protocol for fifo constraints
Interface
Version 1
When a Wayland compositor considers applying a content update,
it must ensure all the update's readiness constraints (fences, etc)
are met.
This protocol provides a way to use the completion of a display refresh
cycle as an additional readiness constraint.
Warning! The protocol described in this file is currently in the testing
phase. Backward compatible changes may be added together with the
corresponding interface version bump. Backward incompatible changes can
only be done by creating a new major version of the extension.
unbind from the manager interface
Destructor
Request
Since Version 1
Informs the server that the client will no longer be using
this protocol object. Existing objects created by this object
are not affected.
request fifo interface for surface
Request
Since Version 1
Establish a fifo object for a surface that may be used to add
display refresh constraints to content updates.
Only one such object may exist for a surface and attempting
to create more than one will result in an already_exists
protocol error. If a surface is acted on by multiple software
components, general best practice is that only the component
performing wl_surface.attach operations should use this protocol.
These fatal protocol errors may be emitted in response to
illegal requests.
| Entry | Value | Since | Description |
|---|
| already_exists | 0 | 1 | fifo manager already exists for surface |
A fifo object for a surface that may be used to add
display refresh constraints to content updates.
sets the start point for a fifo constraint
Request
Since Version 1
When the content update containing the "set_barrier" is applied,
it sets a "fifo_barrier" condition on the surface associated with
the fifo object. The condition is cleared immediately after the
following latching deadline for non-tearing presentation.
The compositor may clear the condition early if it must do so to
ensure client forward progress assumptions.
To wait for this condition to clear, use the "wait_barrier" request.
"set_barrier" is double-buffered state, see wl_surface.commit.
Requesting set_barrier after the fifo object's surface is
destroyed will generate a "surface_destroyed" error.
adds a fifo constraint to a content update
Request
Since Version 1
Indicate that this content update is not ready while a
"fifo_barrier" condition is present on the surface.
This means that when the content update containing "set_barrier"
was made active at a latching deadline, it will be active for
at least one refresh cycle. A content update which is allowed to
tear might become active after a latching deadline if no content
update became active at the deadline.
The constraint must be ignored if the surface is a subsurface in
synchronized mode. If the surface is not being updated by the
compositor (off-screen, occluded) the compositor may ignore the
constraint. Clients must use an additional mechanism such as
frame callbacks or timestamps to ensure throttling occurs under
all conditions.
"wait_barrier" is double-buffered state, see wl_surface.commit.
Requesting "wait_barrier" after the fifo object's surface is
destroyed will generate a "surface_destroyed" error.
destroy the fifo interface
Destructor
Request
Since Version 1
Informs the server that the client will no longer be using
this protocol object.
Surface state changes previously made by this protocol are
unaffected by this object's destruction.
These fatal protocol errors may be emitted in response to
illegal requests.
| Entry | Value | Since | Description |
|---|
| surface_destroyed | 0 | 1 | the associated surface no longer exists |
Copyright
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