/* Copyright (c) 2008 Google Inc.
*
* 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.google.gdata.data.geo.impl;
import com.google.gdata.util.common.xml.XmlWriter;
import com.google.gdata.data.Extension;
import com.google.gdata.data.ExtensionDescription;
import com.google.gdata.data.ExtensionPoint;
import com.google.gdata.data.ExtensionProfile;
import com.google.gdata.data.geo.GeoLat;
import com.google.gdata.data.geo.GeoLong;
import com.google.gdata.data.geo.Namespaces;
import com.google.gdata.data.geo.Point;
import com.google.gdata.util.ParseException;
import com.google.gdata.util.XmlParser.ElementHandler;
import org.xml.sax.Attributes;
import java.io.IOException;
/**
* Extension for a W3C geo:Point element. It contains the getter/setter for
* specifying the longitude and latitude of a geo-coordinate.
* Please see the W3C document
* <a href="http://www.w3.org/2003/01/geo">http://www.w3.org/2003/01/geo</a> for
* more information.
*
*
*/
public class W3CPoint extends ExtensionPoint implements Point {
static final String NAME = "Point";
/**
* Constructs an empty geo:Point element.
*/
public W3CPoint() {}
/**
* Constructs a geo:Point element with child geo:lat and geo:long
* elements based on the parameters passed in.
*
* @param lat The latitude coordinate of this point.
* @param lon The longitude coordinate of this point.
*/
public W3CPoint(Double lat, Double lon) {
setGeoLocation(lat, lon);
}
/**
* Constructs a geo:Point element copying the lat and lon values from the
* given point. If the given point is null an empty geo:Point element will
* be created.
*/
public W3CPoint(Point copyFrom) {
this(copyFrom == null ? null : copyFrom.getLatitude(),
copyFrom == null ? null : copyFrom.getLongitude());
}
/**
* Returns the suggested extension description with configurable
* repeatability.
*/
public static ExtensionDescription getDefaultDescription(boolean repeatable) {
ExtensionDescription desc = new ExtensionDescription();
desc.setExtensionClass(W3CPoint.class);
desc.setNamespace(Namespaces.W3C_GEO_NAMESPACE);
desc.setLocalName(NAME);
desc.setRepeatable(repeatable);
return desc;
}
/**
* Returns the suggested extension description and is repeatable.
*/
public static ExtensionDescription getDefaultDescription() {
return getDefaultDescription(true);
}
/*
* Declare the extensions for geo point. This contains elements for
* latitude and longitude. In the future, it will also include other geo
* information such as altitude.
*/
@Override
public void declareExtensions(ExtensionProfile extProfile) {
// Declare the latitude and longitude extensions.
extProfile.declare(W3CPoint.class,
ExtensionDescription.getDefaultDescription(GeoLat.class));
extProfile.declare(W3CPoint.class,
ExtensionDescription.getDefaultDescription(GeoLong.class));
super.declareExtensions(extProfile);
}
/**
* @return the value of the geo:lat element within this Point.
*/
public Double getLatitude() {
GeoLat lat = getExtension(GeoLat.class);
return lat != null ? lat.getLatitude() : null;
}
/**
* @return the value of the geo:long element within this Point.
*/
public Double getLongitude() {
GeoLong lon = getExtension(GeoLong.class);
return lon != null ? lon.getLongitude() : null;
}
/**
* Sets the geo location based on the passed in lat and lon values. Both
* must be null or non null, and the lat must be between -90 and 90, and the
* lon between -180 and 180.
*/
public void setGeoLocation(Double lat, Double lon) {
if (lat != null && lon != null) {
setExtension(new GeoLat(lat));
setExtension(new GeoLong(lon));
} else if (lat != null || lon != null) {
throw new IllegalArgumentException(
"'lat' and 'lon' must either both be null or non-null.");
} else {
removeExtension(GeoLat.class);
removeExtension(GeoLong.class);
}
}
/**
* Generates the XML corresponding to this GeoPoint.
*/
@Override
public void generate(XmlWriter w, ExtensionProfile extProfile)
throws IOException {
generateStartElement(w, Namespaces.W3C_GEO_NAMESPACE, NAME, null, null);
// Generate the inner extensions (lat, long).
generateExtensions(w, extProfile);
w.endElement(Namespaces.W3C_GEO_NAMESPACE, NAME);
}
/**
* @return a handler for processing a W3C geo:Point element. All
* points must have a latitude and longitude element.
*/
@Override
public ElementHandler getHandler(ExtensionProfile extProfile,
String namespace, String localName, Attributes attrs) {
return new Handler(extProfile);
}
/**
* Simple delegating handler implementation that uses (only)
* ExtensionProfile linkages for child element lookup. Ensures that all points
* have a latitude and longitude element.
*/
protected class Handler extends ExtensionPoint.ExtensionHandler {
public Handler(ExtensionProfile extProfile) {
super(extProfile, W3CPoint.class);
}
/**
* Overrides the base implementation by adding checks to make sure
* the point has a latitude and longitude.
*/
@Override
public void processEndElement() throws ParseException {
super.processEndElement();
Extension lat = getExtension(GeoLat.class);
Extension lon = getExtension(GeoLong.class);
if (lat != null || lon != null) {
// If lat OR long is specified, then both are required.
if (lat == null) {
throw new ParseException("All geo:Point elements must have a " +
"latitude coordinate.");
}
if (lon == null) {
throw new ParseException("All geo:Point elements must have a " +
"longitude coordinate.");
}
}
}
}
}