Java 绘制环形的文字 (Circle Text Demo)，circledemo,import java.

Java 绘制环形的文字 (Circle Text Demo)，circledemo,import 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();       }   }    }}//该片段来自于http://byrx.net