wayland_data_offer_t - Man Page

offer to transfer data

Synopsis

#include <wayland-client-protocol.hpp>

Inherits wayland::proxy_t.

Public Types

enum class wrapper_type { standard, display, foreign, proxy_wrapper }

void accept (uint32_t serial, std::string const &mime_type)
accept one of the offered mime types
void receive (std::string const &mime_type, int fd)
request that the data is transferred
void finish ()
the offer will no longer be used
bool can_finish () const
Check whether the finish function is available with the currently bound version of the protocol.
void set_actions (data_device_manager_dnd_action const &dnd_actions, data_device_manager_dnd_action const &preferred_action)
set the available/preferred drag-and-drop actions
bool can_set_actions () const
Check whether the set_actions function is available with the currently bound version of the protocol.
std::function< void(std::string)> & on_offer ()
advertise offered mime type
std::function< void(data_device_manager_dnd_action)> & on_source_actions ()
notify the source-side available actions
std::function< void(data_device_manager_dnd_action)> & on_action ()
notify the selected action
uint32_t get_id () const
Get the id of a proxy object.
std::string get_class () const
Get the interface name (class) of a proxy object.
uint32_t get_version () const
Get the protocol object version of a proxy object.
wrapper_type get_wrapper_type () const
Get the type of a proxy object.
void set_queue (event_queue_t queue)
Assign a proxy to an event queue.
wl_proxy * c_ptr () const
Get a pointer to the underlying C struct.
bool proxy_has_object () const
Check whether this wrapper actually wraps an object.
operator bool () const
Check whether this wrapper actually wraps an object.
bool operator== (const proxy_t &right) const
Check whether two wrappers refer to the same object.
bool operator!= (const proxy_t &right) const
Check whether two wrappers refer to different objects.
void proxy_release ()
Release the wrapped object (if any), making this an empty wrapper.

Static Public Attributes

static constexpr std::uint32_t accept_since_version = 1
Minimum protocol version required for the accept function.
static constexpr std::uint32_t receive_since_version = 1
Minimum protocol version required for the receive function.
static constexpr std::uint32_t finish_since_version = 3
Minimum protocol version required for the finish function.
static constexpr std::uint32_t set_actions_since_version = 3
Minimum protocol version required for the set_actions function.

Detailed Description

offer to transfer data

A wl_data_offer represents a piece of data offered for transfer by another client (the source client). It is used by the copy-and-paste and drag-and-drop mechanisms. The offer describes the different mime types that the data can be converted to and provides the mechanism for transferring the data directly from the source client.

Definition at line 760 of file wayland-client-protocol.hpp.

Member Enumeration Documentation

enum class wayland::proxy_t::wrapper_type [strong], [inherited]

Underlying wl_proxy type and properties of a proxy_t that affect construction, destruction, and event handling

Enumerator

standard: C pointer is a standard type compatible with wl_proxy*. Events are dispatched and it is destructed when the proxy_t is destructed. User data is set.
display: C pointer is a wl_display*. No events are dispatched, wl_display_disconnect is called when the proxy_t is destructed. User data is set.
foreign: C pointer is a standard type compatible with wl_proxy*, but another library owns it and it should not be touched in a way that could affect the operation of the other library. No events are dispatched, wl_proxy_destroy is not called when the proxy_t is destructed, user data is not touched. Consequently, there is no reference counting for the proxy_t. Lifetime of such wrappers should preferably be short to minimize the chance that the owning library decides to destroy the wl_proxy.
proxy_wrapper: C pointer is a wl_proxy* that was constructed with wl_proxy_create_wrapper. No events are dispatched, wl_proxy_wrapper_destroy is called when the proxy_t is destroyed. Reference counting is active. A reference to the proxy_t creating this proxy wrapper is held to extend its lifetime until after the proxy wrapper is destroyed.

Definition at line 116 of file wayland-client.hpp.

Member Function Documentation

void data_offer_t::accept (uint32_t serial, std::string const & mime_type)

accept one of the offered mime types

Parameters: serial serial number of the accept request
mime_type mime type accepted by the client

Indicate that the client can accept the given mime type, or NULL for not accepted.

