Take a screenshot of a Shiny app

Description

appshot performs a webshot using two different methods depending upon the object provided. If a 'character' is provided (pointing to an app.R file or app directory) an isolated background R process is launched to run the Shiny application. The current R process then captures the webshot. When a Shiny application object is supplied to appshot, it is reversed: the Shiny application runs in the current R process and an isolated background R process is launched to capture a webshot. The reason it is reversed in the second case has to do with scoping: although it would be preferable to run the Shiny application in a background process and call webshot from the current process, with Shiny application objects, there are potential scoping errors when run this way.

Usage

appshot(
  app,
  file = "webshot.png",
  ...,
  port = getOption("shiny.port"),
  envvars = NULL
)

## S3 method for class 'character'
appshot(
  app,
  file = "webshot.png",
  ...,
  port = getOption("shiny.port"),
  envvars = NULL
)

## S3 method for class 'shiny.appobj'
appshot(
  app,
  file = "webshot.png",
  ...,
  port = getOption("shiny.port"),
  envvars = NULL,
  webshot_timeout = 60
)

Arguments

Examples

if (interactive()) {
  appdir <- system.file("examples", "01_hello", package="shiny")

  # With a Shiny directory
  appshot(appdir, "01_hello.png")

  # With a Shiny App object
  shinyapp <- shiny::shinyAppDir(appdir)
  appshot(shinyapp, "01_hello_app.png")
}

Install PhantomJS

Description

Download the zip package, unzip it, and copy the executable to a system directory in which webshot can look for the PhantomJS executable.

Usage

install_phantomjs(
  version = "2.1.1",
  baseURL = "https://github.com/wch/webshot/releases/download/v0.3.1/",
  force = FALSE
)

Arguments

Details

This function was designed primarily to help Windows users since it is cumbersome to modify the PATH variable. Mac OS X users may install PhantomJS via Homebrew. If you download the package from the PhantomJS website instead, please make sure the executable can be found via the PATH variable.

On Windows, the directory specified by the environment variable APPDATA is used to store ‘phantomjs.exe’. On OS X, the directory ‘~/Library/Application Support’ is used. On other platforms (such as Linux), the directory ‘~/bin’ is used. If these directories are not writable, the directory ‘PhantomJS’ under the installation directory of the webshot package will be tried. If this directory still fails, you will have to install PhantomJS by yourself.

If PhantomJS is not already installed on the computer, this function will attempt to install it. However, if the version of PhantomJS installed is greater than or equal to the requested version, this function will not perform the installation procedure again unless the force parameter is set to TRUE. As a result, this function may also be used to reinstall or downgrade the version of PhantomJS found.

Value

NULL (the executable is written to a system directory).

Determine if PhantomJS is Installed

Description

Verifies that a version of PhantomJS is installed and available for use on the user's computer.

Usage

is_phantomjs_installed()

Value

TRUE if the PhantomJS is installed. Otherwise, FALSE if PhantomJS is not installed.

Objects exported from other packages

Description

These objects are imported from other packages. Follow the links below to see their documentation.

magrittr

%>%

Resize an image

Description

This does not change size of the image in pixels, nor does it affect appearance – it is lossless compression. This requires GraphicsMagick (recommended) or ImageMagick to be installed.

Usage

resize(filename, geometry)

Arguments

Examples

if (interactive()) {
  # Can be chained with webshot() or appshot()
  webshot("https://www.r-project.org/", "r-small-1.png") %>%
    resize("75%")

  # Generate image that is 400 pixels wide
  webshot("https://www.r-project.org/", "r-small-2.png") %>%
    resize("400x")
}

Take a snapshot of an R Markdown document

Description

This function can handle both static Rmd documents and Rmd documents with runtime: shiny.

