graphicsutil.java

Reinforcement Learning

 import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Polygon;

// This appears in Core Web Programming from
// Prentice Hall Publishers, and may be freely used
// or adapted. 1997 Marty Hall, [e-mail].

/**
 * A class that extends the draw<I>Xxx</I> and
 * fill<I>Xxx</I> methods of java.awt.Graphics. In
 * particular, it adds line width (pen thickness)
 * arguments to most of the draw<I>Xxx</I> methods,
 * a Color argument to most of the draw<I>Xxx</I> and
 * fill<I>Xxx</I> methods, and a Font argument to
 * drawString and drawChars. Also creates drawCircle
 * and fillCircle methods.
 * <P>
 * Rather than including the Graphics object in a call
 * to a constructor, the methods are all static, and
 * the Graphics is included as the <I>first</I>
 * argument to each of the methods. 
 * <B>Don't forget to include it.</B>
 * <P>
 * For instance, here is how you would draw a 10-pixel
 * wide blue line from (10,10) to (200, 200) and a
 * 5-pixel thick red circle of radius 50 centered at
 * (200, 200):
 * <PRE>
 *    public void paint(Graphics g) {
 *      ...
 *      GraphicsUtil.drawLine(g, 10, 10, 200, 200,
 *                            10, Color.blue);
 *      GraphicsUtil.drawCircle(g, 200, 200, 50,
 *                              5, Color.red);
 *      ...
 *    }
 * </PRE>
 *
 * @author Marty Hall ([e-mail])
 * @version 1.0 (1997)
 */

public class GraphicsUtil {

  //----------------------------------------------------
  /** Draws an arc with the specified pen width. Note
   *  that the rectangle specified falls in the
   *  <B>middle</B> of the thick line (half inside it,
   *  half outside).
   *
   * @param g The Graphics object.
   * @param left The left side of the bounding rectangle
   * @param top The top of the bounding rectangle
   * @param width The width of the bounding rectangle
   * @param height The height of the bounding rectangle
   * @param startAngle The beginning angle
   *                   <B>in degrees.</B> 0 is 3
   *                   o'clock, increasing
   *                   counterclockwise.
   * @param deltaAngle The sweep angle in degrees
   *                   (going counterclockwise).
   * @param lineWidth The pen width (thickness of
   *                  line drawn).
   */

  public static void drawArc(Graphics g,
                             int left, int top,
                             int width, int height,
                             int startAngle,
                             int deltaAngle,
                             int lineWidth) {
    left = left - lineWidth/2;
    top = top - lineWidth/2;
    width = width + lineWidth;
    height = height + lineWidth;
    for(int i=0; i<lineWidth; i++) {
      g.drawArc(left, top, width, height,
                startAngle, deltaAngle);
      if((i+1)<lineWidth) {
        g.drawArc(left, top, width-1, height-1,
                  startAngle, deltaAngle);
        g.drawArc(left+1, top, width-1, height-1,
                  startAngle, deltaAngle);
        g.drawArc(left, top+1, width-1, height-1,
                  startAngle, deltaAngle);
        g.drawArc(left+1, top+1, width-1, height-1,
                  startAngle, deltaAngle);
        left = left + 1;
        top = top + 1;
        width = width - 2;
        height = height - 2;
      }
    }
  }

  /** Draws an arc with the specified pen width
   *  and color. 
   *
   * @param g The Graphics object.
   * @param left The left side of the bounding rectangle
   * @param top The top of the bounding rectangle
   * @param width The width of the bounding rectangle
   * @param height The height of the bounding rectangle
   * @param startAngle The beginning angle
   *                   <B>in degrees.</B> 0 is 3
   *                   o'clock, increasing
   *                   counterclockwise.
   * @param deltaAngle The sweep angle in degrees
   *                   (going counterclockwise).
   * @param lineWidth The pen width (thickness of
   *                  line drawn).
   * @param c The Color in which to draw.
   */

  public static void drawArc(Graphics g,
                             int left, int top,
                             int width, int height,
                             int startAngle,
                             int deltaAngle,
                             int lineWidth, Color c) {
    Color origColor = g.getColor();
    g.setColor(c);
    drawArc(g, left, top, width, height,
            startAngle, deltaAngle, lineWidth);
    g.setColor(origColor);
  }

