Fix resampling logic for duplicate events.

When events with identical coordinates are
reported by the input driver, resampling can lead to
false change of direction due to extrapolation.
The added logic will compare the current event to the
previous event, and will use the previously resampled values
for the new event if the raw (as reported by the driver)
coordinates of the two events match.
This commit makes events with identical coordinates possible,
so it must be submitted together with the new impulse-based
VelocityTracker strategy commit. The currently used 2nd degree
polynomical unweighted least squares strategy cannot handle
consecutive events with identical coordinates.

Bug: 35412046
Test: Recorded bad scroll event on swordfish, and replayed
the event to reproduce this bug. To twitch is no longer observed.
Also tested common usecase scenarios on sailfish, no regressions observed.

Change-Id: Icb5cf6c76959f3514b8b94c09e38cc5434f31b23
(cherry picked from commit 0aeec07971d86c635412c672bd69d91f589a0cd9)
Merged-In: Icb5cf6c76959f3514b8b94c09e38cc5434f31b23

diff --git a/include/input/InputTransport.h b/include/input/InputTransport.h
index efa1ffb..0dd15b1 100644 (file)
--- a/include/input/InputTransport.h
+++ b/include/input/InputTransport.h
@@ -370,14 +370,14 @@ private:
         int32_t idToIndex[MAX_POINTER_ID + 1];
         PointerCoords pointers[MAX_POINTERS];
 
-        void initializeFrom(const InputMessage* msg) {
-            eventTime = msg->body.motion.eventTime;
+        void initializeFrom(const InputMessage& msg) {
+            eventTime = msg.body.motion.eventTime;
             idBits.clear();
-            for (uint32_t i = 0; i < msg->body.motion.pointerCount; i++) {
-                uint32_t id = msg->body.motion.pointers[i].properties.id;
+            for (uint32_t i = 0; i < msg.body.motion.pointerCount; i++) {
+                uint32_t id = msg.body.motion.pointers[i].properties.id;
                 idBits.markBit(id);
                 idToIndex[id] = i;
-                pointers[i].copyFrom(msg->body.motion.pointers[i].coords);
+                pointers[i].copyFrom(msg.body.motion.pointers[i].coords);
             }
         }
 
@@ -402,7 +402,7 @@ private:
             lastResample.idBits.clear();
         }
 
-        void addHistory(const InputMessage* msg) {
+        void addHistory(const InputMessage& msg) {
             historyCurrent ^= 1;
             if (historySize < 2) {
                 historySize += 1;
@@ -413,6 +413,21 @@ private:
         const History* getHistory(size_t index) const {
             return &history[(historyCurrent + index) & 1];
         }
+
+        bool recentCoordinatesAreIdentical(uint32_t id) const {
+            // Return true if the two most recently received "raw" coordinates are identical
+            if (historySize < 2) {
+                return false;
+            }
+            float currentX = getHistory(0)->getPointerById(id).getX();
+            float currentY = getHistory(0)->getPointerById(id).getY();
+            float previousX = getHistory(1)->getPointerById(id).getX();
+            float previousY = getHistory(1)->getPointerById(id).getY();
+            if (currentX == previousX && currentY == previousY) {
+                return true;
+            }
+            return false;
+        }
     };
     Vector<TouchState> mTouchStates;
 
@@ -432,8 +447,8 @@ private:
             Batch& batch, size_t count, uint32_t* outSeq, InputEvent** outEvent,
             int32_t* displayId);
 
-    void updateTouchState(InputMessage* msg);
-    void rewriteMessage(const TouchState& state, InputMessage* msg);
+    void updateTouchState(InputMessage& msg);
+    bool rewriteMessage(const TouchState& state, InputMessage& msg);
     void resampleTouchState(nsecs_t frameTime, MotionEvent* event,
             const InputMessage *next);
 

diff --git a/libs/input/InputTransport.cpp b/libs/input/InputTransport.cpp
index d5c5927..d8dc957 100644 (file)
--- a/libs/input/InputTransport.cpp
+++ b/libs/input/InputTransport.cpp
@@ -496,7 +496,7 @@ status_t InputConsumer::consume(InputEventFactoryInterface* factory,
             MotionEvent* motionEvent = factory->createMotionEvent();
             if (! motionEvent) return NO_MEMORY;
 
