CircleTextDemo.java

import java.awt.*;  import java.awt.event.*;  import java.awt.geom.*;    /**   * A demo class that illustrates drawing text   * along the outside of a circle.   */  public class CircleTextDemo extends Canvas {      Frame myframe;      TextField text;      Button printBtn;      Font myfont;      Color textcolor;      Color circlecolor;        /**       * Create a CircleTextDemo canvas and frame       * with default settings.       */      public CircleTextDemo() {          this("Serif", Font.PLAIN, 18, Color.pink, Color.black);      }        /**       * Create a CircleTextDemo canvas and frame       * with supplied settings.       *       * @param ff Font family (usually "Serif")       * @param fs Font style (usually Font.PLAIN)       * @param fz Font size (usually 18)       * @param bg Background color for this canvas (usually pink)       * @param fg Foreground color for text (usually black)       */      public CircleTextDemo(String ff, int fs, int fz, Color bg, Color fg) {          setBackground(bg);          circlecolor = bg.brighter();          textcolor = fg;          myfont = new Font(ff, fs, fz);            text = new TextField("Text on a circle using Java 2D Graphics!");          myframe = new Frame("CircleTextDemo");     printBtn = new Button("Print");          myframe.add(text, BorderLayout.NORTH);          myframe.add(this, BorderLayout.CENTER);     myframe.add(printBtn, BorderLayout.SOUTH);          myframe.setSize(new Dimension(300,340));          myframe.setLocation(150,140);          myframe.addWindowListener(new WindowAdapter() {                  public void windowClosing(WindowEvent we) {                      System.exit(0);                  }              });          text.addActionListener(new ActionListener() {                  public void actionPerformed(ActionEvent ae) {                      repaint();                  }              });     printBtn.addActionListener(new FramePrinter(myframe));          myframe.setVisible(true);      }        /**       * Paint the contents of the CircleDemoText canvas.       *       * @param g - a Graphics, hopefully a Graphics2D       */      public void paint(Graphics g) {          String st = text.getText();          if (st.length() == 0) return;          if (g instanceof Graphics2D) {              Dimension cd = getSize();              Point pt = new Point(cd.width / 2, cd.height / 2);              int radius = (int)(pt.x * 0.84);              g.setColor(circlecolor);              g.drawArc(pt.x - radius, pt.y - radius,                        radius*2-1, radius*2-1,                        0, 360);              g.setColor(textcolor);              g.setFont(myfont);              drawCircleText((Graphics2D)g, st, pt, radius, -Math.PI/2, 1.0);          }          else {              System.out.println("Cannot draw curved text without a Graphics2D");          }      }        /**       * Draw a piece of text on a circular curve, one       * character at a time.  This is harder than it looks...       *       * This method accepts many arguments:       *   g - a Graphics2D ready to be used to draw,       *   st - the string to draw,       *   center - the center point of the circle (Point),       *   r - the radius of the circle,       *   a1 - the beginning angle on the circle to start, in radians,       *   af - the angle advance factor (usually 1.0)       */      static void drawCircleText(Graphics2D g, String st, Point center,                                 double r, double a1, double af)      {          double curangle = a1;     double curangleSin;          Point2D c = new Point2D.Double(center.x, center.y);          char ch[] = st.toCharArray();          FontMetrics fm = g.getFontMetrics();          AffineTransform xform1, cxform;          xform1 = AffineTransform.getTranslateInstance(c.getX(),c.getY());          for(int i = 0; i < ch.length; i++) {              double cwid = (double)(getWidth(ch[i],fm));              if (!(ch[i] == ' ' || Character.isSpaceChar(ch[i]))) {                  cwid = (double)(fm.charWidth(ch[i]));                  cxform = new AffineTransform(xform1);                  cxform.rotate(curangle, 0.0, 0.0);                  String chstr = new String(ch, i, 1);                  g.setTransform(cxform);                  g.drawString(chstr, (float)(-cwid/2), (float)(-r));              }                // compute advance of angle assuming cwid<<radius              if (i < (ch.length - 1)) {                  double adv = cwid/2.0 + fm.getLeading() + getWidth(ch[i + 1],fm)/2.0;        // Use of atan() suggested by Michael Moradzadeh                  curangle += Math.atan(adv / r);        // Original code was:        // curangle += Math.sin(adv / r);                }          }      }        /**       * Get the width of a given character under the       * specified FontMetrics, interpreting all spaces as       * en-spaces.       */      static int getWidth(char c, FontMetrics fm) {          if (c == ' ' || Character.isSpaceChar(c)) {              return fm.charWidth('n');          }          else {              return fm.charWidth(c);          }      }        public static void main(String args[]) {          CircleTextDemo ctd;          ctd = new CircleTextDemo();      }        class FramePrinter implements ActionListener {     private Frame fr;     public FramePrinter(Frame f) { fr = f; }     public void actionPerformed(ActionEvent ae) {         PrintJob pjob;         pjob = fr.getToolkit().getPrintJob(fr,            "Printing Circle Demo", null, null);         if (pjob != null) {        Graphics g = pjob.getGraphics();        if (g != null) {            g.translate(100,100);            fr.printAll(g);            g.dispose();        }        pjob.end();         }     }      }    }