Error in plot /pdf(...): failed to load default encoding

[psychemedia]

I am trying to run a local version of webr via the JupyterLite (3.3) kernel in a self-contained package served usig flask and bundled using pyinstaller. It works well enough on a Mac, but on Windows I get an Error: Error in pdf(...): failed to load default encoding when I try a simple plot.

Any suggestions about workarounds / fixes much appreciated.

If I run:

Sys.getlocale()
localeToCharset()

On both Mac and Win I get: [1] "UTF-8" "ISO8859-1"

[psychemedia]

Encodings in: /vfs/usr/lib/R/library/grDevices/enc.js.metadata:

{"files":[{"filename":"/AdobeStd.enc","start":0,"end":2094},
{"filename":"/AdobeSym.enc","start":2094,"end":4608},
{"filename":"/CP1250.enc","start":4608,"end":6832},
{"filename":"/CP1251.enc","start":6832,"end":9221},
{"filename":"/CP1253.enc","start":9221,"end":11406},
{"filename":"/CP1257.enc","start":11406,"end":13653},
{"filename":"/Cyrillic.enc","start":13653,"end":16002},
{"filename":"/Greek.enc","start":16002,"end":18214},
{"filename":"/ISOLatin1.enc","start":18214,"end":20427},
{"filename":"/ISOLatin2.enc","start":20427,"end":22614},
{"filename":"/ISOLatin7.enc","start":22614,"end":24886},
{"filename":"/ISOLatin9.enc","start":24886,"end":27082},
{"filename":"/KOI8-R.enc","start":27082,"end":29372},
{"filename":"/KOI8-U.enc","start":29372,"end":31680},
{"filename":"/MacRoman.enc","start":31680,"end":33942}
{"filename":"/PDFDoc.enc","start":33942,"end":36149},
{"filename":"/TeXtext.enc","start":36149,"end":38240},
{"filename":"/WinAnsi.enc","start":38240,"end":40551}]
,"remote_package_size":40551}

Settings in webkernel.ts::setupEnvironment():

options(device = function(...){
        pdf(...)
        dev.control("enable")
      }, webr.plot.new = FALSE)

Using constructions of the form pdf(encoding="CP1250.enc", ...) have no effect other than changing the form of the error message (Error: Error in pdf(encoding = "CP1250.enc", ...): failed to load default encoding etc.).

[psychemedia]

Try with canvas? Notes on setting driver options to canvas here: https://docs.r-wasm.org/webr/latest/plotting.html

[psychemedia]

Exploring:

• trying to set webr::canvas() in https://r-wasm.github.io/jupyterlite-webr-kernel/lab/index.html gives error Error: Cannot read properties of undefined (reading 'width'). Is this a webr error or a JupyterLite kernel error?

[georgestagg]

Could you post an image of the browser's network log from DevTools? Are there any downloading errors as you run the plot() command (as in the first example)?

Does setting the device option to the following instead work?

options(device = function(...){
    png(...)
    dev.control("enable")
 }, webr.plot.new = FALSE)

plot(1)

It seems strange that OS matters here. I wonder if there is some issue with line ending in the served VFS content.

[psychemedia]

Ok - the above device option works - thanks for that tip...

There were no issues in the dev log otherwise, eg from the following in a new kernel:

So the encoding file is read but then there's some sort of mismatch presumably against the claimed default encoding and the encoding catalogue?

[georgestagg]

In 0df3b2b the underlying graphics device was switched from pdf() to webr::canvas().

This should not make a difference to the eventual output, since plots were replayed into the canvas graphics device in any case, but it should avoid the errors in the above thread.

Please do open another thread if similar errors continue to occur in future releases.