pub enum Request {
Destroy,
Attach {
buffer: ObjectId,
x: i32,
y: i32,
},
Damage {
x: i32,
y: i32,
width: i32,
height: i32,
},
Frame {
callback: NewId,
},
SetOpaqueRegion {
region: ObjectId,
},
SetInputRegion {
region: ObjectId,
},
Commit,
SetBufferTransform {
transform: Transform,
},
SetBufferScale {
scale: i32,
},
DamageBuffer {
x: i32,
y: i32,
width: i32,
height: i32,
},
}Variants§
Destroy
delete surface
Deletes the surface and invalidates its object ID.
Attach
set the surface contents
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.
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. However, if the client destroys the wl_buffer before receiving the wl_buffer.release event, 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.
Fields
buffer: ObjectIdbuffer of surface contents
Damage
mark part of the surface damaged
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.
Fields
Frame
request a frame throttling hint
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.
Fields
callback: NewIdcallback object for the frame request
SetOpaqueRegion
set opaque region
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.
Fields
region: ObjectIdopaque region of the surface
SetInputRegion
set input region
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.
Fields
region: ObjectIdinput region of the surface
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.
SetBufferTransform
sets the buffer transformation
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.
SetBufferScale
sets the buffer scaling factor
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.
DamageBuffer
mark part of the surface damaged using buffer coordinates
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.