e0fd693c60
Previously any geofence (proximity alert) would turn the GPS on at full rate. Now, we modify the GPS interval with the distance to the nearest geofence. A speed of 100m/s is assumed to calculate the next GPS update. Also o Major refactor of geofencing code, to make it easier to continue to improve. o Discard proximity alerts when an app is removed. o Misc cleanup of nearby code. There are other upcoming changes that make this a good time for some house-keeping. TODO: The new geofencing heuristics are much better than before, but still relatively naive. The next steps could be: - Improve boundary detection - Improve update thottling for large geofences - Consider velocity when throttling Change-Id: Ie6e23d2cb2b931eba5d2a2fc759543bb96e2f7d0
101 lines
2.8 KiB
Java
101 lines
2.8 KiB
Java
/*
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* Copyright (C) 2012 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.location;
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import android.location.Location;
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/**
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* Represents a simple circular GeoFence.
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*/
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public class Geofence {
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public final static int FLAG_ENTER = 0x01;
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public final static int FLAG_EXIT = 0x02;
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static final int STATE_UNKNOWN = 0;
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static final int STATE_INSIDE = 1;
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static final int STATE_OUTSIDE = 2;
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final double mLatitude;
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final double mLongitude;
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final float mRadius;
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final Location mLocation;
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int mState; // current state
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double mDistance; // current distance to center of fence
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public Geofence(double latitude, double longitude, float radius, Location prevLocation) {
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mState = STATE_UNKNOWN;
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mLatitude = latitude;
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mLongitude = longitude;
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mRadius = radius;
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mLocation = new Location("");
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mLocation.setLatitude(latitude);
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mLocation.setLongitude(longitude);
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if (prevLocation != null) {
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processLocation(prevLocation);
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}
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}
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/**
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* Process a new location.
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* @return FLAG_ENTER or FLAG_EXIT if the fence was crossed, 0 otherwise
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*/
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public int processLocation(Location location) {
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mDistance = mLocation.distanceTo(location);
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int prevState = mState;
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//TODO: inside/outside detection could be made more rigorous
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boolean inside = mDistance <= Math.max(mRadius, location.getAccuracy());
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if (inside) {
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mState = STATE_INSIDE;
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} else {
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mState = STATE_OUTSIDE;
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}
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if (prevState != 0 && mState != prevState) {
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if (mState == STATE_INSIDE) return FLAG_ENTER;
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if (mState == STATE_OUTSIDE) return FLAG_EXIT;
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}
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return 0;
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}
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public double getDistance() {
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return mDistance;
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}
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@Override
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public String toString() {
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String state;
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switch (mState) {
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case STATE_INSIDE:
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state = "IN";
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break;
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case STATE_OUTSIDE:
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state = "OUT";
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break;
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default:
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state = "?";
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}
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return String.format("(%.4f, %.4f r=%.0f d=%.0f %s)", mLatitude, mLongitude, mRadius,
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mDistance, state);
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}
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}
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