Android/frameworks_base
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Merge "Move brightness color conversion from SysUI to settingslib" into pi-dev

Browse Source
This commit is contained in:
TreeHugger Robot
2018-04-25 15:07:31 +00:00
committed by Android (Google) Code Review
parent 628e9b3d37 106b1c0d80
commit 04d504be03
3 changed files with 158 additions and 82 deletions
Download Patch File Download Diff File Expand all files Collapse all files

101
packages/SettingsLib/src/com/android/settingslib/display/BrightnessUtils.java Normal file
View File

@@ -0,0 +1,101 @@
/*
* 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));
}
}

52
packages/SettingsLib/tests/robotests/src/com/android/settingslib/display/BrightnessUtilsTest.java Normal file
View File

@@ -0,0 +1,52 @@
/*
* 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);
}
}

87
packages/SystemUI/src/com/android/systemui/settings/BrightnessController.java
View File

@@ -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));
}
}