Swing Hacks

440

|

Chapter 11, Native Integration and Packaging

#87 Create an Inverse Black-and-White Theme

HACK

A Black-and-White Theme

A Metal theme is defined by a series of colors and fonts. The most impor-

tant ones are the three primary and three secondary colors. These define the

standard set of colors used for every widget on screen. Certain components

have additional colors, like the text selection, but almost everything is based

on these six. Example 11-9 is a theme that uses only white and black. It is

useful for embedded devices that can’t afford the hardware or memory

requirements of a color display.

Two of the primary colors are all white, and the third is black. The three sec-

ondary colors are just the reverse: two black and one white. This introduces

extra contrast. Each color controls a different part of the component. The

MetalTheme documentation is very sparse, so the only way to know what a

particular color will do is to try it. Without the theme, the screen will look

like Figure 11-17.

With the

InverseTheme installed, the window will look like Figure 11-18.

Example 11-9. A black-and-white Metal theme

import javax.swing.plaf.metal.*;

import javax.swing.plaf.ColorUIResource;

public class InverseTheme extends DefaultMetalTheme {

protected ColorUIResource getPrimary1( ) {

return new ColorUIResource(255,255,255);

}

protected ColorUIResource getPrimary2( ) {

return new ColorUIResource(0,0,0);

}

protected ColorUIResource getPrimary3( ) {

return new ColorUIResource(255,255,255);

}

// component borders

protected ColorUIResource getSecondary1( ) {

return new ColorUIResource(0,0,0);

}

// selected components (button down state)

protected ColorUIResource getSecondary2( ) {

return new ColorUIResource(0,0,0);

}

// component backgrounds

protected ColorUIResource getSecondary3( ) {

return new ColorUIResource(255,255,255);

}

Create an Inverse Black-and-White Theme #87

Chapter 11, Native Integration and Packaging

|

441

HACK

Setting the six colors gets us most of the way, but there are still some prob-

lems. In particular, the label is hidden and the text field looks wrong when

you select it. To correct these, you’ll need to set three more colors:

//for label text

public ColorUIResource getSystemTextColor( ) {

return new ColorUIResource(0,0,0);

}

// background of selected text

public ColorUIResource getTextHighlightColor( ) {

return new ColorUIResource(0,0,0);

}

// foreground of selected text

public ColorUIResource getHighlightedTextColor( ) {

return new ColorUIResource(255,255,255);

}

Figure 11-17. Window with no changes

Figure 11-18. Window with an inverse theme

442

|

Chapter 11, Native Integration and Packaging

#87 Create an Inverse Black-and-White Theme

HACK

The SystemTextColor is used for labels and titled borders, so you have to set

this to black as well. The highlighted text, as well as the background of the

highlight, are controlled by the

HighlightedTextColor

and

TextHighlightColor

,

respectively (confusing, I know).

The only remaining problem is the menus. They have their own set of prop-

erties, which you can also set:

public ColorUIResource getMenuBackground( ) {

return new ColorUIResource(255,255,255);

}

public ColorUIResource getMenuForeground( ) {

return new ColorUIResource(0,0,0);

}

public ColorUIResource getMenuSelectedBackground( ) {

return new ColorUIResource(0,0,0);

}

public ColorUIResource getMenuSelectedForeground( ) {

return new ColorUIResource(255,255,255);

}

With all of the colors set, you are ready to load up the theme. All you have

to do is call

MetalLookAndFeel.setCurrentTheme( ) before you create any

Swing components.

public static void main(String[] args) {

MetalLookAndFeel.setCurrentTheme(new InverseTheme( ));

//.. set up Swing components now

}

If you set it as the first line of the main( ) method in the demonstration pro-

gram from the previous hack, you will see your themed window as in

Figure 11-19.

Figure 11-19. A better inverse theme