| gvSIG desktop 1

package org.gvsig.fmap.geom.operation;

import org.gvsig.fmap.geom.Geometry;

import org.gvsig.fmap.geom.GeometryLocator;

/**

 * Every geometry operation that is registered dynamically must extend this class.<br>

 *

 * The following example shows how to implement and register a custom operation:

 *  

 * <pre>

 * public class MyOperation extends GeometryOperation {

 * 

 *   // Check GeometryManager for alternative methods to register an operation  

 *   public static final int CODE = 

 *     GeometryManager.getInstance()

 *        .registerGeometryOperation("MyOperation", new MyOperation(), geomType);

 *   

 *   public Object invoke(Geometry geom, GeometryOperationContext ctx) throws GeometryOperationException {

 *        // Operation logic goes here

 *   }     

 *   

 *   public int getOperationIndex() {

 *      return CODE;

 *   }

 *   

 * }

 * </pre>

 *

 * @author jiyarza

 *

 */

public abstract class GeometryOperation {

        // Constants for well-known operations to avoid dependency between geometry model and

        // operations.

        public static final String OPERATION_INTERSECTS_NAME = "intersects";

        public static final String OPERATION_CONTAINS_NAME = "contains";

        public static int OPERATION_INTERSECTS_CODE =

                GeometryLocator.getGeometryManager().getGeometryOperationCode(OPERATION_INTERSECTS_NAME);;

        public static int OPERATION_CONTAINS_CODE =

                GeometryLocator.getGeometryManager().getGeometryOperationCode(OPERATION_CONTAINS_NAME);;

        /**

         * Invokes this operation given the geometry and context 

         * @param geom Geometry to which apply this operation

         * @param ctx Parameter container

         * @return Place-holder object that may contain any specific return value. 

         * @throws GeometryOperationException The implementation is responsible to throw this exception when needed.

         */

        public abstract Object invoke(Geometry geom, GeometryOperationContext ctx) throws GeometryOperationException;

        /**

         * Returns the constant value that identifies this operation and that was obtained upon registering it. 

         * @return operation unique index 

         */

        public abstract int getOperationIndex();

}