wayland::surface_t(3)

NAME
wayland::surface_t - an onscreen surface

SYNOPSIS

#include <wayland-client-protocol.hpp>

Inherits wayland::proxy_t.

  Public Types

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

  Public Member Functions

void attach (buffer_t const &buffer, int32_t x, int32_t y)
set the surface contents
void damage (int32_t x, int32_t y, int32_t width, int32_t height)
mark part of the surface damaged
callback_t frame ()
request a frame throttling hint
void set_opaque_region (region_t const &region)
set opaque region
void set_input_region (region_t const &region)
set input region
void commit ()
commit pending surface state
void set_buffer_transform (output_transform const &transform)
sets the buffer transformation
bool can_set_buffer_transform () const
Check whether the set_buffer_transform function is available with the currently bound version of the protocol.
void set_buffer_scale (int32_t scale)
sets the buffer scaling factor
bool can_set_buffer_scale () const
Check whether the set_buffer_scale function is available with the currently bound version of the protocol.
void damage_buffer (int32_t x, int32_t y, int32_t width, int32_t height)
mark part of the surface damaged using buffer coordinates
bool can_damage_buffer () const
Check whether the damage_buffer function is available with the currently bound version of the protocol.
void offset (int32_t x, int32_t y)
set the surface contents offset
bool can_offset () const
Check whether the offset function is available with the currently bound version of the protocol.
std::function< void(output_t)> & on_enter ()
surface enters an output
std::function< void(output_t)> & on_leave ()
surface leaves an output
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 attach_since_version = 1
Minimum protocol version required for the attach function.
static constexpr std::uint32_t damage_since_version = 1
Minimum protocol version required for the damage function.
static constexpr std::uint32_t frame_since_version = 1
Minimum protocol version required for the frame function.
static constexpr std::uint32_t set_opaque_region_since_version = 1
Minimum protocol version required for the set_opaque_region function.
static constexpr std::uint32_t set_input_region_since_version = 1
Minimum protocol version required for the set_input_region function.
static constexpr std::uint32_t commit_since_version = 1
Minimum protocol version required for the commit function.
static constexpr std::uint32_t set_buffer_transform_since_version = 2
Minimum protocol version required for the set_buffer_transform function.
static constexpr std::uint32_t set_buffer_scale_since_version = 3
Minimum protocol version required for the set_buffer_scale function.
static constexpr std::uint32_t damage_buffer_since_version = 4
Minimum protocol version required for the damage_buffer function.
static constexpr std::uint32_t offset_since_version = 5
Minimum protocol version required for the offset function.

Detailed Description

an onscreen surface

A surface is a rectangular area that may be displayed on zero or more outputs, and shown any number of times at the compositor's discretion. They can present wl_buffers, receive user input, and define a local coordinate system.

The size of a surface (and relative positions on it) is described in surface-local coordinates, which may differ from the buffer coordinates of the pixel content, in case a buffer_transform or a buffer_scale is used.

A surface without a 'role' is fairly useless: a compositor does not know where, when or how to present it. The role is the purpose of a wl_surface. Examples of roles are a cursor for a pointer (as set by wl_pointer.set_cursor), a drag icon (wl_data_device.start_drag), a sub-surface (wl_subcompositor.get_subsurface), and a window as defined by a shell protocol (e.g. wl_shell.get_shell_surface).

A surface can have only one role at a time. Initially a wl_surface does not have a role. Once a wl_surface is given a role, it is set permanently for the whole lifetime of the wl_surface object. Giving the current role again is allowed, unless explicitly forbidden by the relevant interface specification.

Surface roles are given by requests in other interfaces such as wl_pointer.set_cursor. The request should explicitly mention that this request gives a role to a wl_surface. Often, this request also creates a new protocol object that represents the role and adds additional functionality to wl_surface. When a client wants to destroy a wl_surface, they must destroy this 'role object' before the wl_surface.

