---
name: "wayland_server_zwp_linux_buffer_params_v1_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_server_zwp_linux_buffer_params_v1_t"
---

# wayland\_server\_zwp\_linux\_buffer\_params\_v1\_t(3)

parameters for creating a dmabuf-based wl\_buffer

## NAME

wayland::server::zwp\_linux\_buffer\_params\_v1\_t - parameters for creating a dmabuf-based wl\_buffer

## SYNOPSIS

`#include <wayland-server-protocol-unstable.hpp>`

Inherits wayland::server::resource\_t.

### Public Member Functions

std::function\< void()\> & **on\_destroy** ()\
 delete this object, used or not  std::function\< void(int, uint32\_t, uint32\_t, uint32\_t, uint32\_t, uint32\_t)\> & **on\_add** ()\
 add a dmabuf to the temporary set  std::function\< void(int32\_t, int32\_t, uint32\_t, zwp\_linux\_buffer\_params\_v1\_flags)\> & **on\_create** ()\
 create a wl\_buffer from the given dmabufs  std::function\< void(**buffer\_t**, int32\_t, int32\_t, uint32\_t, zwp\_linux\_buffer\_params\_v1\_flags)\> & **on\_create\_immed** ()\
 immediately create a wl\_buffer from the given dmabufs  void **created** (bool post=true)\
 buffer creation succeeded  void **failed** (bool post=true)\
 buffer creation failed  void **post\_already\_used** (std::string const &msg)\
 Post error: the dmabuf\_batch object has already been used to create a wl\_buffer.  void **post\_plane\_idx** (std::string const &msg)\
 Post error: plane index out of bounds.  void **post\_plane\_set** (std::string const &msg)\
 Post error: the plane index was already set.  void **post\_incomplete** (std::string const &msg)\
 Post error: missing or too many planes to create a buffer.  void **post\_invalid\_format** (std::string const &msg)\
 Post error: format not supported.  void **post\_invalid\_dimensions** (std::string const &msg)\
 Post error: invalid width or height.  void **post\_out\_of\_bounds** (std::string const &msg)\
 Post error: offset + stride \* height goes out of dmabuf bounds.  void **post\_invalid\_wl\_buffer** (std::string const &msg)\
 Post error: invalid wl\_buffer resulted from importing dmabufs via the create\_immed request on given buffer\_params.  bool **proxy\_has\_object** () const\
 Check whether this wrapper actually wraps an object.  void **post\_no\_memory** () const\
 uint32\_t **get\_id** () const\
 client\_t **get\_client** () const\
 unsigned int **get\_version** () const\
 std::string **get\_class** ()\

### Static Public Attributes

static constexpr std::uint32\_t **created\_since\_version** = 1\
 Minimum protocol version required for the **created** function.  static constexpr std::uint32\_t **failed\_since\_version** = 1\
 Minimum protocol version required for the **failed** function.

## Detailed Description

parameters for creating a dmabuf-based wl\_buffer

This temporary object is a collection of dmabufs and other parameters that together form a single logical buffer. The temporary object may eventually create one wl\_buffer unless cancelled by destroying it before requesting 'create'.

Single-planar formats only require one dmabuf, however multi-planar formats may require more than one dmabuf. For all formats, an 'add' request must be called once per plane (even if the underlying dmabuf fd is identical).

You must use consecutive plane indices ('plane\_idx' argument for 'add') from zero to the number of planes used by the drm\_fourcc format code. All planes required by the format must be given exactly once, but can be given in any order. Each plane index can be set only once.

Definition at line **1790** of file **wayland-server-protocol-unstable.hpp**.

## Member Function Documentation

### void zwp\_linux\_buffer\_params\_v1\_t::created (bool post = `true`)

buffer creation succeeded

**Returns**

the newly created wl\_buffer

This event indicates that the attempted buffer creation was successful. It provides the new wl\_buffer referencing the dmabuf(s).

Upon receiving this event, the client should destroy the zlinux\_dmabuf\_params object.

Definition at line **5029** of file **wayland-server-protocol-unstable.cpp**.

### void zwp\_linux\_buffer\_params\_v1\_t::failed (bool post = `true`)

buffer creation failed This event indicates that the attempted buffer creation has failed. It usually means that one of the dmabuf constraints has not been fulfilled.

Upon receiving this event, the client should destroy the zlinux\_buffer\_params object.

Definition at line **5034** of file **wayland-server-protocol-unstable.cpp**.

### std::string wayland::server::resource\_t::get\_class ()` [inherited]`

Retrieve the interface name (class) of a resource object.

**Returns**

Interface name of the resource object.

