webshot: Take a screenshot of a URL

Description Usage Arguments Examples

View source: R/webshot.R

Description

Take a screenshot of a URL

Usage

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
webshot(
  url = NULL,
  file = "webshot.png",
  vwidth = 992,
  vheight = 744,
  selector = NULL,
  cliprect = NULL,
  expand = NULL,
  delay = 0.2,
  zoom = 1,
  useragent = NULL,
  max_concurrent = getOption("webshot.concurrent", default = 6)
)

Arguments

url

A vector of URLs to visit. If multiple URLs are provided, it will load and take screenshots of those web pages in parallel.

file

A vector of names of output files. Should end with .png or .pdf. If several screenshots have to be taken and only one filename is provided, then the function appends the index number of the screenshot to the file name. For PDF output, it is just like printing the page to PDF in a browser; selector, cliprect, expand, and zoom will not be used for PDFs.

vwidth

Viewport width. This is the width of the browser "window".

vheight

Viewport height This is the height of the browser "window".

selector

One or more CSS selectors specifying a DOM element to set the clipping rectangle to. The screenshot will contain these DOM elements. For a given selector, if it has more than one match, all matching elements will be used. This option is not compatible with cliprect. When taking screenshots of multiple URLs, this parameter can also be a list with same length as url with each element of the list containing a vector of CSS selectors to use for the corresponding URL.

cliprect

Clipping rectangle. If cliprect and selector are both unspecified, the clipping rectangle will contain the entire page. This can be the string "viewport", in which case the clipping rectangle matches the viewport size, or it can be a four-element numeric vector specifying the top, left, width, and height. When taking screenshots of multiple URLs, this parameter can also be a list with same length as url with each element of the list being "viewport" or a four-elements numeric vector. This option is not compatible with selector.

expand

A numeric vector specifying how many pixels to expand the clipping rectangle by. If one number, the rectangle will be expanded by that many pixels on all sides. If four numbers, they specify the top, right, bottom, and left, in that order. When taking screenshots of multiple URLs, this parameter can also be a list with same length as url with each element of the list containing a single number or four numbers to use for the corresponding URL.

delay

Time to wait before taking screenshot, in seconds. Sometimes a longer delay is needed for all assets to display properly.

zoom

A number specifying the zoom factor. A zoom factor of 2 will result in twice as many pixels vertically and horizontally. Note that using 2 is not exactly the same as taking a screenshot on a HiDPI (Retina) device: it is like increasing the zoom to 200 doubling the height and width of the browser window. This differs from using a HiDPI device because some web pages load different, higher-resolution images when they know they will be displayed on a HiDPI device (but using zoom will not report that there is a HiDPI device).

useragent

The User-Agent header used to request the URL.

max_concurrent

(Currently not implemented)

Examples

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
if (interactive()) {

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

# Might need a 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")

# Specific size
webshot("https://www.r-project.org", vwidth = 1600, vheight = 900,
        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")
# With multiple selectors, the screenshot will contain all selected elements
webshot("http://reddit.com/", "reddit-top.png",
        selector = c("[aria-label='Home']", "input[type='search']"))

# 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 will take a screenshot that
# contains all matching elements.
webshot("http://rstudio.github.io/leaflet", "leaflet-p.png", selector = "p")
webshot("https://github.com/rstudio/shiny/", "shiny-stats.png",
         selector = "ul.numbers-summary")

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

}

rstudio/webshot2 documentation built on Aug. 9, 2021, 5:25 p.m.