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protocol: add wl_pointer.frame, axis_source, axis_stop, and axis_discrete

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The frame event groups separate pointer events together. The primary use-case
for this at the moment is diagonal scrolling - a vertical/horizontal scroll
event can be grouped together to calculate the correct motion vector.
Frame events group all wl_pointer events. An example sequence of motion events
followed by a diagonal scroll followed by a button event is:
wl_pointer.motion
wl_pointer.frame
wl_pointer.motion
wl_pointer.frame
wl_pointer.axis
wl_pointer.axis
wl_pointer.frame
wl_pointer.button
wl_pointer.frame

In the future, other extensions may insert additional information about an
event into the frame. For example, an extension may add information about the
physical device that generated an event into the frame. For this reason,
enter/leave events are grouped by a frame event too.

The axis_source event determines how an axis event was generated. That enables
clients to judge when to use kinetic scrolling. Only one axis_source event is
allowed per frame and applies to all events in this frame.

The axis_stop event notifies a client about the termination of a scroll
sequence, likewise needed to calculate kinetic scrolling parameters.
Multiple axis_stop events within the same frame indicate that scrolling has
stopped in all these axis at the same time.

The axis_discrete event provides the wheel click count. Previously the axis
value was some hardcoded number (10), with the discrete steps this enables a
client to differ between line-based scrolling on a mouse wheel and smooth
scrolling with a touchpad. The axis_discrete event carries the axis
information and the discrete value and can occur at any time in the frame
provided it is ordered before the matching axis event. Specifically, this
sequence is valid:

wl_pointer.axis_source
wl_pointer.axis_discrete (vert)
wl_pointer.axis_discrete (horiz)
wl_pointer.axis (horiz)
wl_pointer.axis (vert)
wl_pointer.frame

