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ltk/examples/inputs.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

133 lines
3.9 KiB
Rust

//! `cargo run --example inputs`
//!
//! Shows a plain username field and a secure password field with a
//! built-in show / hide-password eye toggle. Tap the eye to flip
//! the bullets ↔ plaintext rendering — the buffer keeps its
//! wipe-on-drop guarantee either way. Tab / Shift+Tab moves focus
//! between fields. Enter or the Login button submits. Esc exits.
//!
//! NOTE: ltk is a Wayland layer-shell toolkit. This example requires a running
//! Wayland compositor (e.g. sway, labwc, or a full desktop session).
use ltk::{ App, Element, Keysym, ButtonVariant, button, column, text, text_edit, spacer };
// ── Messages ──────────────────────────────────────────────────────────────────
#[ derive( Clone ) ]
enum Message
{
UsernameChanged( String ),
PasswordChanged( String ),
TogglePasswordVisibility,
Submit,
}
// ── App state ─────────────────────────────────────────────────────────────────
struct InputsApp
{
username: String,
password: String,
password_visible: bool,
submitted: bool,
}
impl InputsApp
{
fn new() -> Self
{
Self
{
username: String::new(),
password: String::new(),
password_visible: false,
submitted: false,
}
}
}
// ── App trait ─────────────────────────────────────────────────────────────────
impl App for InputsApp
{
type Message = Message;
fn app_id( &self ) -> &str { "net.liberux.ltk.example.inputs" }
fn save_state( &self ) -> Option<Vec<u8>> { None }
fn restore_state( &mut self, _state: Vec<u8> ) {}
fn view( &self ) -> Element<Message>
{
let palette = ltk::theme_palette();
let primary = palette.text_primary;
let secondary = palette.text_secondary;
let status = if self.submitted
{
format!( "Submitted as: {}", self.username )
} else {
String::from( "Fill in the fields and press Login" )
};
column::<Message>()
.padding( 32.0 )
.spacing( 16.0 )
.max_width( 380.0 )
.center_y( true )
.push( text( "ltk — text input showcase" ).size( 24.0 ).color( primary ).align_center() )
.push( text( status ).size( 14.0 ).color( secondary ).align_center() )
.push( spacer() )
.push(
text_edit::<Message>( "Username", &self.username )
.on_change( Message::UsernameChanged )
.on_submit( Message::Submit ),
)
.push(
text_edit::<Message>( "Password", &self.password )
.on_change( Message::PasswordChanged )
.on_submit( Message::Submit )
.password_toggle( self.password_visible, Message::TogglePasswordVisibility ),
)
.push(
button::<Message>( "Login" )
.variant( ButtonVariant::Primary )
.on_press( Message::Submit ),
)
.push( spacer() )
.push(
text( "Tab = next field · Enter = submit · Esc = quit" )
.size( 12.0 )
.color( secondary )
.align_center(),
)
.into()
}
fn update( &mut self, msg: Message )
{
match msg
{
Message::UsernameChanged( v ) => self.username = v,
Message::PasswordChanged( v ) => self.password = v,
Message::TogglePasswordVisibility => self.password_visible = !self.password_visible,
Message::Submit => self.submitted = true,
}
}
fn on_key( &mut self, keysym: Keysym ) -> Option<Message>
{
if keysym == Keysym::Escape
{
std::process::exit( 0 );
}
None
}
}
// ── Entry point ───────────────────────────────────────────────────────────────
fn main()
{
ltk::run( InputsApp::new() );
}