Qt 3.0 adds a wide range of major new features as well as substantialimprovements over the Qt 2.x series. Some internals have undergonemajor redesign and new classes and methods have been added.The Qt version 3.x series is not binary compatible with the 2.xseries. This means programs compiled with Qt version 2.x must berecompiled to work with Qt 3.0.In addition to the traditional Qt platforms Linux, Unix and thevarious flavours of MS-Windows. Qt 3.0 for the first time introduces anative port to MacOS X. Like all Qt versions, Qt/Mac is sourcecompatible with the other editions and follows closely the platform'snative look and feel guidelines.We have tried to keep the API of Qt 3.0 as compatible as possible withthe Qt 2.x series. For most applications, only minor changes will beneeded to compile and run them successfully using Qt 3.0.One of the major new features that has been added in the 3.0 releaseis a module allowing you to easily work with databases. The API isplatform independent and database neutral. This module is seamlesslyintegrated into Qt Designer, greatly simplifying the process ofbuilding database applications and using data aware widgets.Other major new features include a plugin architecture to extend Qt'sfunctionality, for styles, text encodings, image formats and databasedrivers. The Unicode support of Qt 2.x has been greatly enhanced, itnow includes full support for scripts written from right to left(e.g. Arabic and Hebrew) and also provides improved support for Asianlanguages.Many new classes have been added to the Qt Library. Amongst them areclasses that provide a docking architecture (QDockArea/QDockWindow), apowerful rich text editor (QTextEdit), a class to store and accessapplication settings (QSettings) and a class to create and communicatewith processes (QProcess).Apart from the changes in the library itself a lot has been done tomake the development of Qt applications with Qt 3.0 even easier thanbefore. Two new applications have been added: Qt Linguist is a tool tohelp you translate your application into different languages; QtAssistant is an easy to use help browser for the Qt documentation thatsupports bookmarks and can search by keyword.Another change concerns the Qt build system, which has been reworkedto make it a lot easier to port Qt to new platforms. You can use thisplatform independent build system - called qmake - for your ownapplications.And last but not least we hope you will enjoy the revisited and widelyextended documentation.Qt/Embedded----------Qt/Embedded 3.0 provides the same features as Qt 3.0, but currentlylacks some of the memory optimizations and fine-tuning capabilities ofQt/Embedded 2.3.x. We will add these in the upcoming maintainancereleases.If you develop a new product based on Qt/Embedded, we recommendswitching to 3.0 because of the greatly improved functionality.However, if you are planning a release within the next two months andrequire memory optimizations not available with Qt/Embedded 3.0, wesuggest using Qt/Embedded 2.3.x.The Qt Library========================================A large number of new features has been added to Qt 3.0. The followinglist gives an overview of the most important new and changed aspectsof the Qt library.Database support----------------One of the major new features in Qt 3.0 is the SQL module thatprovides cross-platform access to SQL databases, making databaseapplication programming with Qt seamless and portable. The API, builtwith standard SQL, is database-neutral and software development isindependent of the underlying database.A collection of tightly focused C++ classes are provided to give theprogrammer direct access to SQL databases. Developers can send raw SQLto the database server or have the Qt SQL classes generate SQL queriesautomatically. Drivers for Oracle, PostgreSQL, MySQL and ODBC areavailable and writing new drivers is straightforward.Tying the results of SQL queries to GUI components is fully supportedby Qt's SQL widgets. These classes include a tabular data widget(for spreadsheet-like data presentation with in-place editing), aform-based data browser (which provides data navigation and editfunctions) and a form-based data viewer (which provides read-onlyforms). This framework can be extended by using custom field editors,allowing for example, a data table to use custom widgets for in-placeediting. The SQL module fully supports Qt's signals/slots mechanism,making it easy for developers to include their own data validation andauditing code.Qt Designer fully supports Qt's SQL module. All SQL widgets can belaid out within Qt Designer, and relationships can be establishedbetween controls visually. Many interactions can be defined purely interms of Qt's signals/slots mechanism directly in Qt Designer.Explicit linking and plugins-------------------------The QLibrary class provides a platform independent wrapper for runtimeloading of shared libraries.Specialized classes that make it possible to extend Qt's functionalitywith plugins: QStylePlugin for user interface styles, QTextCodecPluginfor text encodings, QImageFormatPlugin for image formats andQSqlDriverPlugin for database drivers.It is possible to remove unused components from the Qt library, andeasy to extend any application with 3rd party