Package org.freedesktop.wayland.server

Interface WlShmPoolRequests

All Known Subinterfaces:

WlShmPoolRequestsV2

public interface WlShmPoolRequests

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.

Field Summary

Fields

Modifier and Type	Field	Description
static final int	VERSION

Method Summary

Modifier and Type	Method	Description
void	createBuffer(WlShmPoolResource requester, int id, int offset, int width, int height, int stride, int format)	create a buffer from the pool
void	destroy(WlShmPoolResource requester)	destroy the pool
void	resize(WlShmPoolResource requester, int size)	change the size of the pool mapping

Field Details

VERSION

static final int VERSION

See Also:

• Constant Field Values

Method Details

createBuffer

void createBuffer(WlShmPoolResource requester,
 int id,
 int offset,
 int width,
 int height,
 int stride,
 int format)

create a buffer from the pool

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.

Parameters:

requester - The protocol object that made the request.

id - buffer to create

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

destroy

void destroy(WlShmPoolResource requester)

destroy the pool

Destroy the shared memory pool.

The mmapped memory will be released when all buffers that have been created from this pool are gone.

Parameters:

requester - The protocol object that made the request.

resize

void resize(WlShmPoolResource requester,
 int size)

change the size of the pool mapping

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.

Parameters:

requester - The protocol object that made the request.

size - new size of the pool, in bytes