Usage

rmdshot(
  doc,
  file = "webshot.png",
  ...,
  delay = NULL,
  rmd_args = list(),
  port = getOption("shiny.port"),
  envvars = NULL
)

Arguments

Examples

if (interactive()) {
  # rmdshot("rmarkdown_file.Rmd", "snapshot.png")

  # R Markdown file
  input_file <- system.file("examples/knitr-minimal.Rmd", package = "knitr")
  rmdshot(input_file, "minimal_rmd.png")

  # Shiny R Markdown file
  input_file <- system.file("examples/shiny.Rmd", package = "webshot")
  rmdshot(input_file, "shiny_rmd.png", delay = 5)
}

Shrink file size of a PNG

Description

This does not change size of the image in pixels, nor does it affect appearance – it is lossless compression. This requires the program optipng to be installed.

Usage

shrink(filename)

Arguments

Details

If other operations like resizing are performed, shrinking should occur as the last step. Otherwise, if the resizing happens after file shrinking, it will be as if the shrinking didn't happen at all.

Examples

if (interactive()) {
  webshot("https://www.r-project.org/", "r-shrink.png") %>%
    shrink()
}

Take a screenshot of a URL

Description

Take a screenshot of a URL

Usage

webshot(
  url = NULL,
  file = "webshot.png",
  vwidth = 992,
  vheight = 744,
  cliprect = NULL,
  selector = NULL,
  expand = NULL,
  delay = 0.2,
  zoom = 1,
  eval = NULL,
  debug = FALSE,
  useragent = NULL
)

Arguments

See Also

appshot for taking screenshots of Shiny applications.

Examples

if (interactive()) {

# Whole web page
webshot("https://github.com/rstudio/shiny")

# Might need a longer delay for all assets to display
webshot("http://rstudio.github.io/leaflet", delay = 0.5)

# One can also take screenshots of several URLs with only one command.
# This is more efficient than calling 'webshot' multiple times.
webshot(c("https://github.com/rstudio/shiny",
          "http://rstudio.github.io/leaflet"),
        delay = 0.5)

# Clip to the viewport
webshot("http://rstudio.github.io/leaflet", "leaflet-viewport.png",
        cliprect = "viewport")

# Manual clipping rectangle
webshot("http://rstudio.github.io/leaflet", "leaflet-clip.png",
        cliprect = c(200, 5, 400, 300))

# Using CSS selectors to pick out regions
webshot("http://rstudio.github.io/leaflet", "leaflet-menu.png", selector = ".list-group")
webshot("http://reddit.com/", "reddit-top.png",
        selector = c("input[type='text']", "#header-bottom-left"))

# Expand selection region
webshot("http://rstudio.github.io/leaflet", "leaflet-boxes.png",
        selector = "#installation", expand = c(10, 50, 0, 50))

# If multiple matches for a given selector, it uses the first match
webshot("http://rstudio.github.io/leaflet", "leaflet-p.png", selector = "p")
webshot("https://github.com/rstudio/shiny/", "shiny-stats.png",
         selector = "ul.numbers-summary")

# Send commands to eval
webshot("http://www.reddit.com/", "reddit-input.png",
  selector = c("#search", "#login_login-main"),
  eval = "casper.then(function() {
    // Check the remember me box
    this.click('#rem-login-main');
    // Enter username and password
    this.sendKeys('#login_login-main input[type=\"text\"]', 'my_username');
    this.sendKeys('#login_login-main input[type=\"password\"]', 'password');

    // Now click in the search box. This results in a box expanding below
    this.click('#search input[type=\"text\"]');
    // Wait 500ms
    this.wait(500);
  });"
)

# Result can be piped to other commands like resize() and shrink()
webshot("https://www.r-project.org/", "r-small.png") %>%
 resize("75%") %>%
 shrink()

# Requests can change the User-Agent header
webshot(
  "https://www.rstudio.com/products/rstudio/download/",
  "rstudio.png",
  useragent = "Mozilla/5.0 (Macintosh; Intel Mac OS X)"
)

# See more examples in the package vignette
}