diff --git a/include/input/InputTransport.h b/include/input/InputTransport.h
index 9449474..ea1d2aa 100644
--- a/include/input/InputTransport.h
+++ b/include/input/InputTransport.h
@@ -381,6 +381,18 @@
             }
         }
 
+        void initializeFrom(const History& other) {
+            eventTime = other.eventTime;
+            idBits = other.idBits; // temporary copy
+            for (size_t i = 0; i < other.idBits.count(); i++) {
+                uint32_t id = idBits.clearFirstMarkedBit();
+                int32_t index = other.idToIndex[id];
+                idToIndex[id] = index;
+                pointers[index].copyFrom(other.pointers[index]);
+            }
+            idBits = other.idBits; // final copy
+        }
+
         const PointerCoords& getPointerById(uint32_t id) const {
             return pointers[idToIndex[id]];
         }
@@ -455,7 +467,6 @@
             int32_t* displayId);
 
     void updateTouchState(InputMessage& msg);
-    bool rewriteMessage(const TouchState& state, InputMessage& msg);
     void resampleTouchState(nsecs_t frameTime, MotionEvent* event,
             const InputMessage *next);
 
@@ -464,6 +475,7 @@
 
     status_t sendUnchainedFinishedSignal(uint32_t seq, bool handled);
 
+    static void rewriteMessage(TouchState& state, InputMessage& msg);
     static void initializeKeyEvent(KeyEvent* event, const InputMessage* msg);
     static void initializeMotionEvent(MotionEvent* event, const InputMessage* msg);
     static void addSample(MotionEvent* event, const InputMessage* msg);
diff --git a/libs/input/InputTransport.cpp b/libs/input/InputTransport.cpp
index 9abd04c..905d336 100644
--- a/libs/input/InputTransport.cpp
+++ b/libs/input/InputTransport.cpp
@@ -614,10 +614,7 @@
         if (index >= 0) {
             TouchState& touchState = mTouchStates.editItemAt(index);
             touchState.addHistory(msg);
-            bool messageRewritten = rewriteMessage(touchState, msg);
-            if (!messageRewritten) {
-                touchState.lastResample.idBits.clear();
-            }
+            rewriteMessage(touchState, msg);
         }
         break;
     }
@@ -645,7 +642,7 @@
     case AMOTION_EVENT_ACTION_SCROLL: {
         ssize_t index = findTouchState(deviceId, source);
         if (index >= 0) {
-            const TouchState& touchState = mTouchStates.itemAt(index);
+            TouchState& touchState = mTouchStates.editItemAt(index);
             rewriteMessage(touchState, msg);
         }
         break;
@@ -655,7 +652,7 @@
     case AMOTION_EVENT_ACTION_CANCEL: {
         ssize_t index = findTouchState(deviceId, source);
         if (index >= 0) {
-            const TouchState& touchState = mTouchStates.itemAt(index);
+            TouchState& touchState = mTouchStates.editItemAt(index);
             rewriteMessage(touchState, msg);
             mTouchStates.removeAt(index);
         }
@@ -664,28 +661,38 @@
     }
 }
 
-bool InputConsumer::rewriteMessage(const TouchState& state, InputMessage& msg) {
-    bool messageRewritten = false;
+/**
+ * Replace the coordinates in msg with the coordinates in lastResample, if necessary.
+ *
+ * If lastResample is no longer valid for a specific pointer (i.e. the lastResample time
+ * is in the past relative to msg and the past two events do not contain identical coordinates),
+ * then invalidate the lastResample data for that pointer.
+ * If the two past events have identical coordinates, then lastResample data for that pointer will
+ * remain valid, and will be used to replace these coordinates. Thus, if a certain coordinate x0 is
+ * resampled to the new value x1, then x1 will always be used to replace x0 until some new value
+ * not equal to x0 is received.
+ */
+void InputConsumer::rewriteMessage(TouchState& state, InputMessage& msg) {
     nsecs_t eventTime = msg.body.motion.eventTime;
     for (uint32_t i = 0; i < msg.body.motion.pointerCount; i++) {
         uint32_t id = msg.body.motion.pointers[i].properties.id;
         if (state.lastResample.idBits.hasBit(id)) {
-            PointerCoords& msgCoords = msg.body.motion.pointers[i].coords;
-            const PointerCoords& resampleCoords = state.lastResample.getPointerById(id);
             if (eventTime < state.lastResample.eventTime ||
                     state.recentCoordinatesAreIdentical(id)) {
-                msgCoords.setAxisValue(AMOTION_EVENT_AXIS_X, resampleCoords.getX());
-                msgCoords.setAxisValue(AMOTION_EVENT_AXIS_Y, resampleCoords.getY());
+                PointerCoords& msgCoords = msg.body.motion.pointers[i].coords;
+                const PointerCoords& resampleCoords = state.lastResample.getPointerById(id);
 #if DEBUG_RESAMPLING
                 ALOGD("[%d] - rewrite (%0.3f, %0.3f), old (%0.3f, %0.3f)", id,
                         resampleCoords.getX(), resampleCoords.getY(),
                         msgCoords.getX(), msgCoords.getY());
 #endif
-                messageRewritten = true;
+                msgCoords.setAxisValue(AMOTION_EVENT_AXIS_X, resampleCoords.getX());
+                msgCoords.setAxisValue(AMOTION_EVENT_AXIS_Y, resampleCoords.getY());
+            } else {
+                state.lastResample.idBits.clearBit(id);
             }
         }
     }
-    return messageRewritten;
 }
 
