/*
 * The Unified Mapping Platform (JUMP) is an extensible, interactive GUI
 * for visualizing and manipulating spatial features with geometry and attributes.
 *
 * Copyright (C) 2003 Vivid Solutions
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * For more information, contact:
 *
 * Vivid Solutions
 * Suite #1A
 * 2328 Government Street
 * Victoria BC  V8T 5G5
 * Canada
 *
 * (250)385-6040
 * www.vividsolutions.com
 */
package com.vividsolutions.jump.workbench.ui.snap;

import com.vividsolutions.jts.geom.Coordinate;

import com.vividsolutions.jump.util.Blackboard;
import com.vividsolutions.jump.workbench.ui.LayerViewPanel;


public class SnapToGridPolicy implements SnapPolicy {
    public static final String ENABLED_KEY = SnapToGridPolicy.class.getName() +
        " - ENABLED";
    public static final String GRID_SIZE_KEY = SnapToGridPolicy.class.getName() +
        " - GRID_SIZE";
    private Blackboard blackboard;

    public SnapToGridPolicy(Blackboard blackboard) {
        this.blackboard = blackboard;
    }

    public Coordinate snap(LayerViewPanel panel, Coordinate originalCoordinate) {
        if (!blackboard.get(ENABLED_KEY, false)) {
            return null;
        }

        double gridSize = blackboard.get(GRID_SIZE_KEY, 20d);

        Coordinate gridCoordinate = new Coordinate(Math.round(
                    originalCoordinate.x / gridSize) * gridSize,
                Math.round(originalCoordinate.y / gridSize) * gridSize);

        return (gridCoordinate.distance(originalCoordinate) <= (SnapManager.getToleranceInPixels(blackboard) / panel.getViewport()
                                                                                                                    .getScale()))
        ? gridCoordinate : originalCoordinate;
    }
}