[PATCH wayland] protocol: Add pointer gestures (swipe/pinch) protocol

[Peter Hutterer]

On Wed, Jul 15, 2015 at 08:02:10PM +0200, Carlos Garnacho wrote:
> The lifetime and progress of gestures is maintained by the separate
> wl_pointer_gesture_pinch and wl_pointer_gesture_swipe interfaces,
> each of these has begin/update(optional)/end phases, as transmitted
> by their events.
> 
> The gesture interfaces can be obtained from the wl_pointer, and
> must be interpreted on the last surface entered by the pointer,
> starting from the pointer coordinates.
> 
> Signed-off-by: Carlos Garnacho <carlosg at gnome.org>
> ---
>  protocol/wayland.xml | 153 ++++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 151 insertions(+), 2 deletions(-)
> 
> diff --git a/protocol/wayland.xml b/protocol/wayland.xml
> index 42c9309..51effad 100644
> --- a/protocol/wayland.xml
> +++ b/protocol/wayland.xml
> @@ -1329,7 +1329,7 @@
>      </request>
>     </interface>
>  
> -  <interface name="wl_seat" version="4">
> +  <interface name="wl_seat" version="5">
>      <description summary="group of input devices">
>        A seat is a group of keyboards, pointer and touch devices. This
>        object is published as a global during start up, or when such a
> @@ -1402,7 +1402,139 @@
>  
>    </interface>
>  
> -  <interface name="wl_pointer" version="3">
> +  <interface name="wl_pointer_gesture_swipe" version="5">
> +    <description summary="a swipe gesture object">
> +      A swipe gesture object notifies a client about a multi-finger swipe
> +      gesture detected on an indirect input device such as a touchpad.
> +      The gesture is usually initiated by multiple fingers moving in the
> +      same direction but once initiated the direction may change.
> +      The precise conditions of when such a gesture is detected are
> +      implementation-dependent.
> +
> +      A gesture consists of three stages: begin, update (optional) and end.
> +
> +      A gesture may be cancelled by the compositor or the hardware.
> +      Destructive actions should not be considered until the end of a
> +      gesture has been received.
> +    </description>
> +
> +    <request name="release" since="5">
> +      <description summary="release the pointer swipe gesture object"/>
> +    </request>
> +
> +    <event name="begin" since="5">
> +      <description summary="multi-finger swipe begin">
> +	This event is sent when a multi-finger swipe gesture is detected
> +	on the device.
> +      </description>
> +      <arg name="serial" type="uint"/>
> +      <arg name="time" type="uint" summary="timestamp with millisecond granularity"/>
> +      <arg name="fingers" type="uint" summary="number of fingers"/>
> +    </event>
> +
> +    <event name="update" since="5">
> +      <description summary="multi-finger swipe motion">
> +	This event is sent when a multi-finger swipe gesture changes the
> +	position of the logical center.
> +
> +	The dx and dy coordinates are relative coordinates of the logical
> +	center of the gesture compared to the previous event.
> +      </description>
> +      <arg name="time" type="uint" summary="timestamp with millisecond granularity"/>
> +      <arg name="dx" type="fixed" summary="delta x coordinate in surface coordinate space"/>
> +      <arg name="dy" type="fixed" summary="delta y coordinate in surface coordinate space"/>
> +    </event>
> +
> +    <event name="end" since="5">
> +      <description summary="multi-finger swipe end">
> +	This event is sent when a multi-finger swipe gesture ceases to
> +	be valid. This may happen when one or more finger is lifted or
> +	the gesture is cancelled.
> +
> +	When a gesture is cancelled, the client should undo state changes
> +	caused by this gesture. What causes a gesture to be cancelled is
> +	implementation-dependent.
> +      </description>
> +      <arg name="serial" type="uint"/>
> +      <arg name="time" type="uint" summary="timestamp with millisecond granularity"/>
> +      <arg name="cancelled" type="int" summary="number of fingers"/>

copy/paste error here (sorry, my fault)

