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358 lines
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358 lines
20 KiB
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<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<title>Key Features in Qt 3.0</title>
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<a href="index.html">
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<font color="#004faf">Home</font></a>
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| <a href="classes.html">
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<font color="#004faf">All Classes</font></a>
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<font color="#004faf">Main Classes</font></a>
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<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>Key Features in Qt 3.0</h1>
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<p> Qt 3.0 adds a lot of new features and improvements over the Qt 2.x
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series. Some internals have undergone major redesign and new classes
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and methods have been added.
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<p> We have tried to keep the API of Qt 3.0 as compatible as possible with
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the Qt 2.x series. For most applications only minor changes will be
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needed to compile and run them successfully using Qt 3.0.
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<p> One of the major new features that has been added in the 3.0 release
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is a module allowing you to easily work with databases. The API is
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platform independent and database neutral. This module is seamlessly
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integrated into Qt Designer, greatly simplifying the process of
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building database applications and using data aware widgets.
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<p>
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Other major new features include a plugin architecture. You can use
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your own and third party plugins your own applications.
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The Unicode support of Qt 2.x has been greatly enhanced, it now
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includes full support for scripts written from right to left (e.g.
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Arabic and Hebrew) and also provides improved support for Asian
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languages.
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<p> Many new classes have been added to the Qt Library. Amongst them are
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classes that provide a docking architecture
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(<a href="qdockarea.html">QDockArea</a>/<a href="qdockwindow.html">QDockWindow</a>), a powerful rich text editor
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(<a href="qtextedit.html">QTextEdit</a>), a class to store and access application settings
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(<a href="qsettings.html">QSettings</a>) and a class to create and communicate with processes
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(<a href="qprocess.html">QProcess</a>).
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<p> Apart from the changes in the library itself a lot has been done to
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make the development of Qt applications with Qt 3.0 even easier than
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before. Two new applications have been added: Qt Linguist is a tool to
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help you translate your application into different languages; Qt
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Assistant is an easy to use help browser for the Qt documentation that
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supports bookmarks and can search by keyword.
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<p> Another change concerns the Qt build system, which has been reworked
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to make it a lot easier to port Qt to new platforms. You can use this
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platform independent build system for your own applications.
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<p> <h2> The Qt Library
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</h2>
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<a name="1"></a><p> A large number of new features has been added to Qt 3.0. The following
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list gives an overview of the most important new and changed aspects
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of the Qt library. A full list of every new method follows the
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overview.
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<p> <h3> Database support
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</h3>
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<a name="1-1"></a><p> One of the major new features in Qt 3.0 is the <a href="sql.html">SQL
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module</a> that provides multiplatform access to SQL databases,
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making database application programming with Qt seamless and portable.
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The API, built with standard SQL, is database-neutral and software
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development is independent of the underlying database.
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<p> A collection of tightly focused C++ classes are provided to give the
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programmer direct access to SQL databases. Developers can send raw SQL
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to the database server or have the Qt SQL classes generate SQL queries
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automatically. Drivers for Oracle, PostgreSQL, MySQL and ODBC are
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available and writing new drivers is straightforward.
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<p> Tying the results of SQL queries to GUI components is fully supported
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by Qt's SQL widgets. These classes include a tabular data widget
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(for spreadsheet-like data presentation with in-place editing), a
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form-based data browser (which provides data navigation and edit
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functions) and a form-based data viewer (which provides read-only
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forms). This framework can be extended by using custom field editors,
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allowing for example, a data table to use custom widgets for in-place
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editing. The SQL module fully supports Qt's signal/slots mechanism,
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making it easy for developers to include their own data validation and
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auditing code.
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<p> Qt Designer fully supports Qt's SQL module. All SQL widgets can be
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laid out within Qt Designer, and relationships can be established
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between controls visually. Many interactions can be defined purely in
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terms of Qt's signals/slots mechanism directly in Qt Designer.
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<p>
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<h3> Plugins
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</h3>
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<a name="1-2"></a><p> The <a href="qlibrary.html">QLibrary</a> class provides a platform independent wrapper for runtime
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loading of shared libraries. QPluginManager makes it trivial to implement
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plugin support in applications. The Qt library is able to load
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additional styles, database drivers and text codecs from plugins.
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<p> Qt Designer supports custom widgets in plugins, and will use the
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widgets both when designing and previewing forms.
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<p> See the <a href="plugins-howto.html">plugins documentation</a>.
