Merge "Tweak VelocityTracker. Bug: 5265529"
diff --git a/include/ui/Input.h b/include/ui/Input.h
index f1385a0..af899ef 100644
--- a/include/ui/Input.h
+++ b/include/ui/Input.h
@@ -660,15 +660,19 @@
static const uint32_t HISTORY_SIZE = 10;
// Oldest sample to consider when calculating the velocity.
- static const nsecs_t MAX_AGE = 200 * 1000000; // 200 ms
+ static const nsecs_t MAX_AGE = 100 * 1000000; // 100 ms
// The minimum duration between samples when estimating velocity.
- static const nsecs_t MIN_DURATION = 10 * 1000000; // 10 ms
+ static const nsecs_t MIN_DURATION = 5 * 1000000; // 5 ms
struct Movement {
nsecs_t eventTime;
BitSet32 idBits;
Position positions[MAX_POINTERS];
+
+ inline const Position& getPosition(uint32_t id) const {
+ return positions[idBits.getIndexOfBit(id)];
+ }
};
uint32_t mIndex;
diff --git a/libs/ui/Input.cpp b/libs/ui/Input.cpp
index 688b998..0d25823 100644
--- a/libs/ui/Input.cpp
+++ b/libs/ui/Input.cpp
@@ -752,6 +752,7 @@
switch (actionMasked) {
case AMOTION_EVENT_ACTION_DOWN:
+ case AMOTION_EVENT_ACTION_HOVER_ENTER:
// Clear all pointers on down before adding the new movement.
clear();
break;
@@ -764,12 +765,11 @@
clearPointers(downIdBits);
break;
}
- case AMOTION_EVENT_ACTION_OUTSIDE:
- case AMOTION_EVENT_ACTION_CANCEL:
- case AMOTION_EVENT_ACTION_SCROLL:
- case AMOTION_EVENT_ACTION_UP:
- case AMOTION_EVENT_ACTION_POINTER_UP:
- // Ignore these actions because they do not convey any new information about
+ case AMOTION_EVENT_ACTION_MOVE:
+ case AMOTION_EVENT_ACTION_HOVER_MOVE:
+ break;
+ default:
+ // Ignore all other actions because they do not convey any new information about
// pointer movement. We also want to preserve the last known velocity of the pointers.
// Note that ACTION_UP and ACTION_POINTER_UP always report the last known position
// of the pointers that went up. ACTION_POINTER_UP does include the new position of
@@ -814,68 +814,36 @@
bool VelocityTracker::getVelocity(uint32_t id, float* outVx, float* outVy) const {
const Movement& newestMovement = mMovements[mIndex];
if (newestMovement.idBits.hasBit(id)) {
- // Find the oldest sample that contains the pointer and that is not older than MAX_AGE.
- nsecs_t minTime = newestMovement.eventTime - MAX_AGE;
- uint32_t oldestIndex = mIndex;
- uint32_t numTouches = 1;
- do {
- uint32_t nextOldestIndex = (oldestIndex == 0 ? HISTORY_SIZE : oldestIndex) - 1;
- const Movement& nextOldestMovement = mMovements[nextOldestIndex];
- if (!nextOldestMovement.idBits.hasBit(id)
- || nextOldestMovement.eventTime < minTime) {
- break;
- }
- oldestIndex = nextOldestIndex;
- } while (++numTouches < HISTORY_SIZE);
-
- // Calculate an exponentially weighted moving average of the velocity estimate
- // at different points in time measured relative to the oldest sample.
- // This is essentially an IIR filter. Newer samples are weighted more heavily
- // than older samples. Samples at equal time points are weighted more or less
- // equally.
- //
- // One tricky problem is that the sample data may be poorly conditioned.
- // Sometimes samples arrive very close together in time which can cause us to
- // overestimate the velocity at that time point. Most samples might be measured
- // 16ms apart but some consecutive samples could be only 0.5sm apart because
- // the hardware or driver reports them irregularly or in bursts.
+ const Position& newestPosition = newestMovement.getPosition(id);
float accumVx = 0;
float accumVy = 0;
- uint32_t index = oldestIndex;
- uint32_t samplesUsed = 0;
- const Movement& oldestMovement = mMovements[oldestIndex];
- const Position& oldestPosition =
- oldestMovement.positions[oldestMovement.idBits.getIndexOfBit(id)];
- nsecs_t lastDuration = 0;
+ float duration = 0;
- while (numTouches-- > 1) {
- if (++index == HISTORY_SIZE) {
- index = 0;
- }
+ // Iterate over movement samples in reverse time order and accumulate velocity.
+ uint32_t index = mIndex;
+ do {
+ index = (index == 0 ? HISTORY_SIZE : index) - 1;
const Movement& movement = mMovements[index];
- nsecs_t duration = movement.eventTime - oldestMovement.eventTime;
-
- // If the duration between samples is small, we may significantly overestimate
- // the velocity. Consequently, we impose a minimum duration constraint on the
- // samples that we include in the calculation.
- if (duration >= MIN_DURATION) {
- const Position& position = movement.positions[movement.idBits.getIndexOfBit(id)];
- float scale = 1000000000.0f / duration; // one over time delta in seconds
- float vx = (position.x - oldestPosition.x) * scale;
- float vy = (position.y - oldestPosition.y) * scale;
-
- accumVx = (accumVx * lastDuration + vx * duration) / (duration + lastDuration);
- accumVy = (accumVy * lastDuration + vy * duration) / (duration + lastDuration);
-
- lastDuration = duration;
- samplesUsed += 1;
+ if (!movement.idBits.hasBit(id)) {
+ break;
}
- }
+
+ nsecs_t age = newestMovement.eventTime - movement.eventTime;
+ if (age > MAX_AGE) {
+ break;
+ }
+
+ const Position& position = movement.getPosition(id);
+ accumVx += newestPosition.x - position.x;
+ accumVy += newestPosition.y - position.y;
+ duration += age;
+ } while (index != mIndex);
// Make sure we used at least one sample.
- if (samplesUsed != 0) {
- *outVx = accumVx;
- *outVy = accumVy;
+ if (duration >= MIN_DURATION) {
+ float scale = 1000000000.0f / duration; // one over time delta in seconds
+ *outVx = accumVx * scale;
+ *outVy = accumVy * scale;
return true;
}
}