Merge "Move brightness color conversion from SysUI to settingslib" into pi-dev (04d504be) · Commits · e / os / android_frameworks_base

packages/SettingsLib/src/com/android/settingslib/display/BrightnessUtils.java

0 → 100644

+101 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2018 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		package com.android.settingslib.display;

		import android.util.MathUtils;

		public class BrightnessUtils {

		public static final int GAMMA_SPACE_MAX = 1023;

		// Hybrid Log Gamma constant values
		private static final float R = 0.5f;
		private static final float A = 0.17883277f;
		private static final float B = 0.28466892f;
		private static final float C = 0.55991073f;

		/**
		* A function for converting from the gamma space that the slider works in to the
		* linear space that the setting works in.
		*
		* The gamma space effectively provides us a way to make linear changes to the slider that
		* result in linear changes in perception. If we made changes to the slider in the linear space
		* then we'd see an approximately logarithmic change in perception (c.f. Fechner's Law).
		*
		* Internally, this implements the Hybrid Log Gamma electro-optical transfer function, which is
		* a slight improvement to the typical gamma transfer function for displays whose max
		* brightness exceeds the 120 nit reference point, but doesn't set a specific reference
		* brightness like the PQ function does.
		*
		* Note that this transfer function is only valid if the display's backlight value is a linear
		* control. If it's calibrated to be something non-linear, then a different transfer function
		* should be used.
		*
		* @param val The slider value.
		* @param min The minimum acceptable value for the setting.
		* @param max The maximum acceptable value for the setting.
		* @return The corresponding setting value.
		*/
		public static final int convertGammaToLinear(int val, int min, int max) {
		final float normalizedVal = MathUtils.norm(0, GAMMA_SPACE_MAX, val);
		final float ret;
		if (normalizedVal <= R) {
		ret = MathUtils.sq(normalizedVal / R);
		} else {
		ret = MathUtils.exp((normalizedVal - C) / A) + B;
		}

		// HLG is normalized to the range [0, 12], so we need to re-normalize to the range [0, 1]
		// in order to derive the correct setting value.
		return Math.round(MathUtils.lerp(min, max, ret / 12));
		}

		/**
		* A function for converting from the linear space that the setting works in to the
		* gamma space that the slider works in.
		*
		* The gamma space effectively provides us a way to make linear changes to the slider that
		* result in linear changes in perception. If we made changes to the slider in the linear space
		* then we'd see an approximately logarithmic change in perception (c.f. Fechner's Law).
		*
		* Internally, this implements the Hybrid Log Gamma opto-electronic transfer function, which is
		* a slight improvement to the typical gamma transfer function for displays whose max
		* brightness exceeds the 120 nit reference point, but doesn't set a specific reference
		* brightness like the PQ function does.
		*
		* Note that this transfer function is only valid if the display's backlight value is a linear
		* control. If it's calibrated to be something non-linear, then a different transfer function
		* should be used.
		*
		* @param val The brightness setting value.
		* @param min The minimum acceptable value for the setting.
		* @param max The maximum acceptable value for the setting.
		* @return The corresponding slider value
		*/
		public static final int convertLinearToGamma(int val, int min, int max) {
		// For some reason, HLG normalizes to the range [0, 12] rather than [0, 1]
		final float normalizedVal = MathUtils.norm(min, max, val) * 12;
		final float ret;
		if (normalizedVal <= 1f) {
		ret = MathUtils.sqrt(normalizedVal) * R;
		} else {
		ret = A * MathUtils.log(normalizedVal - B) + C;
		}

		return Math.round(MathUtils.lerp(0, GAMMA_SPACE_MAX, ret));
		}
		}

packages/SettingsLib/tests/robotests/src/com/android/settingslib/display/BrightnessUtilsTest.java

0 → 100644

+52 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2018 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		package com.android.settingslib.display;

		import static com.android.settingslib.display.BrightnessUtils.GAMMA_SPACE_MAX;
		import static com.google.common.truth.Truth.assertThat;

		import com.android.settingslib.SettingsLibRobolectricTestRunner;

		import org.junit.Test;
		import org.junit.runner.RunWith;

		@RunWith(SettingsLibRobolectricTestRunner.class)
		public class BrightnessUtilsTest {

		private static final int MIN = 1;
		private static final int MAX = 255;

		@Test
		public void linearToGamma_minValue_shouldReturn0() {
		assertThat(BrightnessUtils.convertLinearToGamma(MIN, MIN, MAX)).isEqualTo(0);
		}

		@Test
		public void linearToGamma_maxValue_shouldReturnGammaSpaceMax() {
		assertThat(BrightnessUtils.convertLinearToGamma(MAX, MIN, MAX)).isEqualTo(GAMMA_SPACE_MAX);
		}

		@Test
		public void gammaToLinear_minValue_shouldReturnMin() {
		assertThat(BrightnessUtils.convertGammaToLinear(MIN, MIN, MAX)).isEqualTo(MIN);
		}

