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.
manager to inform clients and begin capturing
Interface
Version 1
This object is a manager with which to start capturing from sources.
capture a frame from an output
Request
Since Version 1
Capture the next frame of an entire output.
Destructor
Request
Since Version 1
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.
delete this object, used or not
Destructor
Request
Since Version 1
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.
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.
| Argument | Type | Description |
|---|
| width | uint | frame width in pixels |
| height | uint | frame height in pixels |
| offset_x | uint | crop offset for the x axis |
| offset_y | uint | crop offset for the y axis |
| buffer_flags | uint | flags which indicate properties (invert, interlacing),
has the same values as zwp_linux_buffer_params_v1:flags |
| flags | uint<flags> | indicates special frame features |
| format | uint | format of the frame (DRM_FORMAT_*) |
| mod_high | uint | drm format modifier, high |
| mod_low | uint | drm format modifier, low |
| num_objects | uint | indicates how many objects (FDs) the frame has (max 4) |
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.
| Argument | Type | Description |
|---|
| index | uint | index of the current object |
| fd | fd | fd of the current object |
| size | uint | size in bytes for the current object |
| offset | uint | starting point for the data in the object's fd |
| stride | uint | line size in bytes |
| plane_index | uint | index of the plane the data in the object applies to |
indicates frame is available for reading
Event
Since Version 1
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.
| Argument | Type | Description |
|---|
| tv_sec_hi | uint | high 32 bits of the seconds part of the timestamp |
| tv_sec_lo | uint | low 32 bits of the seconds part of the timestamp |
| tv_nsec | uint | nanoseconds part of the timestamp |
indicates the frame is no longer valid
Event
Since Version 1
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.
| Argument | Type | Description |
|---|
| reason | uint<cancel_reason> | indicates a reason for cancelling this frame capture |
Special flags that should be respected by the client.
| Entry | Value | Since | Description |
|---|
| transient | 0x1 | 1 | clients should copy frame before processing |
Indicates reason for cancelling the frame.
| Entry | Value | Since | Description |
|---|
| temporary | 0 | 1 | temporary error, source will produce more frames |
| permanent | 1 | 1 | fatal error, source will not produce frames |
| resizing | 2 | 1 | temporary error, source will produce more frames |
Copyright
Copyright © 2018 Rostislav Pehlivanov
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice (including the next
paragraph) shall be included in all copies or substantial portions of the
Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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DEALINGS IN THE SOFTWARE.