location/java/android/location/LocationProvider.java

/*
 * Copyright (C) 2007 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 android.location;

/**
 * An abstract superclass for location providers.  A location provider
 * provides periodic reports on the geographical location of the
 * device.
 *
 * <p> Each provider has a set of criteria under which it may be used;
 * for example, some providers require GPS hardware and visibility to
 * a number of satellites; others require the use of the cellular
 * radio, or access to a specific carrier's network, or to the
 * internet.  They may also have different battery consumption
 * characteristics or monetary costs to the user.  The {@link
 * Criteria} class allows providers to be selected based on
 * user-specified criteria.
 */
public abstract class LocationProvider {
    private static final String TAG = "LocationProvider";
    // A regular expression matching characters that may not appear
    // in the name of a LocationProvider.
    static final String BAD_CHARS_REGEX = "[^a-zA-Z0-9]";

    private String mName;

    public static final int OUT_OF_SERVICE = 0;
    public static final int TEMPORARILY_UNAVAILABLE = 1;
    public static final int AVAILABLE = 2;

    /**
     * Constructs a LocationProvider with the given name.   Provider names must
     * consist only of the characters [a-zA-Z0-9].
     *
     * @throws IllegalArgumentException if name contains an illegal character
     *
     * {@hide}
     */
    public LocationProvider(String name) {
        if (name.matches(BAD_CHARS_REGEX)) {
            throw new IllegalArgumentException("name " + name +
                " contains an illegal character");
        }
        // Log.d(TAG, "Constructor: name = " + name);
        mName = name;
    }

    /**
     * Returns the name of this provider.
     */
    public String getName() {
        return mName;
    }

    /**
     * Returns true if this provider meets the given criteria,
     * false otherwise.
     */
    public boolean meetsCriteria(Criteria criteria) {
        // We do not want to match the special passive provider based on criteria.
        if (LocationManager.PASSIVE_PROVIDER.equals(mName)) {
            return false;
        }
        if ((criteria.getAccuracy() != Criteria.NO_REQUIREMENT) && 
            (criteria.getAccuracy() < getAccuracy())) {
            return false;
        }
        int criteriaPower = criteria.getPowerRequirement();
        if ((criteriaPower != Criteria.NO_REQUIREMENT) &&
            (criteriaPower < getPowerRequirement())) {
            return false;
        }
        if (criteria.isAltitudeRequired() && !supportsAltitude()) {
            return false;
        }
        if (criteria.isSpeedRequired() && !supportsSpeed()) {
            return false;
        }
        if (criteria.isBearingRequired() && !supportsBearing()) {
            return false;
        }
        return true;
    }

    /**
     * Returns true if the provider requires access to a
     * data network (e.g., the Internet), false otherwise.
     */
    public abstract boolean requiresNetwork();

    /**
     * Returns true if the provider requires access to a
     * satellite-based positioning system (e.g., GPS), false
     * otherwise.
     */
    public abstract boolean requiresSatellite();

    /**
     * Returns true if the provider requires access to an appropriate
     * cellular network (e.g., to make use of cell tower IDs), false
     * otherwise.
     */
    public abstract boolean requiresCell();

    /**
     * Returns true if the use of this provider may result in a
     * monetary charge to the user, false if use is free.  It is up to
     * each provider to give accurate information.
     */
    public abstract boolean hasMonetaryCost();

    /**
     * Returns true if the provider is able to provide altitude
     * information, false otherwise.  A provider that reports altitude
     * under most circumstances but may occassionally not report it
     * should return true.
     */
    public abstract boolean supportsAltitude();

    /**
     * Returns true if the provider is able to provide speed
     * information, false otherwise.  A provider that reports speed
     * under most circumstances but may occassionally not report it
     * should return true.
     */
    public abstract boolean supportsSpeed();

    /**
     * Returns true if the provider is able to provide bearing
     * information, false otherwise.  A provider that reports bearing
     * under most circumstances but may occassionally not report it
     * should return true.
     */
    public abstract boolean supportsBearing();

    /**
     * Returns the power requirement for this provider.
     *
     * @return the power requirement for this provider, as one of the
     * constants Criteria.POWER_REQUIREMENT_*.
     */
    public abstract int getPowerRequirement();

    /**
     * Returns a constant describing horizontal accuracy of this provider.
     * If the provider returns finer grain or exact location,
     * {@link Criteria#ACCURACY_FINE} is returned, otherwise if the
     * location is only approximate then {@link Criteria#ACCURACY_COARSE}
     * is returned.
     */
    public abstract int getAccuracy();
}