Wayland: Fix primary clipboard handling

[hunterkepley]

Fixes #96214

Fixes issue with middle-mouse click (even if enabled) not working with Wayland. From the issue, it works when Wayland is not in use, same system settings. But, when Wayland is in use, it breaks

[hunterkepley]

pre-commit checks passed

[hunterkepley]

@fire Working on one more fix, this only fixes single line text boxes such as searching for a project

[hunterkepley]

@fire fix for script editing merged, squashed

There is also the possibility of wrapping the clipboard_get function in the Wayland display server within the clipboard_get_primary.
It seems to not be used anywhere else besides these places, and the latter does not seemingly work with Wayland

[hunterkepley]

Went ahead and pushed the other fix. Confirmed the function which returns an empty string from the clipboard primary is not working + only used in two places

Wrapping it like this prevents if statements + code smell

Unless changes are requested, this MR is done being edited by me

[Riteo]

Hi, thank you for your contribution! The primary clipboard is different form the regular clipboard, so aliasing it to the regular one is not an acceptable solution unfortunately.

Instead, the proper fix would be to fix the primary clipboard logic itself.

Calling DisplayServer.clipboard_get_primary from GDScript (with a random string in my primary clipboard) returns this in a verbose log:

Selecting media type "text/plain;charset=utf-8" from offered types.
Read chunk of 15 bytes.
Done reading 15 bytes.

So it's clearly trying to read something, although in the end it returns an empty string. The regular and the primary clipboard work in a very similar way, so perhaps there's some difference between their handling? I can see a flush instead of a roundtrip but it seems to make no difference once swapped in.

The part from the above log is printed from _read_fd in platforms/linuxbsd/wayland/wayland_thread.cpp, you could take a look there.

I hope this is a good starting point and thank you again for contributing!

[hunterkepley]

thanks- will make a fix soon

[hunterkepley]

@Riteo PTAL- i am embarassed at how long it took to find this issue. We were throwing away the data gotten back from primary_get_mime. Assigned it to data and all is well

[Riteo]

@hunterkepley lol no worries I did not notice that either! Thank you for your patience!

[Riteo]

Looks perfect! One small nitpick, please rename the commit and title to match the new change, prefixing it with Wayland: (e.g. Wayland: Fix primary clipboard handling)

[hunterkepley]

Will do 🙂

[akien-mga]

Thanks! And congrats for your first merged Godot contribution 🎉