Add pinch classification and scale factor axis

Bug: 251196347
Test: check events received by a custom tester app, and touches shown by
      pointer location overlay
Test: atest inputflinger_tests
Change-Id: I0cb7ade63139ab35025ff1e12609e2b411b1f5f8

core/api/current.txt

@@ -50482,6 +50482,7 @@ package android.view {
     field public static final int AXIS_GENERIC_7 = 38; // 0x26
     field public static final int AXIS_GENERIC_8 = 39; // 0x27
     field public static final int AXIS_GENERIC_9 = 40; // 0x28
+    field public static final int AXIS_GESTURE_PINCH_SCALE_FACTOR = 52; // 0x34
     field public static final int AXIS_GESTURE_SCROLL_X_DISTANCE = 50; // 0x32
     field public static final int AXIS_GESTURE_SCROLL_Y_DISTANCE = 51; // 0x33
     field public static final int AXIS_GESTURE_X_OFFSET = 48; // 0x30
@@ -50522,6 +50523,7 @@ package android.view {
     field public static final int CLASSIFICATION_AMBIGUOUS_GESTURE = 1; // 0x1
     field public static final int CLASSIFICATION_DEEP_PRESS = 2; // 0x2
     field public static final int CLASSIFICATION_NONE = 0; // 0x0
+    field public static final int CLASSIFICATION_PINCH = 5; // 0x5
     field public static final int CLASSIFICATION_TWO_FINGER_SWIPE = 3; // 0x3
     field @NonNull public static final android.os.Parcelable.Creator<android.view.MotionEvent> CREATOR;
     field public static final int EDGE_BOTTOM = 2; // 0x2

core/java/android/view/MotionEvent.java

@@ -1283,6 +1283,8 @@ public final class MotionEvent extends InputEvent implements Parcelable {
      * swipe gesture starts at X = 500 then moves to X = 400, this axis would have a value of
      * -0.1.
      * </ul>
+     * 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.
      */
     public static final int AXIS_GESTURE_X_OFFSET = 48;
 
@@ -1300,6 +1302,8 @@ public final class MotionEvent extends InputEvent implements Parcelable {
      * <li>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.
      * </ul>
+     * 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.
      */
     public static final int AXIS_GESTURE_SCROLL_X_DISTANCE = 50;
 
@@ -1310,6 +1314,19 @@ public final class MotionEvent extends InputEvent implements Parcelable {
      */
     public static final int AXIS_GESTURE_SCROLL_Y_DISTANCE = 51;
 
+    /**
+     * Axis constant: pinch scale factor of a motion event.
+     * <p>
+     * <ul>
+     * <li>For a touch pad, reports the change in distance between the fingers when the user is
+     * making a pinch gesture, as a proportion of the previous distance. For example, if the fingers
+     * were 50 units apart and are now 52 units apart, the scale factor would be 1.04.
+     * </ul>
+     * 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.
+     */
+    public static final int AXIS_GESTURE_PINCH_SCALE_FACTOR = 52;
+
     // NOTE: If you add a new axis here you must also add it to:
     //  frameworks/native/include/android/input.h
     //  frameworks/native/libs/input/InputEventLabels.cpp
@@ -1369,6 +1386,7 @@ public final class MotionEvent extends InputEvent implements Parcelable {
         names.append(AXIS_GESTURE_Y_OFFSET, "AXIS_GESTURE_Y_OFFSET");
         names.append(AXIS_GESTURE_SCROLL_X_DISTANCE, "AXIS_GESTURE_SCROLL_X_DISTANCE");
         names.append(AXIS_GESTURE_SCROLL_Y_DISTANCE, "AXIS_GESTURE_SCROLL_Y_DISTANCE");
+        names.append(AXIS_GESTURE_PINCH_SCALE_FACTOR, "AXIS_GESTURE_PINCH_SCALE_FACTOR");
     }
 
     /**
@@ -1522,11 +1540,22 @@ public final class MotionEvent extends InputEvent implements Parcelable {
      */
     public static final int CLASSIFICATION_MULTI_FINGER_SWIPE = 4;
 
+    /**
+     * Classification constant: touchpad pinch.
+     *
+     * The current event stream represents the user pinching with two fingers on a touchpad. The
+     * gesture is centered around the current cursor position.
+     *
+     * @see #getClassification
+     */
+    public static final int CLASSIFICATION_PINCH = 5;
+
     /** @hide */
     @Retention(SOURCE)
     @IntDef(prefix = { "CLASSIFICATION" }, value = {
             CLASSIFICATION_NONE, CLASSIFICATION_AMBIGUOUS_GESTURE, CLASSIFICATION_DEEP_PRESS,
-            CLASSIFICATION_TWO_FINGER_SWIPE, CLASSIFICATION_MULTI_FINGER_SWIPE})
+            CLASSIFICATION_TWO_FINGER_SWIPE, CLASSIFICATION_MULTI_FINGER_SWIPE,
+            CLASSIFICATION_PINCH})
     public @interface Classification {};
 
     /**

native/android/input.cpp

@@ -299,6 +299,8 @@ int32_t AMotionEvent_getClassification(const AInputEvent* motion_event) {
             return AMOTION_EVENT_CLASSIFICATION_TWO_FINGER_SWIPE;
         case android::MotionClassification::MULTI_FINGER_SWIPE:
             return AMOTION_EVENT_CLASSIFICATION_MULTI_FINGER_SWIPE;
+        case android::MotionClassification::PINCH:
+            return AMOTION_EVENT_CLASSIFICATION_PINCH;
     }
 }