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InputResampling: Don't extrapolate for very low frame rates.

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In very low framerate situations, extrapolation is generally going to
either cause no benefit or make a mistake. We can safely turn it off
with no user-visible negative impact.

BUG=https://buganizer.corp.google.com/u/0/issues/24550942
TEST=Scrolled very slowly and saw mispredictions on Angler. With change,
saw the log message that the mispredictions were suppressed.

Change-Id: Ic9747d3ff098d7918047ada2ed1c2d21282c65b0
This commit is contained in:
Andrew de los Reyes 2015-10-01 15:57:25 -07:00
parent b0127aadaf
commit de18f6c32a
1 changed files with 11 additions and 2 deletions
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13
libs/input/InputTransport.cpp
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@ -51,6 +51,10 @@ static const nsecs_t RESAMPLE_LATENCY = 5 * NANOS_PER_MS;
// Minimum time difference between consecutive samples before attempting to resample.
static const nsecs_t RESAMPLE_MIN_DELTA = 2 * NANOS_PER_MS;
// Maximum time difference between consecutive samples before attempting to resample
// by extrapolation.
static const nsecs_t RESAMPLE_MAX_DELTA = 20 * NANOS_PER_MS;
// Maximum time to predict forward from the last known state, to avoid predicting too
// far into the future. This time is further bounded by 50% of the last time delta.
static const nsecs_t RESAMPLE_MAX_PREDICTION = 8 * NANOS_PER_MS;
@ -724,7 +728,7 @@ void InputConsumer::resampleTouchState(nsecs_t sampleTime, MotionEvent* event,
nsecs_t delta = future.eventTime - current->eventTime;
if (delta < RESAMPLE_MIN_DELTA) {
#if DEBUG_RESAMPLING
ALOGD("Not resampled, delta time is %lld ns.", delta);
ALOGD("Not resampled, delta time is too small: %lld ns.", delta);
#endif
return;
}
@ -736,7 +740,12 @@ 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 %lld ns.", delta);
ALOGD("Not resampled, delta time is too small: %lld ns.", delta);
#endif
return;
} else if (delta > RESAMPLE_MAX_DELTA) {
#if DEBUG_RESAMPLING
ALOGD("Not resampled, delta time is too large: %lld ns.", delta);
#endif
return;
}