protocol: add presentation extension v5

Add accurate presentation timing features to Wayland: queueing and
feedback.

This specification is based on the draft written by Frederic Plourde
<frederic.plourde@collabora.co.uk> and redesigned by Pekka Paalanen.

The RFC v2 version is from
http://lists.freedesktop.org/archives/wayland-devel/2014-January/012988.html

Changes in v3:

* associate presentation time to current surface contents

This implements the suggestion from
http://lists.freedesktop.org/archives/wayland-devel/2014-February/013066.html

which prevents surface content from jumping backwards in time if a
client retroactively queues an update with a target time in the past.

* use 64-bit tv_sec in presentation

The time_t type used in struct timespec could be almost anything. POSIX
probably defines it to be an integer, but not the size. Apparently it is
usually 'long', which makes it 64-bit on x86_64.

To be able to fully represent timespec values returned by clock_gettime,
change the protocol to use 64 bits for the tv_sec part.

* define an error for invalid tv_nsec

This allow us to rely on the normalized timestamp form.

* define some interactions with sub-surfaces

Sub-surface cached state updates (synchronized mode) are designed
especially for resizing. As queued updates are not meant to produce any
resizing-like effects, they also do not trigger any sub-surface
operations.

* add sub-headings as xml comments

* queued update cannot map

Because before mapping, the surface has no main output assigned. An
immediate commit is needed anyway, to be able to set all the surface
state, which a queued update cannot touch.

* frame callbacks are not queued

It is not known when queueing frame callbacks would be useful.

Changes in v4:

* remove mentions of the queuing feature

The specification has been split and the queuing feature will be added
back in another version of the extension.

* add flags argument to 'presented' event

Describe the nature of how the update was presented to screen and the
characteristics of the feedback information. No flags have been
defined for now.

* add a protocol error code for invalid flags

Changes in v5:

* remove the destroy method for the feedback object

The protocol object should instead be automatically destroyed after
a 'presented' or 'discarded' event has been triggered.

* some grammatical corrections to the specification

[Louis-Francis Ratté-Boulianne: split the spec in two parts]

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Signed-off-by: Louis-Francis Ratté-Boulianne <lfrb@collabora.com>
v3 Reviewed-by: Mario Kleiner <mario.kleiner.de@gmail.com>
compositor: add stub implementation of presentation interface

You can bind to the global interface, and it delivers a fake clock id.
All requests on it raise an error.

Changes in v4:

* queuing methods were extractracted for a later series

[Louis-Francis Ratté-Boulianne: split queuing feature]

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Signed-off-by: Louis-Francis Ratté-Boulianne <lfrb@collabora.com>
Reviewed-by: Mario Kleiner <mario.kleiner.de@gmail.com>
weston-info: report presentation clock

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
v3 Reviewed-by: Mario Kleiner <mario.kleiner.de@gmail.com>
compositor: set and use the presentation clock everywhere

Add presentation clock setters that verify the given clock actually
works. Offer an automatic choice of a software fallback clock, when a
backend has to always use clock_gettime() to approximate the
presentation time.

The DRM backend already queried the DRM about the clock id, just let the
DRM backend set the presentation clock from that.

For all other backends which do not get a timestamp from the driver,
call the software clock setter to choose a suitable clock.

Report the chosen clock via presentation.clock_id event to clients.

In finish_frame(), upgrade the argument from uint32_t milliseconds to
struct timespec which can accurately hold the presentation clock values.
This will be needed when weston_output_finish_frame() starts to send out
presentation_feedback.presented events.

While at it, replace gettimeofday() calls with clock_gettime() using the
chosen presentation clock, so we manufacture presentation timestamps
from the presentation clock when the gfx drivers cannot give us a proper
timestamp.

Rpi patch is more verbose due to not having the compositor pointer
available in rpi_flippipe_update_complete(). Explicitly carry the clock
id with flippipe so it is available in the thread.

Changes in v4:

* rpi debug build fix

v4 Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
v3 Reviewed-by: Mario Kleiner <mario.kleiner.de@gmail.com>
compositor: implement presentation_feedback

Implement the presentation.feedback request, and the
presentation_feedback protocol interface. Feedback information is
delivered to clients as the backend reports it, except the refresh
counter (MSC) which is always reported as zero.

