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|
//! glimmer's libcosmic backend: the retained-tree ABI, with iced reading it.
//!
//! The edit half is libvidya's — integer node handles, string-keyed props,
//! events queued and polled — so `glimmer-cosmic` is `glimmer-vidya` pointed
//! at a different object. What changes is who owns the loop.
//!
//! egui lets its caller drive frames; iced does not. `cosmic::app::run` takes
//! the main thread (winit insists) and returns when the window closes. So the
//! arrangement is inverted:
//!
//! * `cosmic_run` blocks the process main thread inside libcosmic.
//! * jolt reconciles on a worker thread, mutating the arena under a mutex.
//! Nothing it does is visible until `cosmic_tree_commit`, which snapshots the
//! tree and wakes iced — so a reconcile half-way through a patch is never
//! painted, and a commit with no edits behind it costs nothing.
//! * Interactions are queued, and `cosmic_wait` blocks the worker until there
//! is one (or `cosmic_wake`, or a timeout), so an idle window burns no CPU on
//! either side.
//!
//! Every call except `cosmic_run` may come from any thread.
mod tree;
pub use tree::{Node, Prop, Tree};
use std::collections::VecDeque;
use std::ffi::{c_char, c_int};
use std::sync::atomic::{AtomicBool, Ordering::SeqCst};
use std::sync::{Arc, Condvar, LazyLock, Mutex, MutexGuard};
use std::time::Duration;
use cosmic::app::{Core, Task};
use cosmic::iced::futures::channel::mpsc;
use cosmic::iced::futures::{Stream, StreamExt};
use cosmic::iced::{Alignment, Length, Subscription};
use cosmic::widget::{self, Column, Row};
use cosmic::{ApplicationExt, Element};
use jolt_abi::{borrowed, empty_str, guard, Scratch};
fn lock<T>(m: &Mutex<T>) -> MutexGuard<'_, T> {
m.lock().unwrap_or_else(|poisoned| poisoned.into_inner())
}
// --- the arena ---------------------------------------------------------------
struct Edits {
tree: Tree,
/// Set by every mutation, cleared by a commit that published it.
dirty: bool,
}
static EDITS: LazyLock<Mutex<Edits>> = LazyLock::new(|| {
Mutex::new(Edits {
tree: Tree::default(),
dirty: false,
})
});
/// What `view` paints: the tree as of the last commit.
static COMMITTED: LazyLock<Mutex<Arc<Tree>>> = LazyLock::new(Default::default);
fn edit<R>(f: impl FnOnce(&mut Tree) -> R) -> R {
let mut e = lock(&EDITS);
e.dirty = true;
f(&mut e.tree)
}
fn read<R>(f: impl FnOnce(&Tree) -> R) -> R {
f(&lock(&EDITS).tree)
}
// --- events, towards jolt ----------------------------------------------------
struct Event {
node: i32,
name: &'static str,
text: String,
num: f64,
}
struct Inbox {
queue: VecDeque<Event>,
current: Option<Event>,
woken: bool,
}
static INBOX: Mutex<Inbox> = Mutex::new(Inbox {
queue: VecDeque::new(),
current: None,
woken: false,
});
static BELL: Condvar = Condvar::new();
fn post(node: i32, name: &'static str, text: String, num: f64) {
lock(&INBOX).queue.push_back(Event {
node,
name,
text,
num,
});
BELL.notify_all();
}
// --- wakes, towards iced -----------------------------------------------------
enum Wake {
Tree,
Quit,
}
static TO_APP: Mutex<Option<mpsc::UnboundedSender<Wake>>> = Mutex::new(None);
static QUIT_ASKED: AtomicBool = AtomicBool::new(false);
static RAN: AtomicBool = AtomicBool::new(false);
static CLOSED: AtomicBool = AtomicBool::new(false);
fn tell_app(wake: Wake) {
if let Some(tx) = lock(&TO_APP).as_ref() {
let _ = tx.unbounded_send(wake);
}
}
/// The subscription's stream. It opens with a `Tree` wake so a commit made
/// between `init` and the subscription starting is not missed, and repeats a
/// quit asked for before there was anyone to tell.
