MotionEvent: Get offsets in raw coordinate space

MotionEvents store the underlying axis values in the coordinate space of
the physical display, or "untransformed" space. The MotionEvent's
mRawTransform takes those coordinates into the coordinate space of the
logical display, or "raw" coordinates. The MotionEvent's mTransform
takes those coordinates into the window/View's local coordinates.

Previously, getting the motion event offset would return the offset with
respect to the origin of the "untransformed" space. This is of little
value to callers, since they are expecting the offset in "raw"
coordinates, which is the offset with respect to the logical display's
origin.

To calculate the raw offset, we calculate where the raw point (0, 0)
would map to in untransformed coordinates by applying the inverse raw
transform, and then apply the window transform.

Bug: 249340921
Test: atest libinput_tests
Test: atest inputflinger_tests
Change-Id: Iadbdde4dd45b5527b73be863b198b4c9a9e713cc

4 files changed, 44 insertions, 12 deletions

diff --git a/include/input/Input.h b/include/input/Input.h
index a84dcfc63c..027e4a5bdc 100644
--- a/include/input/Input.h
+++ b/include/input/Input.h
@@ -662,10 +662,6 @@ public:
 
     inline void setActionButton(int32_t button) { mActionButton = button; }
 
-    inline float getXOffset() const { return mTransform.tx(); }
-
-    inline float getYOffset() const { return mTransform.ty(); }
-
     inline const ui::Transform& getTransform() const { return mTransform; }
 
     std::optional<ui::Rotation> getSurfaceRotation() const;
@@ -876,6 +872,22 @@ public:
 
     void offsetLocation(float xOffset, float yOffset);
 
+    /**
+     * Get the X offset of this motion event relative to the origin of the raw coordinate space.
+     *
+     * In practice, this is the delta that was added to the raw screen coordinates (i.e. in logical
+     * display space) to adjust for the absolute position of the containing windows and views.
+     */
+    float getRawXOffset() const;
+
+    /**
+     * Get the Y offset of this motion event relative to the origin of the raw coordinate space.
+     *
+     * In practice, this is the delta that was added to the raw screen coordinates (i.e. in logical
+     * display space) to adjust for the absolute position of the containing windows and views.
+     */
+    float getRawYOffset() const;
+
     void scale(float globalScaleFactor);
 
     // Set 3x3 perspective matrix transformation.
diff --git a/libs/input/Input.cpp b/libs/input/Input.cpp
index 9e0ce1db33..63f5ca4c58 100644
--- a/libs/input/Input.cpp
+++ b/libs/input/Input.cpp
@@ -690,6 +690,18 @@ void MotionEvent::offsetLocation(float xOffset, float yOffset) {
     mTransform.set(currXOffset + xOffset, currYOffset + yOffset);
 }
 
+float MotionEvent::getRawXOffset() const {
+    // This is equivalent to the x-coordinate of the point that the origin of the raw coordinate
+    // space maps to.
+    return (mTransform * mRawTransform.inverse()).tx();
+}
+
+float MotionEvent::getRawYOffset() const {
+    // This is equivalent to the y-coordinate of the point that the origin of the raw coordinate
+    // space maps to.
+    return (mTransform * mRawTransform.inverse()).ty();
+}
+
 void MotionEvent::scale(float globalScaleFactor) {
     mTransform.set(mTransform.tx() * globalScaleFactor, mTransform.ty() * globalScaleFactor);
     mRawTransform.set(mRawTransform.tx() * globalScaleFactor,
diff --git a/libs/input/tests/InputEvent_test.cpp b/libs/input/tests/InputEvent_test.cpp
index a9655730fc..ba09ece925 100644
--- a/libs/input/tests/InputEvent_test.cpp
+++ b/libs/input/tests/InputEvent_test.cpp
@@ -358,8 +358,10 @@ void MotionEventTest::assertEqualsEventWithHistory(const MotionEvent* event) {
     ASSERT_EQ(AMOTION_EVENT_BUTTON_PRIMARY, event->getButtonState());
     ASSERT_EQ(MotionClassification::NONE, event->getClassification());
     EXPECT_EQ(mTransform, event->getTransform());
-    ASSERT_EQ(X_OFFSET, event->getXOffset());
-    ASSERT_EQ(Y_OFFSET, event->getYOffset());
+    ASSERT_NEAR((-RAW_X_OFFSET / RAW_X_SCALE) * X_SCALE + X_OFFSET, event->getRawXOffset(),
+                EPSILON);
+    ASSERT_NEAR((-RAW_Y_OFFSET / RAW_Y_SCALE) * Y_SCALE + Y_OFFSET, event->getRawYOffset(),
+                EPSILON);
     ASSERT_EQ(2.0f, event->getXPrecision());
     ASSERT_EQ(2.1f, event->getYPrecision());
     ASSERT_EQ(ARBITRARY_DOWN_TIME, event->getDownTime());
@@ -557,22 +559,26 @@ TEST_F(MotionEventTest, CopyFrom_DoNotKeepHistory) {
 TEST_F(MotionEventTest, OffsetLocation) {
     MotionEvent event;
     initializeEventWithHistory(&event);
+    const float xOffset = event.getRawXOffset();
+    const float yOffset = event.getRawYOffset();
 
