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diff --git a/doc/src/porting/porting4-designer.qdoc b/doc/src/porting/porting4-designer.qdoc new file mode 100644 index 0000000..d356392 --- /dev/null +++ b/doc/src/porting/porting4-designer.qdoc @@ -0,0 +1,349 @@ +/**************************************************************************** +** +** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies). +** Contact: Nokia Corporation (qt-info@nokia.com) +** +** This file is part of the documentation of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** No Commercial Usage +** This file contains pre-release code and may not be distributed. +** You may use this file in accordance with the terms and conditions +** contained in the either Technology Preview License Agreement or the +** Beta Release License Agreement. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 2.1 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 2.1 requirements +** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html. +** +** In addition, as a special exception, Nokia gives you certain +** additional rights. These rights are described in the Nokia Qt LGPL +** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this +** package. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 3.0 as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL included in the +** packaging of this file. Please review the following information to +** ensure the GNU General Public License version 3.0 requirements will be +** met: http://www.gnu.org/copyleft/gpl.html. +** +** If you are unsure which license is appropriate for your use, please +** contact the sales department at http://qt.nokia.com/contact. +** $QT_END_LICENSE$ +** +****************************************************************************/ + +/*! + \page porting4-designer.html + \title Porting UI Files to Qt 4 + \contentspage {Porting Guides}{Contents} + \previouspage Porting to Qt 4 - Drag and Drop + \nextpage Porting to Graphics View + \ingroup porting + \brief Information about changes to the UI file format in Qt 4. + + Qt Designer has changed significantly in the Qt 4 release. We + have moved away from viewing Qt Designer as an IDE and + concentrated on creating a robust form builder which can be + extended and embedded in existing IDEs. Our efforts are ongoing + and include the \l{Visual Studio Integration}, + as well as integrating Designer with KDevelop and possibly other + IDEs. + + The most important changes in Qt Designer 4 which affect porting + for UI files are summarized below: + + \list + \o \bold{Removed project manager.} + Qt Designer now only reads and edits UI + files. It has no notion of a project file (\c .pro). + + \o \bold{Removed code editor.} + Qt Designer can no longer be used to edit source files. + + \o \bold{Changed format of UI files.} + Qt Designer 4 cannot read files created by Qt Designer 3 and + vice versa. However, we provide the tool \c uic3 to generate Qt + 4 code out of Qt 3 UI files, and to convert old UI files + into a format readable by Qt Designer 4. + + \o \bold{Changed structure of the code generated by \c uic.} + The \c myform.ui file containing the form \c MyForm is now + converted into a single header file \c ui_myform.h, which + contains the declaration and inline definition of a POD class + \c Ui::MyForm. + + \o \bold{New resource file system.} Icon data is no longer + stored in the UI file. Instead, icons are put into resource + files (\c .qrc). + \endlist + + The rest of this document explains how to deal with the main + differences between Qt Designer 3 and Qt Designer 4: + + \tableofcontents + + See \l{Porting to Qt 4} and \l{qt3to4 - The Qt 3 to 4 Porting + Tool} for more information about porting from Qt 3 to Qt 4. See + also the \l{Qt Designer Manual}. + + \section1 uic Output + + In Qt 3, \c uic generated a header file and an implementation for + a class, which inherited from one of Qt's widgets. To use the + form, the programmer included the generated sources into the + application and created an instance of the class. + + In Qt 4, \c uic creates a header file containing a POD class. The + name of this class is the object name of the main container, + qualified with the \c Ui namespace (e.g., \c Ui::MyForm). The + class is implemented using inline functions, removing the need of + a separate \c .cpp file. Just as in Qt 3, this class contains + pointers to all the widgets inside the form as public members. In + addition, the generated class provides the public method \c + setupUi(). + + The class generated by \c uic is not a QWidget; in fact, it's not + even a QObject. Instead, it is a class which knows how to + populate an instance of a main container with the contents of the + form. The programmer creates the main container himself, then + passes it to \c setupUi(). + + For example, here's the \c uic output for a simple \c + helloworld.ui form (some details were