-            updateTouchState(&mMsg);
+            updateTouchState(mMsg);
             initializeMotionEvent(motionEvent, &mMsg);
             *outSeq = mMsg.body.motion.seq;
             *outEvent = motionEvent;
@@ -564,7 +564,7 @@ status_t InputConsumer::consumeSamples(InputEventFactoryInterface* factory,
     uint32_t chain = 0;
     for (size_t i = 0; i < count; i++) {
         InputMessage& msg = batch.samples.editItemAt(i);
-        updateTouchState(&msg);
+        updateTouchState(msg);
         if (i) {
             SeqChain seqChain;
             seqChain.seq = msg.body.motion.seq;
@@ -584,20 +584,19 @@ status_t InputConsumer::consumeSamples(InputEventFactoryInterface* factory,
     return OK;
 }
 
-void InputConsumer::updateTouchState(InputMessage* msg) {
+void InputConsumer::updateTouchState(InputMessage& msg) {
     if (!mResampleTouch ||
-            !(msg->body.motion.source & AINPUT_SOURCE_CLASS_POINTER)) {
+            !(msg.body.motion.source & AINPUT_SOURCE_CLASS_POINTER)) {
         return;
     }
 
-    int32_t deviceId = msg->body.motion.deviceId;
-    int32_t source = msg->body.motion.source;
-    nsecs_t eventTime = msg->body.motion.eventTime;
+    int32_t deviceId = msg.body.motion.deviceId;
+    int32_t source = msg.body.motion.source;
 
     // Update the touch state history to incorporate the new input message.
     // If the message is in the past relative to the most recently produced resampled
     // touch, then use the resampled time and coordinates instead.
-    switch (msg->body.motion.action & AMOTION_EVENT_ACTION_MASK) {
+    switch (msg.body.motion.action & AMOTION_EVENT_ACTION_MASK) {
     case AMOTION_EVENT_ACTION_DOWN: {
         ssize_t index = findTouchState(deviceId, source);
         if (index < 0) {
@@ -615,9 +614,8 @@ void InputConsumer::updateTouchState(InputMessage* msg) {
         if (index >= 0) {
             TouchState& touchState = mTouchStates.editItemAt(index);
             touchState.addHistory(msg);
-            if (eventTime < touchState.lastResample.eventTime) {
-                rewriteMessage(touchState, msg);
-            } else {
+            bool messageRewritten = rewriteMessage(touchState, msg);
+            if (!messageRewritten) {
                 touchState.lastResample.idBits.clear();
             }
         }
@@ -628,7 +626,7 @@ void InputConsumer::updateTouchState(InputMessage* msg) {
         ssize_t index = findTouchState(deviceId, source);
         if (index >= 0) {
             TouchState& touchState = mTouchStates.editItemAt(index);
-            touchState.lastResample.idBits.clearBit(msg->body.motion.getActionId());
+            touchState.lastResample.idBits.clearBit(msg.body.motion.getActionId());
             rewriteMessage(touchState, msg);
         }
         break;
@@ -639,7 +637,7 @@ void InputConsumer::updateTouchState(InputMessage* msg) {
         if (index >= 0) {
             TouchState& touchState = mTouchStates.editItemAt(index);
             rewriteMessage(touchState, msg);
-            touchState.lastResample.idBits.clearBit(msg->body.motion.getActionId());
+            touchState.lastResample.idBits.clearBit(msg.body.motion.getActionId());
         }
         break;
     }
@@ -666,23 +664,28 @@ void InputConsumer::updateTouchState(InputMessage* msg) {
     }
 }
 
