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+****************************************************************************/
+/*!
+\page tutorials-addressbook.html
+\startpage {index.html}{Qt Reference Documentation}
+\contentspage Tutorials
+\nextpage {tutorials/addressbook/part1}{Chapter 1}
+\title Address Book Tutorial
+\brief An introduction to GUI programming, showing how to put together a
+simple yet fully-functioning application.
+This tutorial gives an introduction to GUI programming using the Qt
+cross-platform framework.
+\image addressbook-tutorial-screenshot.png
+\omit
+It doesn't cover everything; the emphasis is on teaching the programming
+philosophy of GUI programming, and Qt's features are introduced as needed.
+Some commonly used features are never used in this tutorial.
+\endomit
+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{tutorials/addressbook/part1}{Designing the User Interface}
+\o \l{tutorials/addressbook/part2}{Adding Addresses}
+\o \l{tutorials/addressbook/part3}{Navigating between Entries}
+\o \l{tutorials/addressbook/part4}{Editing and Removing Addresses}
+\o \l{tutorials/addressbook/part5}{Adding a Find Function}
+\o \l{tutorials/addressbook/part6}{Loading and Saving}
+\o \l{tutorials/addressbook/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-part1.html
+\contentspage {Address Book Tutorial}{Contents}
+\nextpage {tutorials/addressbook/part2}{Chapter 2}
+\example tutorials/addressbook/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 require two QLabel objects, \c nameLabel and \c addressLabel, as well
+as two input fields, a QLineEdit object, \c nameLine, and a QTextEdit
+object, \c addressText, to enable the user to enter a contact's name and
+address. The widgets used and their positions are shown in the figure
+below.
+\image addressbook-tutorial-part1-labeled-screenshot.png
+There are three files used to implement this address book:
+\list
+\o \c{addressbook.h} - the definition file for the \c AddressBook
+class,
+\o \c{addressbook.cpp} - the implementation file for the
+\c AddressBook class, and
+\o \c{main.cpp} - the file containing a \c main() function, with
+an instance of \c AddressBook.
+\endlist
+\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 don't 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 provide 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 widget is needed.
+\section1 Defining the AddressBook Class
+The \l{tutorials/addressbook/part1/addressbook.h}{\c addressbook.h} file is
+used to define the \c AddressBook class.
+We start by defining \c AddressBook as a QWidget subclass and declaring
+a constructor. We also use the Q_OBJECT macro to indicate that the class
+uses internationalization and Qt's signals and slots features, even
+if we do not use all of these features at this stage.
+\snippet tutorials/addressbook/part1/addressbook.h class definition
+The class holds declarations of \c nameLine and \c addressText, the
+private instances of QLineEdit and QTextEdit mentioned earlier.
+You will see, in the coming chapters, that data stored in \c nameLine and
+\c addressText is needed for many of the address book's functions.
+We do not need to include declarations of the QLabel objects we will use
+because we will not need to reference them once they have been created.
+The way Qt tracks the ownership of objects is explained in the next section.
+The Q_OBJECT macro itself implements some of the more advanced features of Qt.
+For now, it is useful to think of the Q_OBJECT macro as a shortcut which allows
+us to use the \l{QObject::}{tr()} and \l{QObject::}{connect()} functions.
+We have now completed the \c addressbook.h file and we move on to
+implement the corresponding \c addressbook.cpp file.
+\section1 Implementing the AddressBook Class
+The constructor of \c AddressBook accepts a QWidget parameter, \a parent.
+By convention, we pass this parameter to the base class's constructor.
+This concept of ownership, where a parent can have one or more children,
+is useful for grouping widgets in Qt. For example, if you delete a parent,
+all of its children will be deleted as well.
+\snippet tutorials/addressbook/part1/addressbook.cpp constructor and input fields
+Within this constructor, we declare and instantiate two local QLabel objects,
+\c nameLabel and \c addressLabel, as well as instantiate \c nameLine and
+\c addressText. The
+\l{QObject::tr()}{tr()} function returns a translated version of the
+string, if there is one available; otherwise, it returns the string itself.
