GestureConverter: add finger count axis for multi-finger swipes

Consumers of multi-finger swipes (i.e. SysUI) previously had to wait
until the first MOVE event to find out how many fingers were swiping,
even though in the framework we knew this when sending the DOWN event.
Adding this as an axis on the DOWN event should let SysUI simplify their
code.

Bug: 283093437
Test: atest inputflinger_tests:GestureConverterTest
Test: modify InputDispatcher to send multi-finger swipes to apps too,
      then check reported values in a test app
Change-Id: I34d1fdf096c49d7eb9b5d8ebd64427eb4e5db1f4

6 files changed, 58 insertions, 21 deletions

diff --git a/include/android/input.h b/include/android/input.h
index a45f065dd0..9a0eb4d838 100644
--- a/include/android/input.h
+++ b/include/android/input.h
@@ -781,6 +781,8 @@ enum {
      *
      * 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.
+     *
+     * This axis is only set on the first pointer in a motion event.
      */
     AMOTION_EVENT_AXIS_GESTURE_X_OFFSET = 48,
     /**
@@ -797,6 +799,8 @@ enum {
      *
      * 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.
+     *
+     * This axis is only set on the first pointer in a motion event.
      */
     AMOTION_EVENT_AXIS_GESTURE_SCROLL_X_DISTANCE = 50,
     /**
@@ -815,16 +819,29 @@ enum {
      *
      * 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.
+     *
+     * This axis is only set on the first pointer in a motion event.
      */
     AMOTION_EVENT_AXIS_GESTURE_PINCH_SCALE_FACTOR = 52,
 
     /**
+     * Axis constant: the number of fingers being used in a multi-finger swipe gesture.
+     *
+     * - For a touch pad, reports the number of fingers being used in a multi-finger swipe gesture
+     *   (with CLASSIFICATION_MULTI_FINGER_SWIPE).
+     *
+     * Since CLASSIFICATION_MULTI_FINGER_SWIPE is a hidden API, so is this axis. It is only set on
+     * the first pointer in a motion event.
+     */
+    AMOTION_EVENT_AXIS_GESTURE_SWIPE_FINGER_COUNT = 53,
+
+    /**
      * Note: This is not an "Axis constant". It does not represent any axis, nor should it be used
      * to represent any axis. It is a constant holding the value of the largest defined axis value,
      * 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_PINCH_SCALE_FACTOR,
+    AMOTION_EVENT_MAXIMUM_VALID_AXIS_VALUE = AMOTION_EVENT_AXIS_GESTURE_SWIPE_FINGER_COUNT,
 
     // 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.
diff --git a/libs/input/InputEventLabels.cpp b/libs/input/InputEventLabels.cpp
index f99a7d640e..1c7cc129bd 100644
--- a/libs/input/InputEventLabels.cpp
+++ b/libs/input/InputEventLabels.cpp
@@ -404,7 +404,8 @@ namespace android {
     DEFINE_AXIS(GESTURE_Y_OFFSET), \
     DEFINE_AXIS(GESTURE_SCROLL_X_DISTANCE), \
     DEFINE_AXIS(GESTURE_SCROLL_Y_DISTANCE), \
-    DEFINE_AXIS(GESTURE_PINCH_SCALE_FACTOR)
+    DEFINE_AXIS(GESTURE_PINCH_SCALE_FACTOR), \
+    DEFINE_AXIS(GESTURE_SWIPE_FINGER_COUNT)
 
 // NOTE: If you add new LEDs here, you must also add them to Input.h
 #define LEDS_SEQUENCE \
diff --git a/services/inputflinger/InputCommonConverter.cpp b/services/inputflinger/InputCommonConverter.cpp
index 2437d0fcfc..781288076c 100644
--- a/services/inputflinger/InputCommonConverter.cpp
+++ b/services/inputflinger/InputCommonConverter.cpp
@@ -258,12 +258,12 @@ static_assert(static_cast<common::Axis>(AMOTION_EVENT_AXIS_GENERIC_13) == common
 static_assert(static_cast<common::Axis>(AMOTION_EVENT_AXIS_GENERIC_14) == common::Axis::GENERIC_14);
 static_assert(static_cast<common::Axis>(AMOTION_EVENT_AXIS_GENERIC_15) == common::Axis::GENERIC_15);
 static_assert(static_cast<common::Axis>(AMOTION_EVENT_AXIS_GENERIC_16) == common::Axis::GENERIC_16);
-// TODO(b/251196347): add GESTURE_{X,Y}_OFFSET, GESTURE_SCROLL_{X,Y}_DISTANCE, and
-// GESTURE_PINCH_SCALE_FACTOR.
+// TODO(b/251196347): add GESTURE_{X,Y}_OFFSET, GESTURE_SCROLL_{X,Y}_DISTANCE,
+// GESTURE_PINCH_SCALE_FACTOR, and GESTURE_SWIPE_FINGER_COUNT.
 // If you added a new axis, consider whether this should also be exposed as a HAL axis. Update the
 // static_assert below and add the new axis here, or leave a comment summarizing your decision.
 static_assert(static_cast<common::Axis>(AMOTION_EVENT_MAXIMUM_VALID_AXIS_VALUE) ==
-              static_cast<common::Axis>(AMOTION_EVENT_AXIS_GESTURE_PINCH_SCALE_FACTOR));
+              static_cast<common::Axis>(AMOTION_EVENT_AXIS_GESTURE_SWIPE_FINGER_COUNT));
 