-void InputConsumer::rewriteMessage(const TouchState& state, InputMessage* msg) {
-    for (uint32_t i = 0; i < msg->body.motion.pointerCount; i++) {
-        uint32_t id = msg->body.motion.pointers[i].properties.id;
+bool InputConsumer::rewriteMessage(const TouchState& state, InputMessage& msg) {
+    bool messageRewritten = false;
+    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;
+            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());
 #if DEBUG_RESAMPLING
-            ALOGD("[%d] - rewrite (%0.3f, %0.3f), old (%0.3f, %0.3f)", id,
-                    resampleCoords.getAxisValue(AMOTION_EVENT_AXIS_X),
-                    resampleCoords.getAxisValue(AMOTION_EVENT_AXIS_Y),
-                    msgCoords.getAxisValue(AMOTION_EVENT_AXIS_X),
-                    msgCoords.getAxisValue(AMOTION_EVENT_AXIS_Y));
+                ALOGD("[%d] - rewrite (%0.3f, %0.3f), old (%0.3f, %0.3f)", id,
+                        resampleCoords.getX(), resampleCoords.getY(),
+                        msgCoords.getX(), msgCoords.getY());
 #endif
-            msgCoords.setAxisValue(AMOTION_EVENT_AXIS_X, resampleCoords.getX());
-            msgCoords.setAxisValue(AMOTION_EVENT_AXIS_Y, resampleCoords.getY());
+                messageRewritten = true;
+            }
         }
     }
+    return messageRewritten;
 }
 
 void InputConsumer::resampleTouchState(nsecs_t sampleTime, MotionEvent* event,
@@ -710,6 +713,7 @@ void InputConsumer::resampleTouchState(nsecs_t sampleTime, MotionEvent* event,
     }
 
     // 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++) {
@@ -720,6 +724,12 @@ void InputConsumer::resampleTouchState(nsecs_t sampleTime, MotionEvent* event,
 #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.
@@ -729,12 +739,12 @@ void InputConsumer::resampleTouchState(nsecs_t sampleTime, MotionEvent* event,
     if (next) {
         // Interpolate between current sample and future sample.
         // So current->eventTime <= sampleTime <= future.eventTime.
-        future.initializeFrom(next);
+        future.initializeFrom(*next);
         other = &future;
         nsecs_t delta = future.eventTime - current->eventTime;
         if (delta < RESAMPLE_MIN_DELTA) {
 #if DEBUG_RESAMPLING
-            ALOGD("Not resampled, delta time is too small: %lld ns.", delta);
+            ALOGD("Not resampled, delta time is too small: %" PRId64 " ns.", delta);
 #endif
             return;
         }
@@ -746,12 +756,12 @@ void InputConsumer::resampleTouchState(nsecs_t sampleTime, MotionEvent* event,
         nsecs_t delta = current->eventTime - other->eventTime;
         if (delta < RESAMPLE_MIN_DELTA) {
 #if DEBUG_RESAMPLING
-            ALOGD("Not resampled, delta time is too small: %lld ns.", delta);
+            ALOGD("Not resampled, delta time is too small: %" PRId64 " ns.", delta);
 #endif
             return;
         } else if (delta > RESAMPLE_MAX_DELTA) {
 #if DEBUG_RESAMPLING
-            ALOGD("Not resampled, delta time is too large: %lld ns.", delta);
+            ALOGD("Not resampled, delta time is too large: %" PRId64 " ns.", delta);
 #endif
             return;
         }
@@ -759,7 +769,7 @@ void InputConsumer::resampleTouchState(nsecs_t sampleTime, MotionEvent* event,
         if (sampleTime > maxPredict) {
 #if DEBUG_RESAMPLING
             ALOGD("Sample time is too far in the future, adjusting prediction "
-                    "from %lld to %lld ns.",
+                    "from %" PRId64 " to %" PRId64 " ns.",
                     sampleTime - current->eventTime, maxPredict - current->eventTime);
 #endif
             sampleTime = maxPredict;