Copyright © 2018 Rostislav Pehlivanov
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An interface to capture surfaces in an efficient way by exporting DMA-BUFs.
Warning! The protocol described in this file is experimental and
backward incompatible changes may be made. Backward compatible changes
may be added together with the corresponding interface version bump.
Backward incompatible changes are done by bumping the version number in
the protocol and interface names and resetting the interface version.
Once the protocol is to be declared stable, the 'z' prefix and the
version number in the protocol and interface names are removed and the
interface version number is reset.
This object is a manager with which to start capturing from sources.
Capture the next frame of an entire output.
All objects created by the manager will still remain valid, until their
appropriate destroy request has been called.
This object represents a single DMA-BUF frame.
If the capture is successful, the compositor will first send a "frame"
event, followed by one or several "object". When the frame is available
for readout, the "ready" event is sent.
If the capture failed, the "cancel" event is sent. This can happen anytime
before the "ready" event.
Once either a "ready" or a "cancel" event is received, the client should
destroy the frame. Once an "object" event is received, the client is
responsible for closing the associated file descriptor.
All frames are read-only and may not be written into or altered.
Special flags that should be respected by the client.
Main event supplying the client with information about the frame. If the
capture didn't fail, this event is always emitted first before any other
events.
This event is followed by a number of "object" as specified by the
"num_objects" argument.
Event which serves to supply the client with the file descriptors
containing the data for each object.
After receiving this event, the client must always close the file
descriptor as soon as they're done with it and even if the frame fails.
This event is sent as soon as the frame is presented, indicating it is
available for reading. This event includes the time at which
presentation happened at.
The timestamp is expressed as tv_sec_hi, tv_sec_lo, tv_nsec triples,
each component being an unsigned 32-bit value. Whole seconds are in
tv_sec which is a 64-bit value combined from tv_sec_hi and tv_sec_lo,
and the additional fractional part in tv_nsec as nanoseconds. Hence,
for valid timestamps tv_nsec must be in [0, 999999999]. The seconds part
may have an arbitrary offset at start.
After receiving this event, the client should destroy this object.
Indicates reason for cancelling the frame.
If the capture failed or if the frame is no longer valid after the
"frame" event has been emitted, this event will be used to inform the
client to scrap the frame.
If the failure is temporary, the client may capture again the same
source. If the failure is permanent, any further attempts to capture the
same source will fail again.
After receiving this event, the client should destroy this object.
Unreferences the frame. This request must be called as soon as its no
longer used.
It can be called at any time by the client. The client will still have
to close any FDs it has been given.