fn wakes() -> impl Stream<Item = Message> {
let (tx, rx) = mpsc::unbounded();
let _ = tx.unbounded_send(Wake::Tree);
if QUIT_ASKED.load(SeqCst) {
let _ = tx.unbounded_send(Wake::Quit);
}
*lock(&TO_APP) = Some(tx);
rx.map(|wake| match wake {
Wake::Tree => Message::Tree,
Wake::Quit => Message::Quit,
})
}
// --- the app -----------------------------------------------------------------
struct App {
core: Core,
tree: Arc<Tree>,
}
#[derive(Clone, Debug)]
enum Message {
Tree,
Quit,
Click(i32),
Toggled(i32, bool),
Change(i32, String),
Activate(i32),
}
impl App {
/// A widget does not own its value: the new state goes into the arena and
/// into what is painted, so a caller that ignores the event still sees a
/// working control, and its next render is what settles it.
fn write_back(&mut self, node: i32, key: &str, value: Prop) {
edit(|t| t.set(node, key, value.clone()));
Arc::make_mut(&mut self.tree).set(node, key, value);
}
}
impl cosmic::Application for App {
type Executor = cosmic::executor::Default;
type Flags = String;
type Message = Message;
const APP_ID: &'static str = "dev.jolt.Glimmer";
fn core(&self) -> &Core {
&self.core
}
fn core_mut(&mut self) -> &mut Core {
&mut self.core
}
fn init(core: Core, title: String) -> (Self, Task<Message>) {
let mut app = App {
core,
tree: lock(&COMMITTED).clone(),
};
// libcosmic's `wayland` feature brings `multi-window` with it, which
// makes a window title a per-window thing.
app.set_header_title(title.clone());
let task = match app.core.main_window_id() {
Some(id) => app.set_window_title(title, id),
None => Task::none(),
};
(app, task)
}
fn subscription(&self) -> Subscription<Message> {
Subscription::run(wakes)
}
fn update(&mut self, message: Message) -> Task<Message> {
match message {
Message::Tree => self.tree = lock(&COMMITTED).clone(),
Message::Quit => return cosmic::iced::exit(),
Message::Click(node) => post(node, "click", String::new(), 0.0),
Message::Toggled(node, on) => {
self.write_back(node, "active", Prop::Bool(on));
post(node, "toggled", String::new(), f64::from(u8::from(on)));
}
Message::Change(node, text) => {
self.write_back(node, "text", Prop::Str(text.clone()));
post(node, "change", text, 0.0);
}
Message::Activate(node) => post(node, "activate", String::new(), 0.0),
}
Task::none()
}
fn view(&self) -> Element<'_, Message> {
let tree = &*self.tree;
element(tree, tree.root_id(), true)
}
}
/// One node and everything under it, as widgets. `enabled` is inherited: an
/// insensitive container takes its whole subtree out of interaction.
