KDE2.0 Widget Themes
From the KDE Widget Theme Tutorial:
Some terms explained
At the very basic level KDE widget themes and styles are accomplished by
allowing programmers to reimplement how widgets are painted as well as
some user interaction parameters. When the developer makes a complete set of
routines to draw all of the widgets this is called a "style". Examples of
widget styles in KDE are Platinum, CDE, Windows, Motif, KStep, and Pillbox.
In KDE, one of these styles can read a configuration file to determine how
widgets should be drawn. This configuration file is called a "theme", and
is what most of this tutorial focuses on. Examples of widget themes in KDE
include System and Marble.
Feature overview
- KDE themes are fast. Really fast. Even themes using pixmaps and gradients
should run at a decent speed. This is mostly due to how pixmaps are stored
and a very optimized cache mechanism.
- KDE allows people to easily design both themes and dedicated widget drawing
plugins that are dynamically loaded and configurable at runtime.
- Included in KDE is an advanced effects engine with built in gradient and
blending support that is fully accessible to people designing KDE themes. This
is in addition to the effects included in the KDE/Qt base classes such as
fast smooth-scaling.
- Dedicated cache. As mentioned above, the theme plugin has a cache designed
specifically for pixmap and gradient themes. Besides greatly increasing the
speed of widget themes it also is configurable in size and has automatic
flushing of old data. If themes are designed well the cache should also always
be relatively small. It can also be disabled for fast machines that don't need
it.
Some Examples
As explained above, there are two basic type of widget styles
supported by KDE: those that support themes and those that don't. One may
ask why if themed plugins are so fast would someone want to use
an unthemed style? Well, for one a lot of people simply don't like pixmaps
and gradients all over their user interface ;-) Another reason is that while
KDE widget themes are fast and low on memory they do of course use more
resources than styles that don't use the extensive graphics. You don't get
something for nothing, although I do try to keep the price as low as possible :)
People even on low end systems should get decent performance. Finally, many
people can't stand wasting any resources on something like pretty pictures,
even is the cost is low. For
these reasons I spend a lot of time designing unthemed as well as themed styles.
Let's first look at the unthemed widget styles. These screenshots use a
combination of unthemed widget and KWin styles:
| Widget style |
KWin style |
Screen shot |
|
| B2/K |
B2/K |
|
| CDE |
B2/K |
|
| KStep |
KStep |
|
| Platinum |
System |
|
| Pillbox |
System |
|
| Win |
Standard |
|
KWin Styles - Streamlining The Window Manager
KWin supports a similar plugin mechanism as widgets to control how windows
look. This means that KWin itself is just a very streamlined window manager,
and then you can choose plugins that control how windows are rendered. In this
manner you can choose exactly how KWin looks and how much overhead it contains.
You can choose a plugin that is very small and does simple window rendering, a
large plugin that does sophisticated rendering, or a themed plugin. And of course,
since the theme and style engines are all plugins developers can write whole new
engines that do things I can't even think of.
Currently KWin supports several dedicated style plugins and one themed one.
The dedicated styles so far are: Standard (the old KDE style with some
improvements), B2/K (A Beos-like style), KStep (A Next-like style), and
System (a rounded Mac-like style). You can see screenshots of all of these
in the above section.
Another thing to note is that since KWin is a KDE application it
can also automatically integrate with widget themes. If you set a widget theme
KWin can automatically use it's pixmaps with no additional configuration or
coding required. The widget theme engine and KDE takes care of everything, from
a development perspective you are drawing with the same brushes you used with
unthemed styles. No additional code or effort needed. For example, the
following shows the same KWin style, system, being used under
different widget themes:
This is the "System" KWin style plugin with no widget theme.
This is the same plugin, but used with the System widget theme. No
additional coding or configuration was needed to make it use the widget theme's
background.
And finally this is the same plugin but with a different widget theme: Marble.
Also interesting to note is that since many of these styles are coded plugins
they can do things themes cannot, such as automatically adjust the window
decorations to the current color scheme. For example, below is the active
window in the B2 style under two different color schemes:
KWM Theme Support
Recently I started on KWM compatible theme support as well. Like all the other
styles except Standard, this is a plugin and dynamically loaded when selected.
This is intended to allow users to use the hundreds of themes available for KDE
1.x with the new window manager. You can see a screenshot of it's progress
below:
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