Jump to content

Qt (software): Difference between revisions

From Wikipedia, the free encyclopedia
Browse history interactively
← Previous editNext edit →
Content deleted Content added
VisualWikitext
Mpx (talk | contribs)
51 edits
→Current: QtScript
Line 52: Line 52:
Qt 4.2, released on [[October 4]], [[2006]], introduced [[Windows Vista]] support, introduced native CSS support for widget styling, as well as the QGraphicsView framework for efficient rendering of thousands of 2D objects onscreen, to replace Qt 3.x's QCanvas class.
Qt 4.2, released on [[October 4]], [[2006]], introduced [[Windows Vista]] support, introduced native CSS support for widget styling, as well as the QGraphicsView framework for efficient rendering of thousands of 2D objects onscreen, to replace Qt 3.x's QCanvas class.


Qt 4.3, released on [[May 30]], [[2007]], improved [[Windows Vista]] support, improved [[OpenGL]] engine, [[SVG]] file generation.<ref name="Qt4.3WhatsNew">[http://trolltech.com/products/qt/whatsnew/whatsnew-qt43 Trolltech: ''What’s New in Qt 4.3'']</ref>
Qt 4.3, released on [[May 30]], [[2007]], improved [[Windows Vista]] support, improved [[OpenGL]] engine, [[SVG]] file generation, added QtScript ([[ECMAScript]] scripting engine based on [[Qt Script for Applications|QSA]]).<ref name="Qt4.3WhatsNew">[http://trolltech.com/products/qt/whatsnew/whatsnew-qt43 Trolltech: ''What’s New in Qt 4.3'']</ref>


== History ==
== History ==

Revision as of 09:44, 17 September 2007

Qt
Developer(s)Trolltech
Stable release
4.3.1 / August 7, 2007
Repository
Operating systemCross-platform
TypeDevelopment Library
LicenseGPL, Proprietary, QPL
WebsiteQt Homepage
For other uses, see Qt.

Qt is a cross-platform application development framework, widely used for the development of GUI programs and also used for developing non-GUI programs such as console tools and servers. Qt is most notably used in KDE, the web browser Opera, Google Earth, Skype, Qtopia and OPIE. It is produced by the Norwegian company Trolltech, formerly Quasar Technologies. Trolltech insiders pronounce Qt as "cute"[1].

Qt uses non-standard C++, extended by an additional pre-processor that generates the standard C++ code which is necessary to implement Qt's extensions. Qt can also be used in several other programming languages; bindings exist for Python (PyQt), Ruby (RubyQt), PHP (PHP-Qt), Pascal, C#[2], Perl and Java[3]. It runs on all major platforms, and has extensive internationalization support. Non-GUI features include SQL database access, XML parsing, thread management, and a unified cross-platform API for file handling.

Varieties

Qt is released by Trolltech on the following platforms:

There are four editions of Qt available on each of these platforms, namely:

  • Qt Console — edition for non-GUI development.
  • Qt Desktop Light — entry level GUI edition, stripped of network and database support.
  • Qt Desktop — complete edition.
  • Qt Open Source Edition — "complete" edition, with some exceptions[4], for free software/open source developers.

Since version 4, Qt has been available under a dual license, the GPL and a proprietary commercial license on all supported platforms including Windows. The commercial license allows the final application to be licensed under various free software/open source licenses such as the LGPL or the Artistic License, or a proprietary software license.

Proprietary commercial development requires the commercial license, and, unlike some open source software libraries, Qt is not licensed under the GNU Lesser General Public License and does not include a GPL linking exception.

All editions support a wide range of compilers, including the GCC C++ compiler. Official support for the Visual Studio suite [1] is, however, restricted to the proprietary Qt/Windows edition. The Q../Free project has released several patches [2] which add support for Microsoft Visual Studio and Borland C++ Builder to the free software/open source version of Qt/Windows.

Current

Trolltech released Qt 4 on June 28, 2005 and introduced five new technologies in the framework:

  • Tulip A set of template container classes.
  • Interview A model/view architecture for item views.
  • Arthur A 2D painting framework.
  • Scribe A Unicode text renderer with a public API for performing low-level text layout.
  • MainWindow A modern action-based main window, toolbar, menu, and docking architecture.

Qt 4.1, released on December 19, 2005, introduced integrated SVG Tiny support, a PDF backend to Qt's printing system, and a few other features.

Qt 4.2, released on October 4, 2006, introduced Windows Vista support, introduced native CSS support for widget styling, as well as the QGraphicsView framework for efficient rendering of thousands of 2D objects onscreen, to replace Qt 3.x's QCanvas class.

Qt 4.3, released on May 30, 2007, improved Windows Vista support, improved OpenGL engine, SVG file generation, added QtScript (ECMAScript scripting engine based on QSA).[5]

History

Haavard Nord and Eirik Chambe-Eng (the original developers of Qt and the CEO and President of Trolltech respectively) began development of "Qt" in 1991, three years before the company was incorporated as Quasar Technologies, then changed the name to Troll Tech, and then to Trolltech.

