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ltk/examples/widgets.rs
Pedro M. de Echanove Pasquin ccf07de593
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Session management: xdg-session-management-v1 client, mandatory App::app_id / save_state / restore_state, runtime-managed state persistence and clean exit on signals (0.3.0)
Applications built on ltk had no way to come back where the user left them: the toolkit hardcoded `app_id = "ltk"` on every toplevel, never wrote anything to disk, and died on SIGTERM without a chance to save. This release gives the runtime the whole plumbing and asks each application only for the bytes worth keeping, in the spirit of Android's saved-instance state.
The `App` trait gains three mandatory methods, deliberately without default bodies so every application states its position: `app_id()` (reverse-DNS, used for `xdg_toplevel.set_app_id`, the AccessKit application name and the state directory — the `app_id` element of the deprecated `window_config` tuple is now ignored and a one-time warning reports a mismatch), `save_state() -> Option<Vec<u8>>` and `restore_state(Vec<u8>)`. The bytes are opaque; the trait carries no serde bound. Their rustdoc is the contract: when the runtime saves, where the files live, when the bytes come back and when they do not, what must never go in them, and a worked serde_json example.
The runtime persists under `$XDG_STATE_HOME/<app_id>/` (falling back to `~/.local/state`): `session.json` holds the compositor session id, a clean-exit marker and the writer's pid; `state.bin` holds the application bytes. Writes are atomic (temp file + rename, mode 0600, directory 0700) and best-effort. State is saved every 30 s when the bytes changed, once after the event loop exits (which covers `on_close_requested`, `requested_exit` and lost connections), and on SIGTERM/SIGINT — a calloop signal source, installed before any thread exists, now turns those into a clean exit of the loop instead of process death. `restore_state` runs synchronously in `try_run` before the window is created and before the first `view()`, and only when the process is relaunched as part of a session restore (`LTK_SESSION_RESTORE=1`, removed from the environment before the app can spawn children) or when the previous run left `clean_exit: false`; a plain launch starts fresh. A second concurrent instance detects the live pid and runs with persistence disabled rather than clobbering the first.
The compositor side of geometry restore goes through `xdg-session-management-v1`. Neither wayland-protocols nor sctk ship generated code for it yet, so the XML is vendored under `protocols/` and `wayland-scanner` generates the client module in-tree (`src/protocol/`), resolving the crate names through sctk's reexports so the bindings stay on the crate instances sctk links. Before the first commit of a `ShellMode::Window` toplevel the runtime binds `xdg_session_manager_v1`, calls `get_session(reason, stored_id)` and `restore_toplevel(toplevel, "main")`; the three window-creation paths in `run.rs` are folded into one `make_window` helper so the attach always sits immediately before `commit()`. `created` persists the id, `replaced` destroys the objects and stops persisting. Compositors without the global lose only the geometry half. Layer-shell and session-lock surfaces skip the whole machinery.
Every `App` implementor in the tree is updated: the twelve examples (`showcase`, `scroll` and `mini_shell` persist real state; the rest return `None`), both integration tests (`event_loop_flow` gains `save_restore_round_trip`), the in-source and markdown doctests, README, onboarding, cookbook (new recipe "Surviving relaunch: session state") and architecture docs, and the changelog. `src/session_state.rs` carries unit tests over a temporary state directory. `Makefile install` now copies `protocols/` into the cargo registry — without it downstream builds would fail inside the proc-macro — and `debian/copyright` covers the vendored XML.
The trait change is breaking, hence 0.3.0. Also fixes the pre-existing `viewport_tests` module in `render/mod.rs`, which used `Length` without importing it and broke `cargo test`.
2026-08-15 10:16:30 +02:00

234 lines
6.6 KiB
Rust

use std::time::Instant;
use ltk::{
App, Element, Keysym, WidgetId,
column, row, text, text_edit, spacer, separator, slider,
toggle, checkbox, radio, progress_bar, scroll,
spinner, tabs,
};
#[ derive( Clone ) ]
enum Msg
{
ToggleWifi,
ToggleBluetooth,
ToggleDarkMode,
CheckNotifications,
CheckUpdates,
SelectThemeLight,
SelectThemeDark,
SelectThemeAuto,
SliderChanged( f32 ),
SelectTab( usize ),
NoteChanged( String ),
Tick,
}
struct WidgetsApp
{
wifi: bool,
bluetooth: bool,
dark_mode: bool,
notifications: bool,
updates: bool,
theme: usize,
progress: f32,
volume: f32,
tab: usize,
note: String,
started_at: Instant,
}
impl WidgetsApp
{
fn new() -> Self
{
Self
{
wifi: true,
bluetooth: false,
dark_mode: true,
notifications: true,
updates: false,
theme: 2,
progress: 0.65,
volume: 0.7,
tab: 0,
note: String::new(),
started_at: Instant::now(),
}
}
}
impl App for WidgetsApp
{
type Message = Msg;
// Stateless demo: nothing worth restoring.
fn app_id( &self ) -> &str { "net.liberux.ltk.example.widgets" }
fn save_state( &self ) -> Option<Vec<u8>> { None }
fn restore_state( &mut self, _state: Vec<u8> ) {}
fn view( &self ) -> Element<Msg>
{
// Pull text colours from the active theme so the example
// reads correctly under both light and dark mode without
// touching the example code.
let palette = ltk::theme_palette();
let primary = palette.text_primary;
let secondary = palette.text_secondary;
let title = text( "ltk widgets" ).size( 24.0 ).color( primary ).align_center();
// Segmented tab strip — each tab shows its own page below.