 static common::VideoFrame getHalVideoFrame(const TouchVideoFrame& frame) {
     common::VideoFrame out;
diff --git a/services/inputflinger/reader/mapper/gestures/GestureConverter.cpp b/services/inputflinger/reader/mapper/gestures/GestureConverter.cpp
index 7eca6fa0b4..108882121d 100644
--- a/services/inputflinger/reader/mapper/gestures/GestureConverter.cpp
+++ b/services/inputflinger/reader/mapper/gestures/GestureConverter.cpp
@@ -385,6 +385,8 @@ NotifyMotionArgs GestureConverter::endScroll(nsecs_t when, nsecs_t readTime) {
         }
 
         mDownTime = when;
+        mFakeFingerCoords[0].setAxisValue(AMOTION_EVENT_AXIS_GESTURE_SWIPE_FINGER_COUNT,
+                                          fingerCount);
         out.push_back(makeMotionArgs(when, readTime, AMOTION_EVENT_ACTION_DOWN,
                                      /* actionButton= */ 0, mButtonState, /* pointerCount= */ 1,
                                      mFingerProps.data(), mFakeFingerCoords.data(), xCursorPosition,
@@ -441,6 +443,7 @@ NotifyMotionArgs GestureConverter::endScroll(nsecs_t when, nsecs_t readTime) {
                                  /* actionButton= */ 0, mButtonState, /* pointerCount= */ 1,
                                  mFingerProps.data(), mFakeFingerCoords.data(), xCursorPosition,
                                  yCursorPosition));
+    mFakeFingerCoords[0].setAxisValue(AMOTION_EVENT_AXIS_GESTURE_SWIPE_FINGER_COUNT, 0);
     mCurrentClassification = MotionClassification::NONE;
     mSwipeFingerCount = 0;
     return out;
diff --git a/services/inputflinger/tests/GestureConverter_test.cpp b/services/inputflinger/tests/GestureConverter_test.cpp
index f115fff128..a3994f08e0 100644
--- a/services/inputflinger/tests/GestureConverter_test.cpp
+++ b/services/inputflinger/tests/GestureConverter_test.cpp
@@ -395,7 +395,7 @@ TEST_F(GestureConverterTest, ThreeFingerSwipe_ClearsClassificationAfterGesture)
                 WithMotionClassification(MotionClassification::NONE));
 }
 
-TEST_F(GestureConverterTest, ThreeFingerSwipe_ClearsOffsetsAfterGesture) {
+TEST_F(GestureConverterTest, ThreeFingerSwipe_ClearsGestureAxesAfterGesture) {
     InputDeviceContext deviceContext(*mDevice, EVENTHUB_ID);
     GestureConverter converter(*mReader->getContext(), deviceContext, DEVICE_ID);
 
@@ -412,7 +412,8 @@ TEST_F(GestureConverterTest, ThreeFingerSwipe_ClearsOffsetsAfterGesture) {
                          GESTURES_ZOOM_START);
     args = converter.handleGesture(ARBITRARY_TIME, READ_TIME, pinchGesture);
     ASSERT_FALSE(args.empty());
-    EXPECT_THAT(std::get<NotifyMotionArgs>(args.front()), WithGestureOffset(0, 0, EPSILON));
+    EXPECT_THAT(std::get<NotifyMotionArgs>(args.front()),
+                AllOf(WithGestureOffset(0, 0, EPSILON), WithGestureSwipeFingerCount(0)));
 }
 