     event.offsetLocation(5.0f, -2.0f);
 
-    ASSERT_EQ(X_OFFSET + 5.0f, event.getXOffset());
-    ASSERT_EQ(Y_OFFSET - 2.0f, event.getYOffset());
+    ASSERT_EQ(xOffset + 5.0f, event.getRawXOffset());
+    ASSERT_EQ(yOffset - 2.0f, event.getRawYOffset());
 }
 
 TEST_F(MotionEventTest, Scale) {
     MotionEvent event;
     initializeEventWithHistory(&event);
     const float unscaledOrientation = event.getOrientation(0);
+    const float unscaledXOffset = event.getRawXOffset();
+    const float unscaledYOffset = event.getRawYOffset();
 
     event.scale(2.0f);
 
-    ASSERT_EQ(X_OFFSET * 2, event.getXOffset());
-    ASSERT_EQ(Y_OFFSET * 2, event.getYOffset());
+    ASSERT_EQ(unscaledXOffset * 2, event.getRawXOffset());
+    ASSERT_EQ(unscaledYOffset * 2, event.getRawYOffset());
 
     ASSERT_NEAR((RAW_X_OFFSET + 210 * RAW_X_SCALE) * 2, event.getRawX(0), EPSILON);
     ASSERT_NEAR((RAW_Y_OFFSET + 211 * RAW_Y_SCALE) * 2, event.getRawY(0), EPSILON);
diff --git a/libs/input/tests/InputPublisherAndConsumer_test.cpp b/libs/input/tests/InputPublisherAndConsumer_test.cpp
index 35430207f9..30f9a42519 100644
--- a/libs/input/tests/InputPublisherAndConsumer_test.cpp
+++ b/libs/input/tests/InputPublisherAndConsumer_test.cpp
@@ -135,8 +135,10 @@ void verifyArgsEqualToEvent(const PublishMotionArgs& args, const MotionEvent& mo
     EXPECT_EQ(args.buttonState, motionEvent.getButtonState());
     EXPECT_EQ(args.classification, motionEvent.getClassification());
     EXPECT_EQ(args.transform, motionEvent.getTransform());
-    EXPECT_EQ(args.xOffset, motionEvent.getXOffset());
-    EXPECT_EQ(args.yOffset, motionEvent.getYOffset());
+    EXPECT_NEAR((-args.rawXOffset / args.rawXScale) * args.xScale + args.xOffset,
+                motionEvent.getRawXOffset(), EPSILON);
+    EXPECT_NEAR((-args.rawYOffset / args.rawYScale) * args.yScale + args.yOffset,
+                motionEvent.getRawYOffset(), EPSILON);
     EXPECT_EQ(args.xPrecision, motionEvent.getXPrecision());
     EXPECT_EQ(args.yPrecision, motionEvent.getYPrecision());
     EXPECT_NEAR(args.xCursorPosition, motionEvent.getRawXCursorPosition(), EPSILON);