Enter and leave event also trigger wl_pointer.frame events, where possible the
compositor should group leave and subsequent enter into the same frame. This
indicates to the client that the pointer has moved between surfaces and may
allow a client to shortcut code otherwise triggerd by the leave or enter
events.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Carlos Garnacho <carlosg@gnome.org>
Reviewed-by: Jonas Ådahl <jadahl@gmail.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Bryce Harrington <bryce@osg.samsung.com>
This commit is contained in:
Peter Hutterer 2015-12-08 11:11:07 +10:00 • committed by Jonas Ådahl
parent 2b236af9b7
commit c5356e9016
1 changed files with 147 additions and 3 deletions
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150
protocol/wayland.xml
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@ -1482,7 +1482,7 @@
</interface>
<interface name="wl_pointer" version="3">
<interface name="wl_pointer" version="5">
<description summary="pointer input device">
The wl_pointer interface represents one or more input devices,
such as mice, which control the pointer location and pointer_focus
@ -1649,9 +1649,153 @@
</description>
</request>
<!-- Version 5 additions -->
<event name="frame" since="5">
<description summary="end of a pointer event sequence">
Indicates the end of a set of events that logically belong together.
A client is expected to accumulate the data in all events within the
frame before proceeding.
All wl_pointer events before a wl_pointer.frame event belong
logically together. For example, in a diagonal scroll motion the
compositor will send an optional wl_pointer.axis_source event, two
wl_pointer.axis events (horizontal and vertical) and finally a
wl_pointer.frame event. The client may use this information to
calculate a diagonal vector for scrolling.
When multiple wl_pointer.axis events occur within the same frame,
the motion vector is the combined motion of all events.
When a wl_pointer.axis and a wl_pointer.axis_stop event occur within
the same frame, this indicates that axis movement in one axis has
stopped but continues in the other axis.
When multiple wl_pointer.axis_stop events occur within in the same
frame, this indicates that these axes stopped in the same instance.
A wl_pointer.frame event is sent for every logical event group,
even if the group only contains a single wl_pointer event.
Specifically, a client may get a sequence: motion, frame, button,
frame, axis, frame, axis_stop, frame.
The wl_pointer.enter and wl_pointer.leave events are logical events
generated by the compositor and not the hardware. These events are
also grouped by a wl_pointer.frame. When a pointer moves from one
surface to the another, a compositor should group the
wl_pointer.leave event within the same wl_pointer.frame.
However, a client must not rely on wl_pointer.leave and
wl_pointer.enter being in the same wl_pointer.frame.
Compositor-specific policies may require the wl_pointer.leave and
wl_pointer.enter event being split across multiple wl_pointer.frame
groups.
</description>
</event>
<enum name="axis_source">
<description summary="axis source types">
Describes the source types for axis events. This indicates to the
client how an axis event was physically generated; a client may
adjust the user interface accordingly. For example, scroll events
from a "finger" source may be in a smooth coordinate space with
kinetic scrolling whereas a "wheel" source may be in discrete steps
of a number of lines.
The "continuous" axis source is a device generating events in a
continuous coordinate space, but using something other than a
finger. One example for this source is button-based scrolling where
the vertical motion of a device is converted to scroll events while
a button is held down.
</description>
<entry name="wheel" value="0" summary="A physical wheel" />
<entry name="finger" value="1" summary="Finger on a touch surface" />
<entry name="continuous" value="2" summary="Continuous coordinate space"/>
</enum>
<event name="axis_source" since="5">
<description summary="axis source event">
Source information for scroll and other axes.
This event does not occur on its own. It is sent before a
wl_pointer.frame event and carries the source information for
all events within that frame.
The source specifies how this event was generated. If the source is
wl_pointer.axis_source.finger, a wl_pointer.axis_stop event will be
sent when the user lifts the finger off the device.
If the source is wl_pointer axis_source.wheel or
wl_pointer.axis_source.continuous, a wl_pointer.axis_stop event may
or may not be sent. Whether a compositor sends a axis_stop event
for these sources is hardware-specific and implementation-dependent;
clients must not rely on receiving an axis_stop event for these
scroll sources and should treat scroll sequences from these scroll
sources as unterminated by default.
This event is optional. If the source is unknown for a particular
axis event sequence, no event is sent.
Only one wl_pointer.axis_source event is permitted per frame.
The order of wl_pointer.axis_discrete and wl_pointer.axis_source is
not guaranteed.
</description>
<arg name="axis_source" type="uint" enum="axis_source"/>
</event>
<event name="axis_stop" since="5">
<description summary="axis stop event">
Stop notification for scroll and other axes.
For some wl_pointer.axis_source types, a wl_pointer.axis_stop event
is sent to notify a client that the axis sequence has terminated.
This enables the client to implement kinetic scrolling.
See the wl_pointer.axis_source documentation for information on when
this event may be generated.
Any wl_pointer.axis events with the same axis_source after this
event should be considered as the start of a new axis motion.
The timestamp is to be interpreted identical to the timestamp in the
wl_pointer.axis event. The timestamp value may be the same as a
preceeding wl_pointer.axis event.
</description>
<arg name="time" type="uint" summary="timestamp with millisecond granularity"/>
<arg name="axis" type="uint" enum="axis" summary="the axis stopped with this event"/>
</event>
<event name="axis_discrete" since="5">
<description summary="axis click event">
Discrete step information for scroll and other axes.
This event carries the axis value of the wl_pointer.axis event in
discrete steps (e.g. mouse wheel clicks).
This event does not occur on its own, it is coupled with a
wl_pointer.axis event that represents this axis value on a
continuous scale. The protocol guarantees that each axis_discrete
event is always followed by exactly one axis event with the same
axis number within the same wl_pointer.frame. Note that the protocol
allows for other events to occur between the axis_discrete and
its coupled axis event, including other axis_discrete or axis
events.
This event is optional; continuous scrolling devices
like two-finger scrolling on touchpads do not have discrete
steps and do not generate this event.
The discrete value carries the directional information. e.g. a value
of -2 is two steps towards the negative direction of this axis.
The axis number is identical to the axis number in the associate
axis event.
The order of wl_pointer.axis_discrete and wl_pointer.axis_source is
not guaranteed.
</description>
<arg name="axis" type="uint" enum="axis" />
<arg name="discrete" type="int"/>
</event>
</interface>
<interface name="wl_keyboard" version="4">
<interface name="wl_keyboard" version="5">
<description summary="keyboard input device">
The wl_keyboard interface represents one or more keyboards
associated with a seat.
@ -1765,7 +1909,7 @@
</event>
</interface>
<interface name="wl_touch" version="3">
<interface name="wl_touch" version="5">
<description summary="touchscreen input device">
The wl_touch interface represents a touchscreen
associated with a seat.