Destroying the role object does not remove the role from the wl_surface, but it may stop the wl_surface from 'playing the role'. For instance, if a wl_subsurface object is destroyed, the wl_surface it was created for will be unmapped and forget its position and z-order. It is allowed to create a wl_subsurface for the same wl_surface again, but it is not allowed to use the wl_surface as a cursor (cursor is a different role than sub-surface, and role switching is not allowed).

Examples
egl.cpp, and shm.cpp.

Definition at line 2004 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 surface_t::attach (buffer_t const & buffer, int32_t x, int32_t y)

set the surface contents

Parameters
    buffer buffer of surface contents
    x surface-local x coordinate
    y surface-local y coordinate

Set a buffer as the content of this surface.

The new size of the surface is calculated based on the buffer size transformed by the inverse buffer_transform and the inverse buffer_scale. This means that at commit time the supplied buffer size must be an integer multiple of the buffer_scale. If that's not the case, an invalid_size error is sent.

The x and y arguments specify the location of the new pending buffer's upper left corner, relative to the current buffer's upper left corner, in surface-local coordinates. In other words, the x and y, combined with the new surface size define in which directions the surface's size changes. Setting anything other than 0 as x and y arguments is discouraged, and should instead be replaced with using the separate wl_surface.offset request.

When the bound wl_surface version is 5 or higher, passing any non-zero x or y is a protocol violation, and will result in an 'invalid_offset' error being raised. To achieve equivalent semantics, use wl_surface.offset.

Surface contents are double-buffered state, see wl_surface.commit.

The initial surface contents are void; there is no content. wl_surface.attach assigns the given wl_buffer as the pending wl_buffer. wl_surface.commit makes the pending wl_buffer the new surface contents, and the size of the surface becomes the size calculated from the wl_buffer, as described above. After commit, there is no pending buffer until the next attach.

Committing a pending wl_buffer allows the compositor to read the pixels in the wl_buffer. The compositor may access the pixels at any time after the wl_surface.commit request. When the compositor will not access the pixels anymore, it will send the wl_buffer.release event. Only after receiving wl_buffer.release, the client may reuse the wl_buffer. A wl_buffer that has been attached and then replaced by another attach instead of committed will not receive a release event, and is not used by the compositor.

If a pending wl_buffer has been committed to more than one wl_surface, the delivery of wl_buffer.release events becomes undefined. A well behaved client should not rely on wl_buffer.release events in this case. Alternatively, a client could create multiple wl_buffer objects from the same backing storage or use wp_linux_buffer_release.

Destroying the wl_buffer after wl_buffer.release does not change the surface contents. Destroying the wl_buffer before wl_buffer.release is allowed as long as the underlying buffer storage isn't re-used (this can happen e.g. on client process termination). However, if the client destroys the wl_buffer before receiving the wl_buffer.release event and mutates the underlying buffer storage, the surface contents become undefined immediately.

If wl_surface.attach is sent with a NULL wl_buffer, the following wl_surface.commit will remove the surface content.

Examples
egl.cpp, and shm.cpp.

Definition at line 2693 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 surface_t::can_damage_buffer () const

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

Definition at line 2757 of file wayland-client-protocol.cpp.

  bool surface_t::can_offset () const

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

Definition at line 2768 of file wayland-client-protocol.cpp.

  bool surface_t::can_set_buffer_scale () const

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

Definition at line 2746 of file wayland-client-protocol.cpp.

  bool surface_t::can_set_buffer_transform () const

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

Definition at line 2735 of file wayland-client-protocol.cpp.

  void surface_t::commit ()

commit pending surface state Surface state (input, opaque, and damage regions, attached buffers, etc.) is double-buffered. Protocol requests modify the pending state, as opposed to the current state in use by the compositor. A commit request atomically applies all pending state, replacing the current state. After commit, the new pending state is as documented for each related request.

On commit, a pending wl_buffer is applied first, and all other state second. This means that all coordinates in double-buffered state are relative to the new wl_buffer coming into use, except for wl_surface.attach itself. If there is no pending wl_buffer, the coordinates are relative to the current surface contents.

