movie.java

java 图形处理

/** Framework for movies.
    To define and show a movie,
    define a class that extends Movie.
    It must include a scene(t) method that returns
    the Picture for any given time t.
    Create an object of this class,
    and call its 'show' method.
    (5 Feb 00)
*/

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import javax.swing.*;

abstract class Movie implements ActionListener {

   private Timer timer;
      // Animation timer.

   private double movieTime;
      // Current time measured in movie time units.

   private Picture picture;
      // Current frame of the movie.

   private AffineTransform convert;
      // Transformation that converts from
      // picture coordinates to user coordinates.

   private JPanel panel;
      // Panel for displaying the movie.

   private double frameRate = 20;
      // Number of pictures displayed per second.

   private double movieRate = 20;
      // Number of units of movie time per second.

   private boolean antialiasOn = true;

   /** Create screen and start the movie.
       (x,y) = bottom-left corner of area of pictures
               to be displayed.
       (w,h) = width and height of area to be displayed.
       s     = Number of pixels per unit distance in picture.
       b     = background colour. (Can be null.)
   */
   public void show
      (double x, double y, double w,
       double h, double s, Color b) {

      /* Create display area. */
      panel = new DisplayPanel();
         // (DisplayPanel is defined below.)
      int width = (int) (w*s);
      int height = (int) (h*s);
      panel.setPreferredSize(new Dimension(width, height));
      if (b != null) panel.setBackground(b);
      JFrame frame = new JFrame();
      frame.setLocation(100,100);
      frame.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent e) {
            System.exit(0);
         }
      });
      frame.getContentPane().add(panel);
      frame.pack();
      frame.setVisible(true);

      /* Create transformation 'convert' that converts
         from picture coordinates to user coordinates. */
      convert = new AffineTransform();
      convert.scale(s,s);
      convert.translate(0,h);
      convert.scale(1,-1);
      convert.translate(-x,-y);

      /* Create Timer. */
      int delay = (int) Math.round(1000.0/frameRate);
      timer = new Timer(delay, this);
      timer.setInitialDelay(0);
      timer.setCoalesce(true);

      /* Start the movie. */
      movieTime = 0;
      timer.start();
   }

   /** Set movie speed
       (= number of movie time units per second).
   */
   public void setMovieRate(double r) {
      movieRate = r;
   }

   /** Set number of frames per second.
   */
   public void setFrameRate(double r) {
      frameRate = r;
   }

   /** If b = true, turn antialiasing on.
       If b = false, turn it off.
   */
   public void setAntialiasingOn(boolean b) {
      antialiasOn = b;
   }
      
   public void actionPerformed(ActionEvent e) {
      picture = scene(movieTime);
      movieTime = movieTime + movieRate/frameRate;
      panel.repaint();
   } 

   /** Return the picture for time t.
   */
   abstract Picture scene(double t);

   /****************************************************/

   /* JPanel which displays the Picture
      stored in 'picture'.
   */
   private class DisplayPanel extends JPanel {

      public void paintComponent(Graphics g) {
         if (picture == null) return;
         final AffineTransform ident = new AffineTransform();
         super.paintComponent(g);
         Graphics2D g2 = (Graphics2D) g;
         g2.transform(convert);
         if (antialiasOn)
            g2.setRenderingHint
               (RenderingHints.KEY_ANTIALIASING,
                RenderingHints.VALUE_ANTIALIAS_ON);
         picture.transDisplay(ident,g2);
      }
   }
}