wl_proxy(3)

NAME
wl_proxy - Represents a protocol object on the client side.

SYNOPSIS

#include <wayland-client-core.h>

  Public Member Functions

struct wl_proxy * wl_proxy_create (struct wl_proxy *factory, const struct wl_interface *interface)
void wl_proxy_destroy (struct wl_proxy *proxy)
int wl_proxy_add_listener (struct wl_proxy *proxy, void(**implementation)(void), void *data)
const void * wl_proxy_get_listener (struct wl_proxy *proxy)
int wl_proxy_add_dispatcher (struct wl_proxy *proxy, wl_dispatcher_func_t dispatcher, const void *implementation, void *data)
struct wl_proxy * wl_proxy_marshal_array_constructor (struct wl_proxy *proxy, uint32_t opcode, union wl_argument *args, const struct wl_interface *interface)
struct wl_proxy * wl_proxy_marshal_array_constructor_versioned (struct wl_proxy *proxy, uint32_t opcode, union wl_argument *args, const struct wl_interface *interface, uint32_t version)
struct wl_proxy * wl_proxy_marshal_flags (struct wl_proxy *proxy, uint32_t opcode, const struct wl_interface *interface, uint32_t version, uint32_t flags,...)
struct wl_proxy * wl_proxy_marshal_array_flags (struct wl_proxy *proxy, uint32_t opcode, const struct wl_interface *interface, uint32_t version, uint32_t flags, union wl_argument *args)
void wl_proxy_marshal (struct wl_proxy *proxy, uint32_t opcode,...)
struct wl_proxy * wl_proxy_marshal_constructor (struct wl_proxy *proxy, uint32_t opcode, const struct wl_interface *interface,...)
struct wl_proxy * wl_proxy_marshal_constructor_versioned (struct wl_proxy *proxy, uint32_t opcode, const struct wl_interface *interface, uint32_t version,...)
void wl_proxy_marshal_array (struct wl_proxy *proxy, uint32_t opcode, union wl_argument *args)
void wl_proxy_set_user_data (struct wl_proxy *proxy, void *user_data)
void * wl_proxy_get_user_data (struct wl_proxy *proxy)
uint32_t wl_proxy_get_version (struct wl_proxy *proxy)
uint32_t wl_proxy_get_id (struct wl_proxy *proxy)
void wl_proxy_set_tag (struct wl_proxy *proxy, const char *const *tag)
const char *const * wl_proxy_get_tag (struct wl_proxy *proxy)
const char * wl_proxy_get_class (struct wl_proxy *proxy)
const struct wl_interface * wl_proxy_get_interface (struct wl_proxy *proxy)
struct wl_display * wl_proxy_get_display (struct wl_proxy *proxy)
void wl_proxy_set_queue (struct wl_proxy *proxy, struct wl_event_queue *queue)
const char * wl_event_queue_get_name (const struct wl_event_queue *queue)
void * wl_proxy_create_wrapper (void *proxy)
void wl_proxy_wrapper_destroy (void *proxy_wrapper)

  Related Symbols
(Note that these are not member symbols.)
#define WL_MARSHAL_FLAG_DESTROY (1 << 0)

Detailed Description

Represents a protocol object on the client side.

A wl_proxy acts as a client side proxy to an object existing in the compositor. The proxy is responsible for converting requests made by the clients with wl_proxy_marshal() into Wayland's wire format. Events coming from the compositor are also handled by the proxy, which will in turn call the handler set with wl_proxy_add_listener().

Note
    With the exception of function wl_proxy_set_queue(), functions accessing a wl_proxy are not normally used by client code. Clients should normally use the higher level interface generated by the scanner to interact with compositor objects.

Member Function Documentation

  const char * wl_event_queue_get_name (const struct wl_event_queue * queue)
Get the name of an event queue

Parameters
    queue The queue to query

Return the human readable name for the event queue

This may be NULL if no name has been set.

  int wl_proxy_add_dispatcher (struct wl_proxy * proxy, wl_dispatcher_func_t dispatcher, const void * implementation, void * data)
Set a proxy's listener (with dispatcher)

Parameters
    proxy The proxy object
    dispatcher The dispatcher to be used for this proxy
    implementation The dispatcher-specific listener implementation
    data User data to be associated with the proxy

Returns
    0 on success or -1 on failure

Set proxy's listener to use dispatcher_func as its dispatcher and dispatcher_data as its dispatcher-specific implementation and its user data to data. If a listener has already been set, this function fails and nothing is changed.

