Swing Hacks

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Chapter 1, Basic JComponents

#3 Fill Your Borders with Pretty Pictures

HACK

H A C K

#3

Fill Your Borders with Pretty Pictures

Hack #3

Swing comes with a set of customizable borders, but sometimes you want

more than they provide. This hack shows how to create a completely image-

based border that can be resized.

Swing has a prefabricated border, called the MatteBorder, which can accept

an image in its constructor. For simple tiled backgrounds, such as a checker-

board pattern, this works fine. However, if you want to have particular

images in each corner, creating a fully resizable image border, then you’ll

need something more powerful. Fortunately, Swing makes it very easy to

create custom border classes. The image border in this hack will produce a

border that looks like Figure 1-12.

The first step to any custom border is to subclass

AbstractBorder and imple-

ment the

paintBorder( ) method. The class will take eight images in the con-

structor, one for each corner and each side; all the code is shown in

Example 1-6.

Figure 1-12. An image-based border

Example 1-6. Building an image-based border

public class ImageBorder extends AbstractBorder {

Image top_center, top_left, top_right;

Image left_center, right_center;

Image bottom_center, bottom_left, bottom_right;

Insets insets;

public ImageBorder(Image top_left, Image top_center, Image top_right,

Image left_center, Image right_center,

Image bottom_left, ...