Change calculateResampledCoords to preserve PointerCoords data

Changed the logic of calculateResampledCoords to not dispose information
of PointerCoords.

Bug: 297226446
Flag: EXEMPT bugfix
Test: TEST=libinput_tests; m $TEST && $ANDROID_HOST_OUT/nativetest64/$TEST/$TEST --gtest_filter="ResamplerTest*"
Change-Id: I81285a65ebb571d11ba35bd18072b5ce18763d2d

2 files changed, 34 insertions, 2 deletions

diff --git a/libs/input/Resampler.cpp b/libs/input/Resampler.cpp
index af8354c70c..836a97af53 100644
--- a/libs/input/Resampler.cpp
+++ b/libs/input/Resampler.cpp
@@ -62,8 +62,8 @@ inline float lerp(float a, float b, float alpha) {
 
 const PointerCoords calculateResampledCoords(const PointerCoords& a, const PointerCoords& b,
                                              const float alpha) {
-    // Ensure the struct PointerCoords is initialized.
-    PointerCoords resampledCoords{};
+    // We use the value of alpha to initialize resampledCoords with the latest sample information.
+    PointerCoords resampledCoords = (alpha < 1.0f) ? a : b;
     resampledCoords.isResampled = true;
     resampledCoords.setAxisValue(AMOTION_EVENT_AXIS_X, lerp(a.getX(), b.getX(), alpha));
     resampledCoords.setAxisValue(AMOTION_EVENT_AXIS_Y, lerp(a.getY(), b.getY(), alpha));
diff --git a/libs/input/tests/Resampler_test.cpp b/libs/input/tests/Resampler_test.cpp
index e160ca06d0..135f8b41a2 100644
--- a/libs/input/tests/Resampler_test.cpp
+++ b/libs/input/tests/Resampler_test.cpp
@@ -229,6 +229,38 @@ void ResamplerTest::assertMotionEventIsNotResampled(const MotionEvent& original,
     EXPECT_EQ(originalSampleSize, notResampledSampleSize);
 }
 
+TEST_F(ResamplerTest, NonResampledAxesArePreserved) {
+    constexpr float TOUCH_MAJOR_VALUE = 1.0f;
+
+    MotionEvent motionEvent =
+            InputStream{{{5ms, {{.id = 0, .x = 1.0f, .y = 1.0f, .isResampled = false}}}},
+                        AMOTION_EVENT_ACTION_MOVE};
+
+    constexpr std::chrono::nanoseconds eventTime{10ms};
+    PointerCoords pointerCoords{};
+    pointerCoords.isResampled = false;
+    pointerCoords.setAxisValue(AMOTION_EVENT_AXIS_X, 2.0f);
+    pointerCoords.setAxisValue(AMOTION_EVENT_AXIS_Y, 2.0f);
+    pointerCoords.setAxisValue(AMOTION_EVENT_AXIS_TOUCH_MAJOR, TOUCH_MAJOR_VALUE);
+
+    motionEvent.addSample(eventTime.count(), &pointerCoords, motionEvent.getId());
+
+    const InputMessage futureSample =
+            InputSample{15ms, {{.id = 0, .x = 3.0f, .y = 4.0f, .isResampled = false}}};
+
+    const MotionEvent originalMotionEvent = motionEvent;
+
+    mResampler->resampleMotionEvent(11ms, motionEvent, &futureSample);
+
+    EXPECT_EQ(motionEvent.getTouchMajor(0), TOUCH_MAJOR_VALUE);
+
+    assertMotionEventIsResampledAndCoordsNear(originalMotionEvent, motionEvent,
+                                              Pointer{.id = 0,
+                                                      .x = 2.2f,
+                                                      .y = 2.4f,
+                                                      .isResampled = true});
+}
+
 TEST_F(ResamplerTest, SinglePointerNotEnoughDataToResample) {
     MotionEvent motionEvent =
             InputStream{{{5ms, {{.id = 0, .x = 1.0f, .y = 1.0f, .isResampled = false}}}},