All requests that need a commit to become effective are documented to affect double-buffered state.

Other interfaces may add further double-buffered surface state.

Examples
egl.cpp, and shm.cpp.

Definition at line 2724 of file wayland-client-protocol.cpp.

  void surface_t::damage (int32_t x, int32_t y, int32_t width, int32_t height)

mark part of the surface damaged

Parameters
    x surface-local x coordinate
    y surface-local y coordinate
    width width of damage rectangle
    height height of damage rectangle

This request is used to describe the regions where the pending buffer is different from the current surface contents, and where the surface therefore needs to be repainted. The compositor ignores the parts of the damage that fall outside of the surface.

Damage is double-buffered state, see wl_surface.commit.

The damage rectangle is specified in surface-local coordinates, where x and y specify the upper left corner of the damage rectangle.

The initial value for pending damage is empty: no damage. wl_surface.damage adds pending damage: the new pending damage is the union of old pending damage and the given rectangle.

wl_surface.commit assigns pending damage as the current damage, and clears pending damage. The server will clear the current damage as it repaints the surface.

Note! New clients should not use this request. Instead damage can be posted with wl_surface.damage_buffer which uses buffer coordinates instead of surface coordinates.

Examples
egl.cpp, and shm.cpp.

Definition at line 2699 of file wayland-client-protocol.cpp.

  void surface_t::damage_buffer (int32_t x, int32_t y, int32_t width, int32_t height)

mark part of the surface damaged using buffer coordinates

Parameters
    x buffer-local x coordinate
    y buffer-local y coordinate
    width width of damage rectangle
    height height of damage rectangle

This request is used to describe the regions where the pending buffer is different from the current surface contents, and where the surface therefore needs to be repainted. The compositor ignores the parts of the damage that fall outside of the surface.

Damage is double-buffered state, see wl_surface.commit.

The damage rectangle is specified in buffer coordinates, where x and y specify the upper left corner of the damage rectangle.

The initial value for pending damage is empty: no damage. wl_surface.damage_buffer adds pending damage: the new pending damage is the union of old pending damage and the given rectangle.

wl_surface.commit assigns pending damage as the current damage, and clears pending damage. The server will clear the current damage as it repaints the surface.

This request differs from wl_surface.damage in only one way - it takes damage in buffer coordinates instead of surface-local coordinates. While this generally is more intuitive than surface coordinates, it is especially desirable when using wp_viewport or when a drawing library (like EGL) is unaware of buffer scale and buffer transform.

Note: Because buffer transformation changes and damage requests may be interleaved in the protocol stream, it is impossible to determine the actual mapping between surface and buffer damage until wl_surface.commit time. Therefore, compositors wishing to take both kinds of damage into account will have to accumulate damage from the two requests separately and only transform from one to the other after receiving the wl_surface.commit.

Definition at line 2752 of file wayland-client-protocol.cpp.

  callback_t surface_t::frame ()

request a frame throttling hint

Returns
    callback object for the frame request

Request a notification when it is a good time to start drawing a new frame, by creating a frame callback. This is useful for throttling redrawing operations, and driving animations.

When a client is animating on a wl_surface, it can use the 'frame' request to get notified when it is a good time to draw and commit the next frame of animation. If the client commits an update earlier than that, it is likely that some updates will not make it to the display, and the client is wasting resources by drawing too often.

The frame request will take effect on the next wl_surface.commit. The notification will only be posted for one frame unless requested again. For a wl_surface, the notifications are posted in the order the frame requests were committed.

The server must send the notifications so that a client will not send excessive updates, while still allowing the highest possible update rate for clients that wait for the reply before drawing again. The server should give some time for the client to draw and commit after sending the frame callback events to let it hit the next output refresh.

A server should avoid signaling the frame callbacks if the surface is not visible in any way, e.g. the surface is off-screen, or completely obscured by other opaque surfaces.

