UiEvents.kt

42 lines · 1.9 KB

Changed in: 0.5.0

1	package dev.stave.ui.events
2
3	import kotlinx.coroutines.channels.BufferOverflow
4	import kotlinx.coroutines.flow.MutableSharedFlow
5	import kotlinx.coroutines.flow.SharedFlow
6	import kotlinx.coroutines.flow.asSharedFlow
7
8	/**
9	* App-wide bus for transient user-facing notifications. Emitters post strings;
10	* [dev.stave.desktop.ui.ToastHost] in StaveApp collects them into a small stack of
11	* Material Snackbar-style banners.
12	*
13	* Design. MutableSharedFlow with replay=0 (a toast that arrives before a
14	* collector is ready is dropped — we don't want last week's error flashing up on
15	* today's launch) and extraBufferCapacity=4 so a brief burst (e.g. three playlist
16	* loads failing in quick succession) queues rather than dropping.
17	*
18	* What goes here. Non-blocking informational messages that the user can safely
19	* ignore. Examples: "Lyrics unavailable for this track", "Couldn't reach LRCLIB",
20	* "Playlist saved to library", "Tag reader timed out". Not here: fatal errors
21	* that should prevent a user action from completing (those deserve a dialog), or
22	* status that's not time-bounded (those belong in the relevant screen's persistent
23	* UI).
24	*/
25	class UiEvents {
26	private val _messages = MutableSharedFlow<String>(
27	replay = 0,
28	extraBufferCapacity = 4,
29	onBufferOverflow = BufferOverflow.DROP_OLDEST,
30	)
31
32	/** Observe toast messages. Collectors are fire-and-forget; missed emissions
33	* while no collector is attached stay missed, which is what we want. */
34	val messages: SharedFlow<String> = _messages.asSharedFlow()
35
36	/** Post a toast. Non-suspending for convenience in non-coroutine call sites
37	* (IO error handlers, VLCJ callbacks). Drops on overflow — at which point the
38	* user probably has bigger problems than one dropped toast. */
39	fun post(message: String) {
40	_messages.tryEmit(message)
41	}
42	}