let tabs_strip: Element<Msg> = tabs( [ "General", "Audio", "Network" ] )
.selected( self.tab )
.on_select( Msg::SelectTab )
.into();
let toggles = column::<Msg>()
.spacing( 0.0 )
.push( text( "Toggle" ).size( 13.0 ).color( secondary ) )
.push( toggle( self.wifi ).label( "Wi-Fi" ).on_toggle( Msg::ToggleWifi ) )
.push( toggle( self.bluetooth ).label( "Bluetooth" ).on_toggle( Msg::ToggleBluetooth ) )
.push( toggle( self.dark_mode ).label( "Dark mode" ).on_toggle( Msg::ToggleDarkMode ) );
let checkboxes = column::<Msg>()
.spacing( 0.0 )
.push( text( "Checkbox" ).size( 13.0 ).color( secondary ) )
.push( checkbox( self.notifications ).label( "Notifications" ).on_toggle( Msg::CheckNotifications ) )
.push( checkbox( self.updates ).label( "Auto updates" ).on_toggle( Msg::CheckUpdates ) );
let radios = column::<Msg>()
.spacing( 0.0 )
.push( text( "Radio" ).size( 13.0 ).color( secondary ) )
.push( radio( self.theme == 0 ).label( "Light" ).on_select( Msg::SelectThemeLight ) )
.push( radio( self.theme == 1 ).label( "Dark" ).on_select( Msg::SelectThemeDark ) )
.push( radio( self.theme == 2 ).label( "Auto" ).on_select( Msg::SelectThemeAuto ) );
let vol_label = format!( "Volume: {:.0}%", self.volume * 100.0 );
let prog_label = format!( "Progress: {:.0}%", self.progress * 100.0 );
// Spinner — animation phase derived from the wall clock so the
// arc rotates at one revolution per second.
let phase = self.started_at.elapsed().as_secs_f32();
let spin_row: Element<Msg> = row::<Msg>()
.spacing( 12.0 )
.push( spinner().phase( phase ) )
.push( text( "Loading…" ).size( 14.0 ).color( primary ) )
.into();
// Multiline text area — Enter inserts a newline, Tab leaves it.
let textarea = text_edit( "Type a note (multi-line)", &self.note )
.multiline( true )
.rows( 4 )
.id( WidgetId( "widgets/note" ) )
.on_change( Msg::NoteChanged );
// One page per tab, so selecting a tab visibly swaps the content.
let page: Element<Msg> = match self.tab.min( 2 )
{
0 => column::<Msg>()
.padding( 0.0 )
.spacing( 12.0 )
.push( toggles )
.push( separator() )
.push( checkboxes )
.push( separator() )
.push( radios )
.into(),
1 => column::<Msg>()
.padding( 0.0 )
.spacing( 12.0 )
.push( text( vol_label ).size( 13.0 ).color( secondary ) )
.push( slider( self.volume ).on_change( Msg::SliderChanged ) )
.push( text( prog_label ).size( 13.0 ).color( secondary ) )
.push( progress_bar( self.progress ) )
.into(),
_ => column::<Msg>()
.padding( 0.0 )
.spacing( 12.0 )
.push( text( "Spinner" ).size( 13.0 ).color( secondary ) )
.push( spin_row )
.push( separator() )
.push( text( "Multiline text edit" ).size( 13.0 ).color( secondary ) )
.push( textarea )
.into(),
};
let content = column::<Msg>()
.padding( 32.0 )
.spacing( 12.0 )
.push( title )
.push( tabs_strip )
.push( separator() )
.push( page )
.push( spacer() )
.push(
text( "Esc = quit" )
.size( 12.0 )
.color( secondary )
.align_center(),
);
scroll( content ).into()
}
fn update( &mut self, msg: Msg )
{
match msg
{
Msg::ToggleWifi => self.wifi = !self.wifi,
Msg::ToggleBluetooth => self.bluetooth = !self.bluetooth,
Msg::ToggleDarkMode => self.dark_mode = !self.dark_mode,
Msg::CheckNotifications => self.notifications = !self.notifications,
Msg::CheckUpdates => self.updates = !self.updates,
Msg::SelectThemeLight => self.theme = 0,
Msg::SelectThemeDark => self.theme = 1,
Msg::SelectThemeAuto => self.theme = 2,
Msg::SliderChanged( v ) => self.volume = v,
Msg::SelectTab( i ) => self.tab = i,
Msg::NoteChanged( s ) => self.note = s,
Msg::Tick => {}
}
}
fn on_key( &mut self, keysym: Keysym ) -> Option<Msg>
{
if keysym == Keysym::Escape { std::process::exit( 0 ); }
None
}
// Drive the spinner — the runtime keeps redrawing while this returns
// `true`, and `view()` reads the wall clock to compute the phase, so
// no explicit Tick message is even needed for the visual to advance.
fn is_animating( &self ) -> bool { true }
fn poll_interval( &self ) -> Option<std::time::Duration>
{
// Suppress the dead-code warning on Msg::Tick; a real app would
// also use the timer to drive non-visual periodic work here.
Some( std::time::Duration::from_millis( 250 ) )
}
fn poll_external( &mut self ) -> Vec<Msg>
{
// Consumed: the timer above keeps the runtime warm, but the
// spinner reads the wall clock directly so no Tick is required.
// We still emit one occasionally so the message variant is
// exercised — keeps the example honest about the pattern apps
// usually use for clock work.
if self.started_at.elapsed().as_millis() % 1_000 < 250
{
vec![ Msg::Tick ]
} else {
vec![]
}
}
}
fn main()
{
ltk::run( WidgetsApp::new() );
}