/**
 * @Homework:  Assignment 6 ( 2 of 2)
 * @Exercise:  9.19 in textbook, page 534
 * @Author:    Richard Parry
 * @Version:   1.0 - August 4, 1998
 * @Filename:  GridRect.java
 * School:     UCSD, Summer 98 Java 1 class
 *
 * Description:
 * This applet displays a grid that is 8 x 8.  It can be easily
 * changed by modifying class constants.  The grid starting point
 * (upper left) is fixed. A button is provided which allows one to
 * change height and width of each cell resulting in the gird size
 * changing.  Random numbers are used for changing the cell
 * width and height. Each cell is created using the Graphics
 * class "drawRect" method. The grid is created by drawing 8
 * rectangles horizontally, moving down a row, drawing another
 * 8 rectangles, moving down, etc. until all 64 cells (rectangles)
 * are drawn giving us the desired grid.
 **/

// import packages
import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;



public class GridRect extends Applet implements ActionListener {

  // declate constants
  private final int X_START = 20;
  private final int Y_START = 40;
  private final int HORIZONTAL_CELLS = 10;
  private final int VERTICAL_CELLS   = 10;
  private Button makeGridButton;

  // declare instance variables
  private int cellWidth = 15;
  private int cellHeight = 20;
  private int horizontalCells, verticalCells, xCellSize, yCellSize;
  private int i, j, xpos, ypos, xBegin, yBegin;


  /**
   * This is the initialization method called once which sets
   * various parameters.  It also configures the window with a
   * button that allows the user to modify the displayed grid.
   *
   * @param   - none
   * @return  - none
   **/
  public void init() {

    // initialize the button
    makeGridButton = new Button( "Make Grid" );
    makeGridButton.addActionListener( this );
    add( makeGridButton );

    horizontalCells = HORIZONTAL_CELLS;
    verticalCells   = VERTICAL_CELLS;

  } // end init method



  /**
   * This paint method displays grid and the grid parameters
   * such as the number of cells, cell width and height, etc.
   *
   * @param  - Graphics object
   * @return -  none
   **/
  public void paint ( Graphics g ) {

    Color fillColor = new Color( 200, 200, 200 );
    Color outlineColor = new Color( 255, 0, 0 );

    xpos = 250;
    ypos = 100;
    g.drawString ( "Horizontal Cells = " + horizontalCells, xpos, ypos );
    ypos += 15;
    g.drawString ( "Vertical Cells   = " + verticalCells, xpos, ypos );
    ypos += 15;
    g.drawString ( "Cell Width       = " + cellWidth, xpos, ypos );
    ypos += 15;
    g.drawString ( "Cell Height      = " + cellHeight, xpos, ypos );
    ypos += 15;

    // draw rectangles
    xBegin = X_START;
    yBegin = Y_START;

    for ( j = 0; j < verticalCells; j++ ) {
      for ( i = 0; i < horizontalCells; i++ ) {
	g.setColor( fillColor );
	g.fillRect( xBegin, yBegin, cellWidth, cellHeight );
	g.setColor( outlineColor );
	g.drawRect( xBegin, yBegin, cellWidth, cellHeight );
	xBegin += cellWidth;
      }
      xBegin = X_START;
      yBegin += cellHeight;
    }
  } // end paint method


  /**
   * This method is called each time the button is depressed
   * by the user. It changes the width and height of the
   * grid cells.
   *
   * @param   - action event from the mouse button
   * @return  - none
   **/
  public void actionPerformed( ActionEvent e ) {
    cellWidth  = 5 + (int) (Math.random() * 20);
    cellHeight = 5 + (int) (Math.random() * 20);
    repaint(); 
  } // end actionPerformed method


} // end class