 void InputConsumer::resampleTouchState(nsecs_t sampleTime, MotionEvent* event,
@@ -713,7 +720,6 @@
     }
 
     // Ensure that the current sample has all of the pointers that need to be reported.
-    // Also ensure that the past two "real" touch events do not contain duplicate coordinates
     const History* current = touchState.getHistory(0);
     size_t pointerCount = event->getPointerCount();
     for (size_t i = 0; i < pointerCount; i++) {
@@ -724,12 +730,6 @@
 #endif
             return;
         }
-        if (touchState.recentCoordinatesAreIdentical(id)) {
-#if DEBUG_RESAMPLING
-            ALOGD("Not resampled, past two historical events have duplicate coordinates");
-#endif
-            return;
-        }
     }
 
     // Find the data to use for resampling.
@@ -783,18 +783,32 @@
     }
 
     // Resample touch coordinates.
+    History oldLastResample;
+    oldLastResample.initializeFrom(touchState.lastResample);
     touchState.lastResample.eventTime = sampleTime;
     touchState.lastResample.idBits.clear();
     for (size_t i = 0; i < pointerCount; i++) {
         uint32_t id = event->getPointerId(i);
         touchState.lastResample.idToIndex[id] = i;
         touchState.lastResample.idBits.markBit(id);
+        if (oldLastResample.hasPointerId(id) && touchState.recentCoordinatesAreIdentical(id)) {
+            // We maintain the previously resampled value for this pointer (stored in
+            // oldLastResample) when the coordinates for this pointer haven't changed since then.
+            // This way we don't introduce artificial jitter when pointers haven't actually moved.
+
+            // We know here that the coordinates for the pointer haven't changed because we
+            // would've cleared the resampled bit in rewriteMessage if they had. We can't modify
+            // lastResample in place becasue the mapping from pointer ID to index may have changed.
+            touchState.lastResample.pointers[i].copyFrom(oldLastResample.getPointerById(id));
+            continue;
+        }
+
         PointerCoords& resampledCoords = touchState.lastResample.pointers[i];
         const PointerCoords& currentCoords = current->getPointerById(id);
+        resampledCoords.copyFrom(currentCoords);
         if (other->idBits.hasBit(id)
                 && shouldResampleTool(event->getToolType(i))) {
             const PointerCoords& otherCoords = other->getPointerById(id);
-            resampledCoords.copyFrom(currentCoords);
             resampledCoords.setAxisValue(AMOTION_EVENT_AXIS_X,
                     lerp(currentCoords.getX(), otherCoords.getX(), alpha));
             resampledCoords.setAxisValue(AMOTION_EVENT_AXIS_Y,
@@ -808,7 +822,6 @@
                     alpha);
 #endif
         } else {
-            resampledCoords.copyFrom(currentCoords);
 #if DEBUG_RESAMPLING
             ALOGD("[%d] - out (%0.3f, %0.3f), cur (%0.3f, %0.3f)",
                     id, resampledCoords.getX(), resampledCoords.getY(),
diff --git a/libs/input/tests/Android.bp b/libs/input/tests/Android.bp
index 0028655..8137e3d 100644
--- a/libs/input/tests/Android.bp
+++ b/libs/input/tests/Android.bp
@@ -9,8 +9,8 @@
     ],
     cflags: [
         "-Wall",
+        "-Wextra",
         "-Werror",
-        "-Wno-error=sign-compare", // to fix later
         "-Wno-unused-variable",
     ],
     shared_libs: [
diff --git a/libs/input/tests/InputEvent_test.cpp b/libs/input/tests/InputEvent_test.cpp
index 3fb1c6d..fd3b7c8 100644
--- a/libs/input/tests/InputEvent_test.cpp
+++ b/libs/input/tests/InputEvent_test.cpp
@@ -184,7 +184,7 @@
 