styles, database driversor text codecs.Qt Designer supports custom widgets in plugins, and will use thewidgets both when designing and previewing forms (QWidgetPlugin).Rich text engine and editor---------------------------The rich text engine originally introduced in Qt 2.0 has been furtheroptimized and extended to support editing. It allows editing formattedtext with different fonts, colors, paragraph styles, tables andimages. The editor supports different word wrap modes, command-basedundo/redo, multiple selections, drag and drop, and many otherfeatures. The engine is highly optimized for proccesing and displayinglarge documents quickly and efficiently.Unicode-------Apart from the rich text engine, another new feature of Qt 3.0 thatrelates to text handling is the greatly improved Unicode support. Qt3.0 includes an implementation of the bidirectional algorithm (BiDi)as defined in the Unicode standard and a shaping engine for Arabic,which gives full native language support to Arabic and Hebrew speakingpeople. At the same time the support for Asian languages has beengreatly enhanced.The support is almost transparent for the developer using Qt todevelop their applications. This means that developers who developedapplications using Qt 2.x will automatically gain the full support forthese languages when switching to Qt 3.0. Developers can rely on theirapplication to work for people using writing systems different fromLatin1, without having to worry about the complexities involved withthese scripts, as Qt takes care of this automatically.Docked and Floating Windows---------------------------Qt 3.0 introduces the concept of dock windows and dock areas. Dockwindows are widgets, that can be attached to, and detached from, dockareas. The most common kind of dock window is a tool bar. Any number ofdock windows may be placed in a dock area. A main window can have dockareas, for example, QMainWindow provides four dock areas (top, left,bottom, right) by default. The user can freely move dock windows andplace them at a convenient place in a dock area, or drag them out ofthe application and have them float freely as top level windows intheir own right. Dock windows can also be minimized or hidden.For developers, dock windows behave just like ordinary widgets. QToolbarfor example is now a specialized subclass of a dock window. The APIof QMainWindow and QToolBar is source compatible with Qt 2.x, soexisting code which uses these classes will continue to work.Regular Expressions-------------------Qt has always provided regular expression support, but that supportwas pretty much limited to what was required in common GUI controlelements such as file dialogs. Qt 3.0 introduces a new regularexpression engine that supports most of Perl's regex features and isUnicode based. The most useful additions are support for parentheses(capturing and non-capturing) and backreferences.Storing application settings----------------------------Most programs will need to store some settings between runs, forexample, user selected fonts, colors and other preferences, or a listof recently used files. The new QSettings class provides a platformindependent way to achieve this goal. The API makes it easy to storeand retrieve most of the basic data types used in Qt (such as basicC++ types, strings, lists, colors, etc). The class uses the registryon the Windows platform and traditional resource files on Unix.Creating and controlling other processes----------------------------------------QProcess is a class that allows you to start other programs fromwithin a Qt application in a platform independent manner. It gives youfull control over the started program. For example you can redirectthe input and output of console applications.Accessibility---------------Accessibility means making software usable and accessible to a widerange of users, including those with disabilities. In Qt 3.0, mostwidgets provide accessibility information for assistive tools that canbe used by a wide range of disabled users. Qt standard widgets likebuttons or range controls are fully supported. Support for complexwidgets, like e.g. QListView, is in development. Existing applicationsthat make use of standard widgets will become accessible just by usingQt 3.0.Qt uses the Active Accessibility infrastructure on Windows, and needsthe MSAA SDK, which is part of most platform SDKs. With improvingstandardization of accessibility on other platforms, Qt will supportassistive technologies on other systems too.XML Improvements----------------The XML framework introduced in Qt 2.2 has been vastly improved. Qt2.2 already supported level 1 of the Document Object Model (DOM), aW3C standard for accessing and modifying XML documents. Qt 3.0 hasadded support for DOM Level 2 and XML namespaces.The XML parser has been extended to allow incremental parsing of XMLdocuments. This allows you to start parsing the document directlyafter the first parts of the data have arrived, and to continuewhenever new data is available. This is especially useful if the XMLdocument is read from a slow source, e.g. over the network, as itallows the application to start working on the data at a very earlystage.SVG support-----------SVG is a W3C standard for "Scalable Vector Graphics". Qt 3.0's SVGsupport means