 TEST_F(GestureConverterTest, ThreeFingerSwipe_Vertical) {
@@ -433,6 +434,7 @@ TEST_F(GestureConverterTest, ThreeFingerSwipe_Vertical) {
     NotifyMotionArgs arg = std::get<NotifyMotionArgs>(args.front());
     ASSERT_THAT(arg,
                 AllOf(WithMotionAction(AMOTION_EVENT_ACTION_DOWN), WithGestureOffset(0, 0, EPSILON),
+                      WithGestureSwipeFingerCount(3),
                       WithMotionClassification(MotionClassification::MULTI_FINGER_SWIPE),
                       WithPointerCount(1u), WithToolType(ToolType::FINGER)));
     PointerCoords finger0Start = arg.pointerCoords[0];
@@ -441,7 +443,7 @@ TEST_F(GestureConverterTest, ThreeFingerSwipe_Vertical) {
     ASSERT_THAT(arg,
                 AllOf(WithMotionAction(AMOTION_EVENT_ACTION_POINTER_DOWN |
                                        1 << AMOTION_EVENT_ACTION_POINTER_INDEX_SHIFT),
-                      WithGestureOffset(0, 0, EPSILON),
+                      WithGestureOffset(0, 0, EPSILON), WithGestureSwipeFingerCount(3),
                       WithMotionClassification(MotionClassification::MULTI_FINGER_SWIPE),
                       WithPointerCount(2u), WithToolType(ToolType::FINGER)));
     PointerCoords finger1Start = arg.pointerCoords[1];
@@ -450,7 +452,7 @@ TEST_F(GestureConverterTest, ThreeFingerSwipe_Vertical) {
     ASSERT_THAT(arg,
                 AllOf(WithMotionAction(AMOTION_EVENT_ACTION_POINTER_DOWN |
                                        2 << AMOTION_EVENT_ACTION_POINTER_INDEX_SHIFT),
-                      WithGestureOffset(0, 0, EPSILON),
+                      WithGestureOffset(0, 0, EPSILON), WithGestureSwipeFingerCount(3),
                       WithMotionClassification(MotionClassification::MULTI_FINGER_SWIPE),
                       WithPointerCount(3u), WithToolType(ToolType::FINGER)));
     PointerCoords finger2Start = arg.pointerCoords[2];
@@ -459,7 +461,7 @@ TEST_F(GestureConverterTest, ThreeFingerSwipe_Vertical) {
     arg = std::get<NotifyMotionArgs>(args.front());
     ASSERT_THAT(arg,
                 AllOf(WithMotionAction(AMOTION_EVENT_ACTION_MOVE),
-                      WithGestureOffset(0, -0.01, EPSILON),
+                      WithGestureOffset(0, -0.01, EPSILON), WithGestureSwipeFingerCount(3),
                       WithMotionClassification(MotionClassification::MULTI_FINGER_SWIPE),
                       WithPointerCount(3u), WithToolType(ToolType::FINGER)));
     EXPECT_EQ(arg.pointerCoords[0].getX(), finger0Start.getX());
@@ -476,7 +478,7 @@ TEST_F(GestureConverterTest, ThreeFingerSwipe_Vertical) {
     arg = std::get<NotifyMotionArgs>(args.front());
     ASSERT_THAT(arg,
                 AllOf(WithMotionAction(AMOTION_EVENT_ACTION_MOVE),
-                      WithGestureOffset(0, -0.005, EPSILON),
+                      WithGestureOffset(0, -0.005, EPSILON), WithGestureSwipeFingerCount(3),
                       WithMotionClassification(MotionClassification::MULTI_FINGER_SWIPE),
                       WithPointerCount(3u), WithToolType(ToolType::FINGER)));
     EXPECT_EQ(arg.pointerCoords[0].getX(), finger0Start.getX());
@@ -492,19 +494,20 @@ TEST_F(GestureConverterTest, ThreeFingerSwipe_Vertical) {
     ASSERT_THAT(std::get<NotifyMotionArgs>(args.front()),
                 AllOf(WithMotionAction(AMOTION_EVENT_ACTION_POINTER_UP |
                                        2 << AMOTION_EVENT_ACTION_POINTER_INDEX_SHIFT),
-                      WithGestureOffset(0, 0, EPSILON),
+                      WithGestureOffset(0, 0, EPSILON), WithGestureSwipeFingerCount(3),
                       WithMotionClassification(MotionClassification::MULTI_FINGER_SWIPE),
                       WithPointerCount(3u), WithToolType(ToolType::FINGER)));
     args.pop_front();
     ASSERT_THAT(std::get<NotifyMotionArgs>(args.front()),
                 AllOf(WithMotionAction(AMOTION_EVENT_ACTION_POINTER_UP |
                                        1 << AMOTION_EVENT_ACTION_POINTER_INDEX_SHIFT),
