qt-creator/doc/addressbook-sdk.qdoc

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/*!
    \page tutorials-addressbook-sdk.html

    \startpage {index.html}{Qt Reference Documentation}
    \nextpage \l{Designing the User Interface}{Chapter 1}

    \title Address Book Tutorial
    \ingroup howto
    \ingroup tutorials
    \brief An introduction to GUI programming with Qt and Qt Creator,
    describing in detail how to put together a simple yet fully-
    functioning application.

    This tutorial gives an introduction to GUI programming using the Qt SDK.

    ### Screenshot

    In the process, we will learn about some basic technologies provided by
    Qt, such as:

    \list
        \o  Widgets and layout managers
        \o  Container classes
        \o  Signals and slots
        \o  Input and output devices
    \endlist

    If you are completely new to Qt, please read \l{How to Learn Qt} if you
    have not already done so.

    The tutorial's source code is located in Qt's
    \c{examples/tutorials/addressbook} directory.

    Tutorial chapters:

    \list 1
        \o \l{examples/addressbook-sdk/part1}{Designing the User Interface}
        \o \l{examples/addressbook-sdk/part2}{Adding Addresses}
        \o \l{examples/addressbook-sdk/part3}{Navigating between Entries}
        \o \l{examples/addressbook-sdk/part4}{Editing and Removing Addresses}
        \o \l{examples/addressbook-sdk/part5}{Adding a Find Function}
        \o \l{examples/addressbook-sdk/part6}{Loading and Saving}
        \o \l{examples/addressbook-sdk/part7}{Additional Features}
    \endlist

    Although this little application does not look much like a fully-fledged
    modern GUI application, it uses many of the basic techniques that are used
    in more complex applications. After you have worked through it, we
    recommend checking out the \l{mainwindows/application}{Application}
    example, which presents a small GUI application, with menus, toolbars, a
    status bar, and so on.
*/


/*!
    \page tutorials-addressbook-sdk-part1.html
    \contentspage {Address Book Tutorial}{Contents}
    \nextpage \l{examples/addressbook-sdk/part2}{Chapter 2}
    \example examples/addressbook-sdk/part1
    \title Address Book 1 - Designing the User Interface

    The first part of this tutorial covers the design of the basic graphical
    user interface (GUI) we use for the Address Book application.

    The first step to creating a GUI program is to design the user interface.
    In this chapter, our goal is to set up the labels and input fields needed
    to implement a basic address book application. The figure below is a
    screenshot of our expected output.

    \image addressbook-tutorial-part1-screenshot.png

    We begin by launching Qt Creator and use it to generate a new project. To
    do this, select \gui New from the \gui File menu. In the
    \gui{New File or Project} dialog. Follow the step by step guide on how to
    create a \gui Project with Qt Creator, refer to the document
    \l{Creating a Project in Qt Creator}{here}. Ensure that you select QWidget
    as your subclass and name it \c AddressBook.

    There are five files generated in this \gui{Project}:

    \list
        \o  \c{addressbook.pro} - the project file,
        \o  \c{addressbook.h} - the definition file for the \c AddressBook
            class,
        \o  \c{addressbook.cpp} - the implementation file for the
            \c AddressBook class,
        \o  \c{main.cpp} - the file containing a \c main() function, with an
            instance of \c AddressBook, and
        \o  \c{addressbook.ui} - the user interface file created with \QD.
    \endlist

    Now we have all the files we need, let's move on to designing the user
    interface.

    \section1 Placing Widgets on the Form

    In the \gui{Project Sidebar}, double-click on the \c{addressbook.ui} file.
    The \QD plugin will be launched, allowing you to design your program's user
    interface.

    We require two \l{QLabel}s to label the input fields as well as a
    QLineEdit and a QTextEdit as the input fields. So, drag those widgets from
    the \gui{Widget Box} to your form. In the \gui{Property Editor}, set their
    \gui{objectName} property to \c nameLabel and \c addressLabel for the
    \l{QLabel}s, \c nameLine for the QLineEdit and finally, \c addressText for
    the QTextEdit.

