1 Qt 3.0 adds a wide range of major new features as well as substantial
2 improvements over the Qt 2.x series. Some internals have undergone
3 major redesign and new classes and methods have been added.
5 The Qt version 3.x series is not binary compatible with the 2.x
6 series. This means programs compiled with Qt version 2.x must be
7 recompiled to work with Qt 3.0.
9 In addition to the traditional Qt platforms Linux, Unix and the
10 various flavours of MS-Windows. Qt 3.0 for the first time introduces a
11 native port to MacOS X. Like all Qt versions, Qt/Mac is source
12 compatible with the other editions and follows closely the platform's
13 native look and feel guidelines.
15 We have tried to keep the API of Qt 3.0 as compatible as possible with
16 the Qt 2.x series. For most applications, only minor changes will be
17 needed to compile and run them successfully using Qt 3.0.
19 One of the major new features that has been added in the 3.0 release
20 is a module allowing you to easily work with databases. The API is
21 platform independent and database neutral. This module is seamlessly
22 integrated into Qt Designer, greatly simplifying the process of
23 building database applications and using data aware widgets.
25 Other major new features include a plugin architecture to extend Qt's
26 functionality, for styles, text encodings, image formats and database
27 drivers. The Unicode support of Qt 2.x has been greatly enhanced, it
28 now includes full support for scripts written from right to left
29 (e.g. Arabic and Hebrew) and also provides improved support for Asian
32 Many new classes have been added to the Qt Library. Amongst them are
33 classes that provide a docking architecture (QDockArea/QDockWindow), a
34 powerful rich text editor (QTextEdit), a class to store and access
35 application settings (QSettings) and a class to create and communicate
36 with processes (QProcess).
38 Apart from the changes in the library itself a lot has been done to
39 make the development of Qt applications with Qt 3.0 even easier than
40 before. Two new applications have been added: Qt Linguist is a tool to
41 help you translate your application into different languages; Qt
42 Assistant is an easy to use help browser for the Qt documentation that
43 supports bookmarks and can search by keyword.
45 Another change concerns the Qt build system, which has been reworked
46 to make it a lot easier to port Qt to new platforms. You can use this
47 platform independent build system - called qmake - for your own
50 And last but not least we hope you will enjoy the revisited and widely
51 extended documentation.
57 Qt/Embedded 3.0 provides the same features as Qt 3.0, but currently
58 lacks some of the memory optimizations and fine-tuning capabilities of
59 Qt/Embedded 2.3.x. We will add these in the upcoming maintainance
62 If you develop a new product based on Qt/Embedded, we recommend
63 switching to 3.0 because of the greatly improved functionality.
64 However, if you are planning a release within the next two months and
65 require memory optimizations not available with Qt/Embedded 3.0, we
66 suggest using Qt/Embedded 2.3.x.
70 ========================================
72 A large number of new features has been added to Qt 3.0. The following
73 list gives an overview of the most important new and changed aspects
80 One of the major new features in Qt 3.0 is the SQL module that
81 provides cross-platform access to SQL databases, making database
82 application programming with Qt seamless and portable. The API, built
83 with standard SQL, is database-neutral and software development is
84 independent of the underlying database.
86 A collection of tightly focused C++ classes are provided to give the
87 programmer direct access to SQL databases. Developers can send raw SQL
88 to the database server or have the Qt SQL classes generate SQL queries
89 automatically. Drivers for Oracle, PostgreSQL, MySQL and ODBC are
90 available and writing new drivers is straightforward.
92 Tying the results of SQL queries to GUI components is fully supported
93 by Qt's SQL widgets. These classes include a tabular data widget
94 (for spreadsheet-like data presentation with in-place editing), a
95 form-based data browser (which provides data navigation and edit
96 functions) and a form-based data viewer (which provides read-only
97 forms). This framework can be extended by using custom field editors,
98 allowing for example, a data table to use custom widgets for in-place
99 editing. The SQL module fully supports Qt's signals/slots mechanism,
100 making it easy for developers to include their own data validation and
103 Qt Designer fully supports Qt's SQL module. All SQL widgets can be
104 laid out within Qt Designer, and relationships can be established
105 between controls visually. Many interactions can be defined purely in
106 terms of Qt's signals/slots mechanism directly in Qt Designer.
109 Explicit linking and plugins
110 -------------------------
112 The QLibrary class provides a platform independent wrapper for runtime
113 loading of shared libraries.
