Struct wayland_client::backend::Backend

pub struct Backend { /* private fields */ }

A Wayland client backend

This type hosts all the interface for interacting with the wayland protocol. It can be cloned, all clones refer to the same underlying connection.

Implementations

impl Backend

pub fn connect(stream: UnixStream) -> Result<Backend, NoWaylandLib>

Try to initialize a Wayland backend on the provided unix stream

The provided stream should correspond to an already established unix connection with the Wayland server.

This method can only fail on the sys backend if the dlopen cargo feature was enabled and the system wayland library could not be found.

pub fn downgrade(&self) -> WeakBackend

Get a WeakBackend from this backend

pub fn flush(&self) -> Result<(), WaylandError>

Flush all pending outgoing requests to the server

Most errors on this method mean that the Wayland connection is no longer valid, the only exception being an IO WouldBlock error. In that case it means that you should try flushing again later.

You can however expect this method returning WouldBlock to be very rare: it can only occur if either your client sent a lot of big messages at once, or the server is very laggy.

pub fn display_id(&self) -> ObjectId

Get the object ID for the wl_display

pub fn last_error(&self) -> Option<WaylandError>

Get the last error that occurred on this backend

If this returns Some, your Wayland connection is already dead.

pub fn info(&self, id: ObjectId) -> Result<ObjectInfo, InvalidId>

Get the detailed protocol information about a wayland object

Returns an error if the provided object ID is no longer valid.

pub fn send_request( &self, msg: Message<ObjectId, i32>, data: Option<Arc<dyn ObjectData + 'static>>, child_spec: Option<(&'static Interface, u32)> ) -> Result<ObjectId, InvalidId>

Sends a request to the server

Returns an error if the sender ID of the provided message is no longer valid.

Panic:

Several checks against the protocol specification are done, and this method will panic if they do not pass:

• the message opcode must be valid for the sender interface
• the argument list must match the prototype for the message associated with this opcode
• if the method creates a new object, a ObjectId::null() must be given in the argument list at the appropriate place, and a child_spec (interface and version) can be provided. If one is provided, it’ll be checked against the protocol spec. If the protocol specification does not define the interface of the created object (notable example is wl_registry.bind), the child_spec must be provided.

pub fn get_data( &self, id: ObjectId ) -> Result<Arc<dyn ObjectData + 'static>, InvalidId>

Access the object data associated with a given object ID

Returns an error if the object ID is not longer valid or if it corresponds to a Wayland object that is not managed by this backend (when multiple libraries share the same Wayland socket via libwayland if using the system backend).

pub fn set_data( &self, id: ObjectId, data: Arc<dyn ObjectData + 'static> ) -> Result<(), InvalidId>

Set the object data associated with a given object ID

Returns an error if the object ID is not longer valid or if it corresponds to a Wayland object that is not managed by this backend (when multiple libraries share the same Wayland socket via libwayland if using the system backend).

pub fn prepare_read(&self) -> Result<ReadEventsGuard, WaylandError>

Create a new reading guard

This is the first step for actually reading events from the Wayland socket. See ReadEventsGuard for how to use it.

This call will not block, but event callbacks may be invoked in the process of preparing the guard.

If it returns an error, you Wayland connection is already dead.

pub fn dispatch_inner_queue(&self) -> Result<usize, WaylandError>

Dispatches the inner queue of this backend if necessary

This function is only relevant when using the system backend that was created from an external display. In this case, it is possible that some other part of the program already takes care of reading the wayland socket and you should not touch it, and thus you cannot use prepare_read(). In this situation, this method will ensure that this Backend still correctly processes its messages.

When using the rust backend, or when using the system backend where you own the connection, this function will do nothing. It is thus safe to unconditionnaly invoke it at some point in your library code to ensure you support all use cases, for example.

Returns the number of messages that were dispatched to their ObjectData callbacks.

Trait Implementations

impl Clone for Backend

fn clone(&self) -> Backend

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Backend

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.