org.eclipse.fmc.blockdiagram.editor/src/org/eclipse/fmc/blockdiagram/editor/features/custom/LayoutConnectionCustomFeature.java

/*******************************************************************************
 * <copyright>
 *
 * Copyright (c) 2013, 2013 SAP AG.
 * 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:
 *    SAP AG - initial API, implementation and documentation
 *
 * </copyright>
 *
 *******************************************************************************/
package org.eclipse.fmc.blockdiagram.editor.features.custom;

import org.eclipse.graphiti.features.IFeatureProvider;
import org.eclipse.graphiti.features.context.ICustomContext;
import org.eclipse.graphiti.mm.pictograms.Anchor;
import org.eclipse.graphiti.mm.pictograms.BoxRelativeAnchor;
import org.eclipse.graphiti.mm.pictograms.Connection;
import org.eclipse.graphiti.mm.pictograms.PictogramElement;
import org.eclipse.graphiti.services.Graphiti;
import org.eclipse.graphiti.services.IPeLayoutService;

/**
 * Layout feature which moves the source or target anchor in such a way that the
 * connection line is straight.
 * 
 * @author Benjamin Schmeling
 * 
 */
public class LayoutConnectionCustomFeature extends FMCCustomFeature {

	/**
	 * Graphiti layout service.
	 */
	private IPeLayoutService pe = Graphiti.getPeLayoutService();

	/**
	 * Default constructor.
	 * 
	 * @param featureProvider
	 */
	public LayoutConnectionCustomFeature(IFeatureProvider featureProvider) {
		super(featureProvider);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.eclipse.graphiti.features.custom.AbstractCustomFeature#canExecute
	 * (org.eclipse.graphiti.features.context.ICustomContext)
	 */
	@Override
	public boolean canExecute(ICustomContext context) {
		for (PictogramElement element : context.getPictogramElements()) {
			if (!(element instanceof Connection)) {
				return false;
			} else {
				Connection con = (Connection) element;
				if (!(con.getStart() instanceof BoxRelativeAnchor && con
						.getEnd() instanceof BoxRelativeAnchor))
					return false;
			}
		}
		return true;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see
	 * org.eclipse.graphiti.features.custom.ICustomFeature#execute(org.eclipse
	 * .graphiti.features.context.ICustomContext)
	 */
	@Override
	public void execute(ICustomContext context) {
		for (PictogramElement element : context.getPictogramElements()) {
			Connection con = (Connection) element;
			Anchor start = con.getStart();
			Anchor end = con.getEnd();
			if (start instanceof BoxRelativeAnchor
					|| end instanceof BoxRelativeAnchor) {
				int difW = pe.getLocationRelativeToDiagram(end).getX()
						- pe.getLocationRelativeToDiagram(start).getX();
				int difH = pe.getLocationRelativeToDiagram(end).getY()
						- pe.getLocationRelativeToDiagram(start).getY();

				if (isVerticalAnchor(start) || isVerticalAnchor(end)) {
					if (!(end instanceof BoxRelativeAnchor))
						((BoxRelativeAnchor) start)
								.setRelativeWidth(((BoxRelativeAnchor) start)
										.getRelativeWidth()
										+ getRelativeWidth(start, difW));
					else
						((BoxRelativeAnchor) end)
								.setRelativeWidth(((BoxRelativeAnchor) end)
										.getRelativeWidth()
										- getRelativeWidth(end, difW));
				} else if (isHorizontalAnchor(start) || isHorizontalAnchor(end)) {
					if (!(end instanceof BoxRelativeAnchor))
						((BoxRelativeAnchor) start)
								.setRelativeHeight(((BoxRelativeAnchor) start)
										.getRelativeHeight()
										+ getRelativeHeight(start, difH));
					else
						((BoxRelativeAnchor) end)
								.setRelativeHeight(((BoxRelativeAnchor) end)
										.getRelativeHeight()
										- getRelativeHeight(end, difH));
				}
			}
		}
	}

	/**
	 * Checks whether the anchor is positioned along a vertical line.
	 * 
	 * @param anchor
	 *            The anchor to be checked.
	 * @return True if it is an anchor along a vertical line.
	 */
	private boolean isVerticalAnchor(Anchor anchor) {
		if (anchor instanceof BoxRelativeAnchor) {
			BoxRelativeAnchor boxAnchor = (BoxRelativeAnchor) anchor;
			return boxAnchor.getRelativeHeight() == 0
					|| boxAnchor.getRelativeHeight() == 1;
		} else
			return false;
	}

	/**
	 * Checks whether the anchor is positioned along a horizontal line.
	 * 
	 * @param anchor
	 *            The anchor to be checked.
	 * @return True if it is an anchor along a horizontal line.
	 */
	private boolean isHorizontalAnchor(Anchor anchor) {
		if (anchor instanceof BoxRelativeAnchor) {
			BoxRelativeAnchor boxAnchor = (BoxRelativeAnchor) anchor;
			return boxAnchor.getRelativeWidth() == 0
					|| boxAnchor.getRelativeWidth() == 1;
		} else
			return false;
	}

	/**
	 * Calculates the relative width of the given anchor.
	 * 
	 * @param anchor
	 *            The anchor the relative width is determined for.
	 * @param dist
	 *            The horizontal anchor distance
	 * @return Relative width.
	 */
	private double getRelativeWidth(Anchor anchor, int dist) {
		double width = anchor.getParent().getGraphicsAlgorithm().getWidth();
		return dist / width;
	}

	/**
	 * Calculates the relative height of the given anchor.
	 * 
	 * @param anchor
	 *            The anchor the relative height is determined for.
	 * @param dist
	 *            The vertical anchor distance.
	 * @return Relative height.
	 */
	private double getRelativeHeight(Anchor anchor, int num) {
		double height = anchor.getParent().getGraphicsAlgorithm().getHeight();
		return num / height;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.graphiti.features.impl.AbstractFeature#getName()
	 */
	@Override
	public String getName() {
		return "Layout Connection";
	}
}