that QPicture can optionally generate and import staticSVG documents. All the SVG features that have an equivalent inQPainter are supported.Multihead support-----------------Many professional applications, such as DTP and CAD software, are ableto display data on two or more monitors. In Qt 3.0 the QDesktopWidgetclass provides the application with runtime information about thenumber and geometry of the desktops on the different monitors and suchallows applications to efficiently use a multi-monitor setup.The virtual desktop of Windows 98 and 2000 is supported, as well asthe traditional multi-screen and the newer Xinerama multihead setupson X11.X11 specific enhancements-------------------------Qt 3.0 now complies with the NET WM Specification, recently adoptedby KDE 2.0. This allows easy integration and proper execution withdesktop environments that support the NET WM specification.The font handling on X11 has undergone major changes. QFont no longerhas a one-to-one relation with window system fonts. QFont is now alogical font that can load multiple window system fonts to simplifyUnicode text display. This completely removes the burden ofchanging/setting fonts for a specific locale/language from theprogrammer. For end-users, any font can be used in any locale. Forexample, a user in Norway will be able to see Korean text withouthaving to set their locale to Korean.Qt 3.0 also supports the new render extension recently added toXFree86. This adds support for anti-aliased text and pixmaps withalpha channel (semi transparency) on the systems that support therendering extension (at the moment XFree 4.0.3 and later).Printing--------Printing support has been enhanced on all platforms. The QPrinterclass now supports setting a virtual resolution for the paintingprocess. This makes WYSIWYG printing trivial, and also allows you totake full advantage of the high resolution of a printer when paintingon it.The postscript driver built into Qt and used on Unix has been greatlyenhanced. It supports the embedding of true/open type and type1 fontsinto the document, and can correctly handle and display Unicode.Support for fonts built into the printer has been enhanced and Qt nowknows about the most common printer fonts used for Asian languages.Networking-----------A new class QHttp provides a simple interface for HTTP downloads anduploads.Compatibility with the Standard Template Library (STL)------------------------------------------------------Support for the C++ Standard Template Library has been added to the QtTemplate Library (QTL). The QTL classes now contain appropriate copyconstructors and typedefs so that they can be freely mixed with otherSTL containers and algorithms. In addition, new member functions havebeen added to QTL template classes which correspond to STL-stylenaming conventions (e.g., push_back()).Qt Designer========================================Qt Designer was a pure dialog editor in Qt 2.2 but has now beenextended to provide the full functionality of a GUI design tool.This includes the ability to lay out main windows with menus andtoolbars. Actions can be edited within Qt Designer and then pluggedinto toolbars and menu bars via drag and drop. Splitters can now beused in a way similar to layouts to group widgets horizontally orvertically.In Qt 2.2, many of the dialogs created by Qt Designer had to besubclassed to implement functionality beyond the predefined signal andslot connections. Whilst the subclassing approach is still fullysupported, Qt Designer now offers an alternative: a plugin for editingcode. The editor offers features such as syntax highlighting,completion, parentheses matching and incremental search.The functionality of Qt Designer can now be extended via plugins.Using Qt Designer's interface or by implementing one of the providedinterfaces in a plugin, a two way communication between plugin and QtDesigner can be established. This functionality is used to implementplugins for custom widgets, so that they can be used as real widgetsinside the designer.Basic support for project management has been added. This allows youto read and edit *.pro files, add and remove files to/from the projectand do some global operations on the project. You can now open theproject file and have one-click access to all the *.ui forms in theproject.In addition to generating code via uic, Qt Designer now supports thedynamic creation of widgets directly from XML user interfacedescription files (*.ui files) at runtime. This eliminates the need ofrecompiling your application when the GUI changes, and could be usedto enable your customers to do their own customizations. Technically,the feature is provided by a new class, QWidgetFactory in theUI-library.Qt Linguist========================================Qt Linguist is a GUI utility to support translating the user-visibletext in applications written with Qt. It comes with two command-linetools: lupdate and lrelease.Translation of a Qt application is a three-step process: 1) Run lupdate to extract user-visible text from the C++ source code of the Qt application, resulting in a translation source file (a *.ts file). 2) Provide translations for the source texts in the *.ts file using Qt Linguist. 