# 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);
}
}``````