For objects of version 2 or older, this request is used by the client to give feedback whether the client can receive the given mime type, or NULL if none is accepted; the feedback does not determine whether the drag-and-drop operation succeeds or not.

For objects of version 3 or newer, this request determines the final result of the drag-and-drop operation. If the end result is that no mime types were accepted, the drag-and-drop operation will be cancelled and the corresponding drag source will receive wl_data_source.cancelled. Clients may still use this event in conjunction with wl_data_source.action for feedback.

Definition at line 2028 of file wayland-client-protocol.cpp.

wl_proxy * wayland::proxy_t::c_ptr () const [inherited]

Get a pointer to the underlying C struct.

Returns: The underlying wl_proxy wrapped by this proxy_t if it exists, otherwise an exception is thrown

bool data_offer_t::can_finish () const

Check whether the finish function is available with the currently bound version of the protocol.

Definition at line 2045 of file wayland-client-protocol.cpp.

bool data_offer_t::can_set_actions () const

Check whether the set_actions function is available with the currently bound version of the protocol.

Definition at line 2056 of file wayland-client-protocol.cpp.

void data_offer_t::finish ()

the offer will no longer be used Notifies the compositor that the drag destination successfully finished the drag-and-drop operation.

Upon receiving this request, the compositor will emit wl_data_source.dnd_finished on the drag source client.

It is a client error to perform other requests than wl_data_offer.destroy after this one. It is also an error to perform this request after a NULL mime type has been set in wl_data_offer.accept or no action was received through wl_data_offer.action.

If wl_data_offer.finish request is received for a non drag and drop operation, the invalid_finish protocol error is raised.

Definition at line 2040 of file wayland-client-protocol.cpp.

std::string wayland::proxy_t::get_class () const [inherited]

Get the interface name (class) of a proxy object.

Returns: The interface name of the object associated with the proxy

uint32_t wayland::proxy_t::get_id () const [inherited]

Get the id of a proxy object.

Returns: The id the object associated with the proxy

uint32_t wayland::proxy_t::get_version () const [inherited]

Get the protocol object version of a proxy object. 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.

display_t will always return version 0.

Returns: The protocol object version of the proxy or 0

wrapper_type wayland::proxy_t::get_wrapper_type () const [inline], [inherited]

Get the type of a proxy object.

Definition at line 302 of file wayland-client.hpp.

std::function< void(data_device_manager_dnd_action)> & data_offer_t::on_action ()

notify the selected action

Parameters: dnd_action action selected by the compositor

This event indicates the action selected by the compositor after matching the source/destination side actions. Only one action (or none) will be offered here.

This event can be emitted multiple times during the drag-and-drop operation in response to destination side action changes through wl_data_offer.set_actions.

This event will no longer be emitted after wl_data_device.drop happened on the drag-and-drop destination, the client must honor the last action received, or the last preferred one set through wl_data_offer.set_actions when handling an 'ask' action.

Compositors may also change the selected action on the fly, mainly in response to keyboard modifier changes during the drag-and-drop operation.

The most recent action received is always the valid one. Prior to receiving wl_data_device.drop, the chosen action may change (e.g. due to keyboard modifiers being pressed). At the time of receiving wl_data_device.drop the drag-and-drop destination must honor the last action received.

Action changes may still happen after wl_data_device.drop, especially on 'ask' actions, where the drag-and-drop destination may choose another action afterwards. Action changes happening at this stage are always the result of inter-client negotiation, the compositor shall no longer be able to induce a different action.

Upon 'ask' actions, it is expected that the drag-and-drop destination may potentially choose a different action and/or mime type, based on wl_data_offer.source_actions and finally chosen by the user (e.g. popping up a menu with the available options). The final wl_data_offer.set_actions and wl_data_offer.accept requests must happen before the call to wl_data_offer.finish.

