programming-examples/java/Computer_Graphics/Text on Circle border.java

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Java
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2019-11-15 12:59:38 +01:00
Text on Circle border
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
public class CircleTextDemo extends Canvas {
Frame myframe;
TextField text;
Font myfont;
Color textcolor;
Color circlecolor;
public CircleTextDemo() {
this("Serif", Font.PLAIN, 18, Color.pink, Color.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");
myframe.add(text, BorderLayout.NORTH);
myframe.add(this, BorderLayout.CENTER);
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();
}
});
myframe.setVisible(true);
}
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.
*/
static void drawCircleText(Graphics2D g, String st, Point center,
double r, double a1, double af)
{
double curangle = a1;
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;
curangle += Math.sin(adv / r);
}
}
}
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();
}
}