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//! Helpers for handling the initialization of an app
//!
//! At the startup of your Wayland app, the initial step is generally to retrieve the list of globals
//! advertized by the compositor from the registry. Using the [`Dispatch`] mechanism for this task can be
//! very unpractical, this is why this module provides a special helper for handling the registry.
//!
//! The entry point of this helper is the [`registry_queue_init`] function. Given a reference to your
//! [`Connection`] it will create an [`EventQueue`], retrieve the initial list of globals, and register a
//! handler using your provided `Dispatch<WlRegistry,_>` implementation for handling dynamic registry events.
//!
//! ## Example
//!
//! ```no_run
//! use wayland_client::{
//! Connection, Dispatch, QueueHandle,
//! globals::{registry_queue_init, Global, GlobalListContents},
//! protocol::{wl_registry, wl_compositor},
//! };
//! # use std::sync::Mutex;
//! # struct State;
//!
//! // You need to provide a Dispatch<WlRegistry, GlobalListContents> impl for your app
//! impl wayland_client::Dispatch<wl_registry::WlRegistry, GlobalListContents> for State {
//! fn event(
//! state: &mut State,
//! proxy: &wl_registry::WlRegistry,
//! event: wl_registry::Event,
//! // This mutex contains an up-to-date list of the currently known globals
//! // including the one that was just added or destroyed
//! data: &GlobalListContents,
//! conn: &Connection,
//! qhandle: &QueueHandle<State>,
//! ) {
//! /* react to dynamic global events here */
//! }
//! }
//!
//! let conn = Connection::connect_to_env().unwrap();
//! let (globals, queue) = registry_queue_init::<State>(&conn).unwrap();
//!
//! # impl wayland_client::Dispatch<wl_compositor::WlCompositor, ()> for State {
//! # fn event(
//! # state: &mut State,
//! # proxy: &wl_compositor::WlCompositor,
//! # event: wl_compositor::Event,
//! # data: &(),
//! # conn: &Connection,
//! # qhandle: &QueueHandle<State>,
//! # ) {}
//! # }
//! // now you can bind the globals you need for your app
//! let compositor: wl_compositor::WlCompositor = globals.bind(&queue.handle(), 4..=5, ()).unwrap();
//! ```
use std::{
fmt,
ops::RangeInclusive,
os::unix::io::OwnedFd,
sync::{
atomic::{AtomicBool, Ordering},
Arc, Mutex,
},
};
use wayland_backend::{
client::{Backend, InvalidId, ObjectData, ObjectId, WaylandError},
protocol::Message,
};
use crate::{
protocol::{wl_display, wl_registry},
Connection, Dispatch, EventQueue, Proxy, QueueHandle,
};
/// Initialize a new event queue with its associated registry and retrieve the initial list of globals
///
/// See [the module level documentation][self] for more.
pub fn registry_queue_init<State>(
conn: &Connection,
) -> Result<(GlobalList, EventQueue<State>), GlobalError>
where
State: Dispatch<wl_registry::WlRegistry, GlobalListContents> + 'static,
{
let event_queue = conn.new_event_queue();
let display = conn.display();
let data = Arc::new(RegistryState {
globals: GlobalListContents { contents: Default::default() },
handle: event_queue.handle(),
initial_roundtrip_done: AtomicBool::new(false),
});
let registry = display.send_constructor(wl_display::Request::GetRegistry {}, data.clone())?;
// We don't need to dispatch the event queue as for now nothing will be sent to it
conn.roundtrip()?;
data.initial_roundtrip_done.store(true, Ordering::Relaxed);
Ok((GlobalList { registry }, event_queue))
}
/// A helper for global initialization.
///
/// See [the module level documentation][self] for more.
#[derive(Debug)]
pub struct GlobalList {
registry: wl_registry::WlRegistry,
}
impl GlobalList {
/// Access the contents of the list of globals
pub fn contents(&self) -> &GlobalListContents {
self.registry.data::<GlobalListContents>().unwrap()
}
/// Binds a global, returning a new protocol object associated with the global.
///
/// The `version` specifies the range of versions that should be bound. This function will guarantee the
/// version of the returned protocol object is the lower of the maximum requested version and the advertised
/// version.
///
/// If the lower bound of the `version` is less than the version advertised by the server, then
/// [`BindError::UnsupportedVersion`] is returned.
///
/// ## Multi-instance/Device globals.
///
/// This function is not intended to be used with globals that have multiple instances such as `wl_output`
/// and `wl_seat`. These types of globals need their own initialization mechanism because these
/// multi-instance globals may be removed at runtime. To handle then, you should instead rely on the
/// `Dispatch` implementation for `WlRegistry` of your `State`.
