lucene/spatial3d/src/java/org/apache/lucene/spatial3d/geom/GeoArea.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.lucene.spatial3d.geom;

/**
 * A GeoArea represents a standard 2-D breakdown of a part of sphere. It can be bounded in latitude,
 * or bounded in both latitude and longitude, or not bounded at all. The purpose of the interface is
 * to describe bounding shapes used for computation of geo hashes.
 *
 * @lucene.experimental
 */
public interface GeoArea extends Membership {
  // Since we don't know what each GeoArea's constraints are,
  // we put the onus on the GeoArea implementation to do the right thing.
  // This will, of course, rely heavily on methods provided by
  // the underlying GeoShape class.

  // Relationship values for "getRelationship()"

  /** The referenced shape CONTAINS this area */
  public static final int CONTAINS = 0;
  /** The referenced shape IS WITHIN this area */
  public static final int WITHIN = 1;
  /** The referenced shape OVERLAPS this area */
  public static final int OVERLAPS = 2;
  /** The referenced shape has no relation to this area */
  public static final int DISJOINT = 3;

  /**
   * Find the spatial relationship between a shape and the current geo area. Note: return value is
   * how the GeoShape relates to the GeoArea, not the other way around. For example, if this GeoArea
   * is entirely within the shape, then CONTAINS should be returned. If the shape is entirely
   * enclosed by this GeoArea, then WITHIN should be returned.
   *
   * <p>It is permissible to return OVERLAPS instead of WITHIN if the shape intersects with the area
   * at even a single point. So, a circle inscribed in a rectangle could return either OVERLAPS or
   * WITHIN, depending on implementation. It is not permissible to return CONTAINS or DISJOINT in
   * this circumstance, however.
   *
   * <p>Similarly, it is permissible to return OVERLAPS instead of CONTAINS under conditions where
   * the shape consists of multiple independent overlapping subshapes, and the area overlaps one of
   * the subshapes. It is not permissible to return WITHIN or DISJOINT in this circumstance,
   * however.
   *
   * @param shape is the shape to consider.
   * @return the relationship, from the perspective of the shape.
   */
  public int getRelationship(GeoShape shape);
}