The exact details of dispatcher_data depend on the dispatcher used. This function is intended to be used by language bindings, not user code.

proxy must not be a proxy wrapper.

  int wl_proxy_add_listener (struct wl_proxy * proxy, void(** implementation )(void), void * data)
Set a proxy's listener

Parameters
    proxy The proxy object
    implementation The listener to be added to proxy
    data User data to be associated with the proxy

Returns
    0 on success or -1 on failure

Set proxy's listener to implementation and its user data to data. If a listener has already been set, this function fails and nothing is changed.

implementation is a vector of function pointers. For an opcode n, implementation[n] should point to the handler of n for the given object.

proxy must not be a proxy wrapper.

  struct wl_proxy * wl_proxy_create (struct wl_proxy * factory, const struct wl_interface * interface)
Create a proxy object with a given interface

Parameters
    factory Factory proxy object
    interface Interface the proxy object should use

Returns
    A newly allocated proxy object or NULL on failure

This function creates a new proxy object with the supplied interface. The proxy object will have an id assigned from the client id space. The id should be created on the compositor side by sending an appropriate request with wl_proxy_marshal().

The proxy will inherit the display and event queue of the factory object.

Note
    This should not normally be used by non-generated code.

See also
    wl_display, wl_event_queue, wl_proxy_marshal()

  void * wl_proxy_create_wrapper (void * proxy)
Create a proxy wrapper for making queue assignments thread-safe

Parameters
    proxy The proxy object to be wrapped

Returns
    A proxy wrapper for the given proxy or NULL on failure

A proxy wrapper is type of 'struct wl_proxy' instance that can be used when sending requests instead of using the original proxy. A proxy wrapper does not have an implementation or dispatcher, and events received on the object is still emitted on the original proxy. Trying to set an implementation or dispatcher will have no effect but result in a warning being logged.

Setting the proxy queue of the proxy wrapper will make new objects created using the proxy wrapper use the set proxy queue. Even though there is no implementation nor dispatcher, the proxy queue can be changed. This will affect the default queue of new objects created by requests sent via the proxy wrapper.

A proxy wrapper can only be destroyed using wl_proxy_wrapper_destroy().

A proxy wrapper must be destroyed before the proxy it was created from.

If a user reads and dispatches events on more than one thread, it is necessary to use a proxy wrapper when sending requests on objects when the intention is that a newly created proxy is to use a proxy queue different from the proxy the request was sent on, as creating the new proxy and then setting the queue is not thread safe.

For example, a module that runs using its own proxy queue that needs to do display roundtrip must wrap the wl_display proxy object before sending the wl_display.sync request. For example:

struct wl_event_queue *queue = ...;
struct wl_display *wrapped_display;
struct wl_callback *callback;

wrapped_display = wl_proxy_create_wrapper(display);
wl_proxy_set_queue((struct wl_proxy *) wrapped_display, queue);
callback = wl_display_sync(wrapped_display);
wl_proxy_wrapper_destroy(wrapped_display);
wl_callback_add_listener(callback, ...);

  void wl_proxy_destroy (struct wl_proxy * proxy)
Destroy a proxy object

Parameters
    proxy The proxy to be destroyed

proxy must not be a proxy wrapper.

Note
    This function will abort in response to egregious errors, and will do so with the display lock held. This means SIGABRT handlers must not perform any actions that would attempt to take that lock, or a deadlock would occur.

  const char * wl_proxy_get_class (struct wl_proxy * proxy)
Get the interface name (class) of a proxy object

Parameters
    proxy The proxy object

Returns
    The interface name of the object associated with the proxy

  struct wl_display * wl_proxy_get_display (struct wl_proxy * proxy)
Get the display of a proxy object

Parameters
    proxy The proxy object

Returns
    The wl_display the proxy is associated with

Since
    1.23

  uint32_t wl_proxy_get_id (struct wl_proxy * proxy)
Get the id of a proxy object

Parameters
    proxy The proxy object

Returns
    The id the object associated with the proxy

  const struct wl_interface * wl_proxy_get_interface (struct wl_proxy * proxy)
Get the interface of a proxy object

Parameters
    proxy The proxy object

Returns
    The interface of the object associated with the proxy

Since
    1.24

  const void * wl_proxy_get_listener (struct wl_proxy * proxy)
Get a proxy's listener

Parameters
    proxy The proxy object

Returns
    The address of the proxy's listener or NULL if no listener is set

Gets the address to the proxy's listener; which is the listener set with wl_proxy_add_listener.

This function is useful in clients with multiple listeners on the same interface to allow the identification of which code to execute.

If wl_proxy_add_dispatcher was used, this function returns the dispatcher_data pointer instead.

  const char *const * wl_proxy_get_tag (struct wl_proxy * proxy)
Get the tag of a proxy object

See wl_proxy_set_tag for details.