  /** Adds a Color argument to the drawArc method of
   *  java.awt.Graphics.
   *
   * @param g The Graphics object.
   * @param left The left side of the bounding rectangle
   * @param top The top of the bounding rectangle
   * @param width The width of the bounding rectangle
   * @param height The height of the bounding rectangle
   * @param deltaAngle The sweep angle in degrees
   *                   (going counterclockwise).
   * @param lineWidth The pen width (thickness of
   *                  line drawn).
   * @param c The color in which to draw the arc.
   */
  
  public static void drawArc(Graphics g,
                             int left, int top,
                             int width, int height,
                             int startAngle,
                             int deltaAngle,
                             Color c) {
    Color origColor = g.getColor();
    g.setColor(c);
    g.drawArc(left, top, width, height,
              startAngle, deltaAngle);
    g.setColor(origColor);
  }

  //----------------------------------------------------
  /** Adds a Color argument to the fillArc method of
   *  java.awt.Graphics.
   *
   * @param g The Graphics object.
   * @param x The left side of the bounding rectangle
   * @param y The top of the bounding rectangle
   * @param width The width of the bounding rectangle
   * @param height The height of the bounding rectangle
   * @param startAngle The beginning angle
   *                   <B>in degrees.</B> 0 is 3
   *                   o'clock, increasing
   *                   counterclockwise.
   * @param deltaAngle The sweep angle in degrees
   *                   (going counterclockwise).
   * @param c The color in which to draw the arc.
   */
  
  public static void fillArc(Graphics g,
                             int left, int top,
                             int width, int height,
                             int startAngle,
                             int deltaAngle,
                             Color c) {
    Color origColor = g.getColor();
    g.setColor(c);
    g.fillArc(left, top, width, height,
              startAngle, deltaAngle);
    g.setColor(origColor);
  }

  //----------------------------------------------------
  /** Adds a Color argument to the drawChars method of
   *  java.awt.Graphics.
   *
   * @param g The Graphics object.
   * @param chars An array of characters.
   * @param start The index in chars at which the
   *              string starts.
   * @param numChars Number of characters to draw
   *                 (starting at start).
   * @param x The left side of the string that gets drawn
   * @param y The <B>bottom</B> (not top) of the string.
   * @param c The color in which to draw the string.
   */
  
  public static void drawChars(Graphics g, char[] chars,
                               int start, int numChars,
                               int x, int y,
                               Color c) {
    Color origColor = g.getColor();
    g.setColor(c);
    g.drawChars(chars, start, numChars, x, y);
    g.setColor(origColor);
  }

  /** Adds a Font argument to the drawChars method of
   *  java.awt.Graphics.
   *
   * @param g The Graphics object.
   * @param chars An array of characters.
   * @param start The index in chars at which the
   *              string starts.
   * @param numChars Number of characters to draw
   *                 (starting at start).
   * @param x The left side of the string that gets drawn
   * @param y The <B>bottom</B> (not top) of the string.
   * @param f The font in which to draw the string.
   */
  
  public static void drawChars(Graphics g, char[] chars,
                               int start, int numChars,
                               int x, int y,
                               Font f) {
    Font origFont = g.getFont();
    g.setFont(f);
    g.drawChars(chars, start, numChars, x, y);
    g.setFont(origFont);
  }

  /** Adds Font and Color arguments to the drawChars
   *  method of java.awt.Graphics.
   *
   * @param g The Graphics object.
   * @param chars An array of characters.
   * @param start The index in chars at which the
   *              string starts.
   * @param numChars Number of characters to draw
   *                 (starting at start).
   * @param x The left side of the string that gets drawn
   * @param y The <B>bottom</B> (not top) of the string.
   * @param f The font in which to draw the string.
   * @param c The color in which to draw the string.
   */
  
  public static void drawChars(Graphics g, char[] chars,
                               int start, int numChars,
                               int x, int y,
                               Font f, Color c) {
    Font origFont = g.getFont();
    g.setFont(f);
    drawChars(g, chars, start, numChars, x, y, c);
    g.setFont(origFont);
  }

