--- name: "wayland_shm_pool_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_shm_pool_t" --- # wayland\_shm\_pool\_t(3) a shared memory pool ## NAME wayland::shm\_pool\_t - a shared memory pool ## SYNOPSIS `#include ` Inherits **wayland::proxy\_t**. ### Public Types enum class **wrapper\_type** { **standard**, **display**, **foreign**, **proxy\_wrapper** }\ ### Public Member Functions **buffer\_t** **create\_buffer** (int32\_t offset, int32\_t width, int32\_t height, int32\_t stride, shm\_format const &format)\ create a buffer from the pool void **resize** (int32\_t size)\ change the size of the pool mapping 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 **create\_buffer\_since\_version** = 1\ Minimum protocol version required for the **create\_buffer** function. static constexpr std::uint32\_t **resize\_since\_version** = 1\ Minimum protocol version required for the **resize** function. ## Detailed Description a shared memory pool The wl\_shm\_pool object encapsulates a piece of memory shared between the compositor and client. Through the wl\_shm\_pool object, the client can allocate shared memory wl\_buffer objects. All objects created through the same pool share the same underlying mapped memory. Reusing the mapped memory avoids the setup/teardown overhead and is useful when interactively resizing a surface or for many small buffers. Definition at line **312** 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 ### 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* ### buffer\_t shm\_pool\_t::create\_buffer (int32\_t offset, int32\_t width, int32\_t height, int32\_t stride, shm\_format const & format) *create a buffer from the pool* **Returns** *buffer to create* **Parameters** *offset buffer byte offset within the pool* \ *width buffer width, in pixels* \ *height buffer height, in pixels* \ *stride number of bytes from the beginning of one row to the beginning of the next row* \ *format buffer pixel format* *Create a wl\_buffer object from the pool.* *The buffer is created offset bytes into the pool and has width and height as specified. The stride argument specifies the number of bytes from the beginning of one row to the beginning of the next. The format is the pixel format of the buffer and must be one of those advertised through the wl\_shm.format event.* *A buffer will keep a reference to the pool it was created from so it is valid to destroy the pool immediately after creating a buffer from it.* **Examples** **shm.cpp***.* *Definition at line* **1816** *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***.* ### 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 shm\_pool\_t::resize (int32\_t size) *change the size of the pool mapping* **Parameters** *size new size of the pool, in bytes* *This request will cause the server to remap the backing memory for the pool from the file descriptor passed when the pool was created, but using the new size. This request can only be used to make the pool bigger.* ``` This request only changes the amount of bytes that are mmapped by the server and does not touch the file corresponding to the file descriptor passed at creation time. It is the client's responsibility to ensure that the file is at least as big as the new pool size. ``` *Definition at line* **1823** *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***.* ## Member Data Documentation ### constexpr std::uint32\_t wayland::shm\_pool\_t::create\_buffer\_since\_version = 1` [static]`, ` [constexpr]` *Minimum protocol version required for the* **create\_buffer** *function.* *Definition at line* **359** *of file* **wayland-client-protocol.hpp***.* ### constexpr std::uint32\_t wayland::shm\_pool\_t::resize\_since\_version = 1` [static]`, ` [constexpr]` *Minimum protocol version required for the* **resize** *function.* *Definition at line* **380** *of file* **wayland-client-protocol.hpp***.* ## Author *Generated automatically by Doxygen for Wayland++ from the source code.*