+Think of this function as an \c{<insert translation here>} marker to mark
+QString objects for translation. You will notice, in the coming chapters as
+well as in the \l{Qt Examples}, that we include it whenever we use a
+translatable string.
+When programming with Qt, it is useful to know how layouts work.
+Qt provides three main layout classes: QHBoxLayout, QVBoxLayout
+and QGridLayout to handle the positioning of widgets.
+\image addressbook-tutorial-part1-labeled-layout.png
+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 above shows the layout cells and the position of our widgets, and
+we specify this arrangement using the following code:
+\snippet tutorials/addressbook/part1/addressbook.cpp layout
+Notice that \c addressLabel is positioned using Qt::AlignTop as an
+additional argument. This is to make sure it is not vertically centered in
+cell (1,0). For a basic overview on Qt Layouts, refer to the
+\l{Layout Management} documentation.
+In order to install the layout object onto the widget, we have to invoke
+the widget's \l{QWidget::setLayout()}{setLayout()} function:
+\snippet tutorials/addressbook/part1/addressbook.cpp setting the layout
+Lastly, we set the widget's title to "Simple Address Book".
+\section1 Running the Application
+A separate file, \c main.cpp, is used for the \c main() function. Within
+this function, we instantiate a QApplication object, \c app. 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 tutorials/addressbook/part1/main.cpp main function
+We construct a new \c AddressBook widget on the stack and invoke
+its \l{QWidget::show()}{show()} function to display it.
+However, the widget will not be shown until the application's event loop
+is started. We start the event loop by calling the application's
+\l{QApplication::}{exec()} function; the result returned by this function
+is used as the return value from the \c main() function. At this point,
+it becomes apparent why we instanciated \c AddressBook on the stack: It
+will now go out of scope. Therefore, \c AddressBook and all its child widgets
+will be deleted, thus preventing memory leaks.
+*/
+/*!
+\page tutorials-addressbook-part2.html
+\previouspage Address Book 1 - Designing the User Interface
+\contentspage {Address Book Tutorial}{Contents}
+\nextpage {tutorials/addressbook/part3}{Chapter 3}
+\example tutorials/addressbook/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 Defining the AddressBook Class
+Now that we have the labels and input fields set up, we add push buttons to
+complete the process of adding a contact. This means that our
+\c addressbook.h file now has three QPushButton objects declared and three
+corresponding public slots.
+\snippet tutorials/addressbook/part2/addressbook.h slots
+A slot is a function that responds to a particular signal. We will discuss
+this concept in further detail when implementing the \c AddressBook class.
+However, for an overview of Qt's signals and slots concept, you can refer
+to the \l{Signals and Slots} document.
+Three QPushButton objects: \c addButton, \c submitButton and
+\c cancelButton, are now included in our private variable declarations,
+along with \c nameLine and \c addressText from the last chapter.
+\snippet tutorials/addressbook/part2/addressbook.h pushbutton declaration
+We need a container to store our address book contacts, so that we can
+traverse and display them. A QMap object, \c contacts, is used for this
+purpose as it holds a key-value pair: the contact's name as the \e key,
+and the contact's address as the \e{value}.
+\snippet tutorials/addressbook/part2/addressbook.h remaining private variables
+We also declare two private QString objects, \c oldName and \c oldAddress.
+These objects are needed to hold the name and address of the contact that
+was last displayed, before the user clicked \gui Add. So, when the user clicks
+\gui Cancel, we can revert to displaying the details of the last contact.
+\section1 Implementing the AddressBook Class
+Within the constructor of \c AddressBook, we set the \c nameLine and
+\c addressText to read-only, so that we can only display but not edit
+existing contact details.
+\dots
+\snippet tutorials/addressbook/part2/addressbook.cpp setting readonly 1
+\dots
+\snippet tutorials/addressbook/part2/addressbook.cpp setting readonly 2
+Then, we instantiate our push buttons: \c addButton, \c submitButton, and
+\c cancelButton.
