PainterVisitor.java

/*
 * This is part of Geomajas, a GIS framework, http://www.geomajas.org/.
 *
 * Copyright 2008-2015 Geosparc nv, http://www.geosparc.com/, Belgium.
 *
 * The program is available in open source according to the GNU Affero
 * General Public License. All contributions in this program are covered
 * by the Geomajas Contributors License Agreement. For full licensing
 * details, see LICENSE.txt in the project root.
 */

package org.geomajas.gwt.client.gfx;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * <p>
 * Visitor pattern implementation for painter.
 * </p>
 * 
 * @author Jan De Moerloose
 */
public class PainterVisitor {

	/**
	 * The context on which all painter registered here should be applied.
	 */
	private MapContext context;

	/**
	 * Dictionary of registered painter. It is possible that more then one painter is registered for a certain type of
	 * object.
	 */
	private Map<String, List<Painter>> painters;

	/**
	 * This class should always be initialized with a <code>GraphicsContext</code> object, since all painter registered
	 * here will apply their painting skills on it.
	 * 
	 * @param context
	 *            Implementation of the MapContext interface.
	 */
	public PainterVisitor(MapContext context) {
		this.context = context;
		this.painters = new HashMap<String, List<Painter>>();
	}

	/**
	 * Register a new painter to this visitor.
	 * 
	 * @param painter
	 *            The painter itself.
	 */
	public void registerPainter(Painter painter) {
		if (painters.containsKey(painter.getPaintableClassName())) {
			List<Painter> list = painters.remove(painter.getPaintableClassName());
			list.add(painter);
			this.painters.put(painter.getPaintableClassName(), list);
		} else {
			List<Painter> list = new ArrayList<Painter>();
			list.add(painter);
			this.painters.put(painter.getPaintableClassName(), list);
		}
	}

	/**
	 * Unregister an existing painter from this visitor.
	 * 
	 * @param painter
	 *            The painter itself.
	 */
	public void unregisterPainter(Painter painter) {
		String className = painter.getPaintableClassName();
		if (painters.containsKey(className)) {
			List<Painter> list = painters.remove(className);
			if (list.size() > 1) {
				list.remove(painter);
				painters.put(className, list);
			}
		}
	}

	/**
	 * The visitors visit function.
	 * 
	 * @param paintable object to draw
	 * @param group group to draw
	 */
	public void visit(Paintable paintable, Object group) {
		if (context.isReady()) {
			String className = paintable.getClass().getName();
			if (painters.containsKey(className)) {
				List<Painter> list = painters.get(className);
				for (Painter painter : list) {
					painter.paint(paintable, group, context);
				}
			}
		}
	}

	/**
	 * Remove a paintable object from the graphics.
	 * 
	 * @param paintable paintable object
	 * @param group group to draw
	 */
	public void remove(Paintable paintable, Object group) {
		String className = paintable.getClass().getName();
		if (painters.containsKey(className)) {
			List<Painter> list = painters.get(className);
			for (Painter painter : list) {
				painter.deleteShape(paintable, group, context);
			}
		}
	}

	/**
	 * Retrieve the full list of painter for a specific type of paintable object.
	 * 
	 * @param paintable
	 *            The type of object to retrieve painter for.
	 * @return Return a list of painter, or null.
	 */
	public List<Painter> getPaintersForObject(Paintable paintable) {
		String className = paintable.getClass().getName();
		if (painters.containsKey(className)) {
			return painters.get(className);
		}
		return null;
	}
}