Crate wayland_server [−] [src]

Server-side Wayland connector

Overview

Setting up the listening socket is done by the create_display function, providing you a Display object and an EventLoop.

On the event loop, you'll be able to register the globals you want to advertize, as well as handlers for all ressources created by the clients.

You then integrate the wayland event loop in your main event loop to run your compositor.

Handlers and event loop

This crate mirrors the callback-oriented design of the Wayland C library by using handler structs: each wayland type defines a Handler trait in its module, which one method for each possible requests this object can receive.

To use it, you need to build a struct (or enum) that will implement all the traits for all the requests you are interested in. All methods of handler traits provide a default implementation foing nothing, so you don't need to write empty methods for events you want to ignore. You also need to declare the handler capability for your struct using the declare_handler!(..) macro. A single struct can be handler for several wayland interfaces at once.

Example of handler

/*  writing a handler for an wl_foo interface */
// import the module of this interface
use wl_foo;

struct MyHandler { /* some fields to store state */ }

// implement handerl trait:
impl wl_foo::Handler for MyHandler {
    fn a_request(&mut self,
                 evlh: &mut EventLoopHandle,
                 client: &Client,
                 me: &wl_foo::WlFoo,
                 arg1, arg2, // the actual args of the request
    ) {
        /* handle the request */
    }
}

// declare the handler capability
// this boring step is necessary because Rust's type system is
// not yet magical enough
declare_handler!(MyHandler, wl_foo::Handler, wl_foo::WlFoo);Run

Event Loop and handlers

In your initialization code, you'll need to instanciate your handler and give it to the event queue:

let handler_id = event_loop.add_handler(MyHandler::new());Run

Then, you can register your wayland objects to this handler:

// This type info is necessary for safety, as at registration
// time the event_loop will check that the handler you
// specified using handler_id has the same type as provided
// as argument, and that this type implements the appropriate
// handler trait.
event_loop.register::<_, MyHandler>(&my_object, handler_id);Run

You can have several handlers in the same event loop, but they cannot share their state without synchronisation primitives like Arc, Mutex and friends, so if two handlers need to share some state, you should consider building them as a single struct.

A given wayland object can only be registered to a single handler at a given time, re-registering it to a new handler will overwrite the previous configuration.

Handlers can be created, and objects registered to them from within a handler method, using the &EventLoopHandle argument.

Globals declaration

Declaring a global is quite similar to declaring a handler for a ressource. But this time via the GlobalHandler<R> trait.

This trait declares a single method, bind, which is called whenever a client binds this global, providing you with a ressource object representing the newly-created global.

You can do what you please with this object, storing it for later if you'll need to send it events, or just let it go go out of scope after having registered it to the appropriate handler.

To register globals on the event loop, you need the register_global method:

struct MyHandler { /* ... */ }

// creating a handler for the global wl_foo
impl GlobalHandler<WlFoo> for MyHandler {
    fn bind(&mut self,
            evlh: &mut EventLoopHandle,
            client: &Client,
            global: WlFoo
    ) {
        /* do something with it */
    }
}

/* ... */

// then somewhere in the initialization code
let handler_id = event_loop.add_handler(MyHandler::new());
// bind this handler to a global for interface wl_foo version 3
// specifying the types is mandatory, and compability of this
// handler with the global is checked at registration time.
let foo = event_loop.register_global::<WlFoo, MyHandler>(handler_is, 3);
// foo contains a handle to the global, that you can use later
// to destroy it:
foo.destroy();
// if you don't plan to ever destroy this global, you can ignore
// this return value, letting it out of scope will not destroy
// the global.Run

Event loop integration

Once the setup phase is done, you can integrate the event loop in the main event loop of your program.

Either all you need is for it to run indefinitely (external events are checked in an other thread?):

event_loop.run();Run

Or you can integrate it with more control:

loop {
    // flush events to client sockets
    display.flush_clients();
    // receive request from clients and dispatch them
    // blocking if no request is pending for at most
    // 10ms
    event_loop.dispatch(Some(10)).unwrap();
    // then you can check events from other sources if
    // you need to
}Run

Protocols integration

This crate provides the basic primitives as well as the core wayland protocol (in the protocol module), but other protocols can be integrated from XML descriptions.

The the crate wayland_scanner and its documentation for details about how to do so.

Modules

protocol	The wayland core protocol
sys	Reexports of types and objects from wayland-sys

Macros

declare_handler

Registers a handler type so it can be used in event loops

Structs

Client	A wayland client connected to your server
Display	A wayland socket
EventLoop
EventLoopHandle	Handle to an event loop
Global	A handle to a global object
StateGuard	Guard to access internal state of an event loop

Enums

EventResult

Possible outcome of the call of a event on a resource

Traits

GlobalHandler	Trait to handle a global object.
Handler	Generic handler trait
Init	A trait to initialize handlers after they've been inserted in an event queue
Resource	Common routines for wayland resource objects.

Functions

create_display

Create a new display