javaGeom

JavaGeom is a geometry library for Java. It provides a general framework for creating, manipulating, and combining geometric primitives. Among the features:

• computation of intersection points between shapes
• composition create new shapes,
• measures on shapes (area, perimeter...)

The project was formerly hosted on SourceForge, but is now hosted on GitHub: https://github.com/dlegland/javaGeom.

Some examples of use are in the "demo" directory.

Sample application

Here is the content of the "JavaGeomDemo" application, that can be found in the demo directory:

import java.awt.Graphics;
import java.awt.Graphics2D;
import java.util.Collection;
  
import javax.swing.JFrame;
import javax.swing.JPanel;

import math.geom2d.AffineTransform2D;
import math.geom2d.Box2D;
import math.geom2d.Point2D;
import math.geom2d.conic.Circle2D;
import math.geom2d.line.LineSegment2D;
import math.geom2d.line.StraightLine2D;

public class JavaGeomDemo extends JPanel{
	
  public JavaGeomDemo() {}

  public void paintComponent(Graphics g){
      Graphics2D g2 = (Graphics2D) g;

      // Create some points
      Point2D p1 = new Point2D(40, 30);
      Point2D p2 = new Point2D(180, 100);
			
      // Draw the two points, using a radius of 2 pixels.
      p1.draw(g2, 2);
      p2.draw(g2, 2);
	  
      // Create and draw a circle
      Circle2D circle1 = new Circle2D(80, 120, 40);
      circle1.draw(g2);
	
      // Create a line
      StraightLine2D line1 = new StraightLine2D(p1, p2);
	
      // Draw the line, after clipping
      Box2D box = new Box2D(0, 200, 0, 200);
      line1.clip(box).draw(g2);
  	
      Point2D p3 = new Point2D(20, 120);
      Point2D p4 = new Point2D(40, 140);
	  
      // Create line segment
      LineSegment2D  edge  = new LineSegment2D(p3, p4);
      edge.draw(g2);
	
      // Compute a median line, and draw it
      StraightLine2D line2 = StraightLine2D.createMedian(p3, p4);
      p4.draw(g2, 2);
      p4.draw(g2, 2);
      line2.clip(box).draw(g2);

      // Compute intersection between 2 lines
      Point2D intLine = line2.intersection(line1);
      intLine.draw(g2, 2);
  
      // Compute intersections between a circle and lines
      Collection<Point2D> intersects = circle1.intersections(line2);
      for(Point2D point : intersects)
          point.draw(g2, 2);
  
      // Create some affine transforms
      AffineTransform2D sca = AffineTransform2D.createScaling(p4, 2, .8);
      AffineTransform2D tra = AffineTransform2D.createTranslation(30, 40);
      AffineTransform2D rot = AffineTransform2D.createRotation(p4, Math.PI/2);
  
      // Display the transformed shapes.
      circle1.transform(sca).draw(g2);
      circle1.transform(tra).draw(g2);
      line2.transform(rot).clip(box).draw(g2);
  }

  public final static void main(String[] args){
      JPanel panel = new JavaGeomDemo();
      JFrame frame = new JFrame("JavaGeom Demo");
      frame.setContentPane(panel);
      frame.setSize(250, 250);
      frame.setVisible(true);
  }
}