-                      WithGestureOffset(0, 0, EPSILON),
+                      WithGestureOffset(0, 0, EPSILON), WithGestureSwipeFingerCount(3),
                       WithMotionClassification(MotionClassification::MULTI_FINGER_SWIPE),
                       WithPointerCount(2u), WithToolType(ToolType::FINGER)));
     args.pop_front();
     ASSERT_THAT(std::get<NotifyMotionArgs>(args.front()),
                 AllOf(WithMotionAction(AMOTION_EVENT_ACTION_UP), WithGestureOffset(0, 0, EPSILON),
+                      WithGestureSwipeFingerCount(3),
                       WithMotionClassification(MotionClassification::MULTI_FINGER_SWIPE),
                       WithPointerCount(1u), WithToolType(ToolType::FINGER)));
 }
@@ -600,6 +603,7 @@ TEST_F(GestureConverterTest, FourFingerSwipe_Horizontal) {
     NotifyMotionArgs arg = std::get<NotifyMotionArgs>(args.front());
     ASSERT_THAT(arg,
                 AllOf(WithMotionAction(AMOTION_EVENT_ACTION_DOWN), WithGestureOffset(0, 0, EPSILON),
+                      WithGestureSwipeFingerCount(4),
                       WithMotionClassification(MotionClassification::MULTI_FINGER_SWIPE),
                       WithPointerCount(1u), WithToolType(ToolType::FINGER)));
     PointerCoords finger0Start = arg.pointerCoords[0];
@@ -608,7 +612,7 @@ TEST_F(GestureConverterTest, FourFingerSwipe_Horizontal) {
     ASSERT_THAT(arg,
                 AllOf(WithMotionAction(AMOTION_EVENT_ACTION_POINTER_DOWN |
                                        1 << AMOTION_EVENT_ACTION_POINTER_INDEX_SHIFT),
-                      WithGestureOffset(0, 0, EPSILON),
+                      WithGestureOffset(0, 0, EPSILON), WithGestureSwipeFingerCount(4),
                       WithMotionClassification(MotionClassification::MULTI_FINGER_SWIPE),
                       WithPointerCount(2u), WithToolType(ToolType::FINGER)));
     PointerCoords finger1Start = arg.pointerCoords[1];
@@ -617,7 +621,7 @@ TEST_F(GestureConverterTest, FourFingerSwipe_Horizontal) {
     ASSERT_THAT(arg,
                 AllOf(WithMotionAction(AMOTION_EVENT_ACTION_POINTER_DOWN |
                                        2 << AMOTION_EVENT_ACTION_POINTER_INDEX_SHIFT),
-                      WithGestureOffset(0, 0, EPSILON),
+                      WithGestureOffset(0, 0, EPSILON), WithGestureSwipeFingerCount(4),
                       WithMotionClassification(MotionClassification::MULTI_FINGER_SWIPE),
                       WithPointerCount(3u), WithToolType(ToolType::FINGER)));
     PointerCoords finger2Start = arg.pointerCoords[2];
@@ -626,7 +630,7 @@ TEST_F(GestureConverterTest, FourFingerSwipe_Horizontal) {
     ASSERT_THAT(arg,
                 AllOf(WithMotionAction(AMOTION_EVENT_ACTION_POINTER_DOWN |
                                        3 << AMOTION_EVENT_ACTION_POINTER_INDEX_SHIFT),
-                      WithGestureOffset(0, 0, EPSILON),
+                      WithGestureOffset(0, 0, EPSILON), WithGestureSwipeFingerCount(4),
                       WithMotionClassification(MotionClassification::MULTI_FINGER_SWIPE),
                       WithPointerCount(4u), WithToolType(ToolType::FINGER)));
     PointerCoords finger3Start = arg.pointerCoords[3];
@@ -635,7 +639,7 @@ TEST_F(GestureConverterTest, FourFingerSwipe_Horizontal) {
     arg = std::get<NotifyMotionArgs>(args.front());
     ASSERT_THAT(arg,
                 AllOf(WithMotionAction(AMOTION_EVENT_ACTION_MOVE),
-                      WithGestureOffset(0.01, 0, EPSILON),
+                      WithGestureOffset(0.01, 0, EPSILON), WithGestureSwipeFingerCount(4),
                       WithMotionClassification(MotionClassification::MULTI_FINGER_SWIPE),
                       WithPointerCount(4u), WithToolType(ToolType::FINGER)));
     EXPECT_EQ(arg.pointerCoords[0].getX(), finger0Start.getX() + 10);
@@ -654,7 +658,7 @@ TEST_F(GestureConverterTest, FourFingerSwipe_Horizontal) {
     arg = std::get<NotifyMotionArgs>(args.front());
