/*
 * Richard A. DeVenezia
 * June 7, 2004
 * www.devenezia.com/java/affine
 *
 * An atypical example demonstrating how to implement
 * viewports and windows using AffineTransform.
 */

import java.awt.*;
import java.awt.image.*;
import java.awt.geom.*;
import javax.swing.*;
import java.text.DecimalFormat ;

public class Sample
{
    int w = 400;
    int h = 400;

    int dvx=0, dvy=0, dvw=w, dvh=h;
    double vllx=0, vlly=0, vurx=1, vury=1, vw=1, vh=1;
    double wllx=0, wlly=0, wurx=w, wury=h, ww=w, wh=h;

    BufferedImage buffer = new
    BufferedImage ( w,h, BufferedImage.TYPE_INT_RGB );

    Graphics2D g = buffer.createGraphics();

    AffineTransform initialTx = g.getTransform();

    void setViewport (double x1, double y1, double x2, double y2) {
        // Viewport, fraction of buffer
        vllx = x1;
        vlly = y1;
        vurx = x2;
        vury = y2;
        vw   = vurx - vllx;
        vh   = vury - vlly;

        dvx = (int) Math.round(   vllx  * w);
        dvy = (int) Math.round((1-vury) * h);
        dvw = (int) Math.round( vw * w);
        dvh = (int) Math.round( vh * h);

        g.setTransform (initialTx);
        g.setClip (dvx,dvy,dvw,dvh);

System.out.println ("vw:"+df.format(vw)+",vh:"+df.format(vh));
System.out.println ("dvx:"+dvx+",dvy:"+dvy+",dvw:"+dvw+",dvh:"+dvh);
    }

    void setWindow (double x1, double y1, double x2, double y2) {
        // Window, world coordinates
        wllx = x1;
        wlly = y1;
        wurx = x2;
        wury = y2;
        ww   = wurx - wllx;
        wh   = wury - wlly;

System.out.println ("ww:"+ww+",wh:"+wh);
    }

    void setVWTransform () {
        // px = 0 + w * ( vllx + (WX - wllx) / (wurx - wllx) * (vurx - vllx) )
        // py = h - h * ( vlly + (Wy - wlly) / (wury - wlly) * (vury - vlly) )

        double kw = vw / ww;
        double kh = vh / wh;

        g.setTransform
        ( new AffineTransform
          ( kw*w, 0
          , 0, -kh*h
          , (vllx-kw*wllx)*w, (1-vlly+kh*wlly)*h
          )
        );
    }

    void resetVWTransform () {
        setViewport (0,0,1,1);
        setWindow (0,0,w,h);
        vllx=0; vlly=0;
        vurx=1; vury=1;
        vw=1;
        vh=1;
    double wllx=0, wlly=0, wurx=100, wury=100, ww=100, wh=100;

    }

    void drawStuff () {
        g.setColor (Color.BLUE);
        for (int radius = 10; radius < 150; radius += 10) {
            g.drawOval (60-radius,60-radius,2*radius,2*radius);
        }
    }

    void show() {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(new JScrollPane(new JPanel() {
            protected void paintComponent(Graphics g) {
                g.fillRect(0, 0, getWidth(), getHeight());
                g.drawImage(buffer, 0, 0, null);
            }

            public Dimension getPreferredSize() {
                return new Dimension(buffer.getWidth(), buffer.getHeight());
            }
        }));
        frame.pack();
        frame.show();
    }


    DecimalFormat df = new DecimalFormat ("####.##");

    public static void main(String args[])
    {
        Sample s = new Sample();

        s.g.setRenderingHint
        ( RenderingHints.KEY_TEXT_ANTIALIASING
        , RenderingHints.VALUE_TEXT_ANTIALIAS_ON);

        s.g.setRenderingHint
        ( RenderingHints.KEY_ANTIALIASING
        , RenderingHints.VALUE_ANTIALIAS_ON);

        s.g.setBackground (Color.WHITE);
        s.g.clearRect (0,0,s.w,s.h);

        // draw some circles and lines, untransformed
        s.drawStuff ();
        s.g.drawLine (40,40,100,100);
        s.g.drawRect (40,40,60,60);

        // specify viewport and window
        s.setViewport (.55,.55,.95,.95);
        s.setWindow   (35,35,110,110);

        s.g.setColor (new Color (0x200000ff, true));
        s.g.fillRect (0,0,s.w,s.h);

        s.setVWTransform ();
        s.drawStuff ();
        s.g.drawLine (40,40,100,100);
        s.g.drawRect (40,40,60,60);

        // specify viewport and window
        s.setViewport (.55,.05,.95,.45);
        s.setWindow   (-10,-10,65,65);

        s.g.setColor (new Color (0x20ffff00, true));
        s.g.fillRect (0,0,s.w,s.h);

        s.setVWTransform ();
        s.drawStuff ();
        s.g.drawLine (40,40,100,100);
        s.g.drawRect (40,40,60,60);


        // specify viewport and window
        // viewport aspect differs from window aspect, causing squarsh or squish
        s.setViewport (0,0,.24,.24);
        s.setWindow   (-10,35,105,105);

        s.g.setColor (new Color (0x2000ff00, true));
        s.g.fillRect (0,0,s.w,s.h);

        s.setVWTransform ();
        s.g.scale (1,1);
        s.drawStuff ();
        s.g.drawLine (40,40,100,100);
        s.g.drawRect (40,40,60,60);

        // specify viewport and window
        s.setViewport (.25,.25,.49,.49);
        s.setWindow   (-150,-150,250,250);

        s.g.setColor (new Color (0x2000ff00, true));
        s.g.fillRect (0,0,s.w,s.h);

        s.setVWTransform ();
        s.drawStuff ();
        s.g.drawLine (40,40,100,100);
        s.g.drawRect (40,40,60,60);

        try {
          javax.imageio.ImageIO.write (s.buffer, "png", new java.io.File ("sample.png"));
        }
        catch (Exception e) {
          System.out.println (e);
        }

        s.show();
    }
}