     ASSERT_EQ(AINPUT_EVENT_TYPE_KEY, event.getType());
     ASSERT_EQ(2, event.getDeviceId());
-    ASSERT_EQ(AINPUT_SOURCE_GAMEPAD, event.getSource());
+    ASSERT_EQ(static_cast<int>(AINPUT_SOURCE_GAMEPAD), event.getSource());
     ASSERT_EQ(AKEY_EVENT_ACTION_DOWN, event.getAction());
     ASSERT_EQ(AKEY_EVENT_FLAG_FROM_SYSTEM, event.getFlags());
     ASSERT_EQ(AKEYCODE_BUTTON_X, event.getKeyCode());
@@ -196,7 +196,7 @@
 
     // Set source.
     event.setSource(AINPUT_SOURCE_JOYSTICK);
-    ASSERT_EQ(AINPUT_SOURCE_JOYSTICK, event.getSource());
+    ASSERT_EQ(static_cast<int>(AINPUT_SOURCE_JOYSTICK), event.getSource());
 }
 
 
@@ -300,7 +300,7 @@
     // Check properties.
     ASSERT_EQ(AINPUT_EVENT_TYPE_MOTION, event->getType());
     ASSERT_EQ(2, event->getDeviceId());
-    ASSERT_EQ(AINPUT_SOURCE_TOUCHSCREEN, event->getSource());
+    ASSERT_EQ(static_cast<int>(AINPUT_SOURCE_TOUCHSCREEN), event->getSource());
     ASSERT_EQ(AMOTION_EVENT_ACTION_MOVE, event->getAction());
     ASSERT_EQ(AMOTION_EVENT_FLAG_WINDOW_IS_OBSCURED, event->getFlags());
     ASSERT_EQ(AMOTION_EVENT_EDGE_FLAG_TOP, event->getEdgeFlags());
@@ -432,7 +432,7 @@
 
     // Set source.
     event.setSource(AINPUT_SOURCE_JOYSTICK);
-    ASSERT_EQ(AINPUT_SOURCE_JOYSTICK, event.getSource());
+    ASSERT_EQ(static_cast<int>(AINPUT_SOURCE_JOYSTICK), event.getSource());
 
     // Set action.
     event.setAction(AMOTION_EVENT_ACTION_CANCEL);
diff --git a/libs/input/tests/InputPublisherAndConsumer_test.cpp b/libs/input/tests/InputPublisherAndConsumer_test.cpp
index a136738..34c52d0 100644
--- a/libs/input/tests/InputPublisherAndConsumer_test.cpp
+++ b/libs/input/tests/InputPublisherAndConsumer_test.cpp
@@ -89,8 +89,9 @@
 
     uint32_t consumeSeq;
     InputEvent* event;
+    int32_t displayId;
     status = mConsumer->consume(&mEventFactory, true /*consumeBatches*/, -1, &consumeSeq, &event,
-            0);
+            &displayId);
     ASSERT_EQ(OK, status)
             << "consumer consume should return OK";
 
@@ -133,7 +134,7 @@
     const uint32_t seq = 15;
     const int32_t deviceId = 1;
     const int32_t source = AINPUT_SOURCE_TOUCHSCREEN;
-    const int32_t displayId = 0;
+    int32_t displayId = 0;
     const int32_t action = AMOTION_EVENT_ACTION_MOVE;
     const int32_t actionButton = 0;
     const int32_t flags = AMOTION_EVENT_FLAG_WINDOW_IS_OBSCURED;
@@ -176,7 +177,7 @@
     uint32_t consumeSeq;
     InputEvent* event;
     status = mConsumer->consume(&mEventFactory, true /*consumeBatches*/, -1, &consumeSeq, &event,
-            0);
+            &displayId);
     ASSERT_EQ(OK, status)
             << "consumer consume should return OK";
 
diff --git a/services/inputflinger/InputDispatcher.cpp b/services/inputflinger/InputDispatcher.cpp
index 98e135d..48fd0cf 100644
--- a/services/inputflinger/InputDispatcher.cpp
+++ b/services/inputflinger/InputDispatcher.cpp
@@ -1992,10 +1992,10 @@
             const PointerCoords* usingCoords = motionEntry->pointerCoords;
 
