Plot viewer

Plot could be displayed in a VS Code editor tab.

PNG file

When R session watcher is enabled, the default behavior of displaying graphics is to replay the plots to a png device created over a temporary PNG file. Whenever the plot is updated, the PNG file is revealed in VS Code in an image viewer.

There are known limitations of PNG plot viewer:

• If the plot contains multiple pages (e.g. par(mfrow =) is used), then the last page will overwrite the previous pages.
• If the code has multiple plot calls, each creating a new plot, then only the last plot will be captured.
• Some plot code based on grid package may not work as the plot updates cannot be captured.

Native plot window

If the PNG plot viewer is not working properly, one might want to disable it with the following code in ~/.Rprofile:

options(vsc.plot = FALSE)

Then the plot viewer will fall back to the native plot window. It only takes effect on R session startup.

SVG in httpgd plot viewer

vscode-R supports an SVG plot viewer based on httpgd. Enable r.plot.useHttpgd in VS Code settings.

Then whenever a plot is created, a Plot viewer tab will be revealed where a number of httpgd features are natively supported.

SVG in httpgd webpage

httpgd is an R package to provide a graphics device that asynchronously serves SVG graphics via HTTP and WebSockets. It works well with VS Code in a browser viewer.

Before using httpgd, install the package via

install.packages("httpgd")

To use httpgd as the default graphics device and make it automatically show up in VS Code, put the following code in ~/.Rprofile:

if (interactive() && Sys.getenv("RSTUDIO") == "") {
  Sys.setenv(TERM_PROGRAM = "vscode")
  if ("httpgd" %in% .packages(all.available = TRUE)) {
    options(vsc.plot = FALSE)
    options(device = function(...) {
      httpgd::hgd(silent = TRUE)
      .vsc.browser(httpgd::hgd_url(history = FALSE), viewer = "Beside")
    })
  }
  source(file.path(Sys.getenv(if (.Platform$OS.type == "windows") "USERPROFILE" else "HOME"), ".vscode-R", "init.R"))
}

The httpgd web page supports live update on resizing, history navigation, zooming, save as png format, and some other great features.