RailroadConnectionRouter.java

/*******************************************************************************
 * Copyright (c) 2010 itemis AG (http://www.itemis.eu)
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 * Contributors:
 *   Jan Koehnlein - Initial API and implementation
 *******************************************************************************/
package com.github.jknack.antlr4ide.ui.railroad.figures.layout;

import java.util.Map;

import org.eclipse.draw2d.AbstractRouter;
import org.eclipse.draw2d.Connection;
import org.eclipse.draw2d.geometry.Point;
import org.eclipse.draw2d.geometry.PointList;

import com.github.jknack.antlr4ide.ui.railroad.figures.ILayoutConstants;
import com.google.common.collect.Maps;
import com.google.inject.Singleton;

/**
 * @author Jan Koehnlein - Initial contribution and API
 */
@Singleton
public class RailroadConnectionRouter extends AbstractRouter {

  public static class BendConstraint {
    private boolean isStart = false;
    private boolean isConvex = false;

    public BendConstraint(final boolean isStart, final boolean isConvex) {
      this.isStart = isStart;
      this.isConvex = isConvex;
    }

    public boolean isStart() {
      return isStart;
    }

    public boolean isConvex() {
      return isConvex;
    }
  }

  private Map<Connection, BendConstraint> constraints = Maps.newHashMap();

  @Override
  public void route(final Connection connection) {
    PointList points = connection.getPoints();
    points.removeAllPoints();
    Point startPoint = getStartPoint(connection);
    connection.translateToRelative(startPoint);
    points.addPoint(startPoint);
    Point endPoint = getEndPoint(connection);
    connection.translateToRelative(endPoint);
    Object constraint = getConstraint(connection);
    if (constraint instanceof BendConstraint) {
      int dx = Integer.signum(endPoint.x - startPoint.x) * ILayoutConstants.connectionRadius();
      int dy = Integer.signum(endPoint.y - startPoint.y) * ILayoutConstants.connectionRadius();
      // can be simplified but becomes unreadable
      if (((BendConstraint) constraint).isConvex()) {
        if (((BendConstraint) constraint).isStart()) {
          points.addPoint(startPoint.x - dx, startPoint.y + dy);
          points.addPoint(startPoint.x - dx, endPoint.y - dy);
          points.addPoint(startPoint.x , endPoint.y);
        } else {
          points.addPoint(endPoint.x, startPoint.y);
          points.addPoint(endPoint.x + dx, startPoint.y + dy);
          points.addPoint(endPoint.x + dx, endPoint.y - dy);
        }
      } else {
        if (((BendConstraint) constraint).isStart()) {
          points.addPoint(startPoint.x + dx, startPoint.y + dy);
          points.addPoint(startPoint.x + dx, endPoint.y - dy);
          points.addPoint(startPoint.x + 2 * dx, endPoint.y);
        } else {
          points.addPoint(endPoint.x - 2 * dx, startPoint.y);
          points.addPoint(endPoint.x - dx, startPoint.y + dy);
          points.addPoint(endPoint.x - dx, endPoint.y - dy);
        }
      }
    }
    points.addPoint(endPoint);
    connection.setPoints(points);
  }

  @Override
  public void setConstraint(final Connection connection, final Object constraint) {
    if (constraint instanceof BendConstraint) {
      constraints.put(connection, (BendConstraint) constraint);
    }
  }

  @Override
  public Object getConstraint(final Connection connection) {
    return constraints.get(connection);
  }

}