/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2001-2008, Open Source Geospatial Foundation (OSGeo)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*/
package org.geotools.coverage.grid;
/**
* A grid coverage backed by the same {@linkplain #image image}, {@linkplain #gridGeometry grid
* geometry} and {@linkplain #getSampleDimensions sample dimension} than an other coverage, but
* performing some additional calculation in its {@code evaluate} methods.
*
* @since 2.5
*
* @source $URL$
* @version $Id$
* @author Martin Desruisseaux (IRD)
*/
public abstract class Calculator2D extends GridCoverage2D {
/**
* For cross-version compatibility.
*/
private static final long serialVersionUID = -6287856672249003253L;
/**
* The source grid coverage which was specified at construction time (never {@code null}).
*
* @serial This field duplicate the value obtained by <code>{@linkplain #getSources()}(0)</code>
* except if this coverage has been deserialized. The source is required in order to get
* the {@link #view} method to work. Because the {@linkplain GridCoverage2D#image image}
* contained in the source is the same one than in this {@link Calculator2D}, there is
* few cost in keeping it.
*/
protected final GridCoverage2D source;
/**
* Constructs a new grid coverage with the same parameter than the specified coverage.
*
* @param name The name for this coverage, or {@code null} for the same than {@code coverage}.
* @param coverage The source grid coverage.
*/
protected Calculator2D(final CharSequence name, final GridCoverage2D coverage) {
super(name, coverage);
this.source = coverage;
}
/**
* Invoked by <code>{@linkplain #view view}(type)</code> when the {@linkplain ViewType#PACKED
* packed}, {@linkplain ViewType#GEOPHYSICS geophysics} or {@linkplain ViewType#PHOTOGRAPHIC
* photographic} view of this grid coverage needs to be created. The {@link #view view} method
* first gets the desired view from the {@linkplain #source} coverage, then passes it as the
* argument to this method. Subclasses should define this method as below:
*
* <blockquote><code>
* return new MyCalculator2D(view, <</code><var>any configuration to copy</var><code>>);
* </code></blockquote>
*
* @param view A view derived from the {@linkplain #source} coverage.
* @return The grid coverage to be returned by {@link #view view}, typically of the same
* class than {@code this} (but this is not a strong requirement).
*/
@Override
protected abstract GridCoverage2D specialize(GridCoverage2D view);
/**
* Returns the native view to be given to a newly created {@link ViewsManager}. We can not
* returns {@code this} like what {@link GridCoverage2D} does because this class is just a
* decorator around a {@linkplain #source}, and the later may not be a native view - it can
* be anything like a geophysics, a packed, <cite>etc</cite>. We can hardly call any instance
* of this decorator as "native", so the safest approach is to use the native view of the
* source. This is needed for proper working of {@link ViewsManager}: if this decorator stands
* between it and the views that it creates, it may not realize that a view was already created.
*/
@Override
final GridCoverage2D getNativeView() {
return source.view(ViewType.NATIVE);
}
/**
* Returns the class of the view returned by {@link #specialize}, or {@code null} if unknown.
* Default implementation returns {@code null} because we don't know how the user will
* implement {@link #specialize}. GeoTools final subclasses like {@link Interpolator2D}
* will return their class.
*/
@Override
Class<? extends Calculator2D> getViewClass() {
return null;
}
}