com/android/systemui/doze/DozeScreenBrightness.java

/*
 * Copyright (C) 2017 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.systemui.doze;

import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Handler;

import com.android.internal.annotations.VisibleForTesting;

/**
 * Controls the screen brightness when dozing.
 */
public class DozeScreenBrightness implements DozeMachine.Part, SensorEventListener {
    private final Context mContext;
    private final DozeMachine.Service mDozeService;
    private final DozeHost mDozeHost;
    private final Handler mHandler;
    private final SensorManager mSensorManager;
    private final Sensor mLightSensor;
    private final int[] mSensorToBrightness;
    private final int[] mSensorToScrimOpacity;
    private boolean mRegistered;
    private boolean mReady = true;
    private ReadyListener mReadyListener;
    private int mDefaultDozeBrightness;

    public DozeScreenBrightness(Context context, DozeMachine.Service service,
            SensorManager sensorManager, Sensor lightSensor, DozeHost host,
            Handler handler, int defaultDozeBrightness, int[] sensorToBrightness,
            int[] sensorToScrimOpacity) {
        mContext = context;
        mDozeService = service;
        mSensorManager = sensorManager;
        mLightSensor = lightSensor;
        mDozeHost = host;
        mHandler = handler;

        mDefaultDozeBrightness = defaultDozeBrightness;
        mSensorToBrightness = sensorToBrightness;
        mSensorToScrimOpacity = sensorToScrimOpacity;
    }

    @VisibleForTesting
    public DozeScreenBrightness(Context context, DozeMachine.Service service,
            SensorManager sensorManager, Sensor lightSensor, DozeHost host,
            Handler handler, AlwaysOnDisplayPolicy policy) {
        this(context, service, sensorManager, lightSensor, host, handler,
                context.getResources().getInteger(
                        com.android.internal.R.integer.config_screenBrightnessDoze),
                policy.screenBrightnessArray, policy.dimmingScrimArray);
    }

    @Override
    public void transitionTo(DozeMachine.State oldState, DozeMachine.State newState) {
        switch (newState) {
            case INITIALIZED:
                resetBrightnessToDefault();
                break;
            case DOZE_AOD:
            case DOZE_REQUEST_PULSE:
                setLightSensorEnabled(true);
                break;
            case DOZE:
                setLightSensorEnabled(false);
                resetBrightnessToDefault();
                break;
            case FINISH:
                setLightSensorEnabled(false);
                break;
        }
    }

    @Override
    public void onSensorChanged(SensorEvent event) {
        if (mRegistered) {
            int sensorValue = (int) event.values[0];
            int brightness = computeBrightness(sensorValue);
            if (brightness > 0) {
                mDozeService.setDozeScreenBrightness(brightness);
            }
            // If the brightness is zero or negative, this indicates that the brightness sensor is
            // covered or reports that the screen should be off, therefore we're not ready to turn
            // on the screen yet.
            setReady(brightness > 0);

            int scrimOpacity = computeScrimOpacity(sensorValue);
            if (scrimOpacity >= 0) {
                mDozeHost.setAodDimmingScrim(scrimOpacity / 255f);
            }
        }
    }

    private int computeScrimOpacity(int sensorValue) {
        if (sensorValue < 0 || sensorValue >= mSensorToScrimOpacity.length) {
            return -1;
        }
        return mSensorToScrimOpacity[sensorValue];
    }

    private int computeBrightness(int sensorValue) {
        if (sensorValue < 0 || sensorValue >= mSensorToBrightness.length) {
            return -1;
        }
        return mSensorToBrightness[sensorValue];
    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {
    }

    private void resetBrightnessToDefault() {
        mDozeService.setDozeScreenBrightness(mDefaultDozeBrightness);
    }

    private void setLightSensorEnabled(boolean enabled) {
        if (enabled && !mRegistered && mLightSensor != null) {
            // Wait until we get an event from the sensor until indicating ready.
            setReady(false);
            mRegistered = mSensorManager.registerListener(this, mLightSensor,
                    SensorManager.SENSOR_DELAY_NORMAL, mHandler);
        } else if (!enabled && mRegistered) {
            mSensorManager.unregisterListener(this);
            mRegistered = false;
            // Sensor is not enabled, hence we use the default brightness and are always ready.
            setReady(true);
        }
    }

    private void setReady(boolean ready) {
        if (ready != mReady) {
            mReady = ready;
            if (mReadyListener != null) {
                mReadyListener.onBrightnessReadyChanged(mReady);
            }
        }
    }

    public void setBrightnessReadyListener(ReadyListener l) {
        mReadyListener = l;
        l.onBrightnessReadyChanged(mReady);
    }

    /**
     * @return true if the screen brightness is properly calculated.
     *
     * Can be used to wait for transitioning out of the paused state, such that we don't turn the
     * display on before the display brightness is properly calculated.
     */
    public boolean isReady() {
        return mReady;
    }

    public interface ReadyListener {
        void onBrightnessReadyChanged(boolean ready);
    }
}