PDAP Programming - Java 2 Micro Edition Application Development - page 100

Most custom components need to overwrite two additional methods that are important for the
appropriate layout of the component. The methods getMinimumSize() and
getPreferredSize() are used by layout managers to query the size information of the component.
Overwriting these methods with custom implementations makes sure that the component is displayed
in an appropriate size.
Listing 4.6 ProgressBar.java
import java.awt.*;
public class ProgressBar extends Component {
int currentValue = 0;
final int MAX_VALUE = 100;
public ProgressBar() {
}
public void setValue (int currentValue) {
if (currentValue >= 0
&& currentValue <= MAX_VALUE) {
this.currentValue = currentValue;
}
}
public Dimension getPreferredSize() {
return new Dimension (100, 20);
}
public Dimension getMinimumSize() {
return new Dimension (10, 10);
}
public void paint (Graphics g) {
Dimension dim = getSize();
int progressPosition = (dim.width-4) * currentValue /
MAX_VALUE;
g.setColor (Color.black);
g.drawRect (0, 0, dim.width-1, dim.height-1);
g.setColor (Color.white);
g.drawRect (1, 1, dim.width-3, dim.height-3);
g.setColor (SystemColor.activeCaption);
g.fillRect (2, 2, progressPosition, dim.height-4);
g.setColor (Color.white);
g.fillRect (progressPosition + 2, 2,
dim.width - progressPosition - 4, dim.height-4);
}
}
For testing purposes, we provide a small application shown in Listing 4.7 to show how the
ProgressBar can be integrated into a MIDlet; the application is shown in Figure 4.8 . The
application just provides a Scrollbar for setting the current progress value and the ProgressBar