Merge "Fix One Euro filter's units of computation" into main (4f9e86fb) · Commits · e / os / android_frameworks_native

include/input/CoordinateFilter.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -44,7 +44,7 @@ public:
		* the previous call.
		* @param coords Coordinates to be overwritten by the corresponding filtered coordinates.
		*/
		void filter(std::chrono::duration<float> timestamp, PointerCoords& coords);
		void filter(std::chrono::nanoseconds timestamp, PointerCoords& coords);

		private:
		OneEuroFilter mXFilter;

include/input/OneEuroFilter.h

+5 −5

Original line number	Diff line number	Diff line
		@@ -56,7 +56,7 @@ public:
		* provided in the previous call.
		* @param rawPosition Position to be filtered.
		*/
		float filter(std::chrono::duration<float> timestamp, float rawPosition);
		float filter(std::chrono::nanoseconds timestamp, float rawPosition);

		private:
		/**
		@@ -67,7 +67,7 @@ private:

		/**
		* Slope of the cutoff frequency criterion. This is the term scaling the absolute value of the
		* filtered signal's speed. The data member is dimensionless, that is, it does not have units.
		* filtered signal's speed. Units are 1 / position.
		*/
		const float mBeta;

		@@ -78,9 +78,9 @@ private:
		const float mSpeedCutoffFreq;

		/**
		* The timestamp from the previous call. Units are seconds.
		* The timestamp from the previous call.
		*/
		std::optional<std::chrono::duration<float>> mPrevTimestamp;
		std::optional<std::chrono::nanoseconds> mPrevTimestamp;

		/**
		* The raw position from the previous call.
		@@ -88,7 +88,7 @@ private:
		std::optional<float> mPrevRawPosition;

		/**
		* The filtered velocity from the previous call. Units are position per second.
		* The filtered velocity from the previous call. Units are position per nanosecond.
		*/
		std::optional<float> mPrevFilteredVelocity;

libs/input/CoordinateFilter.cpp

+1 −1

Original line number	Diff line number	Diff line
		@@ -23,7 +23,7 @@ namespace android {
		CoordinateFilter::CoordinateFilter(float minCutoffFreq, float beta)
		: mXFilter{minCutoffFreq, beta}, mYFilter{minCutoffFreq, beta} {}

		void CoordinateFilter::filter(std::chrono::duration<float> timestamp, PointerCoords& coords) {
		void CoordinateFilter::filter(std::chrono::nanoseconds timestamp, PointerCoords& coords) {
		coords.setAxisValue(AMOTION_EVENT_AXIS_X, mXFilter.filter(timestamp, coords.getX()));
		coords.setAxisValue(AMOTION_EVENT_AXIS_Y, mYFilter.filter(timestamp, coords.getY()));
		}

libs/input/OneEuroFilter.cpp

+21 −13

Original line number	Diff line number	Diff line
		@@ -25,16 +25,24 @@
		namespace android {
		namespace {

		using namespace std::literals::chrono_literals;

		const float kHertzPerGigahertz = 1E9f;
		const float kGigahertzPerHertz = 1E-9f;

		// filteredSpeed's units are position per nanosecond. beta's units are 1 / position.
		inline float cutoffFreq(float minCutoffFreq, float beta, float filteredSpeed) {
		return minCutoffFreq + beta * std::abs(filteredSpeed);
		return kHertzPerGigahertz *
		((minCutoffFreq * kGigahertzPerHertz) + beta * std::abs(filteredSpeed));
		}

		inline float smoothingFactor(std::chrono::duration<float> samplingPeriod, float cutoffFreq) {
		return samplingPeriod.count() / (samplingPeriod.count() + (1.0 / (2.0 * M_PI * cutoffFreq)));
		inline float smoothingFactor(std::chrono::nanoseconds samplingPeriod, float cutoffFreq) {
		const float constant = 2.0f * M_PI * samplingPeriod.count() * (cutoffFreq * kGigahertzPerHertz);
		return constant / (constant + 1);
		}

		inline float lowPassFilter(float rawPosition, float prevFilteredPosition, float smoothingFactor) {
		return smoothingFactor * rawPosition + (1 - smoothingFactor) * prevFilteredPosition;
		inline float lowPassFilter(float rawValue, float prevFilteredValue, float smoothingFactor) {
		return smoothingFactor * rawValue + (1 - smoothingFactor) * prevFilteredValue;
		}

		} // namespace
		@@ -42,17 +50,17 @@ inline float lowPassFilter(float rawPosition, float prevFilteredPosition, float
		OneEuroFilter::OneEuroFilter(float minCutoffFreq, float beta, float speedCutoffFreq)
		: mMinCutoffFreq{minCutoffFreq}, mBeta{beta}, mSpeedCutoffFreq{speedCutoffFreq} {}

		float OneEuroFilter::filter(std::chrono::duration<float> timestamp, float rawPosition) {
		LOG_IF(FATAL, mPrevFilteredPosition.has_value() && (timestamp <= *mPrevTimestamp))
		<< "Timestamp must be greater than mPrevTimestamp";
		float OneEuroFilter::filter(std::chrono::nanoseconds timestamp, float rawPosition) {
		LOG_IF(FATAL, mPrevTimestamp.has_value() && (*mPrevTimestamp >= timestamp))
		<< "Timestamp must be greater than mPrevTimestamp. Timestamp: " << timestamp.count()
		<< "ns. mPrevTimestamp: " << mPrevTimestamp->count() << "ns";

		const std::chrono::duration<float> samplingPeriod = (mPrevTimestamp.has_value())
		? (timestamp - *mPrevTimestamp)
		: std::chrono::duration<float>{1.0};
		const std::chrono::nanoseconds samplingPeriod =
		(mPrevTimestamp.has_value()) ? (timestamp - *mPrevTimestamp) : 1s;

		const float rawVelocity = (mPrevFilteredPosition.has_value())
		? ((rawPosition - *mPrevFilteredPosition) / samplingPeriod.count())
		: 0.0;
		? ((rawPosition - *mPrevFilteredPosition) / (samplingPeriod.count()))
		: 0.0f;

		const float speedSmoothingFactor = smoothingFactor(samplingPeriod, mSpeedCutoffFreq);

libs/input/tests/Android.bp

+1 −0

Original line number	Diff line number	Diff line
		@@ -17,6 +17,7 @@ cc_test {
		"IdGenerator_test.cpp",
		"InputChannel_test.cpp",
		"InputConsumer_test.cpp",
		"InputConsumerFilteredResampling_test.cpp",
		"InputConsumerResampling_test.cpp",
		"InputDevice_test.cpp",
		"InputEvent_test.cpp",