Prentice.Hall.Introduction.to.Java.Programming,.Brief.Version.9th.(2014).[sharethefiles.com]

where (x1, y1) and (x2, y2) specify two endpoints and (ctrlx, ctrly) is
a control point. The control point is usually not on the curve instead
of defining the trend of the curve, as shown in Figure 49.19a.
(ctrlx, ctrly)
(ctrlx1, ctrly1)
(x1, y1)
(x2, y2)
(x1, y1) (x2, y2)
(ctrlx2, ctrly2)
(a)
(b)
Figure 49.19
(a) A quadratic curve is specified using three points. (b) A cubic
curve is specified using four points.
A cubic curve is mathematically defined as a cubic polynomial. To
create a CubicCurve2D.Double, use the following constructor:
CubicCurve2D.Double(double x1, double y1, double ctrlx1,
double ctrly1, double ctrlx2, double ctrly2, double x2, double y2)
where (x1, y1) and (x2, y2) specify two endpoints and (ctrlx1, ctrly1)
and (ctrlx2, ctrly2) are two control points. The control points are
usually not on the curve instead of defining the trend of the curve, as
shown in Figure 49.19(b).
Listing 49.7 gives a program that demonstrates how to draw quadratic
curves and cubic curves. Figure 49.20 shows a sample run of the
program.
Listing 49.7 CurveDemo.java
import java.awt.*;
import java.awt.geom.*;
import javax.swing.*;
public class CurveDemo extends JApplet {
public CurveDemo() {
add(new CurvePanel());
}
static class CurvePanel extends JPanel {
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D)g;
20