Use previous pressure value if the current fusion data is zero.

Occasionally we'll receive the stylus up signal (pressure = 0) before
we receive the touch screen up signal. Rather than giving pointer a
pressure value of 0 (which is one of the signals of hovering) or
falling back to the touchscreen pressure values (which would make for
an inconsistent stream), use the previous pressure value which should
always be non-zero for a stream of fused data.

Bug: 20449776
Change-Id: I71eb97e7c4ea53e42b0eb54fc1f8ae7f89aad9d1

2 files changed, 14 insertions, 8 deletions

diff --git a/services/inputflinger/InputReader.cpp b/services/inputflinger/InputReader.cpp
index c6389a9c9..28887854d 100644
--- a/services/inputflinger/InputReader.cpp
+++ b/services/inputflinger/InputReader.cpp
@@ -4076,14 +4076,20 @@ void TouchInputMapper::applyExternalStylusButtonState(nsecs_t when) {
 }
 
 void TouchInputMapper::applyExternalStylusTouchState(nsecs_t when) {
-    CookedPointerData& cpd = mCurrentCookedState.cookedPointerData;
-    if (mExternalStylusId != -1 && cpd.isTouching(mExternalStylusId)) {
-        if (mExternalStylusState.pressure != 0.0f) {
-            PointerCoords& coords = cpd.editPointerCoordsWithId(mExternalStylusId);
-            coords.setAxisValue(AMOTION_EVENT_AXIS_PRESSURE, mExternalStylusState.pressure);
+    CookedPointerData& currentPointerData = mCurrentCookedState.cookedPointerData;
+    const CookedPointerData& lastPointerData = mLastCookedState.cookedPointerData;
+
+    if (mExternalStylusId != -1 && currentPointerData.isTouching(mExternalStylusId)) {
+        float pressure = mExternalStylusState.pressure;
+        if (pressure == 0.0f && lastPointerData.isTouching(mExternalStylusId)) {
+            const PointerCoords& coords = lastPointerData.pointerCoordsForId(mExternalStylusId);
+            pressure = coords.getAxisValue(AMOTION_EVENT_AXIS_PRESSURE);
         }
+        PointerCoords& coords = currentPointerData.editPointerCoordsWithId(mExternalStylusId);
+        coords.setAxisValue(AMOTION_EVENT_AXIS_PRESSURE, pressure);
 
-        PointerProperties& properties = cpd.editPointerPropertiesWithId(mExternalStylusId);
+        PointerProperties& properties =
+                currentPointerData.editPointerPropertiesWithId(mExternalStylusId);
         if (mExternalStylusState.toolType != AMOTION_EVENT_TOOL_TYPE_UNKNOWN) {
             properties.toolType = mExternalStylusState.toolType;
         }
diff --git a/services/inputflinger/InputReader.h b/services/inputflinger/InputReader.h
index aadc37fb4..ae090c11c 100644
--- a/services/inputflinger/InputReader.h
+++ b/services/inputflinger/InputReader.h
@@ -881,11 +881,11 @@ struct CookedPointerData {
         return pointerProperties[idToIndex[id]];
     }
 
-    inline bool isHovering(uint32_t pointerIndex) {
+    inline bool isHovering(uint32_t pointerIndex) const {
         return hoveringIdBits.hasBit(pointerProperties[pointerIndex].id);
     }
 
-    inline bool isTouching(uint32_t pointerIndex) {
+    inline bool isTouching(uint32_t pointerIndex) const {
         return touchingIdBits.hasBit(pointerProperties[pointerIndex].id);
     }
 };