Parameters
    proxy The proxy object

Since
    1.17.90

  void * wl_proxy_get_user_data (struct wl_proxy * proxy)
Get the user data associated with a proxy

Parameters
    proxy The proxy object

Returns
    The user data associated with proxy

  uint32_t wl_proxy_get_version (struct wl_proxy * proxy)
Get the protocol object version of a proxy object

Parameters
    proxy The proxy object

Returns
    The protocol object version of the proxy or 0

Gets the protocol object version of a proxy object, or 0 if the proxy was created with unversioned API.

A returned value of 0 means that no version information is available, so the caller must make safe assumptions about the object's real version.

wl_display's version will always return 0.

  void wl_proxy_marshal (struct wl_proxy * proxy, uint32_t opcode, ...)
Prepare a request to be sent to the compositor

Parameters
    proxy The proxy object
    opcode Opcode of the request to be sent
    ... Extra arguments for the given request

This function is similar to wl_proxy_marshal_constructor(), except it doesn't create proxies for new-id arguments.

Note
    This should not normally be used by non-generated code.

See also
    wl_proxy_create()

  void wl_proxy_marshal_array (struct wl_proxy * proxy, uint32_t opcode, union wl_argument * args)
Prepare a request to be sent to the compositor

Parameters
    proxy The proxy object
    opcode Opcode of the request to be sent
    args Extra arguments for the given request

This function is similar to wl_proxy_marshal_array_constructor(), except it doesn't create proxies for new-id arguments.

Note
    This is intended to be used by language bindings and not in non-generated code.

See also
    wl_proxy_marshal()

  struct wl_proxy * wl_proxy_marshal_array_constructor (struct wl_proxy * proxy, uint32_t opcode, union wl_argument * args, const struct wl_interface * interface)
Prepare a request to be sent to the compositor

Parameters
    proxy The proxy object
    opcode Opcode of the request to be sent
    args Extra arguments for the given request
    interface The interface to use for the new proxy

This function translates a request given an opcode, an interface and a wl_argument array to the wire format and writes it to the connection buffer.

For new-id arguments, this function will allocate a new wl_proxy and send the ID to the server. The new wl_proxy will be returned on success or NULL on error with errno set accordingly. The newly created proxy will inherit their version from their parent.

Note
    This is intended to be used by language bindings and not in non-generated code.

See also
    wl_proxy_marshal()

  struct wl_proxy * wl_proxy_marshal_array_constructor_versioned (struct wl_proxy * proxy, uint32_t opcode, union wl_argument * args, const struct wl_interface * interface, uint32_t version)
Prepare a request to be sent to the compositor

Parameters
    proxy The proxy object
    opcode Opcode of the request to be sent
    args Extra arguments for the given request
    interface The interface to use for the new proxy
    version The protocol object version for the new proxy

Translates the request given by opcode and the extra arguments into the wire format and write it to the connection buffer. This version takes an array of the union type wl_argument.

For new-id arguments, this function will allocate a new wl_proxy and send the ID to the server. The new wl_proxy will be returned on success or NULL on error with errno set accordingly. The newly created proxy will have the version specified.

Note
    This is intended to be used by language bindings and not in non-generated code.

See also
    wl_proxy_marshal()

  struct wl_proxy * wl_proxy_marshal_array_flags (struct wl_proxy * proxy, uint32_t opcode, const struct wl_interface * interface, uint32_t version, uint32_t flags, union wl_argument * args)
Prepare a request to be sent to the compositor

Parameters
    proxy The proxy object
    opcode Opcode of the request to be sent
    interface The interface to use for the new proxy
    version The protocol object version for the new proxy
    flags Flags that modify marshalling behaviour
    args Extra arguments for the given request

Translates the request given by opcode and the extra arguments into the wire format and write it to the connection buffer. This version takes an array of the union type wl_argument.

For new-id arguments, this function will allocate a new wl_proxy and send the ID to the server. The new wl_proxy will be returned on success or NULL on error with errno set accordingly. The newly created proxy will have the version specified.

The flag WL_MARSHAL_FLAG_DESTROY may be passed to ensure the proxy is destroyed atomically with the marshalling in order to prevent races that can occur if the display lock is dropped between the marshal and destroy operations.

Note
    This is intended to be used by language bindings and not in non-generated code.

See also
    wl_proxy_marshal_flags()

  struct wl_proxy * wl_proxy_marshal_constructor (struct wl_proxy * proxy, uint32_t opcode, const struct wl_interface * interface, ...)
Prepare a request to be sent to the compositor

Parameters
    proxy The proxy object
    opcode Opcode of the request to be sent
    interface The interface to use for the new proxy
    ... Extra arguments for the given request

Returns
    A new wl_proxy for the new_id argument or NULL on error

This function translates a request given an opcode, an interface and extra arguments to the wire format and writes it to the connection buffer. The types of the extra arguments must correspond to the argument types of the method associated with the opcode in the interface.