Changes in v4:

* add 'flags' argument to 'presented' event without implementation

Changes in v5:

* remove the 'destroy' method implementation for feedback objects
  [Pekka Paalanen: do not leak struct feedback.]

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
v3 Reviewed-by: Mario Kleiner <mario.kleiner.de@gmail.com>
compositor-drm: deliver frame seq for feedback

Add 'msc' field to weston_output to maintain the refresh counter, and
use it in presentation_feedback.presented.

Make compositor-drm update the per-output refresh counter with the
values reported by DRM. If the DRM reported value jumps backwards,
assume it wrapped around once.

Other backends do not update weston_output::msc, and there
presentation_feedback will always deliver refresh counter as zero.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
v3 Reviewed-by: Mario Kleiner <mario.kleiner.de@gmail.com>
tests: presentation test, simple

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
clients: add presentation-shm demo

This started as a copy of simple-shm.c before it was converted to
xdg_shell.

This demo excercises the presentation feedback interface in five
different modes:

- A continuous repaint loop triggered by frame callbacks, and using
  immediate commits, just gathering presentation feedback and computing
  some time intervals for statistics.

- The same as above, except with 1s sleep before actually repainting as
  a response to frame callback. This tests how well the compositor can
  do a repaint from idle state (not continuously repainting), assuming
  nothing else is causing repaints.

- A continuous repaint loop triggered by 'presented' events rather than
  by frame callbacks. If Weston uses an appropriate scheduling
  algorithm, this mode achieves the smallest possible frame latency
  (below one output refresh period).

In all modes, all frames are pre-rendered at startup, so no rendering
happens during the animation.

[Louis-Francis Ratté-Boulianne: split queuing feature]

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Signed-off-by: Louis-Francis Ratté-Boulianne <lfrb@collabora.com>
shell: don't crash on create_common_surface() failure

Noticed while reading code, that create_common_surface() may return
NULL, and callers of its direct callers check for NULL, but the
intermediate function in between would crash.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
weston_surface: Add surface-to-buffer and buffer-to-surface matrices
gl-renderer: Call glViewport after the context is made current
Use pixel coordinates for weston_output.matrix

Previously, weston_output.matrix was in GL coordinates and therefore only
really useful for the GL backend.
zoom: Use pixels instead of GL coordinates

Previously, the zoom functions used GL coordinates natively which doesn't
work with the new output matrix calculations.  This changes zoom to work in
pixel coordinates to match the new output matrix format.  This also cleans
up the math in the zoom code substantially.
pixman-renderer: Add a weston_matrix_to_pixman_transform function and
simplify the buffer-to-output matrix computation

Now that we have a buffer-to-surface matrix and the global-to-output matrix
is in pixels, we can remove a large chunk of confusing code from the pixman
renderer.  Hopefully, having this stuff in weston core will keep the pixman
renderer from gettin broken quite as often.
pixman-renderer: Use output->matrix for region transformations and enable output zoom
compositor: Move weston_matrix_transform_region to compositor.c and export it

We're going to use this to replace much of the other transform code so
it's no longer just relevant to pixman-renderer.c
compositor: add weston_matrix_transform_rect() and use it for where appropriate

New function that transforms a pixman_box32_t rectangle by a matrix.

Since pixman rectangles are represented by 2 corners, non-90 degree
rotations can't be properly represented.  This function gives the
axis aligned rectangle that encloses the rotated rectangle.

We use this for matrix_transform_region() and weston_matrix_transform_rect(),
simplifying them and allowing them to work for non 90 degree rotations.
compositor: use matrix transforms for surface_to_buffer functions

Now that we have weston_matrix_transform and appropriate matrices we can
use that instead of weston_transformed_coord + scaler_surface_to_buffer.

scaler_surface_to_buffer no longer has users, so remove it.
compositor: use weston_matrix_transform_region for overlay setup
compositor: Remove weston_transformed_region

Replace all uses of weston_transform_region with
weston_matrix_transform_region, then remove the function completely.