Combining shapes example

Ilias TsagklisNovember 11th, 2012Last Updated: February 16th, 2013

0 417 2 minutes read

In this tutorial we shall show you how to create a simple graphic by combining basic shapes. We are going to use some the built in classes that Java offers.

Basically to create and combine shapes in Java:

Use Line2D, Ellipse2D, Rectangle2D, RoundRectangle2D, Arc2D, Area to create some simple shapes
Use add, subtract, intersect, exclusiveOr methods of the Area class to combine in the respective ways some of the basic shapes you’ve created

Let’s see how the code looks like:

package com.javacodegeeks.snippets.desktop;

import java.awt.Component;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Shape;
import java.awt.geom.Arc2D;
import java.awt.geom.Area;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import java.awt.geom.Rectangle2D;
import java.awt.geom.RoundRectangle2D;

public class CombineShapes {

    public static void main(String[] args) {

  // Create a frame

  Frame frame = new Frame();

  // Add a component with a custom paint method

  frame.add(new CustomPaintComponent());

  // Display the frame

  int frameWidth = 300;

  int frameHeight = 300;

  frame.setSize(frameWidth, frameHeight);

  frame.setVisible(true);

    }

    /**
     * To draw on the screen, it is first necessary to subclass a Component 
     * and override its paint() method. The paint() method is automatically called 
     * by the windowing system whenever component's area needs to be repainted.
     */
    static class CustomPaintComponent extends Component {

  public void paint(Graphics g) {

    // Retrieve the graphics context; this object is used to paint shapes

    Graphics2D g2d = (Graphics2D)g;

    /**

     * The coordinate system of a graphics context is such that the origin is at the 

     * northwest corner and x-axis increases toward the right while the y-axis increases 

     * toward the bottom.

     */

    int x = 0;

    int y = 0;

    int w = getSize().width-1;

    int h = getSize().height-1;

    Shape line = new Line2D.Float(x, y, w, h);

    Shape oval = new Ellipse2D.Float(x, y, w, h);

    Shape rectangle = new Rectangle2D.Float(x, y, w, h);

    Shape roundRectangle = new RoundRectangle2D.Float(x, y, w, h, w/2, h/2);

    // A start angle of 0 represents a 3 o'clock position, 90 represents a 12 o'clock position,

    // and -90 (or 270) represents a 6 o'clock position

    int startAngle = 45;

    int arcAngle = -60;

    Shape arc = new Arc2D.Float(x, y, w/2, h/2, startAngle, arcAngle, Arc2D.OPEN);

    Area shape = new Area(line);

    shape.add(new Area(oval));

    shape.subtract(new Area(rectangle));

    shape.intersect(new Area(roundRectangle));

    shape.exclusiveOr(new Area(arc));

    g2d.draw(shape);

  }

    }

}

This was an example on how to combine shapes to create a simple graphic.