X11 shell does not support clipboards.

[luleyleo]

No description provided.

[psychon]

The relevant standard here is ICCCM. I recently-ish had the joy of implementing support for this. Since this X11, of course you need to create windows. Read the sections of ICCCM about selections.

The general process (for getting the selection) is that you send a ConvertSelection request and some time later receive a SelectionNotify event. Large data transfers then additionally involve some dance with window properties. This is called INCR and described in ICCCM.

For setting a selection, you create a window and make it the selection owner with SetSelectionOwner. Then you have to react to SelectionRequest events. SelectionClear tells you when something else became the selection owner.

The relevant selections are CLIPBOARD. Perhaps you also want to handle the PRIMARY selection. This is the currently selected text. Most (?) programs support pasting this via the middle mouse button.

Edit: And of course ICCCM makes things more complicated. You are not supposed to just call SetSelectionOwner, but there is a procedure to follow.

[psychon]

I took another look at the API and... I really would prefer a callback-based clipboard API in druid. That would be easier to implement.

The GTK backend uses gtk_clipboard_wait_for_contents() which is documented as: https://developer.gnome.org/gtk3/stable/gtk3-Clipboards.html#gtk-clipboard-wait-for-contents

This function waits for the data to be received using the main loop, so events, timeouts, etc, may be dispatched during the wait.

Something similar would be needed for the x11 backend for a synchronous API. And no idea what then should happen when "the other end" does not reply to a clipboard event. Perhaps one could just "collect" all X11 events and stuff them into a list for later processing, waiting only for clipboard events.

On the other hand, a synchronous API is likely way nicer for the API user, so... yeah, I'm not really sure. At least I'll remove this from my list of "things to try to implement in druid-x11 during vacation".

[psychon]

#1805 handles the "get clipboard contents"-part. I also implemented setting clipboard contents: https://github.com/linebender/druid/compare/master...psychon:x11-put-clipboard?expand=1

I want to wait for #1805 to "go through" before tackling setting the clipboard contents. So far I only tested this with something like the following (I also tested this with a shorter string):

fn main() {
    tracing_subscriber::fmt().init();
    let app = druid_shell::Application::new().unwrap();
    let mut contents = String::from("1234567890");
    while contents.len() < 17 * 1024 * 1024 {
        let copy = contents.clone();
        contents = contents + &copy;
    }
    app.clipboard().put_string(contents);
    app.run(None);
}

(A first version of my code forgot to update the "current position" in incremental transfers. Providing an "infinite paste" made gvim die with:)

(gvim:61438): GLib-ERROR **: 14:18:05.607: ../../../glib/gmem.c:177: failed to allocate 18446744071562100412 bytes
Vim: Caught deadly signal TRAP
Vim: preserving files...
Vim: Finished.