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137.

The Qt Toolkit

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http://qt.nokia.com

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Qt's latest version is 4.7 but it is usually referred to as "Qt4" to avoid confusion with the previous major release, Qt3. The KDE 3.5.x desktop was built using Qt3 and the KDE 4.x desktop was built using Qt4. The two versions are not compatible, and a tool is provided to migrate applications built with Qt3 to Qt4. However, some classes, methods and properties in Qt3 were not carried forward into Qt4 and those will have to be replaced using existing Qt4 objects.

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The <application>Qt</application> (pronounced <quote>cute</quote>) toolkit includes three major components, plus the QtCreator IDE and and the Qt-SDK. They are produced by Nokia, which purchased Qt from the original developer, Trolltech so that they could use Qt to develop their mobile phone OS, Symbian. They also use Qt to support MeeGo, an open source Linux project which brings together the Moblin project, headed up by Intel, and Maemo, by Nokia, into a single open source activity. Nokia states that <quote>MeeGo integrates the experience and skills of two significant development ecosystems, versed in communications and computing technologies. The MeeGo project believes these two pillars form the technical foundations for next generation platforms and usages in the mobile and device platforms space. MeeGo currently targets platforms such as netbooks/entry-level desktops, hand held computing and communications devices, in-vehicle infotainment devices, connected TVs, and media phones.</quote>

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On February 11, 2011, Nokia announced a <quote>partnership</quote> with Microsoft in which Nokia will replace Symbian with Windows Phone 7 in wealthy American and European markets, but continue to use Symbian in India and other poorer regions. Because of a huge outcry by Qt and open source supporters who contributed to Symbian, Meego and Maemo, Nokia released a <ulink url="http://blog.qt.nokia.com/2011/02/12/nokia-new-strategic-direction-what-is-the-future-for-qt">blog message</ulink> the next day. It seems they need Qt in order to continue to support Symbian on the 200 million Nokia phones that run it, and MeeGo and Maemo for a <quote>disruptive</quote> presence in the markets for which they are being offered. But, the partnership puts the commercial version of Qt in a questionable light due to the influence of Microsoft and the history of its partnership with Novell, and others which no longer exist.

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Qt's the three major components are the Designer, the Linguist and the Application Programming Interface (API). The Qt toolkit allows you to write source code for advanced applications with graphical user interfaces on either Linux, Windows or Mac and compile them on all three platforms and embedded operating systems with little or no rewriting of the source code, saving time and development cost.

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Since the Qt Toolkit is under the GPL/LGPL it is not threatened by this partnership, and Canonical announced that they are going to use Qt instead of Gnome to develop their Unity 2D desktop. So, considering that, and the fact that Qt is under the GPL/LGPL license, Qt remains as viable a development tool as it was before the announcement. Because Kubuntu uses the KDE desktop and KDE was built with Qt, and Qt is the most powerful GUI RAD tool available on Linux, and some would say Windows as well, the following is information is about how to install Qt.

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Installation of Qt

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The entire Qt toolkit is in the repository as qt-sdk or as part of the Qt SDK available from the <ulink url="http://qt.nokia.com/downloads"> http://qt.nokia.com/downloads </ulink> website under either the LGPL or a commercial license. The latest version the Qt-SDK-1.1 zip file available from Nokia in either the <ulink url="http://qt.nokia.com/downloads/sdk-linux-x11-64bit-cpp">32 bit</ulink> or <ulink url="http://qt.nokia.com/downloads/sdk-linux-x11-32bit-cpp">64 bit</ulink> version. Either includes the QtCreator, the Designer, the Assistant (API), the Linguist and all the necessary libraries and utilities. The Qt SDK can be installed in the user's home account and used to create applications regardless of which version of Qt libraries the KDE desktop requires because the SDK startup scripts sets the shell environment to point to the SDK libraries.

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qt4-dev-tools