The toolkit was called Qt because the letter Q looked beautiful in Haavard's Emacs font, and T was inspired by Xt, the X toolkit.

Controversy erupted around 1998 when it became clear that KDE was going to become one of the leading desktop environments for Linux. As KDE was based on Qt, many people in the free software movement worried that an essential piece of one of their major operating systems would be proprietary.

This gave rise to two efforts: the Harmony toolkit, which sought to duplicate the Qt Toolkit under a free software license, and the GNOME desktop, which intended to supplant KDE entirely. The GNOME Desktop uses the GTK+ toolkit, which was originally written for the GIMP, and primarily uses the C programming language.

Until version 1.45, source code for Qt was released under the FreeQt license — which was viewed as not compliant to the open source principle by the Open Source Initiative and the free software definition by Free Software Foundation, because while the source was available it did not allow the redistribution of modified versions. With the release of version 2.0 of the toolkit, the license was changed to the Q Public License (QPL), a free software license but one regarded by the Free Software Foundation as incompatible with the GPL. Compromises were sought between KDE and Trolltech wherein Qt would not be able to fall under a more restrictive license than the QPL, even if Trolltech was bought out or went bankrupt. This led to the creation of the KDE Free Qt foundation, which guarantees that Qt would fall under a BSD-style license should no free software/open source version of Qt be released during 12 months.

The first two versions of Qt had only two flavours: Qt/X11 for Unix and Qt/Windows for the Windows platform. The Windows platform was only available under the proprietary license which meant free/open source applications written in Qt for X11 could not be ported to Windows without purchasing the QPL edition. In the end of 2001, Trolltech released Qt 3.0 which added support for the Mac OS X platform. The Mac OS X support was available only in the proprietary license, until June 2003, where Trolltech released Qt 3.2 with Mac OS X support available under the GPL.

In 2002 members of the KDE on Cygwin project began porting the GPL licensed Qt/X11 code base to Windows[6]. This was in response to Trolltech's refusal to license Qt/Windows under the GPL on the grounds that Windows was not a free software/open source platform[7][8]. The project achieved reasonable success although it never reached production quality.

This was resolved when Trolltech released Qt/Windows 4 under the GPL in June 2005. Qt 4 now supports the same set of platforms in the free software/open source editions as in the proprietary edition, so it is now possible to create GPL-licensed free/open source applications using Qt on all supported platforms.

Design

The innovation of Qt when it was first released relied on a few key concepts.

Complete abstraction of the GUI

Qt used to emulate the native look of its intended platforms, which occasionally led to slight discrepancies where that emulation wasn't perfect. Recent versions of Qt use the native APIs of the different platforms to draw the Qt controls, and so do not suffer from such issues.

Qt Script for Applications (QSA)

Qt Script for Applications is a cross-platform toolkit that allows developers to make their Qt/C++ applications scriptable using an interpreted scripting language: Qt Script (based on ECMAScript/JavaScript).

From Qt 4.3.0 onward, the scripting API [9], which is based on QSA [10] is integrated as core part of Qt and is no longer a separate library.

Meta Object Compiler

Known as the moc, this is a tool that is run on the sources of a Qt program prior to compiling it. The tool will generate "Meta Information" about the classes used in the program. This meta information is used by Qt to provide programming features not available in C++: The signal/slot system, introspection and asynchrone function calls.

The use of an additional tool has been criticized for making Qt programming different from pure C++ programming. In particular, the choice of an implementation based on macros has been criticized for its absence of type safety and pollution of the namespace. This is viewed by Trolltech as a necessary trade-off to provide introspection and the dynamically generated slot and signal mechanism.

Applications Using Qt

There are many programs built using the Qt toolkit, here are a few popular examples:

References

  1. ^ Interview with Trolltech president Eirik Eng on dot.kde.org
  2. ^ The Qyoto / Kimono Project, a .Net and C# bindings for Qt
  3. ^ Qt Jambi, Java bindings for Qt from Trolltech
  4. ^ The ActiveQt class for ActiveX on Windows, for example, is not available in the Open Source Edition
  5. ^ Trolltech: What’s New in Qt 4.3
  6. ^ Q../Windows Edition history, 5 June 2006
  7. ^ E-mail to the kde-cygwin mailing list by Chris January, 4 February 2003
  8. ^ Qt Non-commercial FAQ, 5 October 2003
  9. ^ http://doc.trolltech.com/4.3/qtscript.html
  10. ^ http://doc.trolltech.com/qsa-1.2.2/
  11. ^ TOra uses the Qt library

See also

The Wikibook X Windows Programming has a page on the topic of: Qt
Retrieved from "https://en.wikipedia.org/enwiki/w/index.php?title=Qt_(software)&oldid=158461072"