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<p> <h3> Rich text engine and editor
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</h3>
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<a name="1-3"></a><p> The rich text engine originally introduced in Qt 2.0 has been further
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optimized and extended to support editing. It allows editing formatted
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text with different fonts, colors, paragraph styles, tables and
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images. The editor supports different word wrap modes, command-based
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undo/redo, multiple selections, drag and drop, and many other
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features. The new <a href="qtextedit.html">QTextEdit</a> engine is highly optimized for proccesing
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and displaying large documents quickly and efficiently.
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<p> <h3> Unicode
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</h3>
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<a name="1-4"></a><p> Apart from the rich text engine, another new feature of Qt 3.0 that
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relates to text handling is the greatly improved Unicode support. Qt
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3.0 includes an implementation of the bidirectional algorithm (BiDi)
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as defined in the Unicode standard and a shaping engine for Arabic,
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which gives full native language support to Arabic and Hebrew speaking
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people. At the same time the support for Asian languages has been
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greatly enhanced.
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<p> The support is almost transparent for the developer using Qt to
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develop their applications. This means that developers who developed
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applications using Qt 2.x will automatically gain the full support for
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these languages when switching to Qt 3.0. Developers can rely on their
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application to work for people using writing systems different from
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Latin1, without having to worry about the complexities involved with
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these scripts, as Qt takes care of this automatically.
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<p> <h3> Docked and Floating Windows
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</h3>
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<a name="1-5"></a><p> Qt 3.0 introduces the concept of Dock Windows and Dock Areas. Dock
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windows are widgets, that can be attached to, and detached from, dock
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areas. The commonest kind of dock window is a tool bar. Any number of
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dock windows may be placed in a dock area. A main window can have dock
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areas, for example, <a href="qmainwindow.html">QMainWindow</a> provides four dock areas (top, left,
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bottom, right) by default. The user can freely move dock windows and
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place them at a convenient place in a dock area, or drag them out of
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the application and have them float freely as top level windows in
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their own right. Dock windows can also be minimized or hidden.
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<p> For developers, dock windows behave just like ordinary widgets. QToolbar
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for example is now a specialized subclass of a dock window. The API
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of QMainWindow and <a href="qtoolbar.html">QToolBar</a> is source compatible with Qt 2.x, so
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existing code which uses these classes will continue to work.
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<p> <h3> Regular Expressions
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</h3>
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<a name="1-6"></a><p> Qt has always provided <a href="qregexp.html#regular-expression">regular expression</a> support, but that support
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was pretty much limited to what was required in common GUI control
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elements such as file dialogs. Qt 3.0 introduces a new regular
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expression engine, <a href="qregexp.html">QRegExp</a>, that supports most of Perl's regex
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features and is Unicode based. The most useful additions are support
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for parentheses (capturing and non-capturing) and backreferences.
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<p> <h3> Storing application settings
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</h3>
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<a name="1-7"></a><p> Most programs will need to store some settings between runs, for
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example, user selected fonts, colors and other preferences, or a list
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of recently used files. The new <a href="qsettings.html">QSettings</a> class provides a platform
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independent way to achieve this goal. The API makes it easy to store
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and retrieve most of the basic data types used in Qt (such as basic
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C++ types, strings, lists, colors, etc). The class uses the registry
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on the Windows platform and traditional resource files on Unix.
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<p> <h3> Creating and controlling other processes
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</h3>
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<a name="1-8"></a><p> <a href="qprocess.html">QProcess</a> is a class that allows you to start other programs from
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within a Qt application in a platform independent manner. It gives you
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full control over the started program, for example you can redirect
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the input and output of console applications.
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<p> <h3> Accessibility
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</h3>
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<a name="1-9"></a><p> Accessibility means making software usable and accessible to a wide
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range of users, including those with disabilities. In Qt 3.0, most
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widgets provide accessibility information for assistive tools that can
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be used by a wide range of disabled users. Qt standard widgets like
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buttons or range controls are fully supported. Support for complex
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widgets, like e.g. <a href="qlistview.html">QListView</a>, is in development. Existing applications
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that make use of standard widgets will become accessible just by using
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Qt 3.0.
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<p> Qt uses the Active Accessibility infrastructure on Windows, and needs
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the MSAA SDK, which is part of most platform SDKs. With improving
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standardization of accessibility on other platforms, Qt will support
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assistive technologies on other systems, too.