3) Run lrelease to obtain a light-weight message file (a *.qm file) from the *.ts file, which provides very fast lookup for released applications.Qt Linguist is a tool suitable for use by translators. Eachuser-visible (source) text is characterized by the text itself, acontext (usually the name of the C++ class containing the text), andan optional comment to help the translator. The C++ class name willusually be the name of the relevant dialog, and the comment will oftencontain instructions that describe how to navigate to the relevantdialog.You can create phrase books for Qt Linguist to provide commontranslations to help ensure consistency and to speed up thetranslation process. Whenever a translator navigates to a new text totranslate, Qt Linguist uses an intelligent algorithm to provide a listof possible translations: the list is composed of relevant text fromany open phrase books and also from identical or similar text that hasalready been translated.Once a translation is complete it can be marked as "done"; suchtranslations are included in the *.qm file. Text that has not been"done" is included in the *.qm file in its original form. Although QtLinguist is a GUI application with dock windows and mouse control,toolbars, etc., it has a full set of keyboard shortcuts to maketranslation as fast and efficient as possible.When the Qt application that you're developing evolves (e.g. fromversion 1.0 to version 1.1), the utility lupdate merges the sourcetexts from the new version with the previous translation source file,reusing existing translations. In some typical cases, lupdate maysuggest translations. These translations are marked as unfinished, soyou can easily find and check them.Qt Assistant========================================Due to the positive feedback we received about the help system builtinto Qt Designer, we decided to offer this part as a separateapplication called Qt Assistant. Qt Assistant can be used to browsethe Qt class documentation as well as the manuals for Qt Designer andQt Linguist. It offers index searching, a contents overview, bookmarkshistory and incremental search. Qt Assistant is used by both QtDesigner and Qt Linguist for browsing their help documentation.qmake========================================qmake is a cross-platform make utility that makes it possible to buildthe Qt library and Qt-based applications on various target platformsfrom one single project description. It is the C++ successor of'tmake' which required Perl.qmake offers additional functionallity that is difficult to reproducein tmake. Qt uses qmake in its build system and we have released it asfree software.Detailed changes=============Qt 3.0 went through 6 beta releases. These are the detailed changessince Beta 6 only. For other changes, please see the changes notesof the respective beta releases.Qt 3.0 final is not binary compatible with Beta6; any programs linkedagainst Beta6 must be recompiled.Below you will find a description of general changes in the QtLibrary, Qt Designer and Qt Assistant. Followed by a detailed list ofchanges in the API.***************************************************************************** General ********************************************************************************************************************************************************** Library *****************************************************************************- QApplication make sure we process deferred deletes before leaving the event loop. This fixes some ocassions of memory leaks on exit. win32: some improvements for modality and dockwindow handling x11 only: read non-gui QSettings when running without GUI.- QCheckListItem Make the checkboxes respect the AlignCenter flag. Also make the boxes look better in case they are not placed in the first column.- QComboBox if we have a currentItem and then we set the combobox to be editable then set the text in the lineedit to be of the current item.- QCommonStyle QToolButton: spacing between a toolbutton's icon and its label. QProgressBar: text color fixed.- QCursor added the What's This? cursor to the collection.- QDataTable fixed broken context menus.- QDate fixed addMonth() overflow.- QDesktopWidget win32 only: works now also for cases where the card handles multiple monitors and GetSystemMetrics returns a single screen only.- QDomAttr fixed a memory leak in setNodeValue()- QDomNodeMap added count() as a Qt-style alias for length()- QDragObject default to the middle of the pixmap as a hot spot, this looks nicer.- QFileDialog (internal dialog) make viewMode() return the correct value even after the dialog is finished. Fixed getOpenFileName and getSaveFileName for non-existant directories. Make sure that when it's in directory mode that the filters reflect this, and change the label from file name to directory. win32 only: Improved modality when using the native file dialog.- QFont x11 only: speed up fontloading with even more clever caching. Make sure we can match scaled bitmap fonts by default. Do not load a backup font for a script that is not default. Make sure the pixel size is correct, even for fonts that are unavailable. Try even harder to find a fontname that is not understood. Some RENDER performance optimizations.- QFontDialog make sure the content is set up correctly when initializing the dialog.