Java Swing, 2nd Edition

Creating Your Own Border

Creating your own border is simple when you extend the AbstractBorder class. You need to define three things: how to draw the border, whether it is opaque, and what its insets are. To accomplish this, you must implement paintBorder( ), both isBorderOpaque( ) methods, and getBorderInsets( ). The hard part of coming up with your own border is doing something creative with the Graphics primitives in the paintBorder( ) method. A reminder: make sure that you paint only in the insets region that you define for yourself. Otherwise, you could be painting over the component you intend to border.

Let’s take a look at a simple border:

// CurvedBorder.java // import java.awt.*; import javax.swing.border.*; public class CurvedBorder extends AbstractBorder { private Color wallColor = Color.gray; private int sinkLevel = 10; public CurvedBorder( ) { } public CurvedBorder(int sinkLevel) { this.sinkLevel = sinkLevel; } public CurvedBorder(Color wall) { this.wallColor = wall; } public CurvedBorder(int sinkLevel, Color wall) { this.sinkLevel = sinkLevel; this.wallColor = wall; } public void paintBorder(Component c, Graphics g, int x, int y, int w, int h) { g.setColor(getWallColor( )); // Paint a tall wall around the component. for (int i = 0; i < sinkLevel; i++) { g.drawRoundRect(x+i, y+i, w-i-1, h-i-1, sinkLevel-i, sinkLevel); g.drawRoundRect(x+i, y+i, w-i-1, h-i-1, sinkLevel, sinkLevel-i); g.drawRoundRect(x+i, y, w-i-1, h-1, sinkLevel-i, sinkLevel); g.drawRoundRect(x, y+i, ...