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<p> <h3> XML Improvements
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</h3>
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<a name="1-10"></a><p> The XML framework introduced in Qt 2.2 has been vastly improved. Qt
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2.2 already supported level 1 of the Document Object Model (DOM), a
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W3C standard for accessing and modifying XML documents. Qt 3.0 has
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added support for DOM Level 2 and XML namespaces.
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<p> The XML parser has been extended to allow incremental parsing of XML
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documents. This allows you to start parsing the document directly
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after the first parts of the data have arrived, and to continue
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whenever new data is available. This is especially useful if the XML
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document is read from a slow source, e.g. over the network, as it
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allows the application to start working on the data at a very early
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stage.
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<p> <h3> SVG support
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</h3>
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<a name="1-11"></a><p> SVG is a W3C standard for "Scalable Vector Graphics". Qt 3.0's XML
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support means that <a href="qpicture.html">QPicture</a> can optionally generate and import static
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SVG documents. All the SVG features that have an equivalent in
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<a href="qpainter.html">QPainter</a> are supported.
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<p> <h3> Multihead support
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</h3>
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<a name="1-12"></a><p> Many professional applications, such as DTP and CAD software, are able
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to display data on two or more monitors. In Qt 3.0 the <a href="qdesktopwidget.html">QDesktopWidget</a>
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class provides the application with runtime information about the
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number and geometry of the desktops on the different monitors and such
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allows applications to efficiently use a multi-monitor setup.
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<p> The virtual desktop of Mac OS X, Windows 98, and 2000 is supported, as well
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as the traditional multi-screen and the newer Xinerama multihead setups on
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X11.
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<p> <h3> X11 specific enhancements
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</h3>
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<a name="1-13"></a><p> Qt 3.0 now complies with the NET WM Specification, recently adopted
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by KDE 2.0. This allows easy integration and proper execution with
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desktop environments that support the NET WM specification.
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<p> The font handling on X11 has undergone major changes. <a href="qfont.html">QFont</a> no longer
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has a one-to-one relation with window system fonts. QFont is now a
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logical font that can load multiple window system fonts to simplify
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Unicode text display. This completely removes the burden of
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changing/setting fonts for a specific locale/language from the
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programmer. For end-users, any font can be used in any locale. For
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example, a user in Norway will be able to see Korean text without
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having to set their locale to Korean.
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<p> Qt 3.0 also supports the new render extension recently added to
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XFree86. This adds support for anti aliased text and pixmaps with
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alpha channel (semi transparency) on the systems that support the
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rendering extension (at the moment XFree 4.0.3 and later).
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<p> <h3> Printing
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</h3>
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<a name="1-14"></a><p> Printing support has been enhanced on all platforms. The <a href="qprinter.html">QPrinter</a>
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class now supports setting a virtual resolution for the painting
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process. This makes WYSIWYG printing trivial, and also allows you to
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take full advantage of the high resolution of a printer when painting
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on it.
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<p> The postscript driver built into Qt and used on Unix has been greatly
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enhanced. It supports the embedding of true/open type and type1 fonts
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into the document, and can correctly handle and display Unicode.
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Support for fonts built into the printer has been enhanced and Qt now
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knows about the most common printer fonts used for Asian languages.
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<p> <h3> <a href="qhttp.html">QHttp</a>
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</h3>
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<a name="1-15"></a><p> This class provides a simple interface for HTTP downloads and uploads.
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<p> <h3> Compatibility with the Standard Template Library (STL)
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</h3>
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<a name="1-16"></a><p> Support for the C++ Standard Template Library has been added to the
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<a href="qt-template-lib.html">Qt Template Library (QTL)</a>. The QTL
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classes now contain appropriate copy constructors and typedefs so that
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they can be freely mixed with other STL containers and algorithms. In
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addition, new member functions have been added to QTL template classes
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which correspond to STL-style naming conventions (e.g., push_back()).
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<p> <h2> Qt Designer
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</h2>
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<a name="2"></a><p> <a href="designer-manual.html">Qt Designer</a> was a pure dialog
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editor in Qt 2.2 but has now been extended to provide the full
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functionality of a GUI design tool.
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<p> This includes the ability to lay out main windows with menus and
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toolbars. Actions can be edited within Qt Designer and then plugged
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into toolbars and menu bars via drag and drop. Splitters can now be
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used in a way similar to layouts to group widgets horizontally or
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vertically.
