examples.geometry.demos.ConvexHullExample.java Source code

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Here is the source code for examples.geometry.demos.ConvexHullExample.java

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/*******************************************************************************
 * Copyright (c) 2011, 2012 itemis AG and others.
 * 
 * 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:
 *     Matthias Wienand (itemis AG) - initial API and implementation
 *     
 *******************************************************************************/
package examples.geometry.demos;

import org.eclipse.gef4.geometry.planar.Line;
import org.eclipse.gef4.geometry.planar.Point;
import org.eclipse.gef4.geometry.planar.Polygon;

import com.google.gwt.canvas.client.Canvas;
import com.google.gwt.canvas.dom.client.Context2d;
import com.google.gwt.event.shared.EventBus;

import examples.geometry.AbstractExample;
import examples.geometry.ControllableShape;

public class ConvexHullExample extends AbstractExample {

    public ConvexHullExample(EventBus eventBus, Canvas canvas) {
        super(eventBus, canvas);
    }

    protected ControllableShape[] createShapes(Canvas canvas, EventBus eventBus) {
        ControllableShape shape = new ControllableShape(canvas, eventBus) {
            {
                // These are the points which are displayed on the screen.
                // We will compute their convex hull later.
                addControlPoints(new Point(100, 100), new Point(150, 400), new Point(200, 300), new Point(250, 150),
                        new Point(300, 250), new Point(350, 200), new Point(400, 350));
            }

            @Override
            public Polygon getShape() {
                // Compute the convex hull of the defined point list.
                // We return the convex hull as a Polygon.
                return new Polygon(Point.getConvexHull(getPoints()));
            }

            @Override
            public void onDraw(Canvas canvas) {
                Context2d context = canvas.getContext2d();
                // This is the code to display the computed convex hull.

                // Compute the convex hull.
                Polygon convexHull = getShape();
                for (Line s : convexHull.getOutlineSegments()) {
                    Point p1 = s.getP1();
                    Point p2 = s.getP2();
                    context.moveTo(p1.x, p1.y);
                    context.lineTo(p2.x, p2.y);
                    context.stroke();
                }

                // Display the convex hull as an SWT Path.
                //            gc.drawPath(new org.eclipse.swt.graphics.Path(Display
                //                  .getCurrent(), Geometry2SWT.toSWTPathData(convexHull
                //                  .toPath())));
            }
        };

        return new ControllableShape[] { shape };
    }

}