KHTML
From Wikipedia, the free encyclopedia
| KHTML | |
|---|---|
 Konqueror using KHTML to render the Wikipedia front page. |
|
| Developed by | KDE Team, Apple Inc., Nokia, Google, others. |
| OS | Linux/Unix |
| Genre | Layout engine |
| License | GNU Lesser General Public License |
KHTML is the HTML layout engine developed by the KDE project. It is the engine used by the Konqueror web browser, and a forked version (WebKit) is used by Apple's Safari web browser. Distributed under the terms of the GNU Lesser General Public License, KHTML is free software.
Built on the KPart framework and written in C++, KHTML has relatively good support for Web standards. To render as many pages as possible, some extra abilities and quirks from Internet Explorer are also supported, even though those are non-standard.
KHTML renders faster than the Gecko layout engine,[1] its main open source rival and core of the Mozilla and Mozilla Firefox browsers, among others. However, being a less widely known browser, many websites fail to support KHTML or claim no support even if the site does work correctly in Konqueror. Gmail, for instance, only works if Konqueror reports itself as Firefox (see User Agent Spoofing).
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[edit] History
KHTML was preceded by an earlier engine called khtmlw or the KDE HTML Widget, developed by Torben Weiss and Martin Jones,[2] which implemented support for HTML 3.2, HTTP 1.0, and HTML frames, but not the W3C DOM, CSS, or scripting.
KHTML came into existence in November 4, 1998,[3] as a copy of the khtmlw library, with some slight refactoring and the addition of Unicode support and changes to support the move to QT 2. Waldo Bastian[4] was among those who did the work of creating that early version of KHTML.[5]
The real work on KHTML actually started between May and October 1999, with the realization that the choice facing the project was "either do a significant effort to move KHTML forward or to use Mozilla"[6] and with adding support for scripting as the highest priority. So in May 1999, Lars Knoll[7] began doing research with an eye toward implementing the W3C DOM specification, finally announcing[8] on August 16, 1999 that he had checked in[9] what amounted to a complete rewrite of the KHTML library — changing KHTML to use the standard W3C DOM as its internal document representation. That in turn allowed the beginnings of Javascript support to be added in October 1999,[10] with the integration of Harri Porten's KJS following shortly afterward.
In the closing months of 1999 and first few months of 2000, Knoll did further work[11] with Antti Koivisto[12] and Dirk Mueller[13] to add CSS support and to refine and stabilize the KHTML architecture,[14] with most of that work being completed by March 2000. Among other things, those changes enabled KTHML to become the first browser other than Internet Explorer to correctly support languages written right-to-left (for example, Hebrew and Arabic)[15] — before Mozilla had such support.
KDE 2.0 was the first KDE release (on October 23, 2000) to include KHTML[16] (as the rendering engine of the new Konqueror file and web browser, which replaced the monolithic KDE File Manager).
[edit] KHTML and Apple
KHTML and KJS were adopted by Apple in 2002 for use in the Safari web browser. Apple publishes the source code for their fork of the KHTML engine, called WebKit, as required by the LGPL.
However, the exchange of code patches between the two branches of KHTML has previously been difficult and the code base diverged because both projects had different approaches in coding.[17] One of the reasons for this is that Apple worked on their version of KHTML for a year before making their fork public. Apple also tended to submit their changes in large patches that incorporated a great number of changes, in some cases leaving code to do with future feature additions barely documented — making it difficult for the KDE developers to sort through and incorporate the changes.[citation needed]
Despite this, the KDE project was able to incorporate some of these changes to improve KHTML's rendering speed and add features, including compliance with the Acid2 rendering test.
According to Apple, some changes involved Mac OS X-specific features (e.g. Objective-C, KWQ, OS X calls), which are absent in KDE's KHTML, which called for different development tactics.[18]
Apple has since released changes of the sourcecode of its KHTML fork in a CVS repository.[19] Since the transfer of the sourcecode into a public CVS repository, Apple and KHTML developers have had increasing collaboration. Many KHTML developers have become reviewers and submitters for Apple's WebKit SVN repository.
[edit] Standards compliance
The following standards are supported by the KHTML engine:
- HTML 4.01
- CSS 1
- CSS 2.1 (screen and paged media)
- CSS 3 Selectors (fully as of KDE 3.5.6[20])
- CSS 3 Other (multiple backgrounds, box-sizing and text-shadow)
- PNG, MNG, JPEG, GIF graphic formats
- DOM 1, 2 and partially 3
- ECMA-262/JavaScript 1.5
- Partial Scalable Vector Graphics support
[edit] See also
[edit] References
- ^ Browser speed comparisons
- ^ around 1:18 in December 8, 2006 From KDE to WebKit presentation at Yahoo! office by Lars Knoll and George Staikos http://yuiblog.com/blog/2006/12/11/knoll-staikos-video/
- ^ around 4:52 in http://yuiblog.com/blog/2006/12/11/knoll-staikos-video/
- ^ Waldo Bastian http://people.kde.org/waldo.html
- ^ around 5:02 in http://yuiblog.com/blog/2006/12/11/knoll-staikos-video/
- ^ around 5:30 in http://yuiblog.com/blog/2006/12/11/knoll-staikos-video/
- ^ Lars Knoll http://people.kde.org/lars.html
- ^ 1999-08-16 "changes in KHTML" message from Lars Knoll http://lists.kde.org/?l=kfm-devel&m=93489518402924
- ^ 1999-08-16 "khtml_to_dom: kdelibs/khtml" commit message http://lists.kde.org/?l=kde-commits&m=93476738632582
- ^ around 8:18 in http://yuiblog.com/blog/2006/12/11/knoll-staikos-video/
- ^ around 9:10 in http://yuiblog.com/blog/2006/12/11/knoll-staikos-video/
- ^ Antti Koivisto http://trac.webkit.org/projects/webkit/wiki/WebKit%20Team#AnttiKoivistoanttikreview>
- ^ Dirk Mueller http://people.kde.org/dirk.html
- ^ around 9:32 in http://yuiblog.com/blog/2006/12/11/knoll-staikos-video/
- ^ around 10:30 in http://yuiblog.com/blog/2006/12/11/knoll-staikos-video/
- ^ around 11:10 in http://yuiblog.com/blog/2006/12/11/knoll-staikos-video/
- ^ http://www.kdedevelopers.org/node/view/1001
- ^ http://www.kdedevelopers.org/node/view/1006
- ^ Apple Opens WebKit CVS and Bug Database
- ^ K Desktop Environment - KDE 3.5.6 Changelog
[edit] External links
- Web Browser – list of KHTML features on Konqueror site
- KHTML – KDE's HTML library – definition from developer.kde.org
- KHTML from KDE API Reference
- Apple WebKit Open Source Project
- From KDE to WebKit: The Open Source Engine That's Here to Stay – video of December 8, 2006 presentation at Yahoo! office by Lars Knoll and George Staikos
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