removed for simplicity): + + \snippet doc/src/snippets/code/doc_src_porting4-designer.qdoc 0 + + In this case, the main container was specified to be a QWidget + (or any subclass of QWidget). Had we started with a QMainWindow + template in Qt Designer, \c setupUi()'s parameter would be of + type QMainWindow. + + There are two ways to create an instance of our form. One + approach is to create an instance of the \c Ui::HelloWorld class, + an instance of the main container (a plain QWidget), and call \c + setupUi(): + + \snippet doc/src/snippets/code/doc_src_porting4-designer.qdoc 1 + + The second approach is to inherit from both the \c Ui::HelloWorld + class and the main container, and to call \c setupUi() in the + constructor of the subclass. In that case, QWidget (or one of + its subclasses, e.g. QDialog) must appear first in the base class + list so that \l{moc} picks it up correctly. For example: + + \snippet doc/src/snippets/code/doc_src_porting4-designer.qdoc 2 + + This second method is useful when porting Qt 3 forms to Qt 4. \c + HelloWorldWidget is a class whose instance is the actual form + and which contains public pointers to all the widgets in it. It + therefore has an interface identical to that of a class generated + by \c uic in Qt 3. + + Creating POD classes from UI files is more flexible and + generic than the old approach of creating widgets. Qt Designer + does not need to know anything about the main container apart from + the base widget class it inherits. Indeed, \c Ui::HelloWorld can + be used to populate any container that inherits QWidget. + Conversely, all non-GUI aspects of the main container may be + implemented by the programmer in the application's sources + without reference to the form. + + \section1 Working with uic3 + + Qt 4 comes with the tool \c uic3 for working with old \c .ui + files. It can be used in two ways: + + \list 1 + \o To generate headers and source code for a widget to implement any + custom signals and slots added using Qt Designer 3. + \o To generate a new UI file that can be used with Qt Designer 4. + \endlist + + You can use both these methods in combination to obtain UI, header + and source files that you can use as a starting point when porting + your user interface to Qt 4. + + The first method generates a Qt 3 style header and implementation + which uses Qt 4 widgets (this includes the Qt 3 compatibility classes + present in the Qt3Support library). This process should be familiar to + anyone used to working with Qt Designer 3: + + \snippet doc/src/snippets/code/doc_src_porting4-designer.qdoc 3 + + The resulting files \c myform.h and \c myform.cpp implement the + form in Qt 4 using a QWidget that will include custom signals, + slots and connections specified in the UI file. However, + see below for the \l{#Limitations of uic3}{limitations} of this + method. + + The second method is to use \c uic3 to convert a Qt Designer 3 \c .ui + file to the Qt Designer 4 format: + + \snippet doc/src/snippets/code/doc_src_porting4-designer.qdoc 4 + + The resulting file \c myform4.ui can be edited in Qt Designer 4. The + header file for the form is generated by Qt 4's \c uic. See the + \l{Using a Designer UI File in Your Application} chapter of the + \l{Qt Designer Manual} for information about the preferred ways to + use forms created with Qt Designer 4. + + \c uic3 tries very hard to map Qt 3 classes and their properties to + Qt 4. However, the behavior of some classes changed significantly + in Qt 4. To keep the form working, some Qt 3 classes are mapped + to classes in the Qt3Support library. Table 1 shows a list of + classes this applies to. + + \table + \header \o Qt 3 class \o Qt 4 class + \row \o \c QButtonGroup \o Q3ButtonGroup + \row \o \c QDateEdit \o Q3DateEdit + \row \o \c QDateTimeEdit \o Q3DateTimeEdit + \row \o \c QGroupBox \o Q3GroupBox + \row \o \c QListBox \o Q3ListBox + \row \o \c QListView \o Q3ListView + \row \o \c QMainWindow \o Q3MainWindow + \row \o \c QTextEdit \o Q3TextEdit + \row \o \c QTextView \o Q3TextView + \row \o \c QTimeEdit \o Q3TimeEdit + \row \o \c QWidgetStack \o Q3WidgetStack + \row \o \c QWizard \o Q3Wizard + \endtable + + \section1 Limitations of uic3 + + Converting Qt 3 UI files to Qt 4 has some limitations. The + most noticeable limitation is the fact that since \c uic no + longer generates a QObject, it's not possible to define custom + signals or slots for the form. Instead, the programmer must + define these signals and slots in the main container and connect + them to the widgets in the form after calling \c setupUi(). For + example: + + \snippet doc/src/snippets/code/doc_src_porting4-designer.qdoc 5 + + A quick and dirty way to port forms containing custom signals and + slots is to generate the code using \c uic3, rather than \c uic. Since + \c uic3 does generate a QWidget, it will populate it with custom + signals, slots and connections specified in the UI file. + However, \c uic3 can only generate code from Qt 3 UI files, which + implies that the UI files never get translated and need to be + edited using Qt Designer 3. + + Note also that it is possible to create implicit connections + between the widgets in a form and the main container. After \c + setupUi() populates the main container with child widgets it + scans the main container's list of slots for names with the form + \tt{on_\e{objectName}_\e{signalName}().