TransformApplet.java

import javax.swing.*; import java.awt.*; import java.awt.geom.*; /**  Demonstration of AffineTransform in Java2D.**/ public class TransformApplet extends JApplet {   public void init () {     Container content_pane = getContentPane ();     // Create an instance of DrawingPanel     TransformPanel transform_panel =         new TransformPanel ();     // Add the DrawingPanel to the contentPane.     content_pane.add (transform_panel);   } //init } // class TransformApplet

import javax.swing.*; import java.awt.*; import java.awt.geom.*; /**  Demonstrate different AffineTransforms of a rectangle.**/ class TransformPanel extends JPanel {   public void paintComponent (Graphics g) {     // First paint background     super.paintComponent (g);     Graphics2D g2 =  (Graphics2D)g;     // Turn on anti-aliasing.     g2.setRenderingHint (RenderingHints.KEY_ANTIALIASING,         RenderingHints.VALUE_ANTIALIAS_ON);     // Create a rectangle.     Shape shape1 =  new Rectangle2D.Double (20.0, 20.0, 30.0, 50.0);     // Now draw it.     g2.draw (shape1);     // Shift the drawing origin 72 units  (1 inch) to the right     // to obtain room for the next drawing     AffineTransform at = AffineTransform.getTranslateInstance (72,0);     g2.transform (at);     // Create a rotation transform of 30 degrees CCW around the     // the top left corner of the rectangle.     AffineTransform  atx =       AffineTransform.getRotateInstance (-Math.PI/6,30,20);     // Take the shape object and create a rotated version     Shape atShape = atx.createTransformedShape (shape1);     g2.draw (atShape);     // Another 72 unit shift.     g2.transform (at);     // Create a scaling transform     atx = AffineTransform.getScaleInstance (1.5,1.5);     // Take the shape object and create a scaled version     atShape = atx.createTransformedShape (shape1);     g2.draw (atShape);     // Another 72 unit shift.     g2.transform (at);     // Create a shear transform     atx = AffineTransform.getShearInstance (0.0,0.5);     // Take the shape object and create a sheared version     atShape = atx.createTransformedShape (shape1);     g2.draw (atShape);     // Another 72 unit shift.     g2.transform (at);     // Illustrate compound transforms     // First get a transform object     atx = new AffineTransform ();     // Then set to a shear transform     atx.setToShear (0.0,0.5);     // and then rotate  about the current origin     atx.rotate (-Math.PI/5,40,50);     // Now apply to the rectangle     atShape = atx.createTransformedShape (shape1);     g2.draw (atShape);   } // paintComponent } //class TransformPanel

In the first four transforms, we used static methods in the AffineTransform class to obtain instances of the class for the particular type of transform desired. For example, a translation transform is obtained with

  AffineTransform at = AffineTransform.getTranslateInstance (72, 0);

Applying this to the graphics context moves its origin horizontally by 72 units:

  g2.transform (at);

All subsequent coordinate values are relative to that new position on the drawing surface. Here the translation lets us draw the rectangle at a different position without changing its internal coordinate values. Then the rectangle is operated on with a rotation transform obtained with the getRotateInstance() static method:

  AffineTransform atx =
    AffineTransform.getRotateInstance (-Math.PI/6, 40, 50);

Then a new rectangle in the rotated orientation is obtained with the createTransformedShape() method as follows:

  Shape atShape = atx.createTransformedShape (shape1);

Finally, the new rotated rectangle is drawn with:

  g2.draw (atShape);

This same process is repeated for scaling and shear transforms. Finally, a combined transform is created by creating an instance of AffineTransform and then its setToShear() and rotate() methods are applied to the original rectangle to obtain a new transformed one.