This article describes the theming functionality of RWT, the RAP Widget Toolkit. This theming defines the default look and feel of the basic RWT controls like Shell, Button, Text etc. It must not be mixed up with the theming of the Eclipse workbench. Instead, it can be compared to the theming functionality of a desktop system that allows the user to set custom colors for title bars, text background and the like.
State of Development
The RWT theming mechanism has been introduced with the M4 milestone and extended in M5. Currently, the RWT theming allows to define custom colors, fonts, borders, dimensions, box dimensions (paddings etc.), and icons.
However, is still not much field-tested and some details are still likely to change, as our experience with this approach grows. Your comments and suggestions are welcome.
How to define a custom RWT Theme
Create a custom theme file
RWT theme files are simple Java Property files.
A template named
theme-template.properties can be found in the
src/ directory of the RWT plug-in (
You only have to specify those properties that are relevant for your customization, as undefined properties will stay at their default value.
Note that some property names are likely to be changed in the future, other properties will emerge and a few properties will even be dropped.
Please refer to the template file shipped with your current version.
See below for the syntax of the property values.
Register the new theme with the extension point
plugin.xml of your application project, add an extension like this:
<extension id="my.application.themes" point="org.eclipse.rap.swt.themes"> <theme id="my.application.aquablue" name="Aqua Blue Test Theme" file="aqua-blue.properties" default="true"/> </extension>
Activate the theme
The extension parameter
default (see above) specifies whether the theme should be active by default.
For testing purposes, a custom theme can also be activated by passing the theme id in the URL parameter
Support for programmatic activation of custom themes is planned for future versions.
Syntax for Property Values
Property values specified in a theme file must conform to the following syntactical rules:
Colors can be specified in one of these ways:
- A color keyword.
Only the 16 basic HTML 4.0 colors (aqua, black, blue, fuchsia, gray, green, lime, maroon, navy, olive, purple, red, silver, teal, white, and yellow) are supported. The keywords are case-insensitive.
- A comma separated list of three decimal integer numbers in the range
0 .. 255that denote the red, green, and blue portion of the color, respectively.
- A hexadecimal color notation in the format
#rrggbb, that is commonly used for HTML pages.
Dimensions are given as integer numbers. As all size calculations in SWT are pixel-based, all numbers represent pixel values. In contrast to CSS, the unit "px" must not be specified.
Box dimensions like margins and paddings can be provided in the shorthand syntax known from CSS2. One, two, three, or four integer numbers may be specified, separated by spaces. If four numbers are given, they stand for the values in clock-wise order: top, right, bottom, left. Three numbers stand for: top, right and left, bottom. Two numbers stand for: top and bottom, right and left. One number stands for: all four values.
Examples for valid box dimension definitions are:
5means: 5px for top, right, bottom, and left edge.
3 5means: 3px for top and bottom edge, 5px for left and right.
2 4 0means: 2px for the top edge, 4px for left and right, and 0px for the bottom.
2 4 0 2means: 2px top, 4px left, 0px bottom, 2px left.
A border definition may contain a size in pixels, a style keyword, and a color.
All parameters are optional.
The valid style keywords are
If one of the complex styles
ridge is used without a color definition, the default system shadow colors (
SWT.COLOR_WIDGET_HIGHLIGHT_SHADOW, etc., see below) are used to paint the border.
Examples for valid border definitions are:
1 solid black
2 solid #fffa00
The syntax for font definitions is very similar to the CSS shorthand property font.
A font definition contains the font size in pixels, a comma-separated list of font-family names, and the optional keywords
italic. The order of the parts does not matter.
Examples of valid font definitions are:
Helvetica 10 bold
10 Helvetica bold italic
12 Tahoma, "Lucida Sans Unicode", sans-serif italic
Custom images must be referred to using a '/'-separated path name that identifies the location of an image resource within the bundle.
SWT System Colors
The SWT system colors, as returned by
Display#getSystemColor(), are also themeable.
The following list indicates which theme parameters manipulate these colors:
SWT.COLOR_WIDGET_DARK_SHADOW: widget.darkshadow SWT.COLOR_WIDGET_NORMAL_SHADOW: widget.shadow SWT.COLOR_WIDGET_LIGHT_SHADOW: widget.lightshadow SWT.COLOR_WIDGET_HIGHLIGHT_SHADOW: widget.highlight SWT.COLOR_WIDGET_BACKGROUND: widget.background SWT.COLOR_WIDGET_BORDER: widget.thinborder SWT.COLOR_WIDGET_FOREGROUND: widget.foreground SWT.COLOR_LIST_FOREGROUND: list.foreground SWT.COLOR_LIST_BACKGROUND: list.background SWT.COLOR_LIST_SELECTION: list.selection.background SWT.COLOR_LIST_SELECTION_TEXT: list.selection.foreground SWT.COLOR_INFO_FOREGROUND: widget.info.foreground SWT.COLOR_INFO_BACKGROUND: widget.info.background SWT.COLOR_TITLE_FOREGROUND: shell.title.foreground SWT.COLOR_TITLE_BACKGROUND: shell.title.background SWT.COLOR_TITLE_BACKGROUND_GRADIENT: shell.title.background.gradient SWT.COLOR_TITLE_INACTIVE_FOREGROUND: shell.title.inactive.foreground SWT.COLOR_TITLE_INACTIVE_BACKGROUND: shell.title.inactive.background SWT.COLOR_TITLE_INACTIVE_BACKGROUND_GRADIENT: shell.title.inactive.background.gradient