             // Set the X and Y offset depending on the input source.
-            float xOffset, yOffset, scaleFactor;
+            float xOffset, yOffset;
             if ((motionEntry->source & AINPUT_SOURCE_CLASS_POINTER)
                     && !(dispatchEntry->targetFlags & InputTarget::FLAG_ZERO_COORDS)) {
-                scaleFactor = dispatchEntry->scaleFactor;
+                float scaleFactor = dispatchEntry->scaleFactor;
                 xOffset = dispatchEntry->xOffset * scaleFactor;
                 yOffset = dispatchEntry->yOffset * scaleFactor;
                 if (scaleFactor != 1.0f) {
@@ -2008,7 +2008,6 @@
             } else {
                 xOffset = 0.0f;
                 yOffset = 0.0f;
-                scaleFactor = 1.0f;
 
                 // We don't want the dispatch target to know.
                 if (dispatchEntry->targetFlags & InputTarget::FLAG_ZERO_COORDS) {
diff --git a/services/inputflinger/InputReader.cpp b/services/inputflinger/InputReader.cpp
index 420d06b..9aef5b8 100644
--- a/services/inputflinger/InputReader.cpp
+++ b/services/inputflinger/InputReader.cpp
@@ -2260,7 +2260,7 @@
     dump.appendFormat(INDENT3 "Orientation: %d\n", mOrientation);
     dump.appendFormat(INDENT3 "KeyDowns: %zu keys currently down\n", mKeyDowns.size());
     dump.appendFormat(INDENT3 "MetaState: 0x%0x\n", mMetaState);
-    dump.appendFormat(INDENT3 "DownTime: %lld\n", (long long)mDownTime);
+    dump.appendFormat(INDENT3 "DownTime: %" PRId64 "\n", mDownTime);
 }
 
 
@@ -2621,7 +2621,7 @@
     dump.appendFormat(INDENT3 "Orientation: %d\n", mOrientation);
     dump.appendFormat(INDENT3 "ButtonState: 0x%08x\n", mButtonState);
     dump.appendFormat(INDENT3 "Down: %s\n", toString(isPointerDown(mButtonState)));
-    dump.appendFormat(INDENT3 "DownTime: %lld\n", (long long)mDownTime);
+    dump.appendFormat(INDENT3 "DownTime: %" PRId64 "\n", mDownTime);
 }
 
 void CursorInputMapper::configure(nsecs_t when,
@@ -5510,18 +5510,15 @@
     // Otherwise choose an arbitrary remaining pointer.
     // This guarantees we always have an active touch id when there is at least one pointer.
     // We keep the same active touch id for as long as possible.
-    bool activeTouchChanged = false;
     int32_t lastActiveTouchId = mPointerGesture.activeTouchId;
     int32_t activeTouchId = lastActiveTouchId;
     if (activeTouchId < 0) {
         if (!mCurrentCookedState.fingerIdBits.isEmpty()) {
-            activeTouchChanged = true;
             activeTouchId = mPointerGesture.activeTouchId =
                     mCurrentCookedState.fingerIdBits.firstMarkedBit();
             mPointerGesture.firstTouchTime = when;
         }
     } else if (!mCurrentCookedState.fingerIdBits.hasBit(activeTouchId)) {
-        activeTouchChanged = true;
         if (!mCurrentCookedState.fingerIdBits.isEmpty()) {
             activeTouchId = mPointerGesture.activeTouchId =
                     mCurrentCookedState.fingerIdBits.firstMarkedBit();
@@ -5617,7 +5614,6 @@
             }
             if (bestId >= 0 && bestId != activeTouchId) {
                 mPointerGesture.activeTouchId = activeTouchId = bestId;
-                activeTouchChanged = true;
 #if DEBUG_GESTURES
                 ALOGD("Gestures: BUTTON_CLICK_OR_DRAG switched pointers, "
                         "bestId=%d, bestSpeed=%0.3f", bestId, bestSpeed);