/*
 Copyright (c) 1998-2008 The Regents of the University of California
 All rights reserved.
 Permission is hereby granted, without written agreement and without
 license or royalty fees, to use, copy, modify, and distribute this
 software and its documentation for any purpose, provided that the above
 copyright notice and the following two paragraphs appear in all copies
 of this software.

 IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
 FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
 ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
 THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
 SUCH DAMAGE.

 THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
 INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
 PROVIDED HEREUNDER IS ON AN  BASIS, AND THE UNIVERSITY OF
 CALIFORNIA HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
 ENHANCEMENTS, OR MODIFICATIONS.

 PT_COPYRIGHT_VERSION_2
 COPYRIGHTENDKEY
 *
 */
package diva.canvas.toolbox;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.NoSuchElementException;

import diva.canvas.CanvasLayer;
import diva.canvas.CanvasPane;
import diva.canvas.FigureLayer;

/** A basic implementation of a canvas pane, provided for simple
 * applications. This class keeps a linear list of canvas layers, and
 * provides a couple of methods so that layers can be added to
 * it. Real applications will probably want to create their own
 * CanvasPane subclass, instead of using this class.
 *
 * @version        $Id$
 * @author John Reekie
 */
public class BasicCanvasPane extends CanvasPane {
    /** The array of layers
     */
    ArrayList _layers = new ArrayList();

    /** Create a new canvas pane with a single figure layer
     * at index zero. This is a convenience constructor for
     * test suites and simple demos -- in general, an application
     * will want to construct a more sophisticated set of layers.
     */
    public BasicCanvasPane() {
        super();
        addLayer(new FigureLayer());
    }

    /** Create a new canvas pane with the given layer at index zero.
     */
    public BasicCanvasPane(CanvasLayer layer) {
        super();
        addLayer(layer);
    }

    /** Add the given layer to the list of layers.   The new
     * layer will be drawn over the top of any existing layers.
     */
    public void addLayer(CanvasLayer layer) {
        _initNewLayer(layer);
        _layers.add(layer);
    }

    /** Insert the given layer into the list of layers at the
     * given index. Lower indexes are drawn above higher indexes.
     */
    public void addLayer(int index, CanvasLayer layer) {
        _initNewLayer(layer);
        _layers.add(index, layer);
    }

    /** Get the layer at the given index.
     */
    public FigureLayer getLayer(int index) {
        return (FigureLayer) _layers.get(index);
    }

    /** Get the index of the given layer, or -1 if it is not
     * in this pane.
     */
    public int indexOf(CanvasLayer layer) {
        return _layers.indexOf(layer);
    }

    /** Return an iteration of the layers, in event-processing order (that is,
     * from front to back).
     */
    public Iterator layersFromFront() {
        return _layers.iterator();
    }

    /** Return an iteration of the layers, in redraw order (that is,
     * from back to front).
     */
    public Iterator layersFromBack() {
        return new Iterator() {
            int cursor = _layers.size();

            public boolean hasNext() {
                return cursor > 0;
            }

            public Object next() throws NoSuchElementException {
                if (!hasNext()) {
                    throw new NoSuchElementException("Can't get " + cursor
                            + "'th element from BoundsGeometry of size "
                            + _layers.size());
                }
                cursor--;
                return _layers.get(cursor);
            }

            public void remove() {
                throw new UnsupportedOperationException(
                        "Cannot delete layer from canvas pane");
            }
        };
    }

    /** Remove the given layer. Do nothing if the layer is
     * not in this pane.
     */
    public void removeLayer(CanvasLayer layer) {
        _layers.remove(layer);
    }
}