fn element(t: &Tree, id: i32, enabled: bool) -> Element<'_, Message> {
let Some(n) = t.get(id) else {
return Column::new().into();
};
let enabled = enabled && n.bool("sensitive") != Some(false);
let spacing = n.num("spacing").unwrap_or(8.0) as f32;
let children = || n.children.iter().map(move |c| element(t, *c, enabled));
let el: Element<'_, Message> = match n.tag.as_str() {
"window" => Column::with_children(children())
.width(Length::Fill)
.height(Length::Fill)
.into(),
"box" => {
let margin = n.num("margin").unwrap_or(0.0) as f32;
if n.str("orientation") == "horizontal" {
Row::with_children(children())
.spacing(spacing)
.padding(margin)
.align_y(Alignment::Center)
.into()
} else {
Column::with_children(children())
.spacing(spacing)
.padding(margin)
.into()
}
}
"page" => {
let column = Column::with_children(children())
.spacing(spacing)
.padding(24)
.width(Length::Fill);
let mut inner = widget::container(column).width(Length::Fill);
if let Some(max) = n.num("max-width") {
inner = inner.max_width(max as f32);
}
widget::scrollable(widget::container(inner).center_x(Length::Fill))
.height(Length::Fill)
.into()
}
"card" | "frame" => {
let mut column = Column::new().spacing(spacing);
if n.tag == "frame" && !n.label().is_empty() {
column = column.push(widget::text::heading(n.label()));
}
widget::container(column.extend(children()))
.padding(16)
.width(Length::Fill)
.class(cosmic::theme::Container::Card)
.into()
}
"scroll" => widget::scrollable(Column::with_children(children()).spacing(spacing)).into(),
"label" => widget::text::body(n.label()).into(),
"title" => widget::text::title3(n.label()).into(),
"title-2" => widget::text::title4(n.label()).into(),
"dim-label" => widget::text::caption(n.label()).into(),
"button" => {
let button = match n.str("kind") {
"primary" => widget::button::suggested(n.label()),
"destructive" => widget::button::destructive(n.label()),
_ => widget::button::standard(n.label()),
};
button
.on_press_maybe(enabled.then_some(Message::Click(id)))
.into()
}
"checkbutton" => {
let mut check = widget::checkbox(n.bool("active").unwrap_or(false)).label(n.label());
if enabled {
check = check.on_toggle(move |on| Message::Toggled(id, on));
}
check.into()
}
"entry" => {
let mut entry = widget::text_input(n.str("placeholder"), n.str("text"));
if enabled {
entry = entry
.on_input(move |text| Message::Change(id, text))
.on_submit(move |_| Message::Activate(id));
}
entry.into()
}
"separator" => widget::divider::horizontal::default().into(),
"spacer" => {
let size = n.num("size").unwrap_or(8.0) as f32;
widget::Space::new().width(size).height(size).into()
}
"progress" => {
let bar =
widget::progress_bar::determinate_linear(n.num("value").unwrap_or(0.0) as f32);
if n.label().is_empty() {
bar.into()
} else {
Column::new()
.spacing(4)
.push(widget::text::caption(n.label()))
.push(bar)
.into()
}
}
// Kept rather than refused, as in libvidya: a tag this backend has not
// grown yet still shows its children.
_ => Column::with_children(children()).spacing(spacing).into(),
};
match n.num("width-request") {
Some(width) => widget::container(el).width(width as f32).into(),
None => el,
}
}
// --- the C ABI: the loop -------------------------------------------------------
static TITLE: Mutex<String> = Mutex::new(String::new());
/// The window's title, read when `cosmic_run` opens it. A call of its own
/// because jolt will not pass a string to a `:blocking` foreign procedure, and
/// `cosmic_run` has to be one.
///
/// # Safety
/// `title` is null or a NUL-terminated string.
#[no_mangle]
pub unsafe extern "C" fn cosmic_set_title(title: *const c_char) {
let title = borrowed(title);
guard((), || *lock(&TITLE) = title)
}
/// Open the window and run libcosmic until it closes. Blocks; call it on the
/// process main thread. `mode` is 0 for the system theme, 1 dark, 2 light.
///
/// Answers 0 on a clean exit, 1 on an error, 2 when a window was already run
/// in this process — winit's event loop cannot be made twice.
#[no_mangle]
pub extern "C" fn cosmic_run(width: c_int, height: c_int, mode: c_int) -> c_int {
let status = guard(1, || {
let title = lock(&TITLE).clone();
if RAN.swap(true, SeqCst) {
log::error!("jolt-cosmic: a window already ran in this process");
return 2;
}
let size = cosmic::iced::Size::new(width.max(1) as f32, height.max(1) as f32);
let mut settings = cosmic::app::Settings::default().size(size);
match mode {
1 => settings = settings.theme(cosmic::Theme::dark()),
2 => settings = settings.theme(cosmic::Theme::light()),
_ => {}
}
match cosmic::app::run::<App>(settings, title) {
Ok(()) => 0,
Err(err) => {
eprintln!("jolt-cosmic: {err}");
1
}
}
});
// Outside the guard, so a panic in libcosmic still releases the worker.
