java怎么画圆弧环_Java 绘制环形的文字 (Circle Text Demo)
1.[代码]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<
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();
}
}
}
}