For new-id arguments, this function will allocate a new wl_proxy and send the ID to the server. The new wl_proxy will be returned on success or NULL on error with errno set accordingly. The newly created proxy will inherit their version from their parent.

Note
    This should not normally be used by non-generated code.

  struct wl_proxy * wl_proxy_marshal_constructor_versioned (struct wl_proxy * proxy, uint32_t opcode, const struct wl_interface * interface, uint32_t version, ...)
Prepare a request to be sent to the compositor

Parameters
    proxy The proxy object
    opcode Opcode of the request to be sent
    interface The interface to use for the new proxy
    version The protocol object version of the new proxy
    ... Extra arguments for the given request

Returns
    A new wl_proxy for the new_id argument or NULL on error

Translates the request given by opcode and the extra arguments into the wire format and write it to the connection buffer.

For new-id arguments, this function will allocate a new wl_proxy and send the ID to the server. The new wl_proxy will be returned on success or NULL on error with errno set accordingly. The newly created proxy will have the version specified.

Note
    This should not normally be used by non-generated code.

  struct wl_proxy * wl_proxy_marshal_flags (struct wl_proxy * proxy, uint32_t opcode, const struct wl_interface * interface, uint32_t version, uint32_t flags, ...)
Prepare a request to be sent to the compositor

Parameters
    proxy The proxy object
    opcode Opcode of the request to be sent
    interface The interface to use for the new proxy
    version The protocol object version of the new proxy
    flags Flags that modify marshalling behaviour
    ... Extra arguments for the given request

Returns
    A new wl_proxy for the new_id argument or NULL on error

Translates the request given by opcode and the extra arguments into the wire format and write it to the connection buffer.

For new-id arguments, this function will allocate a new wl_proxy and send the ID to the server. The new wl_proxy will be returned on success or NULL on error with errno set accordingly. The newly created proxy will have the version specified.

The flag WL_MARSHAL_FLAG_DESTROY may be passed to ensure the proxy is destroyed atomically with the marshalling in order to prevent races that can occur if the display lock is dropped between the marshal and destroy operations.

Note
    This should not normally be used by non-generated code.

  void wl_proxy_set_queue (struct wl_proxy * proxy, struct wl_event_queue * queue)
Assign a proxy to an event queue

Parameters
    proxy The proxy object
    queue The event queue that will handle this proxy or NULL

Assign proxy to event queue. Events coming from proxy will be queued in queue from now. If queue is NULL, then the display's default queue is set to the proxy.

In order to guarantee proper handing of all events which were queued before the queue change takes effect, it is required to dispatch the proxy's old event queue after setting a new event queue.

This is particularly important for multi-threaded setups, where it is possible for events to be queued to the proxy's old queue from a different thread during the invocation of this function.

To ensure that all events for a newly created proxy are dispatched on a particular queue, it is necessary to use a proxy wrapper if events are read and dispatched on more than one thread. See wl_proxy_create_wrapper() for more details.

Note
    By default, the queue set in proxy is the one inherited from parent.

See also
    wl_display_dispatch_queue()

  void wl_proxy_set_tag (struct wl_proxy * proxy, const char *const * tag)
Set the tag of a proxy object

A toolkit or application can set a unique tag on a proxy in order to identify whether an object is managed by itself or some external part.

To create a tag, the recommended way is to define a statically allocated constant char array containing some descriptive string. The tag will be the pointer to the non-const pointer to the beginning of the array.

For example, to define and set a tag on a surface managed by a certain subsystem:

    static const char *my_tag = "my tag";

    wl_proxy_set_tag((struct wl_proxy *) surface, &my_tag);

Then, in a callback with wl_surface as an argument, in order to check whether it's a surface managed by the same subsystem.

    const char * const *tag;

    tag = wl_proxy_get_tag((struct wl_proxy *) surface);
    if (tag != &my_tag)
    return;

 ...

For debugging purposes, a tag should be suitable to be included in a debug log entry, e.g.

    const char * const *tag;

    tag = wl_proxy_get_tag((struct wl_proxy *) surface);
    printf("Got a surface with the tag %p (%s)\n",
           tag, (tag && *tag) ? *tag : "");

Parameters
    proxy The proxy object
    tag The tag

Since
    1.17.90

  void wl_proxy_set_user_data (struct wl_proxy * proxy, void * user_data)
Set the user data associated with a proxy

Parameters
    proxy The proxy object
    user_data The data to be associated with proxy

Set the user data associated with proxy. When events for this proxy are received, user_data will be supplied to its listener.

  void wl_proxy_wrapper_destroy (void * proxy_wrapper)
Destroy a proxy wrapper

Parameters
    proxy_wrapper The proxy wrapper to be destroyed

Friends And Related Symbol Documentation

  #define WL_MARSHAL_FLAG_DESTROY (1 << 0) [related]
Destroy proxy after marshalling

Author

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