Report pinch gestures

Bug: 251196347
Test: check events received by a custom tester app, and touches shown by
      pointer location overlay
Test: atest inputflinger_tests
Change-Id: I249ca6208091e3c4291c5be68c77339bf5f69a5b

1 files changed, 26 insertions, 1 deletions

diff --git a/include/android/input.h b/include/android/input.h
index e1aac65457..d6f9d633b6 100644
--- a/include/android/input.h
+++ b/include/android/input.h
@@ -778,6 +778,9 @@ enum {
      *   proportion of the touch pad's size. For example, if a touch pad is 1000 units wide, and a
      *   swipe gesture starts at X = 500 then moves to X = 400, this axis would have a value of
      *   -0.1.
+     *
+     * These values are relative to the state from the last event, not accumulated, so developers
+     * should make sure to process this axis value for all batched historical events.
      */
     AMOTION_EVENT_AXIS_GESTURE_X_OFFSET = 48,
     /**
@@ -791,6 +794,9 @@ enum {
      *
      * - For a touch pad, reports the distance that should be scrolled in the X axis as a result of
      *   the user's two-finger scroll gesture, in display pixels.
+     *
+     * These values are relative to the state from the last event, not accumulated, so developers
+     * should make sure to process this axis value for all batched historical events.
      */
     AMOTION_EVENT_AXIS_GESTURE_SCROLL_X_DISTANCE = 50,
     /**
@@ -799,6 +805,18 @@ enum {
      * The same as {@link AMOTION_EVENT_AXIS_GESTURE_SCROLL_X_DISTANCE}, but for the Y axis.
      */
     AMOTION_EVENT_AXIS_GESTURE_SCROLL_Y_DISTANCE = 51,
+    /**
+     * Axis constant: pinch scale factor of a motion event.
+     *
+     * - For a touch pad, reports the change in distance between the fingers when the user is making
+     *   a pinch gesture, as a proportion of that distance when the gesture was last reported. For
+     *   example, if the fingers were 50 units apart and are now 52 units apart, the scale factor
+     *   would be 1.04.
+     *
+     * These values are relative to the state from the last event, not accumulated, so developers
+     * should make sure to process this axis value for all batched historical events.
+     */
+    AMOTION_EVENT_AXIS_GESTURE_PINCH_SCALE_FACTOR = 52,
 
     /**
      * Note: This is not an "Axis constant". It does not represent any axis, nor should it be used
@@ -806,7 +824,7 @@ enum {
      * to make some computations (like iterating through all possible axes) cleaner.
      * Please update the value accordingly if you add a new axis.
      */
-    AMOTION_EVENT_MAXIMUM_VALID_AXIS_VALUE = AMOTION_EVENT_AXIS_GESTURE_SCROLL_Y_DISTANCE,
+    AMOTION_EVENT_MAXIMUM_VALID_AXIS_VALUE = AMOTION_EVENT_AXIS_GESTURE_PINCH_SCALE_FACTOR,
 
     // NOTE: If you add a new axis here you must also add it to several other files.
     //       Refer to frameworks/base/core/java/android/view/MotionEvent.java for the full list.
@@ -891,6 +909,13 @@ enum AMotionClassification : uint32_t {
      * why they have a separate constant from two-finger swipes.
      */
     AMOTION_EVENT_CLASSIFICATION_MULTI_FINGER_SWIPE = 4,
+    /**
+     * Classification constant: pinch.
+     *
+     * The current event stream represents the user pinching with two fingers on a touchpad. The
+     * gesture is centered around the current cursor position.
+     */
+    AMOTION_EVENT_CLASSIFICATION_PINCH = 5,
 };
 
 /**