    Next, we have to position the widgets properly, according to the screenshot
    earlier. We use a QGridLayout to position our labels and input fields in a
    structured manner. QGridLayout divides the available space into a grid and
    places widgets in the cells we specify with row and column numbers. The
    diagram below shows the layout cells and the position of our widgets.

    \image addressbook-tutorial-part1-labeled-screenshot.png

    Place your widgets accordingly and save the form by choosing
    \gui{File | Save} or using the \key{Ctrl+S} shortcut.


    \section1 The AddressBook Class

    The \l{examples/addressbook-sdk/part1/addressbook.h}{\c addressbook.h} file
    is used to define the \c AddressBook class.

    Let's take a look at what is already provided for us by Qt Creator. The
    \c AddressBook class has been defined as a QWidget subclass with a
    constructor and destructor.The Q_OBJECT macro is used to indicate that this
    class uses internationalization and Qt's signals and slots features.
    Although the macro implements some of the more advanced features of Qt, for
    now, it is useful to think of it as a shortcut that allows us to use the
    \l{QObject::}{tr()} and \l{QObject::}{connect()} functions.

    \snippet examples/addressbook-sdk/part1/addressbook.h class definition

    Qt Creator's \gui{Project Wizard} provides us with the \c Ui object as a
    way to access the widgets on our form.

    The \l{examples/addressbook-sdk/part1/addressbook.cpp}{\c addressbook.cpp}
    file is used to implement the \c AddressBook class. The constructor sets up
    the \c ui file; the destructor deletes it.

    \snippet examples/addressbook-sdk/part1/addressbook.cpp class implementation


    \section1 The \c{main()} Function

    The \l{examples/addressbook-sdk/part1/main.cpp}{\c main.cpp} file contains
    the \c{main()} function  It is generated by the \gui{Project Wizard}.
    Within this function, a QApplication object, \c a, is instantiated.
    QApplication is responsible for various application-wide resources, such as
    the default font and cursor, and for running an event loop. Hence, there is
    always one QApplication object in every GUI application using Qt.

    \snippet examples/addressbook-sdk/part1/main.cpp main function

    The code constructs a new \c AddressBook widget on the heap using the
    \c new keyword and invokes its \l{QWidget::}{show()} function to display
    it. However, the widget will not be shown until the application's event
    loop is started, by calling the application's \l{QApplication::}{exec()}
    function. Finally, the result returned by \l{QApplication::}{exec()} is
    used as the return value from the \c main() function.


    \section1 Qt Programming - Subclassing

    When writing Qt programs, we usually subclass Qt objects to add
    functionality. This is one of the essential concepts behind creating custom
    widgets or collections of standard widgets. Subclassing to extend or change
    the behavior of a widget has the following advantages:

    \list
        \o  We can write implementations of virtual or pure virtual functions
            to obtain exactly what we need, falling back on the base class's
            implementation when necessary.
        \o  It allows us to encapsulate parts of the user interface within a
            class, so that the other parts of the application do not need to
            know about the individual widgets in the user interface.
        \o  The subclass can be used to create multiple custom widgets in the
            same application or library, and the code for the subclass can be
            reused in other projects.
    \endlist

    Since Qt does not provided a specific address book widget, we subclass a
    standard Qt widget class and add features to it. The \c AddressBook class
    we create in this tutorial can be reused in situations where a basic
    address book is needed.

*/

/*!
    \page tutorials-addressbook-sdk-part2.html
    \previouspage Address Book 1 - Designing the User Interface
    \contentspage {Address Book Tutorial}{Contents}
    \nextpage \l{examples/addressbook-sdk/part3}{Chapter 3}
    \example examples/addressbook-sdk/part2
    \title Address Book 2 - Adding Addresses

    The next step to creating our basic address book application is to allow a
    little bit of user interaction.

    ### \image addressbook-tutorial-part2-add-contact.png

    We will provide a push button that the user can click to add a new contact.
    Also, some form of data structure is needed to store these contacts in an
    organized way.


    \section1 Placing Widgets on the Form

    Now that we have the labels and input fields set up, we add push buttons to
    complete the process of adding a contact.

*/