115 Specialized classes that make it possible to extend Qt's functionality
116 with plugins: QStylePlugin for user interface styles, QTextCodecPlugin
117 for text encodings, QImageFormatPlugin for image formats and
118 QSqlDriverPlugin for database drivers.
120 It is possible to remove unused components from the Qt library, and
121 easy to extend any application with 3rd party styles, database drivers
124 Qt Designer supports custom widgets in plugins, and will use the
125 widgets both when designing and previewing forms (QWidgetPlugin).
128 Rich text engine and editor
129 ---------------------------
131 The rich text engine originally introduced in Qt 2.0 has been further
132 optimized and extended to support editing. It allows editing formatted
133 text with different fonts, colors, paragraph styles, tables and
134 images. The editor supports different word wrap modes, command-based
135 undo/redo, multiple selections, drag and drop, and many other
136 features. The engine is highly optimized for proccesing and displaying
137 large documents quickly and efficiently.
143 Apart from the rich text engine, another new feature of Qt 3.0 that
144 relates to text handling is the greatly improved Unicode support. Qt
145 3.0 includes an implementation of the bidirectional algorithm (BiDi)
146 as defined in the Unicode standard and a shaping engine for Arabic,
147 which gives full native language support to Arabic and Hebrew speaking
148 people. At the same time the support for Asian languages has been
151 The support is almost transparent for the developer using Qt to
152 develop their applications. This means that developers who developed
153 applications using Qt 2.x will automatically gain the full support for
154 these languages when switching to Qt 3.0. Developers can rely on their
155 application to work for people using writing systems different from
156 Latin1, without having to worry about the complexities involved with
157 these scripts, as Qt takes care of this automatically.
160 Docked and Floating Windows
161 ---------------------------
163 Qt 3.0 introduces the concept of dock windows and dock areas. Dock
164 windows are widgets, that can be attached to, and detached from, dock
165 areas. The most common kind of dock window is a tool bar. Any number of
166 dock windows may be placed in a dock area. A main window can have dock
167 areas, for example, QMainWindow provides four dock areas (top, left,
168 bottom, right) by default. The user can freely move dock windows and
169 place them at a convenient place in a dock area, or drag them out of
170 the application and have them float freely as top level windows in
171 their own right. Dock windows can also be minimized or hidden.
173 For developers, dock windows behave just like ordinary widgets. QToolbar
174 for example is now a specialized subclass of a dock window. The API
175 of QMainWindow and QToolBar is source compatible with Qt 2.x, so
176 existing code which uses these classes will continue to work.
182 Qt has always provided regular expression support, but that support
183 was pretty much limited to what was required in common GUI control
184 elements such as file dialogs. Qt 3.0 introduces a new regular
185 expression engine that supports most of Perl's regex features and is
186 Unicode based. The most useful additions are support for parentheses
187 (capturing and non-capturing) and backreferences.
190 Storing application settings
191 ----------------------------
193 Most programs will need to store some settings between runs, for
194 example, user selected fonts, colors and other preferences, or a list
195 of recently used files. The new QSettings class provides a platform
196 independent way to achieve this goal. The API makes it easy to store
197 and retrieve most of the basic data types used in Qt (such as basic
198 C++ types, strings, lists, colors, etc). The class uses the registry
199 on the Windows platform and traditional resource files on Unix.
202 Creating and controlling other processes
203 ----------------------------------------
205 QProcess is a class that allows you to start other programs from
206 within a Qt application in a platform independent manner. It gives you
207 full control over the started program. For example you can redirect
208 the input and output of console applications.
214 Accessibility means making software usable and accessible to a wide
215 range of users, including those with disabilities. In Qt 3.0, most
216 widgets provide accessibility information for assistive tools that can
217 be used by a wide range of disabled users. Qt standard widgets like
218 buttons or range controls are fully supported. Support for complex
219 widgets, like e.g. QListView, is in development. Existing applications
220 that make use of standard widgets will become accessible just by using
223 Qt uses the Active Accessibility infrastructure on Windows, and needs
224 the MSAA SDK, which is part of most platform SDKs. With improving
225 standardization of accessibility on other platforms, Qt will support
226 assistive technologies on other systems too.
232 The XML framework introduced in Qt 2.2 has been vastly improved. Qt
233 2.2 already supported level 1 of the Document Object Model (DOM), a
234 W3C standard for accessing and modifying XML documents. Qt 3.0 has
235 added support for DOM Level 2 and XML namespaces.
