/*
   MultiCellAnim.java
   a demonstration program of how to read in a single .gif or .jpg file
   that contains a number of smaller image cells and cycle thru them
   to create an animation
 */

//********************************************************************
//  Copyright 1998  Grey Creations, Ltd.
//  permission granted for all non-commercial use.
//********************************************************************

import java.awt.*;
import java.applet.*;
import java.util.*;

public class MultiCellAnim extends Applet implements Runnable {
    Thread animator;
    Graphics backbuf;
    Image backbufImage;    // backbuffer image
    int x =0, y = 0;
    cellImage testImage;
   
    public void init() {
      setLayout(null);
      setBackground(new Color(0,0,0));
      
      backbufImage = createImage(320, 240);
      backbuf = backbufImage.getGraphics();
      
      /* 
       * 0. object
       * 1. put your filename here
       * 2. cellSize in pixels
       * 3. cellLayout
       * 4. # of cells
       */
      testImage = new cellImage(this, "bluesphere.gif",
                                new Dimension(48, 48),
                                new Dimension(5, 6),
                                30);
   }
   
   public void start() {
      animator = new Thread(this);
      if(animator != null) 
         animator.start();
   }

   public void run() {
      while(true) {
         repaint();
         Thread.currentThread().yield();
         try {
            animator.sleep(70);
         } catch(Exception e) {}
      }
   }
   
   public void update(Graphics g) {
      paint(g); 
   }

   public void paint(Graphics g) {
      backbuf.clearRect(0,0, 640, 480); // clear back buffer

      // draw the current cell
      testImage.paint(backbuf);
      
      g.drawImage(backbufImage, 0, 0, 320, 240, this);
   }
} // end of applet

class cellImage {
    // parent applet
    Applet mom;
    
    // how many cells across and down (col/row) in layout
    Dimension cellLayout;

    // the dimensions of a single cell
    Dimension cellSize;

    int numCells; // The number of cells in the image
    
    Image image;  // the master image that holds all the cells
    
    int curCellNum = 0; // which cell to paint on request
    
    // pass Applet context, Image filename, width/height of a cell, 
    // how many cells fit across and down the image,
    // and how many actual cells there are to display
    public cellImage(Applet aMom, String imgName, 
                     Dimension aCellSize, Dimension aCellLayout, 
                     int aNumCells) {
           mom = aMom;
           cellSize = aCellSize;
           cellLayout = aCellLayout;
           numCells = aNumCells;
       
           image = mom.getImage(mom.getCodeBase(), imgName);
    }    
    
    public void paint(Graphics g) {
      // note that this advances the curCellNum!!!   
        
      // paint which cell #?
      int iNum = curCellNum++;

      // check for overflow
      if(iNum > numCells - 1) 
         curCellNum = 0;
        
      // where to paint cell
      // you would want to change where the cell is painted
      Point p = new Point(0, 0); 
      int userX = p.x;
      int userY = p.y;
      
      // locate the cell to paint
      int col = iNum % cellLayout.width;
      int row = iNum / cellLayout.height;
      
      // this is the amount to shift the entire source image
      int offsetX = - (col * cellSize.width);
      int offsetY = - (row * cellSize.height);
      
      // set clipping rect to cell size at specified location
      g.setClip(userX, userY, cellSize.width, cellSize.height);
      
      // paint into graphics context
      g.drawImage(image, userX + offsetX, userY + offsetY, mom);
    }
} // end cellImage