		@Test
		public void gammaToLinear_gammaSpaceValue_shouldReturnMax() {
		assertThat(BrightnessUtils.convertGammaToLinear(GAMMA_SPACE_MAX, MIN, MAX)).isEqualTo(MAX);
		}
		}

packages/SystemUI/src/com/android/systemui/settings/BrightnessController.java

+5 −82

Original line number	Diff line number	Diff line
		@@ -16,6 +16,10 @@

		package com.android.systemui.settings;

		import static com.android.settingslib.display.BrightnessUtils.GAMMA_SPACE_MAX;
		import static com.android.settingslib.display.BrightnessUtils.convertGammaToLinear;
		import static com.android.settingslib.display.BrightnessUtils.convertLinearToGamma;

		import android.animation.ValueAnimator;
		import android.content.ContentResolver;
		import android.content.Context;
		@@ -24,7 +28,6 @@ import android.hardware.display.DisplayManager;
		import android.net.Uri;
		import android.os.AsyncTask;
		import android.os.Handler;
		import android.os.IPowerManager;
		import android.os.Looper;
		import android.os.Message;
		import android.os.PowerManager;
		@@ -36,7 +39,6 @@ import android.provider.Settings;
		import android.service.vr.IVrManager;
		import android.service.vr.IVrStateCallbacks;
		import android.util.Log;
		import android.util.MathUtils;
		import android.widget.ImageView;

		import com.android.internal.logging.MetricsLogger;
		@@ -50,15 +52,8 @@ public class BrightnessController implements ToggleSlider.Listener {
		private static final String TAG = "StatusBar.BrightnessController";
		private static final boolean SHOW_AUTOMATIC_ICON = false;

		private static final int SLIDER_MAX = 1023;
		private static final int SLIDER_ANIMATION_DURATION = 3000;

		// Hybrid Log Gamma constant values
		private static final float R = 0.5f;
		private static final float A = 0.17883277f;
		private static final float B = 0.28466892f;
		private static final float C = 0.55991073f;

		private static final int MSG_UPDATE_ICON = 0;
		private static final int MSG_UPDATE_SLIDER = 1;
		private static final int MSG_SET_CHECKED = 2;
		@@ -273,7 +268,7 @@ public class BrightnessController implements ToggleSlider.Listener {
		mContext = context;
		mIcon = icon;
		mControl = control;
		mControl.setMax(SLIDER_MAX);
		mControl.setMax(GAMMA_SPACE_MAX);
		mBackgroundHandler = new Handler((Looper) Dependency.get(Dependency.BG_LOOPER));
		mUserTracker = new CurrentUserTracker(mContext) {
		@Override
		@@ -481,76 +476,4 @@ public class BrightnessController implements ToggleSlider.Listener {
		mSliderAnimator.start();
		}

		/**
		* A function for converting from the linear space that the setting works in to the
		* gamma space that the slider works in.
		*
		* The gamma space effectively provides us a way to make linear changes to the slider that
		* result in linear changes in perception. If we made changes to the slider in the linear space
		* then we'd see an approximately logarithmic change in perception (c.f. Fechner's Law).
		*
		* Internally, this implements the Hybrid Log Gamma opto-electronic transfer function, which is
		* a slight improvement to the typical gamma transfer function for displays whose max
		* brightness exceeds the 120 nit reference point, but doesn't set a specific reference
		* brightness like the PQ function does.
		*
		* Note that this transfer function is only valid if the display's backlight value is a linear
		* control. If it's calibrated to be something non-linear, then a different transfer function
		* should be used.
		*
		* @param val The brightness setting value.
		* @param min The minimum acceptable value for the setting.
		* @param max The maximum acceptable value for the setting.
		*
		* @return The corresponding slider value
		*/
		private static final int convertLinearToGamma(int val, int min, int max) {
		// For some reason, HLG normalizes to the range [0, 12] rather than [0, 1]
		final float normalizedVal = MathUtils.norm(min, max, val) * 12;
		final float ret;
		if (normalizedVal <= 1f) {
		ret = MathUtils.sqrt(normalizedVal) * R;
		} else {
		ret = A * MathUtils.log(normalizedVal - B) + C;
		}

		return Math.round(MathUtils.lerp(0, SLIDER_MAX, ret));
		}

		/**
		* A function for converting from the gamma space that the slider works in to the
		* linear space that the setting works in.
		*
		* The gamma space effectively provides us a way to make linear changes to the slider that
		* result in linear changes in perception. If we made changes to the slider in the linear space
		* then we'd see an approximately logarithmic change in perception (c.f. Fechner's Law).
		*
		* Internally, this implements the Hybrid Log Gamma electro-optical transfer function, which is
		* a slight improvement to the typical gamma transfer function for displays whose max
		* brightness exceeds the 120 nit reference point, but doesn't set a specific reference
		* brightness like the PQ function does.
		*
		* Note that this transfer function is only valid if the display's backlight value is a linear
		* control. If it's calibrated to be something non-linear, then a different transfer function
		* should be used.
		*
		* @param val The slider value.
		* @param min The minimum acceptable value for the setting.
		* @param max The maximum acceptable value for the setting.
		*
		* @return The corresponding setting value.
		*/
		private static final int convertGammaToLinear(int val, int min, int max) {
		final float normalizedVal = MathUtils.norm(0, SLIDER_MAX, val);
		final float ret;
		if (normalizedVal <= R) {
		ret = MathUtils.sq(normalizedVal/R);
		} else {
		ret = MathUtils.exp((normalizedVal - C) / A) + B;
		}

		// HLG is normalized to the range [0, 12], so we need to re-normalize to the range [0, 1]
		// in order to derive the correct setting value.
		return Math.round(MathUtils.lerp(min, max, ret / 12));
		}
		}