The object returned by this request will be destroyed by the compositor after the callback is fired and as such the client must not attempt to use it after that point.

The callback_data passed in the callback is the current time, in milliseconds, with an undefined base.

Examples
egl.cpp, and shm.cpp.

Definition at line 2705 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.

  void surface_t::offset (int32_t x, int32_t y)

set the surface contents offset

Parameters
    x surface-local x coordinate
    y surface-local y coordinate

The x and y arguments specify the location of the new pending buffer's upper left corner, relative to the current buffer's upper left corner, in surface-local coordinates. In other words, the x and y, combined with the new surface size define in which directions the surface's size changes.

Surface location offset is double-buffered state, see wl_surface.commit.

This request is semantically equivalent to and the replaces the x and y arguments in the wl_surface.attach request in wl_surface versions prior to 5. See wl_surface.attach for details.

Definition at line 2763 of file wayland-client-protocol.cpp.

  std::function< void(output_t)> & surface_t::on_enter ()

surface enters an output

Parameters
    output output entered by the surface

This is emitted whenever a surface's creation, movement, or resizing results in some part of it being within the scanout region of an output.

Note that a surface may be overlapping with zero or more outputs.

Definition at line 2774 of file wayland-client-protocol.cpp.

  std::function< void(output_t)> & surface_t::on_leave ()

surface leaves an output

Parameters
    output output left by the surface

This is emitted whenever a surface's creation, movement, or resizing results in it no longer having any part of it within the scanout region of an output.

Clients should not use the number of outputs the surface is on for frame throttling purposes. The surface might be hidden even if no leave event has been sent, and the compositor might expect new surface content updates even if no enter event has been sent. The frame event should be used instead.

Definition at line 2779 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 surface_t::set_buffer_scale (int32_t scale)

sets the buffer scaling factor

Parameters
    scale positive scale for interpreting buffer contents

This request sets an optional scaling factor on how the compositor interprets the contents of the buffer attached to the window.

Buffer scale is double-buffered state, see wl_surface.commit.

A newly created surface has its buffer scale set to 1.

wl_surface.set_buffer_scale changes the pending buffer scale. wl_surface.commit copies the pending buffer scale to the current one. Otherwise, the pending and current values are never changed.

The purpose of this request is to allow clients to supply higher resolution buffer data for use on high resolution outputs. It is intended that you pick the same buffer scale as the scale of the output that the surface is displayed on. This means the compositor can avoid scaling when rendering the surface on that output.

Note that if the scale is larger than 1, then you have to attach a buffer that is larger (by a factor of scale in each dimension) than the desired surface size.

If scale is not positive the invalid_scale protocol error is raised.

Definition at line 2741 of file wayland-client-protocol.cpp.

  void surface_t::set_buffer_transform (output_transform const & transform)

sets the buffer transformation

Parameters
    transform transform for interpreting buffer contents

This request sets an optional transformation on how the compositor interprets the contents of the buffer attached to the surface. The accepted values for the transform parameter are the values for wl_output.transform.

Buffer transform is double-buffered state, see wl_surface.commit.

A newly created surface has its buffer transformation set to normal.

wl_surface.set_buffer_transform changes the pending buffer transformation. wl_surface.commit copies the pending buffer transformation to the current one. Otherwise, the pending and current values are never changed.

The purpose of this request is to allow clients to render content according to the output transform, thus permitting the compositor to use certain optimizations even if the display is rotated. Using hardware overlays and scanning out a client buffer for fullscreen surfaces are examples of such optimizations. Those optimizations are highly dependent on the compositor implementation, so the use of this request should be considered on a case-by-case basis.

Note that if the transform value includes 90 or 270 degree rotation, the width of the buffer will become the surface height and the height of the buffer will become the surface width.

If transform is not one of the values from the wl_output.transform enum the invalid_transform protocol error is raised.

