R Shiny Demo - how to embed pdf into shiny app

server.r

library(shiny)

shinyServer(function(input, output,session){
  
  
})

ui.r

# R Shiny app demo - display PDF in app as reference document
library(shiny)
# Simple shiny layout for demo sake
shinyUI(fluidPage(
  sidebarLayout(
    sidebarPanel(
      h5("use case - embed a pdf user guide in the app - embed as a local pdf or from web URL")
    ), 
    mainPanel(
      tabsetPanel(
        # using iframe along with tags() within tab to display pdf with scroll, height and width could be adjusted
        tabPanel("Reference", 
                 tags$iframe(style="height:400px; width:100%; scrolling=yes", 
                  src="https://cran.r-project.org/doc/manuals/r-release/R-intro.pdf")),
        tabPanel("Summary"),
        tabPanel("Plot")
      )
))
    
  ))


# Example web url used in our demo app
# https://cran.r-project.org/doc/manuals/r-release/R-intro.pdf

# Please note that the code might not work with all https:// links such as 
# this drop box link might not work 
# https://www.dropbox.com/s/clzf4cd92nqd706/Get%20Started%20with%20Dropbox.pdf?dl=0

# Replace dl=0 with raw=1 to fix if drop box link does not work
# https://www.dropbox.com/s/clzf4cd92nqd706/Get%20Started%20with%20Dropbox.pdf?raw=1

# If problems with drop box link not showing pdf, refer to the below stackoverflow 
# http://stackoverflow.com/questions/29763759/how-to-open-a-dropbox-file-in-the-application-webpage

# if using the local copy of pdf, ensure that the pdf is in www folder 
# and specify the relative path accordingly against src
# Example I am in my working directory and "shiny-cheatsheet.pdf" is in www folder withn working directory

# tabPanel("Reference", 
#                 tags$iframe(style="height:400px; width:100%; scrolling=yes", 
#                  src="shiny-cheatsheet.pdf"))

Is there a way to set width and height to some sort of screen.height and screen.width property? I want the PDF to occupy all the available space in the tab view.

Is there a way to display local pdf files that are not in the www folder?

Is there a way to display a page, header (table of content) or paragraph of the .pdf when you select an option on a checkbox?