  //----------------------------------------------------
  /** Calls the drawOval method of java.awt.Graphics
   *  with a square bounding box centered at specified
   *  location with width/height of 2r.
   *
   * @param g The Graphics object.
   * @param x The x-coordinate of the center of the
   *          circle.
   * @param y The y-coordinate of the center of the
   *          circle.
   * @param r The radius of the circle.
   */
   
  public static void drawCircle(Graphics g,
                                int x, int y, int r) {
    g.drawOval(x-r, y-r, 2*r, 2*r);
  }

  // Calling drawOval directly would save having to do
  // x-r, 2*r calculations each time, but that time is
  // insignificant compared to the drawing time,
  // and it is easier and more extensible to use
  // existing drawCircle method.
  //
  // Unfortunately, drawOval calls with concentric
  // radii do not exactly fall next to each other in
  // all cases, since ovals are being approximated by
  // filling in pixels in a rectangular grid. So
  // occasional pixels will get omitted. 
  // If you knew nothing was inside your circle, you
  // could avoid this by implementing line thickness
  // by two consecutive calls to fillOval (the second
  // using the current background color), but this
  // would require the circle drawing to be done
  // first when things are inside it, prevent
  // overlapping circles, etc. So instead 4 offset
  // inner circles are drawn before each centered
  // inner circle.

  /** Draws a circle of radius r at location (x,y) with
   *  the specified line width. Note that the radius r
   *  is to the <B>center</B> of the doughnut drawn.
   *  The outside radius will be r+lineWidth/2 (rounded
   *  down). Inside radius will be r-lineWidth/2
   *  (rounded down).
   *
   * @param g The Graphics object.
   * @param x The x-coordinate of the center of the
   *          circle.
   * @param y The y-coordinate of the center of the
   *          circle.
   * @param r The radius of the circle.
   * @param lineWidth Pen thickness of circle drawn.
   */
  
  public static void drawCircle(Graphics g,
                                int x, int y, int r,
                                int lineWidth) {
    r = r+lineWidth/2;  
    for(int i=0; i<lineWidth; i++) {
      drawCircle(g, x, y, r);
      if ((i+1)<lineWidth) {
        drawCircle(g, x+1, y, r-1);
        drawCircle(g, x-1, y, r-1);
        drawCircle(g, x, y+1, r-1);
        drawCircle(g, x, y-1, r-1);
        r = r-1;
      }
    }
  }

  /** Draws a circle of radius r at location (x,y) with
   *  the specified line width and color. Note that
   *  the radius r is to the <B>center</B> of the
   *  doughnut drawn. The outside radius will
   *  be r+lineWidth/2 (rounded down). Inside radius
   *  will be r-lineWidth/2 (rounded down).
   *
   * @param g The Graphics object.
   * @param x The x-coordinate of the center of the
   *          circle.
   * @param y The y-coordinate of the center of the
   *          circle.
   * @param r The radius of the circle.
   * @param lineWidth Pen thickness of circle drawn.
   * @param c The color in which to draw.
   */
  
  public static void drawCircle(Graphics g,
                                int x, int y, int r,
                                int lineWidth, Color c) {
    Color origColor = g.getColor();
    g.setColor(c);
    drawCircle(g, x, y, r, lineWidth);
    g.setColor(origColor);
  }

  /** Calls the drawOval method of java.awt.Graphics
   *  with a square bounding box centered at specified
   *  location with width/height of 2r. Draws in the
   *  color specified.
   *
   * @param g The Graphics object.
   * @param x The x-coordinate of the center of the
   *          circle.
   * @param y The y-coordinate of the center of the
   *          circle.
   * @param r The radius of the circle.
   * @param c The color in which to draw.
   */
  
  public static void drawCircle(Graphics g,
                                int x, int y, int r,
                                Color c) {