> +    </event>
> +  </interface>
> +
> +  <interface name="wl_pointer_gesture_pinch" version="5">
> +    <description summary="a pinch gesture object">
> +      A swipe gesture object notifies a client about a multi-finger pinch

s/swipe/pinch/

> +      gesture detected on an indirect input device such as a touchpad.
> +      The gesture is usually initiated by multiple fingers moving towards
> +      each other or away from each other, or by two or more fingers rotating
> +      around a logical center of gravity.  The precise conditions of when
> +      such a gesture is detected are implementation-dependent.
> +
> +      A gesture consists of three stages: begin, update (optional) and end.
> +
> +      A gesture may be cancelled by the compositor or the hardware.
> +      Destructive actions should not be considered until the end of a
> +      gesture has been received.
> +    </description>
> +
> +    <request name="release" since="5">
> +      <description summary="release the pinch gesture object"/>
> +    </request>
> +
> +    <event name="begin" since="5">
> +      <description summary="multi-finger pinch begin">
> +	This event is sent when a multi-finger pinch gesture is detected
> +	on the device.
> +
> +	The gesture is assigned a unique @id. Future events from this
> +	gesture reference this ID. The ID ceases to be valid after a
> +	pointer_gesture_swipe.end and may be re-used in the future.

you can drop this paragraph now. for the archives: the original version of
this patchset had an ID for each gesture sequence similar to touches.

Carlos and I agreed that this isn't really necessary - while it's
technically possible to have two gestures on two different devices at the
same time this is something that the compositor should suppress. If we find
a sensible use-case for this, we can add the gesture sequence ID later.

Carlos: you may want to add a paragraph explicitly stating that only one
gesture of a type may be active at a time.

> +      </description>
> +      <arg name="serial" type="uint"/>
> +      <arg name="time" type="uint" summary="timestamp with millisecond granularity"/>
> +      <arg name="fingers" type="uint" summary="number of fingers"/>
> +    </event>
> +
> +    <event name="update" since="5">
> +      <description summary="multi-finger pinch motion">
> +	This event is sent when a multi-finger pinch gesture changes the
> +	position of the logical center, the rotation or the relative scale.
> +
> +	The dx and dy coordinates are relative coordinates in the
> +	surface coordinate space of the logical center of the gesture.
> +
> +	The scale factor is an absolute scale compared to the
> +	pointer_gesture_pinch.begin event, i.e. a scale of 2 means the fingers

actually, this should be e.g., not i.e. (though I guess both would be ok here)

Reviewed-by: Peter Hutterer <peter.hutterer at who-t.net> with the above fixed

Cheers,
   Peter

> +	are now twice as far apart as on pointer_gesture_pinch.begin.
> +
> +	The rotation is the relative angle in degrees clockwise compared to the previous
> +	pointer_gesture_pinch.begin or pointer_gesture_pinch.update event.
> +      </description>
> +      <arg name="time" type="uint" summary="timestamp with millisecond granularity"/>
> +      <arg name="dx" type="fixed" summary="delta x coordinate in surface coordinate space"/>
> +      <arg name="dy" type="fixed" summary="delta y coordinate in surface coordinate space"/>
> +      <arg name="scale" type="fixed" summary="scale relative to the initial finger position"/>
> +      <arg name="rotation" type="fixed" summary="angle in degrees cw relative to the previous event"/>
> +    </event>
> +
> +    <event name="end" since="5">
> +      <description summary="multi-finger pinch end">
> +	This event is sent when a multi-finger pinch gesture ceases to
> +	be valid. This may happen when one or more finger is lifted or
> +	the gesture is cancelled.
> +
> +	When a gesture is cancelled, the client should undo state changes
> +	caused by this gesture. What causes a gesture to be cancelled is
> +	implementation-dependent.
> +      </description>
> +      <arg name="serial" type="uint"/>
> +      <arg name="time" type="uint" summary="timestamp with millisecond granularity"/>
> +      <arg name="cancelled" type="int" summary="number of fingers"/>
> +    </event>
> +
> +  </interface>
> +
> +  <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
> @@ -1569,6 +1701,23 @@
>        </description>
>      </request>
>  
> +    <!-- Version 5 additions -->
> +
> +    <request name="get_swipe_gesture" since="5">
> +      <description summary="get swipe gesture">
> +	Create a swipe gesture object for the given pointer. See the
> +	wl_pointer_gesture_swipe interface for details.
> +      </description>
> +      <arg name="id" type="new_id" interface="wl_pointer_gesture_swipe"/>
> +    </request>
> +
> +    <request name="get_pinch_gesture" since="5">
> +      <description summary="get pinch gesture">
> +	Create a pinch gesture object for the given pointer. See the
> +	wl_pointer_gesture_pinch interface for details.
> +      </description>
> +      <arg name="id" type="new_id" interface="wl_pointer_gesture_pinch"/>
> +    </request>
>    </interface>
>  
>    <interface name="wl_keyboard" version="4">
> -- 
> 2.4.3
>