237 The XML parser has been extended to allow incremental parsing of XML
238 documents. This allows you to start parsing the document directly
239 after the first parts of the data have arrived, and to continue
240 whenever new data is available. This is especially useful if the XML
241 document is read from a slow source, e.g. over the network, as it
242 allows the application to start working on the data at a very early
249 SVG is a W3C standard for "Scalable Vector Graphics". Qt 3.0's SVG
250 support means that QPicture can optionally generate and import static
251 SVG documents. All the SVG features that have an equivalent in
252 QPainter are supported.
258 Many professional applications, such as DTP and CAD software, are able
259 to display data on two or more monitors. In Qt 3.0 the QDesktopWidget
260 class provides the application with runtime information about the
261 number and geometry of the desktops on the different monitors and such
262 allows applications to efficiently use a multi-monitor setup.
264 The virtual desktop of Windows 98 and 2000 is supported, as well as
265 the traditional multi-screen and the newer Xinerama multihead setups
269 X11 specific enhancements
270 -------------------------
272 Qt 3.0 now complies with the NET WM Specification, recently adopted
273 by KDE 2.0. This allows easy integration and proper execution with
274 desktop environments that support the NET WM specification.
276 The font handling on X11 has undergone major changes. QFont no longer
277 has a one-to-one relation with window system fonts. QFont is now a
278 logical font that can load multiple window system fonts to simplify
279 Unicode text display. This completely removes the burden of
280 changing/setting fonts for a specific locale/language from the
281 programmer. For end-users, any font can be used in any locale. For
282 example, a user in Norway will be able to see Korean text without
283 having to set their locale to Korean.
285 Qt 3.0 also supports the new render extension recently added to
286 XFree86. This adds support for anti-aliased text and pixmaps with
287 alpha channel (semi transparency) on the systems that support the
288 rendering extension (at the moment XFree 4.0.3 and later).
294 Printing support has been enhanced on all platforms. The QPrinter
295 class now supports setting a virtual resolution for the painting
296 process. This makes WYSIWYG printing trivial, and also allows you to
297 take full advantage of the high resolution of a printer when painting
300 The postscript driver built into Qt and used on Unix has been greatly
301 enhanced. It supports the embedding of true/open type and type1 fonts
302 into the document, and can correctly handle and display Unicode.
303 Support for fonts built into the printer has been enhanced and Qt now
304 knows about the most common printer fonts used for Asian languages.
310 A new class QHttp provides a simple interface for HTTP downloads and
314 Compatibility with the Standard Template Library (STL)
315 ------------------------------------------------------
317 Support for the C++ Standard Template Library has been added to the Qt
318 Template Library (QTL). The QTL classes now contain appropriate copy
319 constructors and typedefs so that they can be freely mixed with other
320 STL containers and algorithms. In addition, new member functions have
321 been added to QTL template classes which correspond to STL-style
322 naming conventions (e.g., push_back()).
326 ========================================
328 Qt Designer was a pure dialog editor in Qt 2.2 but has now been
329 extended to provide the full functionality of a GUI design tool.
331 This includes the ability to lay out main windows with menus and
332 toolbars. Actions can be edited within Qt Designer and then plugged
333 into toolbars and menu bars via drag and drop. Splitters can now be
334 used in a way similar to layouts to group widgets horizontally or
337 In Qt 2.2, many of the dialogs created by Qt Designer had to be
338 subclassed to implement functionality beyond the predefined signal and
339 slot connections. Whilst the subclassing approach is still fully
340 supported, Qt Designer now offers an alternative: a plugin for editing
341 code. The editor offers features such as syntax highlighting,
342 completion, parentheses matching and incremental search.
344 The functionality of Qt Designer can now be extended via plugins.
345 Using Qt Designer's interface or by implementing one of the provided
346 interfaces in a plugin, a two way communication between plugin and Qt
347 Designer can be established. This functionality is used to implement
348 plugins for custom widgets, so that they can be used as real widgets
351 Basic support for project management has been added. This allows you
352 to read and edit *.pro files, add and remove files to/from the project
353 and do some global operations on the project. You can now open the
354 project file and have one-click access to all the *.ui forms in the
357 In addition to generating code via uic, Qt Designer now supports the
358 dynamic creation of widgets directly from XML user interface
359 description files (*.ui files) at runtime. This eliminates the need of
360 recompiling your application when the GUI changes, and could be used
361 to enable your customers to do their own customizations. Technically,
362 the feature is provided by a new class, QWidgetFactory in the
367 ========================================
369 Qt Linguist is a GUI utility to support translating the user-visible
370 text in applications written with Qt. It comes with two command-line
371 tools: lupdate and lrelease.
