clipboard: add --clipboard-backends option

[na-na-hi]

This allows specifying a priority list of clipboard backends to use. This is mostly useful on Linux where multiple clipboard backends exist.

[github-actions]

Download the artifacts for this pull request:

Windows

• mpv-i686-w64-mingw32
• mpv-x86_64-w64-mingw32
• mpv-x86_64-windows-msvc

macOS

• mpv-macos-13-intel
• mpv-macos-14-arm
• mpv-macos-15-arm

[llyyr]

I can't envision any priority list that's more than 2 backends "X,vo", even taking into account future backends for e.g. X11. It would be far simpler to implement a --clipboard-backend=<native|vo> option IMO.

[na-na-hi]

I can't envision any priority list that's more than 2 backends "X,vo", even taking into account future backends for e.g. X11.

X11 backend won't be VO depedent, which means that mpv with a wayland VO window can use 3 backends: X11, Wayland, and VO.

[llyyr]

mpv with a wayland VO window can use 3 backends: X11

Elaborate?

[na-na-hi]

Elaborate?

X11 backend can be used to access Xwayland clipboard, or the clipboard of some other X session (like from Xephyr/another VT). This can be done regardless if mpv VO window is Wanyland or X11, or even with no VO window at all.

[llyyr]

I can't think of any good practical reason to allow that. It's just another attack vector if mpv can access the X11 clipboard while having no VO or having a wayland VO active. A vo native clipboard backend should only be possible to be used if mpv has a VO window of the same backend. This is already the case for every backend except X11 due to platform limitations.

[kasper93]

I can't think of any good practical reason to allow that.

It's only an option. I think it is good to have. And having it directly liked to implementation makes sense, instead of creating another list of pseudo-implementation names.

Also this option makes --clipboard-enable redundant. Do you plan to handle that?

[na-na-hi]

Also this option makes --clipboard-enable redundant. Do you plan to handle that?

It's now removed, and updated --clipboard-backends doc to include how to disable all backends. Better to do this now before it goes into a release.

[kasper93]

Also this option makes --clipboard-enable redundant. Do you plan to handle that?

It's now removed, and updated --clipboard-backends doc to include how to disable all backends. Better to do this now before it goes into a release.

Thanks. Except one remaining comment, the change looks ok to me.