Drawing in a Window - Beginning Java

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Directory "CurveApplet 1"

You need an HTML file to run the applet. The contents can be something like:

<html>

<head>

</head>

<applet

code = "CurveApplet.class"

width = "300"

height = "300"

>

</applet>

</center>

</body>

</html>

If you run the applet using appletviewer , you get a window that looks like the one shown in Figure

19-13 .

FIGURE 19-13

How It Works

To display the curves, you need an object of your own class type so that you can implement the paint()

method for it. You define the inner class, CurvePane , for this purpose with JComponent as the base class

so it is a Swing component. You create an object of this class (which is a member of the CurveApplet

class) and add it to the content pane for the applet using its inherited add() method. The layout man-

ager for the content pane is BorderLayout , and the default positioning is BorderLayout.CENTER so the

CurvePane object fills the content pane.

The points defining the quadratic and cubic curves are defined as fields in the CurveApplet class and the

fields that store references to the curve objects are used in the paint() method for the CurvePane class

to display curves. The fields that store points are used in the CurvePane class constructor to create the

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