373 Translation of a Qt application is a three-step process:
375 1) Run lupdate to extract user-visible text from the C++ source
376 code of the Qt application, resulting in a translation source file
378 2) Provide translations for the source texts in the *.ts file using
380 3) Run lrelease to obtain a light-weight message file (a *.qm file)
381 from the *.ts file, which provides very fast lookup for released
384 Qt Linguist is a tool suitable for use by translators. Each
385 user-visible (source) text is characterized by the text itself, a
386 context (usually the name of the C++ class containing the text), and
387 an optional comment to help the translator. The C++ class name will
388 usually be the name of the relevant dialog, and the comment will often
389 contain instructions that describe how to navigate to the relevant
392 You can create phrase books for Qt Linguist to provide common
393 translations to help ensure consistency and to speed up the
394 translation process. Whenever a translator navigates to a new text to
395 translate, Qt Linguist uses an intelligent algorithm to provide a list
396 of possible translations: the list is composed of relevant text from
397 any open phrase books and also from identical or similar text that has
398 already been translated.
400 Once a translation is complete it can be marked as "done"; such
401 translations are included in the *.qm file. Text that has not been
402 "done" is included in the *.qm file in its original form. Although Qt
403 Linguist is a GUI application with dock windows and mouse control,
404 toolbars, etc., it has a full set of keyboard shortcuts to make
405 translation as fast and efficient as possible.
407 When the Qt application that you're developing evolves (e.g. from
408 version 1.0 to version 1.1), the utility lupdate merges the source
409 texts from the new version with the previous translation source file,
410 reusing existing translations. In some typical cases, lupdate may
411 suggest translations. These translations are marked as unfinished, so
412 you can easily find and check them.
416 ========================================
418 Due to the positive feedback we received about the help system built
419 into Qt Designer, we decided to offer this part as a separate
420 application called Qt Assistant. Qt Assistant can be used to browse
421 the Qt class documentation as well as the manuals for Qt Designer and
422 Qt Linguist. It offers index searching, a contents overview, bookmarks
423 history and incremental search. Qt Assistant is used by both Qt
424 Designer and Qt Linguist for browsing their help documentation.
428 ========================================
430 qmake is a cross-platform make utility that makes it possible to build
431 the Qt library and Qt-based applications on various target platforms
432 from one single project description. It is the C++ successor of
433 'tmake' which required Perl.
435 qmake offers additional functionallity that is difficult to reproduce
436 in tmake. Qt uses qmake in its build system and we have released it as
444 Qt 3.0 went through 6 beta releases. These are the detailed changes
445 since Beta 6 only. For other changes, please see the changes notes
446 of the respective beta releases.
449 Qt 3.0 final is not binary compatible with Beta6; any programs linked
450 against Beta6 must be recompiled.
452 Below you will find a description of general changes in the Qt
453 Library, Qt Designer and Qt Assistant. Followed by a detailed list of
456 ****************************************************************************
458 ****************************************************************************
460 ****************************************************************************
462 ****************************************************************************
465 make sure we process deferred deletes before leaving the event
466 loop. This fixes some ocassions of memory leaks on exit.
467 win32: some improvements for modality and dockwindow handling
468 x11 only: read non-gui QSettings when running without GUI.
472 Make the checkboxes respect the AlignCenter flag. Also make
473 the boxes look better in case they are not placed in the first
477 if we have a currentItem and then we set the combobox to be
478 editable then set the text in the lineedit to be of the
482 QToolButton: spacing between a toolbutton's icon and its label.
483 QProgressBar: text color fixed.
486 added the What's This? cursor to the collection.
489 fixed broken context menus.
492 fixed addMonth() overflow.
495 win32 only: works now also for cases where the card handles
496 multiple monitors and GetSystemMetrics returns a single screen
500 fixed a memory leak in setNodeValue()
503 added count() as a Qt-style alias for length()
506 default to the middle of the pixmap as a hot spot, this looks
509 - QFileDialog (internal dialog)
510 make viewMode() return the correct value even after the dialog
511 is finished. Fixed getOpenFileName and getSaveFileName for
512 non-existant directories. Make sure that when it's in
513 directory mode that the filters reflect this, and change the
514 label from file name to directory.
515 win32 only: Improved modality when using the native file
519 x11 only: speed up fontloading with even more clever
520 caching. Make sure we can match scaled bitmap fonts by
521 default. Do not load a backup font for a script that is not
522 default. Make sure the pixel size is correct, even for fonts
523 that are unavailable. Try even harder to find a fontname that
524 is not understood. Some RENDER performance optimizations.
527 make sure the content is set up correctly when initializing
531 IRIX only: fixed reparent/resize bug, QGLContext::setContext()
532 is incredibly sensitive on different X servers.
535 fixed missing updates on height resp. width changes like the
536 occur when changing the application font.
