KDE Software Compilation 4
KDE Software Compilation 4 was the only series of the so-called KDE Software Compilation, first released in January 2008. The final release was version 4.14.3 in November 2014. It was the follow-up to K Desktop Environment 3. Following KDE SC 4, the compilation was broken up into basic framework libraries, desktop environment, and applications, which are termed KDE Frameworks 5, KDE Plasma 5, and KDE Applications, respectively. Major releases were released every six months, while minor bugfix releases were released monthly.
The series included updates to several of the KDE Platform's core components, notably a port to Qt 4. It contained a new multimedia API called Phonon, a device integration framework called Solid, and a new style guide and default icon set called Oxygen. It also included a new, unified desktop and panel user interface called Plasma, which supported desktop widgets, replacing K Desktop Environment 3's separate components.
One of the overall goals of KDE Platform 4 was to make it easy for KDE applications to be portable to different operating systems. This was made possible by the port to Qt 4, which facilitated support for non-X11-based platforms, including Microsoft Windows and Mac OS X. Versions 4.0 to 4.3 of KDE Software Compilation were known simply as KDE 4 – the name change being a result of the KDE project's re-branding to reflect KDE's increased scope.
Major updates
This is a short overview of major changes in KDE Software Compilation 4.General
The port to the Qt 4 series was expected to enable KDE 4 to use less memory and be noticeably faster than KDE 3. The KDE libraries themselves have also been made more efficient. However, tests reveal that KDE 4.4 has the highest memory utilization on default Ubuntu installations when compared to GNOME 2.29, Xfce 4.6, and LXDE 0.5. Qt 4 is available under the LGPL for Mac OS X and Windows, which allows KDE 4 to run on those platforms. The ports to both platforms are in an early state., KDE Software compilation 4 on Mac OS X is considered beta, while on Windows it is not in the final state, so applications can be unsuitable for day to day use yet. Both ports are trying to use as little divergent code as possible to make the applications function almost identically on all platforms. During Summer of Code 2007 an icon cache was created to decrease application start-up times for use in KDE 4. Improvements were varied – Kfind, an application which used several hundred icons, started up in about a quarter of the time it took previously. Other applications and a full KDE session started up a little over a second faster.Many applications in the Extragear and KOffice modules have received numerous improvements with the new features of KDE 4 and Qt 4. But since they follow their own release schedule, they were not all available at the time of the first KDE 4 release – these include Amarok, K3b, digiKam, KWord, and Krita.
Visual
The most noticeable changes for users are the new icons, theme and sounds provided by the Oxygen Project. These represent a break from previous KDE icons and graphics, which had a cartoonish look. Instead Oxygen icons opt for a more photorealistic style. The Oxygen Project builds on the freedesktop.org Icon Naming Specification and Icon Theme Specification, allowing consistency across applications. The Oxygen team uses community help for better visuals in KDE 4, with both alternate icon sets and the winners of a wallpaper contest held by the Oxygen project being included in KDE 4. There is also a new set of human interface guidelines for a more standardized layout.Plasma provides the main desktop user interface and is a rewrite of several core KDE applications, like the desktop drawing and most notably the widget engine. Plasma allows a more customisable desktop and more versatile widgets.
KWin, the KDE Window Manager, now provides its own compositing effects, similar to Compiz.
Development
is the name of the multimedia API in KDE 4. Phonon is a different approach to multimedia backends than in previous versions of KDE. This is because Phonon only functions as a wrapper, abstracting the various multimedia frameworks available for Unix-like operating systems into runtime switchable backends that can be accessed through a single API. This was done to provide a stable API for KDE 4 and to prevent it from depending on a single multimedia framework. Applications that use the Phonon API can be switched between multimedia frameworks seamlessly by simply changing the backend used in System Settings. Nokia adopted Phonon for multimedia use in Qt 4.4 and are developing backends for Gstreamer, Windows and OS X in the KDE SVN repository under the LGPL.Solid is the hardware API in KDE 4. It functions similarly to Phonon as it does not manage hardware on its own but makes existing solutions accessible through a single API. The current solution uses HAL, NetworkManager and BlueZ, but any and all parts can be replaced without breaking the application, making applications using Solid extremely flexible and portable.
ThreadWeaver is a programming library to help applications take advantage of multicore processors and is included with kdelibs.
Kross is the new scripting framework for KDE 4. Kross itself is not a scripting language, but makes it easier for developers to add support for other scripting languages. Once an application adds support for Kross, any language Kross supports can be used by developers. New scripting languages can be added by creating a plugin for Kross, which benefits all applications using it.
