All files Rerun can open should support command line, drag, and open from menu

[nikolausWest]

Since 0.6, Rerun supports opening png images, meshes and rrd files form the command line, but only rrd files can be opened through the Rerun menu -> open flow or by dragging and dropping into the viewport. All files that Rerun can open should be accessible through the same methods.

[emilk]

This affects the text on the welcome screen:

[abey79]

I'm getting that when dropping files on demo.rerun.io:

edit: apparently not on newer builds 🤔

[abey79]

Also, preview_files_being_dropped() appears to be inoperative on wasm builds. (that's the black overlay)

[abey79]

Currently, CLI loading of files uses SmartChannels, where as Open/file drop use SystemCommand::LoadRrd. The latter is bad, because it hogs the SystemCommand thread and doesn't "stream" the RRD into a recording–it loads all of it at once. This could be bad for big files.

It appears that the way forward is:

• reimplement SystemCommand::LoadRrd by creating a smart channel (App will need some kind of Arc<HashSet<Receiver<_>>>)
• add new system command for other types of files (jpg, etc.), reusing the existing support in loading.rs
• it'll probably be cleaner to move the load_rrd_file_to_channel from rerun/src/run.rs to re_viewer/src/loading.rs?
• re-implement the file arguments to CLI by using the new SystemCommand mechanism, which will allow to still have a Tcp server when launching a viewer with file arguments (basically it'll decouple the two features).

Thanks to @jleibs for helping me gain clarity on this.

[abey79]

• This is going in the direction of Support loading multiple http:// and ws:// streams at once with rerun #2121

[emilk]

Me, @abey79 and @jleibs discussed this at length with the following conclusions:

We need something like this:

enum DataSource {
    /// A remote RRD file, served over http.
    RrdHttpUrl(String),

    /// A path to a local file.
    #[cfg(not(target_arch = "wasm32"))]
    FilePath(std::path::PathBuf),

    /// Used mostly on Web where there are no paths
    FileContents(FileContents),

    /// A remote Rerun server.
    WebSocketAddr(String),
}

which replaces ArgumentCategory in run.rs. There will be a SystemCommand to load it.

We then have a function like so:

fn stream_data_source(ds: DataSource) -> Result<smart_channel::Receiver<LogMsg>> {
    …
}

that will be called by run.rs but also by app.rs.

The other change is that App stores a RecieverSet which is something like struct RecieverSet(Vec<Receiver<LogMsg>>) which handles pruning closed channels.