writing Unicode text to the Windows clipboard

Hello,

I'm interested in moving text from and to the clipboard that cannot
necessarily be represented in the native encoding. So, really, this is
about Windows.

I can successfully read from the clipboard by specifying the format that
corresponds to unicode text.

From R >=2.7.0, it seems you should also be able to write unicode text
to the Windows clipboard.

https://github.com/wch/r-source/blob/5a156a0865362bb8381dcd69ac335f5174a4f60c/src/gnuwin32/CHANGES0#L535-L536

Jennifer Bryan 
    on Thu, 23 May 2019 00:03:05 -0400 writes:

diff --git a/src/library/utils/src/windows/util.c
b/src/library/utils/src/windows/util.c
index 373049495dd..fc3dc39e3a7 100644
--- a/src/library/utils/src/windows/util.c
+++ b/src/library/utils/src/windows/util.c
@@ -318,7 +318,7 @@ SEXP writeClipboard(SEXP text, SEXP sformat)
  warning(_("unable to open the clipboard"));
  GlobalFree(hglb);
      } else {
- success = SetClipboardData(CF_TEXT, hglb) != 0;
+ success = SetClipboardData(format, hglb) != 0;
  if(!success) {
      warning(_("unable to write to the clipboard"));
      GlobalFree(hglb);

Example:

"?" is "GREATER-THAN OVER EQUAL TO", which is unicode <U+2267>, has
UTF-16LE bytes 67 22, and is not representable in latin1.

I copy ? to the Windows clipboard and attempt a round trip. I see:

x <- readClipboard(format = 13, raw = TRUE) # 13 <--> "Unicode text"
#> [1] 67 22 00 00
writeClipboard(x, format = 13L)
readClipboard(format = 13, raw = TRUE)
#> [1] 67 00 22 00 00 00 00 00

and, literally, pasting yields: g"

If I build r-devel with the patch, the same process yields

x <- readClipboard(format = 13, raw = TRUE)
#> [1] 67 22 00 00
writeClipboard(x, format = 13)
readClipboard(format = 13, raw = TRUE)
#> [1] 67 22 00 00

and pasting returns the original input: ?

Passing the `format` to SetClipboardData() instead of hard-wiring
"CF_TEXT" brings behaviour in line with the docs.

-- Jenny

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