*lock(&TO_APP) = None;
CLOSED.store(true, SeqCst);
BELL.notify_all();
status
}
/// 1 once `cosmic_run` has returned.
#[no_mangle]
pub extern "C" fn cosmic_should_close() -> c_int {
c_int::from(CLOSED.load(SeqCst))
}
/// Close the window. Asked before the window exists, it closes on opening.
#[no_mangle]
pub extern "C" fn cosmic_quit() {
guard((), || {
QUIT_ASKED.store(true, SeqCst);
tell_app(Wake::Quit);
})
}
/// Publish the edits since the last commit. Answers 1 when there were any.
#[no_mangle]
pub extern "C" fn cosmic_tree_commit() -> c_int {
guard(0, || {
let snapshot = {
let mut e = lock(&EDITS);
if !e.dirty {
return 0;
}
e.dirty = false;
Arc::new(e.tree.clone())
};
*lock(&COMMITTED) = snapshot;
tell_app(Wake::Tree);
1
})
}
/// Block up to `timeout_ms` for an event, a `cosmic_wake`, or the window
/// closing. Answers 1 when an event is waiting.
#[no_mangle]
pub extern "C" fn cosmic_wait(timeout_ms: c_int) -> c_int {
guard(0, || {
let timeout = Duration::from_millis(timeout_ms.max(0) as u64);
let (mut inbox, _) = BELL
.wait_timeout_while(lock(&INBOX), timeout, |i| {
i.queue.is_empty() && !i.woken && !CLOSED.load(SeqCst)
})
.unwrap_or_else(|poisoned| poisoned.into_inner());
inbox.woken = false;
c_int::from(!inbox.queue.is_empty())
})
}
/// Cut a `cosmic_wait` short — for work queued for the worker from elsewhere.
#[no_mangle]
pub extern "C" fn cosmic_wake() {
guard((), || {
lock(&INBOX).woken = true;
BELL.notify_all();
})
}
// --- the C ABI: events -----------------------------------------------------------
static EVENT_NAME: Scratch = Scratch::new();
static EVENT_TEXT: Scratch = Scratch::new();
/// Dequeue one event; 1 while there was one. The accessors describe it.
#[no_mangle]
pub extern "C" fn cosmic_tree_poll_event() -> c_int {
guard(0, || {
let mut inbox = lock(&INBOX);
let next = inbox.queue.pop_front();
let got = next.is_some();
inbox.current = next;
c_int::from(got)
})
}
#[no_mangle]
pub extern "C" fn cosmic_tree_event_node() -> c_int {
guard(0, || lock(&INBOX).current.as_ref().map_or(0, |e| e.node))
}
#[no_mangle]
pub extern "C" fn cosmic_tree_event_name() -> *const c_char {
guard(empty_str(), || {
EVENT_NAME.lend(lock(&INBOX).current.as_ref().map_or("", |e| e.name))
})
}
#[no_mangle]
pub extern "C" fn cosmic_tree_event_text() -> *const c_char {
guard(empty_str(), || {
let text = lock(&INBOX)
.current
.as_ref()
.map(|e| e.text.clone())
.unwrap_or_default();
EVENT_TEXT.lend(text)
})
}
#[no_mangle]
pub extern "C" fn cosmic_tree_event_num() -> f64 {
guard(0.0, || lock(&INBOX).current.as_ref().map_or(0.0, |e| e.num))
}
// --- the C ABI: nodes --------------------------------------------------------------
static PROPS: Scratch = Scratch::new();
static DUMP: Scratch = Scratch::new();
#[no_mangle]
pub extern "C" fn cosmic_tree_root() -> c_int {
guard(0, || edit(Tree::root))
}
/// # Safety
/// `tag` is null or a NUL-terminated string.
