bfca3a0056
The automatic switching between night/notnight is based on the calulcation of the civil twilight of the current location. The location is mainly retrieved from the NetworkLocationProvider. Automatic switching will only be available, when 1) the device is in UI_MODE_TYPE_CAR 2) the setting for the UI mode are set to 'automatic' If mode is set to automatic, the next twilight is caluclated and an alarm is set that timestamp. The alarm will trigger a new calculation of the twilight and sets the UI_MODE_NIGHT to the appropriate value. modified: services/java/com/android/server/DockObserver.java new file: services/java/com/android/server/TwilightCalculator.java
104 lines
3.7 KiB
Java
104 lines
3.7 KiB
Java
/*
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* Copyright (C) 2010 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.server;
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import android.text.format.DateUtils;
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import android.util.FloatMath;
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/** @hide */
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public class TwilightCalculator {
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/** Value of {@link #mState} if it is currently day */
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public static final int DAY = 0;
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/** Value of {@link #mState} if it is currently night */
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public static final int NIGHT = 1;
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private static final float DEGREES_TO_RADIANS = (float) (Math.PI / 180.0f);
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// element for calculating solar transit.
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private static final float J0 = 0.0009f;
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// correction for civil twilight
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private static final float ALTIDUTE_CORRECTION_CIVIL_TWILIGHT = -0.104719755f;
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// coefficients for calculating Equation of Center.
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private static final float C1 = 0.0334196f;
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private static final float C2 = 0.000349066f;
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private static final float C3 = 0.000005236f;
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private static final float OBLIQUITY = 0.40927971f;
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// Java time on Jan 1, 2000 12:00 UTC.
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private static final long UTC_2000 = 946728000000L;
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/** Time of sunset (civil twilight) in milliseconds. */
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public long mSunset;
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/** Time of sunrise (civil twilight) in milliseconds. */
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public long mSunrise;
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/** Current state */
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public int mState;
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/**
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* calculates the civil twilight bases on time and geo-coordinates.
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*
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* @param time time in milliseconds.
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* @param latiude latitude in degrees.
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* @param longitude latitude in degrees.
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*/
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public void calculateTwilight(long time, double latiude, double longitude) {
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final float daysSince2000 = (float) (time - UTC_2000) / DateUtils.DAY_IN_MILLIS;
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// mean anomaly
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final float meanAnomaly = 6.240059968f + daysSince2000 * 0.01720197f;
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// true anomaly
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final float trueAnomaly = meanAnomaly + C1 * FloatMath.sin(meanAnomaly) + C2
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* FloatMath.sin(2 * meanAnomaly) + C3 * FloatMath.sin(3 * meanAnomaly);
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// ecliptic longitude
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final float solarLng = trueAnomaly + 1.796593063f + (float) Math.PI;
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// solar transit in days since 2000
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final double arcLongitude = -longitude / 360;
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float n = Math.round(daysSince2000 - J0 - arcLongitude);
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double solarTransitJ2000 = n + J0 + arcLongitude + 0.0053f * FloatMath.sin(meanAnomaly)
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+ -0.0069f * FloatMath.sin(2 * solarLng);
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// declination of sun
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double solarDec = Math.asin(FloatMath.sin(solarLng) * FloatMath.sin(OBLIQUITY));
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final double latRad = latiude * DEGREES_TO_RADIANS;
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float hourAngle = (float) (Math
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.acos((FloatMath.sin(ALTIDUTE_CORRECTION_CIVIL_TWILIGHT) - Math.sin(latRad)
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* Math.sin(solarDec))
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/ (Math.cos(latRad) * Math.cos(solarDec))) / (2 * Math.PI));
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mSunset = Math.round((solarTransitJ2000 + hourAngle) * DateUtils.DAY_IN_MILLIS) + UTC_2000;
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mSunrise = Math.round((solarTransitJ2000 - hourAngle) * DateUtils.DAY_IN_MILLIS) + UTC_2000;
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if (mSunrise < time && mSunset > time) {
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mState = DAY;
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} else {
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mState = NIGHT;
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}
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}
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}
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