     ASSERT_THAT(arg,
                 AllOf(WithMotionAction(AMOTION_EVENT_ACTION_MOVE),
-                      WithGestureOffset(0.005, 0, EPSILON),
+                      WithGestureOffset(0.005, 0, EPSILON), WithGestureSwipeFingerCount(4),
                       WithMotionClassification(MotionClassification::MULTI_FINGER_SWIPE),
                       WithPointerCount(4u), WithToolType(ToolType::FINGER)));
     EXPECT_EQ(arg.pointerCoords[0].getX(), finger0Start.getX() + 15);
@@ -672,26 +676,27 @@ TEST_F(GestureConverterTest, FourFingerSwipe_Horizontal) {
     ASSERT_THAT(std::get<NotifyMotionArgs>(args.front()),
                 AllOf(WithMotionAction(AMOTION_EVENT_ACTION_POINTER_UP |
                                        3 << AMOTION_EVENT_ACTION_POINTER_INDEX_SHIFT),
-                      WithGestureOffset(0, 0, EPSILON),
+                      WithGestureOffset(0, 0, EPSILON), WithGestureSwipeFingerCount(4),
                       WithMotionClassification(MotionClassification::MULTI_FINGER_SWIPE),
                       WithPointerCount(4u), WithToolType(ToolType::FINGER)));
     args.pop_front();
     ASSERT_THAT(std::get<NotifyMotionArgs>(args.front()),
                 AllOf(WithMotionAction(AMOTION_EVENT_ACTION_POINTER_UP |
                                        2 << AMOTION_EVENT_ACTION_POINTER_INDEX_SHIFT),
-                      WithGestureOffset(0, 0, EPSILON),
+                      WithGestureOffset(0, 0, EPSILON), WithGestureSwipeFingerCount(4),
                       WithMotionClassification(MotionClassification::MULTI_FINGER_SWIPE),
                       WithPointerCount(3u), WithToolType(ToolType::FINGER)));
     args.pop_front();
     ASSERT_THAT(std::get<NotifyMotionArgs>(args.front()),
                 AllOf(WithMotionAction(AMOTION_EVENT_ACTION_POINTER_UP |
                                        1 << AMOTION_EVENT_ACTION_POINTER_INDEX_SHIFT),
-                      WithGestureOffset(0, 0, EPSILON),
+                      WithGestureOffset(0, 0, EPSILON), WithGestureSwipeFingerCount(4),
                       WithMotionClassification(MotionClassification::MULTI_FINGER_SWIPE),
                       WithPointerCount(2u), WithToolType(ToolType::FINGER)));
     args.pop_front();
     ASSERT_THAT(std::get<NotifyMotionArgs>(args.front()),
                 AllOf(WithMotionAction(AMOTION_EVENT_ACTION_UP), WithGestureOffset(0, 0, EPSILON),
+                      WithGestureSwipeFingerCount(4),
                       WithMotionClassification(MotionClassification::MULTI_FINGER_SWIPE),
                       WithPointerCount(1u), WithToolType(ToolType::FINGER)));
 }
diff --git a/services/inputflinger/tests/TestInputListenerMatchers.h b/services/inputflinger/tests/TestInputListenerMatchers.h
index db6f2548e8..01b79ca5da 100644
--- a/services/inputflinger/tests/TestInputListenerMatchers.h
+++ b/services/inputflinger/tests/TestInputListenerMatchers.h
@@ -23,6 +23,8 @@
 #include <gtest/gtest.h>
 #include <input/Input.h>
 
+#include "TestConstants.h"
+
 namespace android {
 
 MATCHER_P(WithMotionAction, action, "MotionEvent with specified action") {
@@ -136,6 +138,15 @@ MATCHER_P2(WithGesturePinchScaleFactor, factor, epsilon,
     return fabs(argScaleFactor - factor) <= epsilon;
 }
 
+MATCHER_P(WithGestureSwipeFingerCount, count,
+          "InputEvent with specified touchpad swipe finger count") {
+    const auto argFingerCount =
+            arg.pointerCoords[0].getAxisValue(AMOTION_EVENT_AXIS_GESTURE_SWIPE_FINGER_COUNT);
+    *result_listener << "expected gesture swipe finger count " << count << " but got "
+                     << argFingerCount;
+    return fabs(argFingerCount - count) <= EPSILON;
+}
+
 MATCHER_P(WithPressure, pressure, "InputEvent with specified pressure") {
     const auto argPressure = arg.pointerCoords[0].getAxisValue(AMOTION_EVENT_AXIS_PRESSURE);
     *result_listener << "expected pressure " << pressure << ", but got " << argPressure;