#[no_mangle]
pub unsafe extern "C" fn cosmic_node_new(tag: *const c_char) -> c_int {
let tag = borrowed(tag);
guard(0, || edit(|t| t.new_node(&tag)))
}
#[no_mangle]
pub extern "C" fn cosmic_node_free(node: c_int) {
guard((), || edit(|t| t.free(node)))
}
#[no_mangle]
pub extern "C" fn cosmic_node_exists(node: c_int) -> c_int {
guard(0, || c_int::from(read(|t| t.exists(node))))
}
/// # Safety
/// `key` and `value` are null or NUL-terminated strings.
#[no_mangle]
pub unsafe extern "C" fn cosmic_node_set_str(
node: c_int,
key: *const c_char,
value: *const c_char,
) {
let (key, value) = (borrowed(key), borrowed(value));
guard((), || edit(|t| t.set(node, &key, Prop::Str(value))))
}
/// # Safety
/// `key` is null or a NUL-terminated string.
#[no_mangle]
pub unsafe extern "C" fn cosmic_node_set_num(node: c_int, key: *const c_char, value: f64) {
let key = borrowed(key);
guard((), || edit(|t| t.set(node, &key, Prop::Num(value))))
}
/// # Safety
/// `key` is null or a NUL-terminated string.
#[no_mangle]
pub unsafe extern "C" fn cosmic_node_set_bool(node: c_int, key: *const c_char, value: c_int) {
let key = borrowed(key);
guard((), || edit(|t| t.set(node, &key, Prop::Bool(value != 0))))
}
#[no_mangle]
pub extern "C" fn cosmic_node_clear_props(node: c_int) {
guard((), || edit(|t| t.clear_props(node)))
}
#[no_mangle]
pub extern "C" fn cosmic_node_tag(node: c_int) -> *const c_char {
guard(empty_str(), || {
PROPS.lend(read(|t| {
t.get(node).map(|n| n.tag.clone()).unwrap_or_default()
}))
})
}
#[no_mangle]
pub extern "C" fn cosmic_node_child_count(node: c_int) -> c_int {
guard(0, || {
read(|t| t.get(node).map_or(0, |n| n.children.len() as c_int))
})
}
#[no_mangle]
pub extern "C" fn cosmic_node_child_at(node: c_int, index: c_int) -> c_int {
guard(0, || {
read(|t| {
t.get(node)
.and_then(|n| n.children.get(usize::try_from(index).ok()?).copied())
.unwrap_or(0)
})
})
}
#[no_mangle]
pub extern "C" fn cosmic_node_append(parent: c_int, child: c_int) -> c_int {
guard(0, || c_int::from(edit(|t| t.append(parent, child))))
}
/// Unparents AND frees `child` with everything under it.
#[no_mangle]
pub extern "C" fn cosmic_node_remove(parent: c_int, child: c_int) {
guard((), || edit(|t| t.remove(parent, child)))
}
#[no_mangle]
pub extern "C" fn cosmic_node_insert_after(parent: c_int, child: c_int, sibling: c_int) -> c_int {
guard(0, || {
c_int::from(edit(|t| t.insert_after(parent, child, sibling)))
})
}
#[no_mangle]
pub extern "C" fn cosmic_node_replace(parent: c_int, old_child: c_int, new_child: c_int) -> c_int {
guard(0, || {
c_int::from(edit(|t| t.replace(parent, old_child, new_child)))
})
}
/// The subtree at `node` as hiccup; 0 is the root.
#[no_mangle]
pub extern "C" fn cosmic_tree_dump(node: c_int) -> *const c_char {
guard(empty_str(), || {
DUMP.lend(read(|t| {
let id = if node == 0 { t.root_id() } else { node };
t.dump(id)
}))
})
}
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