Decibel is a Telepathy-based communication framework, which was expected to be fully used by Kopete by KDE 4.2, but which is reported to be postponed indefinitely.
Strigi is the default search tool for KDE 4, chosen for its speed and few dependencies. In concert with other software like Soprano, an RDF storage framework, and the NEPOMUK specification, Strigi will provide the beginnings of a semantic desktop in KDE 4. Users can tag files with additional information through Dolphin, which Strigi can index for more accurate searches.
KDE 4 uses CMake for its build system. Since previous versions of KDE were only on Unix systems, autotools were used, but a new build system was needed for builds on operating systems like Windows. CMake also dramatically simplified the build process. The autotools build system had become so complicated by KDE 3 that few developers understood it, requiring hours of work for simple changes. In early 2007 CMake was shown to compile KDE 4 version of KDElibs 40 % faster than the autotools compiled KDE 3 version.
DXS, previously known as GHNS and now adopted by freedesktop.org, is a web service that lets applications download and install data from the Internet with one click. It was used in the KDE 3 series but has been extended for use throughout KDE 4. One example was Kstars, that can use Astronomical data that is free for personal use but cannot be redistributed. DXS allows that data to be easily downloaded and installed from within the application instead of manually downloading it.
Akonadi is a new PIM framework for KDE 4. Akonadi is a unification of previously separate KDE PIM components. In the past each application would have its own method for storing information and handling data. Akonadi itself functions as a server that provides data and search functions to PIM applications. It is also able to update the status of contacts. So if one application changes information about a contact, all other applications are immediately informed of the change.
Released versions
KDE 4.0
The majority of development went into implementing most of the new technologies and frameworks of KDE 4. Plasma and the Oxygen style were two of the biggest user-facing changes.Dolphin replaces Konqueror as the default file manager in KDE 4.0. This was done to address complaints of Konqueror being too complicated for a simple file manager. However Dolphin and Konqueror will share as much code as possible, and Dolphin can be embedded in Konqueror to allow Konqueror to still be used as a file manager.
Okular replaces several document viewers used in KDE 3, like KPDF, KGhostView and KDVI. Okular makes use of software libraries and can be extended to view almost any kind of document. Like Konqueror and KPDF in KDE 3, Okular can be embedded in other applications.
Pre-releases
On 11 May 2007, KDE 4.0 Alpha 1 was released marking the end of the addition of large features to KDE base libraries and shifting the focus onto integrating the new technologies into applications and the basic desktop. Alpha 1 included new frameworks to build applications with, providing improved hardware and multimedia integration through Solid and Phonon. Dolphin and Okular were integrated and a new visual appearance was provided through Oxygen icons.On 4 July 2007, Alpha 2 was released. The release focused on integrating the Plasma desktop, improving functionality and stabilizing KDE.
On 2 August 2007, Beta 1 was released. Major features included a pixmap cache – speeding up icon loading, KDE PIM improvements, improved KWin effects and configuration, better interaction between Konqueror and Dolphin and Metalink support added to KGet for improved downloads.
On 6 September 2007, Beta 2 was released with improved BSD and Solaris support. The release included the addition of the Blitz graphic library – allowing for developers to use high performance graphical tricks like icon animation – and an overhaul of KRDC for Google's Summer of Code. Plasma was also integrated with Amarok to provide Amarok's central context view.
On 16 October 2007, Beta 3 was released. The beta 3 release was focused on stabilizing and finishing the design of libraries for the release of KDE Development Platform. Plasma received many new features including an applet browser. The educational software received many improvements in Marble and Parley with bugfixes in other applications. A program called Step, an interactive physics simulator, was produced as part of the Google Summer of Code.
On 30 October 2007, Beta 4 was released. A list of release blockers was compiled, listing issues that need to be resolved before KDE will start with the release candidate cycle for the desktop. The goals were to focus on stabilization and fixing the release blockers.
At the same time, the first release candidate of KDE 4.0 Development Platform was released. The development platform contains all the base libraries to develop KDE applications, including "high-level widget libraries, a network abstraction layer and various libraries for multimedia integration, hardware integration and transparent access to resources on the network."
On 20 November 2007, Release Candidate 1 was released. This release was called a "Release Candidate" despite Plasma requiring further work and not being ready for release. On 11 December 2007, RC2 was released. The codebase was declared feature-complete. Some work was still required to fix bugs, finish off artwork and smooth out the user experience.