Merge "Add new "fast" filter for ambient light." into oc-dr1-dev (c6349f39) · Commits · e / os / android_frameworks_base

services/core/java/com/android/server/display/AutomaticBrightnessController.java

+63 −10

Original line number	Diff line number	Diff line
		@@ -59,6 +59,13 @@ class AutomaticBrightnessController {
		private static final int MSG_UPDATE_AMBIENT_LUX = 1;
		private static final int MSG_BRIGHTNESS_ADJUSTMENT_SAMPLE = 2;

		// Length of the ambient light horizon used to calculate the long term estimate of ambient
		// light.
		private static final int AMBIENT_LIGHT_LONG_HORIZON_MILLIS = 10000;

		// Length of the ambient light horizon used to calculate short-term estimate of ambient light.
		private static final int AMBIENT_LIGHT_SHORT_HORIZON_MILLIS = 2000;

		// Callbacks for requesting updates to the display's power state
		private final Callbacks mCallbacks;

		@@ -345,22 +352,51 @@ class AutomaticBrightnessController {
		}

		private void setAmbientLux(float lux) {
		if (DEBUG) {
		Slog.d(TAG, "setAmbientLux(" + lux + ")");
		}
		mAmbientLux = lux;
		mBrighteningLuxThreshold = mDynamicHysteresis.getBrighteningThreshold(lux);
		mDarkeningLuxThreshold = mDynamicHysteresis.getDarkeningThreshold(lux);
		}

		private float calculateAmbientLux(long now) {
		private float calculateAmbientLux(long now, long horizon) {
		if (DEBUG) {
		Slog.d(TAG, "calculateAmbientLux(" + now + ", " + horizon + ")");
		}
		final int N = mAmbientLightRingBuffer.size();
		if (N == 0) {
		Slog.e(TAG, "calculateAmbientLux: No ambient light readings available");
		return -1;
		}

		// Find the first measurement that is just outside of the horizon.
		int endIndex = 0;
		final long horizonStartTime = now - horizon;
		for (int i = 0; i < N-1; i++) {
		if (mAmbientLightRingBuffer.getTime(i + 1) <= horizonStartTime) {
		endIndex++;
		} else {
		break;
		}
		}
		if (DEBUG) {
		Slog.d(TAG, "calculateAmbientLux: selected endIndex=" + endIndex + ", point=("
		+ mAmbientLightRingBuffer.getTime(endIndex) + ", "
		+ mAmbientLightRingBuffer.getLux(endIndex)
		+ ")");
		}
		float sum = 0;
		float totalWeight = 0;
		long endTime = AMBIENT_LIGHT_PREDICTION_TIME_MILLIS;
		for (int i = N - 1; i >= 0; i--) {
		long startTime = (mAmbientLightRingBuffer.getTime(i) - now);
		for (int i = N - 1; i >= endIndex; i--) {
		long eventTime = mAmbientLightRingBuffer.getTime(i);
		if (i == endIndex && eventTime < horizonStartTime) {
		// If we're at the final value, make sure we only consider the part of the sample
		// within our desired horizon.
		eventTime = horizonStartTime;
		}
		final long startTime = eventTime - now;
		float weight = calculateWeight(startTime, endTime);
		float lux = mAmbientLightRingBuffer.getLux(i);
		if (DEBUG) {
		@@ -435,7 +471,7 @@ class AutomaticBrightnessController {
		timeWhenSensorWarmedUp);
		return;
		}
		setAmbientLux(calculateAmbientLux(time));
		setAmbientLux(calculateAmbientLux(time, AMBIENT_LIGHT_SHORT_HORIZON_MILLIS));
		mAmbientLuxValid = true;
		if (DEBUG) {
		Slog.d(TAG, "updateAmbientLux: Initializing: "
		@@ -447,14 +483,25 @@ class AutomaticBrightnessController {

		long nextBrightenTransition = nextAmbientLightBrighteningTransition(time);
		long nextDarkenTransition = nextAmbientLightDarkeningTransition(time);
		float ambientLux = calculateAmbientLux(time);

		if (ambientLux >= mBrighteningLuxThreshold && nextBrightenTransition <= time
		\|\| ambientLux <= mDarkeningLuxThreshold && nextDarkenTransition <= time) {
		setAmbientLux(ambientLux);
		// Essentially, we calculate both a slow ambient lux, to ensure there's a true long-term
		// change in lighting conditions, and a fast ambient lux to determine what the new
		// brightness situation is since the slow lux can be quite slow to converge.
		//
		// Note that both values need to be checked for sufficient change before updating the
		// proposed ambient light value since the slow value might be sufficiently far enough away
		// from the fast value to cause a recalculation while its actually just converging on
		// the fast value still.
		float slowAmbientLux = calculateAmbientLux(time, AMBIENT_LIGHT_LONG_HORIZON_MILLIS);
		float fastAmbientLux = calculateAmbientLux(time, AMBIENT_LIGHT_SHORT_HORIZON_MILLIS);

		if (slowAmbientLux >= mBrighteningLuxThreshold &&
		fastAmbientLux >= mBrighteningLuxThreshold && nextBrightenTransition <= time
		\|\| slowAmbientLux <= mDarkeningLuxThreshold
		&& fastAmbientLux <= mDarkeningLuxThreshold && nextDarkenTransition <= time) {
		setAmbientLux(fastAmbientLux);
		if (DEBUG) {
		Slog.d(TAG, "updateAmbientLux: "
		+ ((ambientLux > mAmbientLux) ? "Brightened" : "Darkened") + ": "
		+ ((fastAmbientLux > mAmbientLux) ? "Brightened" : "Darkened") + ": "
		+ "mBrighteningLuxThreshold=" + mBrighteningLuxThreshold
		+ ", mAmbientLightRingBuffer=" + mAmbientLightRingBuffer
		+ ", mAmbientLux=" + mAmbientLux);
		@@ -616,6 +663,12 @@ class AutomaticBrightnessController {
		void updateBrightness();
		}

		/**
		* A ring buffer of ambient light measurements sorted by time.
		*
		* Each entry consists of a timestamp and a lux measurement, and the overall buffer is sorted
		* from oldest to newest.
		*/
		private static final class AmbientLightRingBuffer {
		// Proportional extra capacity of the buffer beyond the expected number of light samples
		// in the horizon