---
name: "wayland_presentation_t"
section: "3"
platform: "linux"
package: "waylandpp-dev"
version: "1.0.0-6+b2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/wayland_presentation_t"
---

# wayland\_presentation\_t(3)

timed presentation related wl\_surface requests

## NAME

wayland::presentation\_t - timed presentation related wl\_surface requests

## SYNOPSIS

`#include <wayland-client-protocol-extra.hpp>`

Inherits **wayland::proxy\_t**.

### Public Types

enum class **wrapper\_type** { **standard**, **display**, **foreign**, **proxy\_wrapper** }\

### Public Member Functions

**presentation\_feedback\_t** **feedback** (**surface\_t** const &surface)\
 request presentation feedback information  std::function\< void(uint32\_t)\> & **on\_clock\_id** ()\
 clock ID for timestamps  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 **feedback\_since\_version** = 1\
 Minimum protocol version required for the **feedback** function.

## Detailed Description

timed presentation related wl\_surface requests

The main feature of this interface is accurate presentation timing feedback to ensure smooth video playback while maintaining audio/video synchronization. Some features use the concept of a presentation clock, which is defined in the presentation.clock\_id event.

A content update for a wl\_surface is submitted by a wl\_surface.commit request. Request 'feedback' associates with the wl\_surface.commit and provides feedback on the content update, particularly the final realized presentation time.

Definition at line **76** of file **wayland-client-protocol-extra.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

### 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*

### presentation\_feedback\_t presentation\_t::feedback (surface\_t const & surface)

*request presentation feedback information*

**Returns**

*new feedback object*

**Parameters**

*surface target surface*

*Request presentation feedback for the current content submission on the given surface. This creates a new presentation\_feedback object, which will deliver the feedback information once. If multiple presentation\_feedback objects are created for the same submission, they will all deliver the same information.*

*For details on what information is returned, see the presentation\_feedback interface.*

*Definition at line* **720** *of file* **wayland-client-protocol-extra.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(uint32\_t)\> & presentation\_t::on\_clock\_id ()

*clock ID for timestamps*

**Parameters**

*clk\_id platform clock identifier*

*This event tells the client in which clock domain the compositor interprets the timestamps used by the presentation extension. This clock is called the presentation clock.*

*The compositor sends this event when the client binds to the presentation interface. The presentation clock does not change during the lifetime of the client connection.*

*The clock identifier is platform dependent. On Linux/glibc, the identifier value is one of the clockid\_t values accepted by clock\_gettime(). clock\_gettime() is defined by POSIX.1-2001.*

*Timestamps in this clock domain are expressed as tv\_sec\_hi, tv\_sec\_lo, tv\_nsec triples, each component being an unsigned 32-bit value. Whole seconds are in tv\_sec which is a 64-bit value combined from tv\_sec\_hi and tv\_sec\_lo, and the additional fractional part in tv\_nsec as nanoseconds. Hence, for valid timestamps tv\_nsec must be in \[0, 999999999\].*

*Note that clock\_id applies only to the presentation clock, and implies nothing about e.g. the timestamps used in the Wayland core protocol input events.*

*Compositors should prefer a clock which does not jump and is not slewed e.g. by NTP. The absolute value of the clock is irrelevant. Precision of one millisecond or better is recommended. Clients must be able to query the current clock value directly, not by asking the compositor.*

*Definition at line* **727** *of file* **wayland-client-protocol-extra.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 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***.*

## Member Data Documentation

### constexpr std::uint32\_t wayland::presentation\_t::feedback\_since\_version = 1` [static]`, ` [constexpr]`

*Minimum protocol version required for the* **feedback** *function.*

*Definition at line* **117** *of file* **wayland-client-protocol-extra.hpp***.*

## Author

*Generated automatically by Doxygen for Wayland++ from the source code.*