### client\_t wayland::server::resource\_t::get\_client () const` [inherited]`

Get the associated client

**Returns**

the client that owns the resource.

### uint32\_t wayland::server::resource\_t::get\_id () const` [inherited]`

Get the internal ID of the resource

**Returns**

the internal ID of the resource

### unsigned int wayland::server::resource\_t::get\_version () const` [inherited]`

Get interface version

**Returns**

Interface version this resource has been constructed with.

### std::function\< void(int, uint32\_t, uint32\_t, uint32\_t, uint32\_t, uint32\_t)\> & zwp\_linux\_buffer\_params\_v1\_t::on\_add ()

add a dmabuf to the temporary set

**Parameters**

*fd* dmabuf fd \
 *plane\_idx* plane index \
 *offset* offset in bytes \
 *stride* stride in bytes \
 *modifier\_hi* high 32 bits of layout modifier \
 *modifier\_lo* low 32 bits of layout modifier

This request adds one dmabuf to the set in this zwp\_linux\_buffer\_params\_v1.

The 64-bit unsigned value combined from modifier\_hi and modifier\_lo is the dmabuf layout modifier. DRM AddFB2 ioctl calls this the fb modifier, which is defined in drm\_mode.h of Linux UAPI. This is an opaque token. Drivers use this token to express tiling, compression, etc. driver-specific modifications to the base format defined by the DRM fourcc code.

Starting from version 4, the invalid\_format protocol error is sent if the format + modifier pair was not advertised as supported.

This request raises the PLANE\_IDX error if plane\_idx is too large. The error PLANE\_SET is raised if attempting to set a plane that was already set.

Definition at line **5011** of file **wayland-server-protocol-unstable.cpp**.

### std::function\< void(int32\_t, int32\_t, uint32\_t, zwp\_linux\_buffer\_params\_v1\_flags)\> & zwp\_linux\_buffer\_params\_v1\_t::on\_create ()

create a wl\_buffer from the given dmabufs

**Parameters**

*width* base plane width in pixels \
 *height* base plane height in pixels \
 *format* DRM\_FORMAT code \
 *flags* see enum flags

This asks for creation of a wl\_buffer from the added dmabuf buffers. The wl\_buffer is not created immediately but returned via the 'created' event if the dmabuf sharing succeeds. The sharing may fail at runtime for reasons a client cannot predict, in which case the 'failed' event is triggered.

The 'format' argument is a DRM\_FORMAT code, as defined by the libdrm's drm\_fourcc.h. The Linux kernel's DRM sub-system is the authoritative source on how the format codes should work.

The 'flags' is a bitfield of the flags defined in enum 'flags'. 'y\_invert' means the that the image needs to be y-flipped.

Flag 'interlaced' means that the frame in the buffer is not progressive as usual, but interlaced. An interlaced buffer as supported here must always contain both top and bottom fields. The top field always begins on the first pixel row. The temporal ordering between the two fields is top field first, unless 'bottom\_first' is specified. It is undefined whether 'bottom\_first' is ignored if 'interlaced' is not set.

This protocol does not convey any information about field rate, duration, or timing, other than the relative ordering between the two fields in one buffer. A compositor may have to estimate the intended field rate from the incoming buffer rate. It is undefined whether the time of receiving wl\_surface.commit with a new buffer attached, applying the wl\_surface state, wl\_surface.frame callback trigger, presentation, or any other point in the compositor cycle is used to measure the frame or field times. There is no support for detecting missed or late frames/fields/buffers either, and there is no support whatsoever for cooperating with interlaced compositor output.

The composited image quality resulting from the use of interlaced buffers is explicitly undefined. A compositor may use elaborate hardware features or software to deinterlace and create progressive output frames from a sequence of interlaced input buffers, or it may produce substandard image quality. However, compositors that cannot guarantee reasonable image quality in all cases are recommended to just reject all interlaced buffers.

Any argument errors, including non-positive width or height, mismatch between the number of planes and the format, bad format, bad offset or stride, may be indicated by fatal protocol errors: INCOMPLETE, INVALID\_FORMAT, INVALID\_DIMENSIONS, OUT\_OF\_BOUNDS.

Dmabuf import errors in the server that are not obvious client bugs are returned via the 'failed' event as non-fatal. This allows attempting dmabuf sharing and falling back in the client if it fails.

This request can be sent only once in the object's lifetime, after which the only legal request is destroy. This object should be destroyed after issuing a 'create' request. Attempting to use this object after issuing 'create' raises ALREADY\_USED protocol error.

It is not mandatory to issue 'create'. If a client wants to cancel the buffer creation, it can just destroy this object.

