/*Affine01.java 12/12/99
Copyright 1999, R.G.Baldwin
 
Illustrates use of the Affine transforms, and the
methods of the Graphics2D class that allow for applying
transforms of the following types:
  
Scale
Translate
Rotate
Shear
 
Also gets and displays the values in the AffineTransform
object after the transform has been applied by invoking
methods with the same names.
 
In addition to displaying a GUI that visually 
illustrates the effects of the transforms, the program 
also displays the following information on the screen.
 
Default Transform
1.0 0.0 0.0 
0.0 1.0 0.0 
 
Add Scale Transform
1.6666666666666667 0.0 0.0 
0.0 1.6666666666666667 0.0 
 
Add Translate Transform
1.6666666666666667 0.0 30.0 
0.0 1.6666666666666667 30.0 
 
Add Shear Transform
1.6666666666666667 0.08333333333333334 30.0 
0.16666666666666669 1.6666666666666667 30.0 
 
Add Rotate Transform
1.6508996608400615 -0.2434184299932779 79.32270275806317 
0.4886147500940855 1.6021270803360292 -7.066823581936546 
 
The visual display consists of five concentric squares
with the text string "Exit->" superimposed on the
squares.  This visual display illustrates the effects of
the transforms pretty well.
 
This program is intended to be used to experiment with
Affine transforms.  By using comment indicators "//"
to disable statements of the form:
 
    System.out.println("Add Translate Transform");
    g2.translate(0.25*ds,0.25*ds);
    displayMatrix(g2.getTransform());
    
and by rearranging those statements, the student can see
the individual and cumulative effects of applying the
transforms.
 
Tested using JDK 1.2.2 under WinNT Workstation 4.0
**************************************/
import java.awt.geom.*;
import java.awt.*;
import java.awt.event.*;
 
class Affine01{
  publicstaticvoid main(String[] args){
    GUI guiObj = new GUI();
  }//end main
}//end controlling class Affine01
 
class GUI extends Frame{
  int res;//store screen resolution here
  staticfinalint ds = 72;//default scale, 72 units/inch
  
  GUI(){//constructor
    //Get screen resolution
    res = Toolkit.getDefaultToolkit().
                           getScreenResolution();
 
    //Set Frame size to four-inches by four-inches
    this.setSize(4*res,4*res);
    this.setVisible(true);
    this.setTitle("Copyright 1999, R.G.Baldwin");
       
    //Window listener to terminate program.
    this.addWindowListener(new WindowAdapter(){
      publicvoid windowClosing(WindowEvent e){
        System.exit(0);}});
  }//end constructor
  
  //Override the paint() method to draw and manipulate a
  // square.
  publicvoid paint(Graphics g){
    //Downcast the Graphics object to a Graphics2D object
    Graphics2D g2 = (Graphics2D)g;
 
    //Display contents of default AffineTransform object
    System.out.println("Default Transform");
    displayMatrix(g2.getTransform());    
    
    //Update transform to include a scale component, 
    // and display the values.
    System.out.println("Add Scale Transform");
    g2.scale((double)res/72,(double)res/72);
    displayMatrix(g2.getTransform());
 
    //Update transform to include a translate component, 
    // and display the values.
    System.out.println("Add Translate Transform");
    g2.translate(0.25*ds,0.25*ds);
    displayMatrix(g2.getTransform());
 
    //Update transform to include a shear component, 
    // and display the values.
    System.out.println("Add Shear Transform");
    g2.shear(0.05,0.1);
    displayMatrix(g2.getTransform());
 
    //Update transform to provide rotation and display, 
    // the transform values.    
    System.out.println("Add Rotate Transform");
    //11.25 degrees about center
    g2.rotate(Math.PI/16,2.0*ds, 2.0*ds);
    displayMatrix(g2.getTransform());
 
    //Draw five concentric squares and apply the transform
    // that results from the above transform updates.  If
    // the above scale transform is applied, the outer
    // square is one inch on each side, and the squares
    // are separated by 0.1 inch 
    double delta = 0.1;
    for(int cnt = 0; cnt < 5; cnt++){
      g2.draw(new Rectangle2D.Double(
         (1.5+cnt*delta)*ds, (1.5+cnt*delta)*ds, 
         (1.0-cnt*2*delta)*ds, (1.0-cnt*2*delta)*ds));
    }//end for loop
 
    //Superimpose some text on the squares with the 
    // lower left corner of the first character at the
    // center of the squares.
    g2.drawString("Exit ->",2.0f*ds,2.0f*ds);
  }//end overridden paint()
    
  //This method receives a reference to an AffineTransform
  // and displays the six controllable values in the
  // transform matrix
  void displayMatrix(AffineTransform theTransform){
    double[] theMatrix = newdouble[6];
    theTransform.getMatrix(theMatrix);
    
    //Display first row of values by displaying every
    // other element in the array starting with element
    // zero.
    for(int cnt = 0; cnt < 6; cnt+=2){
      System.out.print(theMatrix[cnt] + " ");
    }//end for loop
    
    //Display second row of values displaying every
    // other element in the array starting with element
    // number one.
    System.out.println();//new line
    for(int cnt = 1; cnt < 6; cnt+=2){
      System.out.print(theMatrix[cnt] + " ");
    }//end for loop
    System.out.println();//end of line
    System.out.println();//blank line
    
  }//end displayMatrix
}//end class GUI
//==============================//






Figure 12