clipboard with an image errors (windows)

[MarcMush]

#46981 still happens, not when the clipboard is empty, but when there is an image in the clipboard

to reproduce, copy an image (outside Julia), then type clipboard() in the Julia terminal:

PS C:\Users\Marc> julia +1.7 --startup-file no
               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.7.3 (2022-05-06)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org/ release
|__/                   |

julia> clipboard()
""

julia>
PS C:\Users\Marc> julia +alpha --startup-file no
               _
   _       _ _(_)_     |  Documentation: https://docs.julialang.org
  (_)     | (_) (_)    |
   _ _   _| |_  __ _   |  Type "?" for help, "]?" for Pkg help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 1.9.0-alpha1 (2022-11-15)
 _/ |\__'_|_|_|\__'_|  |  Official https://julialang.org/ release
|__/                   |

julia> clipboard()
ERROR: SystemError: GetClipboardData: L’opération a réussi.
Stacktrace:
 [1] windowserror(p::Symbol, code::UInt32; extrainfo::Nothing)
   @ Base .\error.jl:191
 [2] windowserror(p::Symbol, code::UInt32)
   @ Base .\error.jl:191
 [3] cleanup
   @ C:\Users\Marc\.julia\juliaup\julia-1.9.0-alpha1+0.x64.w64.mingw32\share\julia\stdlib\v1.9\InteractiveUtils\src\clipboard.jl:118 [inlined]
 [4] clipboard()
   @ InteractiveUtils C:\Users\Marc\.julia\juliaup\julia-1.9.0-alpha1+0.x64.w64.mingw32\share\julia\stdlib\v1.9\InteractiveUtils\src\clipboard.jl:125
 [5] top-level scope
   @ REPL[1]:1

the error doesn't happen in 1.7, but it does happen in 1.8.3 (where I believe #47311 was merged) and 1.9-alpha

Note that in 1.7, it appeared as an empty string, even though there is actually an image in the clipboard. 1.8.3 or 1.9 doesn't error with an empty string

Also note that ironically, the error message "L’opération a réussi" means "The operation succeeded" in French (my system language)

[StefanKarpinski]

I guess the question is what should this do?

[aviks]

In Windows 11, English, the error I see is, for the record, ERROR: SystemError: GetClipboardData: Element not found.

I'd probably expect an empty string in these situations. This is what happens if I copy and image, and try to paste it in Notepad, for example, which only supports textual content.

[MarcMush]

I think returning an empty string makes sense, and it is also consistent with the 1.7 and earlier behaviour

[inkydragon]

We could first check if the contents of the clipboard can be converted to text, and if not, return the empty string.

• IsClipboardFormatAvailable
  Perhaps a whitelist could be used:
  • CF_UNICODETEXT: Unicode text format.
  • CF_TEXT: Use this format for ANSI text.
  • Maybe CF_OEMTEXT: Text format containing characters in the OEM character set.

Sample Code: Using the Clipboard: Pasting Information from the Clipboard

[sefffal]

It would be amazing if the clipboard function could be extended by libraries somehow.
I would love to be able paste images into a Matrix{RGB}. This might vary too much by platform though.