Definition at line **5017** of file **wayland-server-protocol-unstable.cpp**.

### std::function\< void(buffer\_t, int32\_t, int32\_t, uint32\_t, zwp\_linux\_buffer\_params\_v1\_flags)\> & zwp\_linux\_buffer\_params\_v1\_t::on\_create\_immed ()

immediately create a wl\_buffer from the given dmabufs

**Parameters**

*buffer\_id* id for the newly created wl\_buffer \
 *width* base plane width in pixels \
 *height* base plane height in pixels \
 *format* DRM\_FORMAT code \
 *flags* see enum flags

This asks for immediate creation of a wl\_buffer by importing the added dmabufs.

In case of import success, no event is sent from the server, and the wl\_buffer is ready to be used by the client.

Upon import failure, either of the following may happen, as seen fit by the implementation:

- •

  the client is terminated with one of the following fatal protocol errors:

- •

  INCOMPLETE, INVALID\_FORMAT, INVALID\_DIMENSIONS, OUT\_OF\_BOUNDS, in case of argument errors such as mismatch between the number of planes and the format, bad format, non-positive width or height, or bad offset or stride.

- •

  INVALID\_WL\_BUFFER, in case the cause for failure is unknown or plaform specific.

- •

  the server creates an invalid wl\_buffer, marks it as failed and sends a 'failed' event to the client. The result of using this invalid wl\_buffer as an argument in any request by the client is defined by the compositor implementation.

This takes the same arguments as a 'create' request, and obeys the same restrictions.

Definition at line **5023** of file **wayland-server-protocol-unstable.cpp**.

### std::function\< void()\> & zwp\_linux\_buffer\_params\_v1\_t::on\_destroy ()

delete this object, used or not Cleans up the temporary data sent to the server for dmabuf-based wl\_buffer creation.

Definition at line **5005** of file **wayland-server-protocol-unstable.cpp**.

### void zwp\_linux\_buffer\_params\_v1\_t::post\_already\_used (std::string const & msg)

Post error: the dmabuf\_batch object has already been used to create a wl\_buffer.

Definition at line **5039** of file **wayland-server-protocol-unstable.cpp**.

### void zwp\_linux\_buffer\_params\_v1\_t::post\_incomplete (std::string const & msg)

Post error: missing or too many planes to create a buffer.

Definition at line **5054** of file **wayland-server-protocol-unstable.cpp**.

### void zwp\_linux\_buffer\_params\_v1\_t::post\_invalid\_dimensions (std::string const & msg)

Post error: invalid width or height.

Definition at line **5064** of file **wayland-server-protocol-unstable.cpp**.

### void zwp\_linux\_buffer\_params\_v1\_t::post\_invalid\_format (std::string const & msg)

Post error: format not supported.

Definition at line **5059** of file **wayland-server-protocol-unstable.cpp**.

### void zwp\_linux\_buffer\_params\_v1\_t::post\_invalid\_wl\_buffer (std::string const & msg)

Post error: invalid wl\_buffer resulted from importing dmabufs via the create\_immed request on given buffer\_params.

Definition at line **5074** of file **wayland-server-protocol-unstable.cpp**.

### void wayland::server::resource\_t::post\_no\_memory () const` [inherited]`

Post 'not enough memory' error to the client

If the compositor has not enough memory to fulfill a certail request of the client, this function can be called to notify the client of this circumstance.

### void zwp\_linux\_buffer\_params\_v1\_t::post\_out\_of\_bounds (std::string const & msg)

Post error: offset + stride \* height goes out of dmabuf bounds.

Definition at line **5069** of file **wayland-server-protocol-unstable.cpp**.

### void zwp\_linux\_buffer\_params\_v1\_t::post\_plane\_idx (std::string const & msg)

Post error: plane index out of bounds.

Definition at line **5044** of file **wayland-server-protocol-unstable.cpp**.

### void zwp\_linux\_buffer\_params\_v1\_t::post\_plane\_set (std::string const & msg)

Post error: the plane index was already set.

Definition at line **5049** of file **wayland-server-protocol-unstable.cpp**.

### bool wayland::server::resource\_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

## Member Data Documentation

### constexpr std::uint32\_t wayland::server::zwp\_linux\_buffer\_params\_v1\_t::created\_since\_version = 1` [static]`, ` [constexpr]`

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

Definition at line **1972** of file **wayland-server-protocol-unstable.hpp**.

### constexpr std::uint32\_t wayland::server::zwp\_linux\_buffer\_params\_v1\_t::failed\_since\_version = 1` [static]`, ` [constexpr]`

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

Definition at line **1988** of file **wayland-server-protocol-unstable.hpp**.

## Author

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