shiny_app <- shinyApp(
  ui = fluidPage(
    titlePanel("Hello Bookdown + Shiny!"),
    sidebarLayout(
      sidebarPanel(
        sliderInput("count", "Number of Points:", min = 10, max = 500, value = 100)
      ),
      mainPanel(
        plotOutput("scatter_plot")
      )
    )
  ),
  server = function(input, output) {
    output$scatter_plot <- renderPlot({
      plot(rnorm(input$count), rnorm(input$count), pch = 16, col = "steelblue")
    })
  }
)

# Wrap the app with explicit Shiny dependencies
tagList(
  htmlDependency(
    name = "shiny",
    version = as.character(packageVersion("shiny")),
    src = system.file("www", package = "shiny"),
    script = "shiny.min.js",
    stylesheet = "shiny.css"
  ),
  my_shiny_app
)

### Fix 2: Force Render with `knitr::knit_print()`
If the first method feels clunky, you can use `knitr`'s dedicated print method for Shiny app objects to handle dependencies automatically:

```r
```{r, echo=FALSE, message=FALSE}
library(shiny)

my_shiny_app <- shinyApp(
  ui = fluidPage(
    titlePanel("Simpler Embedded Shiny"),
    numericInput("num", "Enter a Number:", value = 5),
    textOutput("result")
  ),
  server = function(input, output) {
    output$result <- renderText({
      paste("Your number squared is:", input$num ^ 2)
    })
  }
)

# Force knitr to render the app correctly
knitr::knit_print(my_shiny_app)

### Critical Notes to Avoid Blank Frames
- **Stick to HTML outputs**: Shiny is a web-based tool—Bookdown outputs like PDF or Word will never render interactive Shiny apps. Use `bookdown::gitbook`, `bookdown::html_book`, or another HTML-based format.
- **Skip `runtime: shiny`**: Don't add this to your YAML header! Bookdown doesn't support this runtime setting, and it will break your build.
- **Test first**: Verify your Shiny app works in a regular R Markdown file before dropping it into Bookdown—this helps rule out app-specific bugs.

内容的提问来源于stack exchange，提问作者Tamas Ferenci