///
/// # Panics
///
/// This function will panic if the maximum requested version is greater than the known maximum version of
/// the interface. The known maximum version is determined by the code generated using wayland-scanner.
pub fn bind<I, State, U>(
&self,
qh: &QueueHandle<State>,
version: RangeInclusive<u32>,
udata: U,
) -> Result<I, BindError>
where
I: Proxy + 'static,
State: Dispatch<I, U> + 'static,
U: Send + Sync + 'static,
{
let version_start = *version.start();
let version_end = *version.end();
let interface = I::interface();
if *version.end() > interface.version {
// This is a panic because it's a compile-time programmer error, not a runtime error.
panic!("Maximum version ({}) of {} was higher than the proxy's maximum version ({}); outdated wayland XML files?",
version.end(), interface.name, interface.version);
}
let globals = &self.registry.data::<GlobalListContents>().unwrap().contents;
let guard = globals.lock().unwrap();
let (name, version) = guard
.iter()
// Find the with the correct interface
.filter_map(|Global { name, interface: interface_name, version }| {
// TODO: then_some
if interface.name == &interface_name[..] {
Some((*name, *version))
} else {
None
}
})
.next()
.ok_or(BindError::NotPresent)?;
// Test version requirements
if version < version_start {
return Err(BindError::UnsupportedVersion);
}
// To get the version to bind, take the lower of the version advertised by the server and the maximum
// requested version.
let version = version.min(version_end);
Ok(self.registry.bind(name, version, qh, udata))
}
/// Returns the [`WlRegistry`][wl_registry] protocol object.
///
/// This may be used if more direct control when creating globals is needed.
pub fn registry(&self) -> &wl_registry::WlRegistry {
&self.registry
}
}
/// An error that may occur when initializing the global list.
#[derive(Debug)]
pub enum GlobalError {
/// The backend generated an error
Backend(WaylandError),
/// An invalid object id was acted upon.
InvalidId(InvalidId),
}
impl std::error::Error for GlobalError {
fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
match self {
GlobalError::Backend(source) => Some(source),
GlobalError::InvalidId(source) => std::error::Error::source(source),
}
}
}
impl std::fmt::Display for GlobalError {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match self {
GlobalError::Backend(source) => {
write!(f, "Backend error: {source}")
}
GlobalError::InvalidId(source) => write!(f, "{source}"),
}
}
}
impl From<WaylandError> for GlobalError {
fn from(source: WaylandError) -> Self {
GlobalError::Backend(source)
}
}
impl From<InvalidId> for GlobalError {
fn from(source: InvalidId) -> Self {
GlobalError::InvalidId(source)
}
}
/// An error that occurs when a binding a global fails.
#[derive(Debug)]
pub enum BindError {
/// The requested version of the global is not supported.
UnsupportedVersion,
/// The requested global was not found in the registry.
NotPresent,
}
impl std::error::Error for BindError {}
impl fmt::Display for BindError {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
match self {
BindError::UnsupportedVersion {} => {
write!(f, "the requested version of the global is not supported")
}
BindError::NotPresent {} => {
write!(f, "the requested global was not found in the registry")
}
}
}
}
/// Description of a global.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Global {
/// The name of the global.
///
/// This is an identifier used by the server to reference some specific global.
pub name: u32,
/// The interface of the global.
///
/// This describes what type of protocol object the global is.
pub interface: String,
/// The advertised version of the global.
///
/// This specifies the maximum version of the global that may be bound. This means any lower version of
/// the global may be bound.
pub version: u32,
}
/// A container representing the current contents of the list of globals
#[derive(Debug)]
pub struct GlobalListContents {
contents: Mutex<Vec<Global>>,
}
impl GlobalListContents {
/// Access the list of globals
///
/// Your closure is invoked on the global list, and its return value is forwarded to the return value
/// of this function. This allows you to process the list without making a copy.
pub fn with_list<T, F: FnOnce(&[Global]) -> T>(&self, f: F) -> T {
let guard = self.contents.lock().unwrap();
f(&guard)
}
/// Get a copy of the contents of the list of globals.
pub fn clone_list(&self) -> Vec<Global> {
self.contents.lock().unwrap().clone()
}
}
struct RegistryState<State> {
globals: GlobalListContents,
handle: QueueHandle<State>,
initial_roundtrip_done: AtomicBool,
}
impl<State: 'static> ObjectData for RegistryState<State>
where
State: Dispatch<wl_registry::WlRegistry, GlobalListContents>,
{
fn event(
self: Arc<Self>,
backend: &Backend,
msg: Message<ObjectId, OwnedFd>,
) -> Option<Arc<dyn ObjectData>> {
let conn = Connection::from_backend(backend.clone());
// The registry messages don't contain any fd, so use some type trickery to
// clone the message
#[derive(Debug, Clone)]
enum Void {}
let msg: Message<ObjectId, Void> = msg.map_fd(|_| unreachable!());
let to_forward = if self.initial_roundtrip_done.load(Ordering::Relaxed) {
Some(msg.clone().map_fd(|v| match v {}))
} else {
None
};
// and restore the type
let msg = msg.map_fd(|v| match v {});
// Can't do much if the server sends a malformed message
if let Ok((_, event)) = wl_registry::WlRegistry::parse_event(&conn, msg) {
match event {
wl_registry::Event::Global { name, interface, version } => {
let mut guard = self.globals.contents.lock().unwrap();
guard.push(Global { name, interface, version });
}
wl_registry::Event::GlobalRemove { name: remove } => {
let mut guard = self.globals.contents.lock().unwrap();
guard.retain(|Global { name, .. }| name != &remove);
}
}
};
if let Some(msg) = to_forward {
// forward the message to the event queue as normal
self.handle
.inner
.lock()
.unwrap()
.enqueue_event::<wl_registry::WlRegistry, GlobalListContents>(msg, self.clone())
}
// We do not create any objects in this event handler.
None
}
fn destroyed(&self, _id: ObjectId) {
// A registry cannot be destroyed unless disconnected.
}
fn data_as_any(&self) -> &dyn std::any::Any {
&self.globals
}
}