Java affine transform using JTS

java_affine.java

import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.Geometry;
import com.vividsolutions.jts.geom.GeometryFactory;
import com.vividsolutions.jts.geom.LinearRing;
import com.vividsolutions.jts.geom.util.AffineTransformationBuilder;
import com.vividsolutions.jts.geom.util.NoninvertibleTransformationException;
import org.geotools.geometry.jts.JTSFactoryFinder;

/**
 *
 * @author huziy
 */
public class TestCreateGeometry {


  public static void main(String[] args) 
                         throws NoninvertibleTransformationException {
    GeometryFactory geometryFactory = JTSFactoryFinder.getGeometryFactory(null);

    double width = 10.0;
    Coordinate c1 = new Coordinate(6,7);
    Coordinate c2 = new Coordinate(10,10);
        
    double height = c1.distance(c2);

    //vector perpendicular to c1c2
    Coordinate c = new Coordinate((c1.y - c2.y) / height * width / 2.0 , (c2.x - c1.x) / height * width / 2.0);
    Coordinate middle = new Coordinate(0.5 * (c1.x + c2.x), 0.5 * (c1.y + c2.y));
    Coordinate perpendicular = new Coordinate(middle.x + c.x, middle.y + c.y);
    Coordinate perpendDest = new Coordinate(0.5, 1.0); //impose it to be like that in the transformed plane

    //transform the points to the coordinates with the lower left at the corner of the crs
    //and edges parellel to the axes
    Coordinate c1Dest = new Coordinate(0, 0.5);
    Coordinate c2Dest = new Coordinate(1, 0.5);
    AffineTransformationBuilder builder = new AffineTransformationBuilder(c1, c2, perpendicular, c1Dest,
                                       c2Dest, perpendDest);



    //work from point1 and create linear ring of points
    Coordinate[] coords = new Coordinate[]{
         new Coordinate(0,0), new Coordinate(0,1), new Coordinate(1,1), new Coordinate(1,0), null
    };
    coords[4] = coords[0];


    LinearRing ring = geometryFactory.createLinearRing(coords);
    Geometry rect = geometryFactory.createPolygon(ring, null);

    rect = builder.getTransformation().getInverse().transform(rect);

    System.out.println("Perimeters");
    System.out.println(rect.getLength());
    System.out.println(2 * (height + width));
    System.out.println("Areas");
    System.out.println(rect.getArea());
    System.out.println(width * height);
  }
}