- QGLWidget IRIX only: fixed reparent/resize bug, QGLContext::setContext() is incredibly sensitive on different X servers.- QHeader fixed missing updates on height resp. width changes like the occur when changing the application font.- QIconView fixed updates of non-auto-arranged views.- QImage no gamma correction by default. x11 only: some alignment issue with the alpha masked fixed.- QIODevice fixed return value of QIODevice::readLine() for sequential access.- QKeyEvent win32 only: generate Direction_R/L events for bidirectional input.- QLabel handle setPixmap( *pixmap() ) gracefully. Apply the WordBreak alignment flag to both plaintext and richtext. Improved alignment of richtext labels. Removed some sizepolicy magic, QLabel now works fine with Preferred/Preferred in all modes.- QLineEdit fixed a crash when doing undo and a validator is set. Emit textChanged() also if the text changed because of undo or redo.- QListBox fixed RMB context-menu offset.- QListView do not start renaming an item is CTRL or SHIFT is pressed. Start renaming on mouse release, not mouse press, so click + click + move on the same item does not start a rename operation.- QMainWindow show dock-menu also when clicking on the menubar.- QPainter win32 only: improved printing performance through printer font caching. boundingRect(): ignore 0-width in the constrain rectangle.- QPicture added overload for load() that takes a QIODevice.- QPrintDialog (internal dialog) fixed enabling of the first page and last page labels.- QPrinter win32 only: make setColorMode() work, some unicode fixes. Make collate the default. Enable the collate checkbox without losing the page selection if you want to print multiple pages. Make the collateCopies property work that it knows checks/unchecks the collate checkbox in the printing dialog. Make settings also work when the print dialog is not shown at all.- QProcess added a new communication mode that duplicates stderr to stdout (i.e. the equivalent of the shell's 2>&1).- QPSPrinter (unix) fixed collate.- QRangeControl simplified code.- QRichText Propagate WhiteSpaceMode to subitems with WhiteSpaceModeNormal. Hide DisplayModeNone items without additional newline. Fixed links inside non-left aligned tables. Fixed some bidi layout problems. Fixed last line layout in right-aligned paragraphs. For plain text, always use the palette's text color.- QScrollView safer destruction.- QSettings win32 only: fixed a dead lock situation when writing to LOCAL_MACHINE, but reading from CURRENT_USER.- QSGIStyle fixed drawing of checkable menu items.- QSimpleRichText use the specified default font.- QSlider optimized drawing in the new style engine.- QString QString::replace() with a regular expression requires a QRegExp object, passing a plain string will cause a compile error.- QStyleSheet additional parameter 'whitespacemode' for QStyleSheet::convertFromPlainText(). Support for superscript ('sup') and subscript ( 'sub' ).- QTabBar react properly on runtime font changes, less flicker.- QTable take the pixmap of a header section into account when adjusting the size.- QTabWidget use the embedded tabbar as focus proxy.- QThread win32 only: possible crash with the thread dictionary fixed.- QValidator In Q{Int,Double}Validator, consider '-' as Invalid rather than Intermediate if bottom() >= 0.- QWidget made showFullScreen() multihead aware. win32 only: Better size and position restoring when switching between fullscreen, maximized and minimized. x11 only: improvements to XIM, overthespot works correctly now.- QWorkspace smarter placement of the minimize button when there is no maximize button. Make titlebars of tool windows a bit smaller. Improved styleability. Do not maximize a widget that has a maximum size that is smaller than the workspace.***************************************************************************** Other *****************************************************************************- moc fixed generation of uncompilable code in conjunction with Q_ENUMS and signal/slots.- unicode allow keyboard switching of paragraph directionality.- installation install $QTDIR/doc/html/ instead of $QTDIR/doc/ install Qt Designer templates as well.- improved build on HP-UX with cc. Solaris 8 with gcc 3.0.1. AIX with xlC and aCC.- inputmethods x11 only: do not reset the input context on focus changes.- uic smaller improvements, handle additional form signals.- Qt Designer make it possible to add new signals to a form without subclassing. Minor fixes.- Qt Assistant fixed Shift-LMB selection bug. Fixed new window and window restoration on restart.- Qt Linguist change fourth parameter of QApplication::translate() from bool to enum type. This affects MOC (new revision) and lupdate (new syntax to parse). Change Qt Linguist's XML file format (.ts) to be consistent with QApplication:<defaultcodec> (rather than <codec>) to match QApp::defaultCodec(); encoding="UTF-8" (rather than utf8="true") to match QApp::translate(). Fixed window decoration on restart. Use 'finished', 'unfinished' and 'unresolved' instead of the (!), (?) symbols on printouts.- QMsDev merge "Add UIC" and "New Dialog". Better user interface and general cleanup. Wwrite (and merge) qmake pro file with active project. Load qmake pro files into Visual Studio.