Definition at line 2072 of file wayland-client-protocol.cpp.

std::function< void(std::string)> & data_offer_t::on_offer ()

advertise offered mime type

Parameters: mime_type offered mime type

Sent immediately after creating the wl_data_offer object. One event per offered mime type.

Definition at line 2062 of file wayland-client-protocol.cpp.

std::function< void(data_device_manager_dnd_action)> & data_offer_t::on_source_actions ()

notify the source-side available actions

Parameters: source_actions actions offered by the data source

This event indicates the actions offered by the data source. It will be sent right after wl_data_device.enter, or anytime the source side changes its offered actions through wl_data_source.set_actions.

Definition at line 2067 of file wayland-client-protocol.cpp.

wayland::proxy_t::operator bool () const [inherited]

Check whether this wrapper actually wraps an object.

Returns: true if there is an underlying object, false if this wrapper is empty

bool wayland::proxy_t::operator!= (const proxy_t & right) const [inherited]

Check whether two wrappers refer to different objects.

bool wayland::proxy_t::operator== (const proxy_t & right) const [inherited]

Check whether two wrappers refer to the same object.

bool wayland::proxy_t::proxy_has_object () const [inherited]

Check whether this wrapper actually wraps an object.

Returns: true if there is an underlying object, false if this wrapper is empty

void wayland::proxy_t::proxy_release () [inherited]

Release the wrapped object (if any), making this an empty wrapper. Note that display_t instances cannot be released this way. Attempts to do so are ignored.

Examples foreign_display.cpp.

void data_offer_t::receive (std::string const & mime_type, int fd)

request that the data is transferred

Parameters: mime_type mime type desired by receiver
fd file descriptor for data transfer

To transfer the offered data, the client issues this request and indicates the mime type it wants to receive. The transfer happens through the passed file descriptor (typically created with the pipe system call). The source client writes the data in the mime type representation requested and then closes the file descriptor.

The receiving client reads from the read end of the pipe until EOF and then closes its end, at which point the transfer is complete.

This request may happen multiple times for different mime types, both before and after wl_data_device.drop. Drag-and-drop destination clients may preemptively fetch data or examine it more closely to determine acceptance.

Definition at line 2034 of file wayland-client-protocol.cpp.

void data_offer_t::set_actions (data_device_manager_dnd_action const & dnd_actions, data_device_manager_dnd_action const & preferred_action)

set the available/preferred drag-and-drop actions

Parameters: dnd_actions actions supported by the destination client
preferred_action action preferred by the destination client

Sets the actions that the destination side client supports for this operation. This request may trigger the emission of wl_data_source.action and wl_data_offer.action events if the compositor needs to change the selected action.

This request can be called multiple times throughout the drag-and-drop operation, typically in response to wl_data_device.enter or wl_data_device.motion events.

This request determines the final result of the drag-and-drop operation. If the end result is that no action is accepted, the drag source will receive wl_data_source.cancelled.

The dnd_actions argument must contain only values expressed in the wl_data_device_manager.dnd_actions enum, and the preferred_action argument must only contain one of those values set, otherwise it will result in a protocol error.

While managing an 'ask' action, the destination drag-and-drop client may perform further wl_data_offer.receive requests, and is expected to perform one last wl_data_offer.set_actions request with a preferred action other than 'ask' (and optionally wl_data_offer.accept) before requesting wl_data_offer.finish, in order to convey the action selected by the user. If the preferred action is not in the wl_data_offer.source_actions mask, an error will be raised.

If the 'ask' action is dismissed (e.g. user cancellation), the client is expected to perform wl_data_offer.destroy right away.

This request can only be made on drag-and-drop offers, a protocol error will be raised otherwise.

Definition at line 2051 of file wayland-client-protocol.cpp.

void wayland::proxy_t::set_queue (event_queue_t queue) [inherited]

Assign a proxy to an event queue.

Parameters: queue The event queue that will handle this proxy

Assign proxy to event queue. Events coming from proxy will be queued in queue instead of the display's main queue.

See also: display_t::dispatch_queue().

Examples proxy_wrapper.cpp.