Definition at line 2730 of file wayland-client-protocol.cpp.

  void surface_t::set_input_region (region_t const & region)

set input region

Parameters
    region input region of the surface

This request sets the region of the surface that can receive pointer and touch events.

Input events happening outside of this region will try the next surface in the server surface stack. The compositor ignores the parts of the input region that fall outside of the surface.

The input region is specified in surface-local coordinates.

Input region is double-buffered state, see wl_surface.commit.

wl_surface.set_input_region changes the pending input region. wl_surface.commit copies the pending region to the current region. Otherwise the pending and current regions are never changed, except cursor and icon surfaces are special cases, see wl_pointer.set_cursor and wl_data_device.start_drag.

The initial value for an input region is infinite. That means the whole surface will accept input. Setting the pending input region has copy semantics, and the wl_region object can be destroyed immediately. A NULL wl_region causes the input region to be set to infinite.

Definition at line 2718 of file wayland-client-protocol.cpp.

  void surface_t::set_opaque_region (region_t const & region)

set opaque region

Parameters
    region opaque region of the surface

This request sets the region of the surface that contains opaque content.

The opaque region is an optimization hint for the compositor that lets it optimize the redrawing of content behind opaque regions. Setting an opaque region is not required for correct behaviour, but marking transparent content as opaque will result in repaint artifacts.

The opaque region is specified in surface-local coordinates.

The compositor ignores the parts of the opaque region that fall outside of the surface.

Opaque region is double-buffered state, see wl_surface.commit.

wl_surface.set_opaque_region changes the pending opaque region. wl_surface.commit copies the pending region to the current region. Otherwise, the pending and current regions are never changed.

The initial value for an opaque region is empty. Setting the pending opaque region has copy semantics, and the wl_region object can be destroyed immediately. A NULL wl_region causes the pending opaque region to be set to empty.

Definition at line 2712 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::surface_t::attach_since_version = 1 [static], [constexpr]

Minimum protocol version required for the attach function.

Definition at line 2095 of file wayland-client-protocol.hpp.

  constexpr std::uint32_t wayland::surface_t::commit_since_version = 1 [static], [constexpr]

Minimum protocol version required for the commit function.

Definition at line 2268 of file wayland-client-protocol.hpp.

  constexpr std::uint32_t wayland::surface_t::damage_buffer_since_version = 4 [static], [constexpr]

Minimum protocol version required for the damage_buffer function.

Definition at line 2398 of file wayland-client-protocol.hpp.

  constexpr std::uint32_t wayland::surface_t::damage_since_version = 1 [static], [constexpr]

Minimum protocol version required for the damage function.

Definition at line 2130 of file wayland-client-protocol.hpp.

  constexpr std::uint32_t wayland::surface_t::frame_since_version = 1 [static], [constexpr]

Minimum protocol version required for the frame function.

Definition at line 2173 of file wayland-client-protocol.hpp.

  constexpr std::uint32_t wayland::surface_t::offset_since_version = 5 [static], [constexpr]

Minimum protocol version required for the offset function.

Definition at line 2427 of file wayland-client-protocol.hpp.

  constexpr std::uint32_t wayland::surface_t::set_buffer_scale_since_version = 3 [static], [constexpr]

Minimum protocol version required for the set_buffer_scale function.

Definition at line 2347 of file wayland-client-protocol.hpp.

  constexpr std::uint32_t wayland::surface_t::set_buffer_transform_since_version = 2 [static], [constexpr]

Minimum protocol version required for the set_buffer_transform function.

Definition at line 2308 of file wayland-client-protocol.hpp.

  constexpr std::uint32_t wayland::surface_t::set_input_region_since_version = 1 [static], [constexpr]

Minimum protocol version required for the set_input_region function.

Definition at line 2241 of file wayland-client-protocol.hpp.

  constexpr std::uint32_t wayland::surface_t::set_opaque_region_since_version = 1 [static], [constexpr]

Minimum protocol version required for the set_opaque_region function.

Definition at line 2208 of file wayland-client-protocol.hpp.

Author

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