inputflinger: Initial support for rotary encoders.

This change introduces support for rotary encoder input devices.

We also define a new input source (namely, AINPUT_SOURCE_ROTARY_ENCODER)
and a new axis of input (namely, AXIS_SCROLL), since the rotary encoder
motion doesn't necessarily tie to a horizontal or vertical scroll
motion.

A ROTARY_ENCODER input device class is also introduced, corresponding to
the new input source.

A new input source can be defined as producing rotary encoder motion
events, if its corresponding .idc file contains the following
declaration:

    device.type = rotaryEncoder

Bug: 18707397

Change-Id: I8ccd540908311d1ff44fdfeba81b691895413641
Signed-off-by: Prashant Malani <pmalani@google.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/include/android/input.h b/include/android/input.h
index 5ab4e29..5eeb7fc 100644
--- a/include/android/input.h
+++ b/include/android/input.h
@@ -644,6 +644,13 @@ enum {
      */
     AMOTION_EVENT_AXIS_TILT = 25,
     /**
+     * Axis constant:  Generic scroll axis of a motion event.
+     *
+     * - This is used for scroll axis motion events that can't be classified as strictly
+     *   vertical or horizontal. The movement of a rotating scroller is an example of this.
+     */
+    AMOTION_EVENT_AXIS_SCROLL = 26,
+    /**
      * Axis constant: Generic 1 axis of a motion event.
      * The interpretation of a generic axis is device-specific.
      */
@@ -817,6 +824,8 @@ enum {
     AINPUT_SOURCE_TOUCH_NAVIGATION = 0x00200000 | AINPUT_SOURCE_CLASS_NONE,
     /** joystick */
     AINPUT_SOURCE_JOYSTICK = 0x01000000 | AINPUT_SOURCE_CLASS_JOYSTICK,
+    /** rotary encoder */
+    AINPUT_SOURCE_ROTARY_ENCODER = 0x00400000 | AINPUT_SOURCE_CLASS_NONE,
 
     /** any */
     AINPUT_SOURCE_ANY = 0xffffff00,