539 fixed updates of non-auto-arranged views.
542 no gamma correction by default.
543 x11 only: some alignment issue with the alpha masked fixed.
546 fixed return value of QIODevice::readLine() for sequential
550 win32 only: generate Direction_R/L events for bidirectional
554 handle setPixmap( *pixmap() ) gracefully. Apply the WordBreak
555 alignment flag to both plaintext and richtext. Improved alignment of
556 richtext labels. Removed some sizepolicy magic, QLabel now
557 works fine with Preferred/Preferred in all modes.
560 fixed a crash when doing undo and a validator is set. Emit
561 textChanged() also if the text changed because of undo or redo.
564 fixed RMB context-menu offset.
567 do not start renaming an item is CTRL or SHIFT is
568 pressed. Start renaming on mouse release, not mouse press, so
569 click + click + move on the same item does not start a rename
573 show dock-menu also when clicking on the menubar.
576 win32 only: improved printing performance through printer font
578 boundingRect(): ignore 0-width in the constrain rectangle.
581 added overload for load() that takes a QIODevice.
583 - QPrintDialog (internal dialog)
584 fixed enabling of the first page and last page labels.
587 win32 only: make setColorMode() work, some unicode fixes. Make
588 collate the default. Enable the collate checkbox without
589 losing the page selection if you want to print multiple
590 pages. Make the collateCopies property work that it knows
591 checks/unchecks the collate checkbox in the printing
592 dialog. Make settings also work when the print dialog is not
596 added a new communication mode that duplicates stderr to
597 stdout (i.e. the equivalent of the shell's 2>&1).
606 Propagate WhiteSpaceMode to subitems with
607 WhiteSpaceModeNormal. Hide DisplayModeNone
608 items without additional newline. Fixed links inside non-left
609 aligned tables. Fixed some bidi layout problems. Fixed last
610 line layout in right-aligned paragraphs. For plain text,
611 always use the palette's text color.
617 win32 only: fixed a dead lock situation when writing
618 to LOCAL_MACHINE, but reading from CURRENT_USER.
621 fixed drawing of checkable menu items.
624 use the specified default font.
627 optimized drawing in the new style engine.
630 QString::replace() with a regular expression requires a
631 QRegExp object, passing a plain string will cause a compile
635 additional parameter 'whitespacemode' for
636 QStyleSheet::convertFromPlainText(). Support for superscript
637 ('sup') and subscript ( 'sub' ).
640 react properly on runtime font changes, less flicker.
643 take the pixmap of a header section into account when
647 use the embedded tabbar as focus proxy.
650 win32 only: possible crash with the thread dictionary fixed.
653 In Q{Int,Double}Validator, consider '-' as Invalid rather than
654 Intermediate if bottom() >= 0.
657 made showFullScreen() multihead aware.
658 win32 only: Better size and position restoring when switching
659 between fullscreen, maximized and minimized.
660 x11 only: improvements to XIM, overthespot works correctly
664 smarter placement of the minimize button when there is no
665 maximize button. Make titlebars of tool windows a bit smaller.
666 Improved styleability. Do not maximize a widget that has a
667 maximum size that is smaller than the workspace.
671 ****************************************************************************
673 ****************************************************************************
676 fixed generation of uncompilable code in conjunction with
677 Q_ENUMS and signal/slots.
680 allow keyboard switching of paragraph directionality.
683 install $QTDIR/doc/html/ instead of $QTDIR/doc/
684 install Qt Designer templates as well.
688 Solaris 8 with gcc 3.0.1.
689 AIX with xlC and aCC.
692 x11 only: do not reset the input context on focus changes.
695 smaller improvements, handle additional form signals.
698 make it possible to add new signals to a form without
699 subclassing. Minor fixes.
702 fixed Shift-LMB selection bug. Fixed new window and window
703 restoration on restart.
706 change fourth parameter of QApplication::translate() from bool
707 to enum type. This affects MOC (new revision) and lupdate (new
708 syntax to parse). Change Qt Linguist's XML file format (.ts)
709 to be consistent with QApplication:<defaultcodec> (rather than
710 <codec>) to match QApp::defaultCodec(); encoding="UTF-8"
711 (rather than utf8="true") to match QApp::translate(). Fixed
712 window decoration on restart. Use 'finished', 'unfinished' and
713 'unresolved' instead of the (!), (?) symbols on printouts.
716 merge "Add UIC" and "New Dialog". Better user interface and
717 general cleanup. Wwrite (and merge) qmake pro file with active
718 project. Load qmake pro files into Visual Studio.
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