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<p> In Qt 2.2, many of the dialogs created by Qt Designer had to be
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subclassed to implement functionality beyond the predefined signal and
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slot connections. Whilst the subclassing approach is still fully supported,
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Qt Designer now offers an alternative: a plugin for editing
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slots. The editor offers features such as syntax highlighting,
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completion, parentheses matching and incremental search.
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<p> The functionality of Qt Designer can now be extended via plugins.
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Using Qt Designer's interface or by implementing one of the provided
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interfaces in a plugin, a two way communication between plugin and Qt
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Designer can be established. This functionality is used to implement
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plugins for custom widgets, so that they can be used as real widgets
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inside the designer.
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<p> Basic support for project management has been added. This allows you
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to read and edit *.pro files, add and remove files to/from the project
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and do some global operations on the project. You can now open the
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project file and have one-click access to all the *.ui forms in the
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project.
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<p> In addition to generating code via uic, Qt Designer now supports the
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dynamic creation of widgets directly from XML user interface
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description files (*.ui files) at runtime. This eliminates the need of
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recompiling your application when the GUI changes, and could be used
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to enable your customers to do their own customizations. Technically,
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the feature is provided by a new class, <a href="qwidgetfactory.html">QWidgetFactory</a> in the
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QResource library.
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<p> <h2> Qt Linguist
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</h2>
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<a name="3"></a><p> <a href="linguist-manual.html">Qt Linguist</a> is a GUI utility to
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support translating the user-visible text in applications written with
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Qt. It comes with two command-line tools: lupdate and lrelease.
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<p> Translation of a Qt application is a three-step process:
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<p> <ul>
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<li> Run lupdate to extract user-visible text from the C++ source
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code of the Qt application, resulting in a translation source file
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(a *.ts file).
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<li> Provide translations for the source texts in the *.ts file using
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Qt Linguist.
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<li> Run lrelease to obtain a light-weight message file (a *.qm file)
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from the *.ts file, which provides very fast lookup for released
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applications.
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</ul>
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<p> Qt Linguist is a tool suitable for use by translators. Each
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user-visible (source) text is characterized by the text itself, a
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context (usually the name of the C++ class containing the text), and
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an optional comment to help the translator. The C++ class name will
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usually be the name of the relevant dialog, and the comment will often
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contain instructions that describe how to navigate to the relevant
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dialog.
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<p> You can create phrase books for Qt Linguist to provide common
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translations to help ensure consistency and to speed up the
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translation process. Whenever a translator navigates to a new text to
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translate, Qt Linguist uses an intelligent algorithm to provide a list
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of possible translations: the list is composed of relevant text from
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any open phrase books and also from identical or similar text that has
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already been translated.
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<p> Once a translation is complete it can be marked as "done"; such
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translations are included in the *.qm file. Text that has not been
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"done" is included in the *.qm file in its original form. Although Qt
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Linguist is a GUI application with dock windows and mouse control,
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toolbars, etc., it has a full set of keyboard shortcuts to make
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translation as fast and efficient as possible.
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<p> When the Qt application that you're developing evolves (e.g. from
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version 1.0 to version 1.1), the utility lupdate merges the source
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texts from the new version with the previous translation source file,
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reusing existing translations. In some typical cases, lupdate may
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suggest translations. These translations are marked as unfinished, so
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you can easily find and check them.
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<p> <h2> Qt Assistant
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</h2>
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<a name="4"></a><p> Thanks to the positive feedback we received about the <a href="helpsystem.html#help-system">help system</a>
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built into <a href="designer-manual.html">Qt Designer</a>, we decided
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to offer this part as a separate application called <a href="assistant.html">Qt Assistant</a>. Qt Assistant can be used to
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browse the Qt class documentation as well as the manuals for Qt
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Designer and Qt Linguist. It offers index searching, a contents
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overview, bookmarks history and incremental search. Qt Assistant is
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used by both Qt Designer and Qt Linguist for browsing their help
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documentation.
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<p> <h2> qmake
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</h2>
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<a name="5"></a><p> To ease portability we now provide the <a href="qmake-manual.html">qmake</a> utility to replace tmake. QMake is a C++ version of
|
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tmake which offers additional functionallity that is difficult to
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reproduce in tmake. Trolltech uses qmake in its build system for Qt
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and related products and we have released it as free software.
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<p>
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<!-- eof -->
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<p><address><hr><div align=center>
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<table width=100% cellspacing=0 border=0><tr>
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<td>Copyright © 2007
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<a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
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<td align=right><div align=right>Qt 3.3.8</div>
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</table></div></address></body>
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</html>
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