} + + If the form contains a widget whose object name is + \tt{\e{objectName}}, and if that widget has a signal called + \tt{\e{signalName}}, then this signal will be connected to the + main container's slot. For example: + + \snippet doc/src/snippets/code/doc_src_porting4-designer.qdoc 6 + + Because of the naming convention, \c setupUi() automatically + connects \c pushButton's \c clicked() signal to \c + HelloWorldWidget's \c on_pushButton_clicked() slot. + + \section1 Icons + + In Qt 3, the binary data for the icons used by a form was stored + in the UI file. In Qt 4 icons and any other external files + can be compiled into the application by listing them in a \l{The + Qt Resource System}{resource file} (\c .qrc). This file is + translated into a C++ source file using Qt's resource compiler + (\c rcc). The data in the files is then available to any Qt class + which takes a file name argument. + + Imagine that we have two icons, \c yes.png and \c no.png. We + create a resource file called \c icons.qrc with the following + contents: + + \snippet doc/src/snippets/code/doc_src_porting4-designer.qdoc 7 + + Next, we add the resource file to our \c .pro file: + + \snippet doc/src/snippets/code/doc_src_porting4-designer.qdoc 8 + + When \c qmake is run, it will create the appropriate Makefile + rules to call \c rcc on the resource file, and compile and link + the result into the application. The icons may be accessed as + follows: + + \snippet doc/src/snippets/code/doc_src_porting4-designer.qdoc 9 + + In each case, the leading colon tells Qt to look for the file in + the virtual file tree defined by the set of resource files + compiled into the application instead of the file system. + + In the \c .qrc file, the \c qresource tag's \c prefix attribute + is used to arrange the files into categories and set a virtual + path where the files will be accessed. + + Caveat: If the resource file was not linked directly into the + application, but instead into a dynamic or static library that + was later linked with the application, its virtual file tree will + not be available to QFile and friends until the Q_INIT_RESOURCE() + macro is called. This macro takes one argument, which is the name + of the \c .qrc file, without the path or the file extension. A + convenient place to initialize resources is at the top of the + application's \c main() function. + + In Qt Designer 4, we can associate any number of resource files + with a form using the resource editor tool. The widgets in the + form can access all icons specified in its associated resource + files. + + In short, porting of icons from a Qt 3 to a Qt 4 form involves + the following steps: + + \list 1 + \o Use \c{uic3 -convert} to obtain a UI file understood by + Qt Designer 4. + + \o Create a \c .qrc file with a list of all the icon files. + + \o Add the resource file to the \c .pro file. + + \o Open the form in Qt Designer 4 and add the resource file to the + form's resource editor. + + \o Set the icon properties for the appropriate widgets. + \endlist + + \section1 Custom Widgets + + Qt Designer 3 supported defining custom widgets by specifying + their name, header file and methods. In Qt Designer 4, a custom + widget is always created by "promoting" an existing Qt widget to + a custom class. Qt Designer 4 assumes that the custom widget will + inherit from the widget that has been promoted. In the form + editor, the custom widget will retain the looks, behavior, + properties, signals and slots of the base widget. It is not + currently possible to tell Qt Designer 4 that the custom widget + will have additional signals or slots. + + \c{uic3 -convert} handles the conversion of custom widgets to the + new \c .ui format, however all custom signals and slots are lost. + Furthermore, since Qt Designer 3 never knew the base widget class + of a custom widget, it is taken to be QWidget. This is often + sufficient. If not, the custom widgets have to be inserted + manually into the form. + + Custom widget plugins, which contain custom widgets to be used in + Qt Designer, must themselves be ported before they can be used in + forms ported with \c{uic3}. + The \l{Porting to Qt 4} document contains information about general + porting issues that may apply to the custom widget code itself, and + the \l{Creating Custom Widgets for Qt Designer} chapter of the + \l{Qt Designer Manual} describes how the ported widget should be + built in order to work in Qt Designer 4. +*/ |