+\snippet tutorials/addressbook/part2/addressbook.cpp pushbutton declaration
+The \c addButton is displayed by invoking the \l{QPushButton::show()}
+{show()} function, while the \c submitButton and \c cancelButton are
+hidden by invoking \l{QPushButton::hide()}{hide()}. These two push
+buttons will only be displayed when the user clicks \gui Add and this is
+handled by the \c addContact() function discussed below.
+\snippet tutorials/addressbook/part2/addressbook.cpp connecting signals and slots
+We connect the push buttons' \l{QPushButton::clicked()}{clicked()} signal
+to their respective slots. The figure below illustrates this.
+\image addressbook-tutorial-part2-signals-and-slots.png
+Next, we arrange our push buttons neatly to the right of our address book
+widget, using a QVBoxLayout to line them up vertically.
+\snippet tutorials/addressbook/part2/addressbook.cpp vertical layout
+The \l{QBoxLayout::addStretch()}{addStretch()} function is used to ensure
+the push buttons are not evenly spaced, but arranged closer to the top of
+the widget. The figure below shows the difference between using
+\l{QBoxLayout::addStretch()}{addStretch()} and not using it.
+\image addressbook-tutorial-part2-stretch-effects.png
+We then add \c buttonLayout1 to \c mainLayout, using
+\l{QGridLayout::addLayout()}{addLayout()}. This gives us nested layouts
+as \c buttonLayout1 is now a child of \c mainLayout.
+\snippet tutorials/addressbook/part2/addressbook.cpp grid layout
+Our layout coordinates now look like this:
+\image addressbook-tutorial-part2-labeled-layout.png
+In the \c addContact() function, we store the last displayed contact
+details in \c oldName and \c oldAddress. Then we clear these input
+fields and turn off the read-only mode. The focus is set on \c nameLine
+and we display \c submitButton and \c cancelButton.
+\snippet tutorials/addressbook/part2/addressbook.cpp addContact
+The \c submitContact() function can be divided into three parts:
+\list 1
+\o We extract the contact's details from \c nameLine and \c addressText
+and store them in QString objects. We also validate to make sure that the
+user did not click \gui Submit with empty input fields; otherwise, a
+QMessageBox is displayed to remind the user for a name and address.
+\snippet tutorials/addressbook/part2/addressbook.cpp submitContact part1
+\o We then proceed to check if the contact already exists. If it does not
+exist, we add the contact to \c contacts and we display a QMessageBox to
+inform the user that the contact has been added.
+\snippet tutorials/addressbook/part2/addressbook.cpp submitContact part2
+If the contact already exists, again, we display a QMessageBox to inform
+the user about this, preventing the user from adding duplicate contacts.
+Our \c contacts object is based on key-value pairs of name and address,
+hence, we want to ensure that \e key is unique.
+\o Once we have handled both cases mentioned above, we restore the push
+buttons to their normal state with the following code:
+\snippet tutorials/addressbook/part2/addressbook.cpp submitContact part3
+\endlist
+The screenshot below shows the QMessageBox object we use to display
+information messages to the user.
+\image addressbook-tutorial-part2-add-successful.png
+The \c cancel() function restores the last displayed contact details and
+enables \c addButton, as well as hides \c submitButton and
+\c cancelButton.
+\snippet tutorials/addressbook/part2/addressbook.cpp cancel
+The general idea behind adding a contact is to give the user the
+flexibility to click \gui Submit or \gui Cancel at any time. The flowchart below
+further explains this concept:
+\image addressbook-tutorial-part2-add-flowchart.png
+*/
+/*!
+\page tutorials-addressbook-part3.html
+\previouspage Address Book 2 - Adding Addresses
+\contentspage {Address Book Tutorial}{Contents}
+\nextpage {tutorials/addressbook/part4}{Chapter 4}
+\example tutorials/addressbook/part3
+\title Address Book 3 - Navigating between Entries
+The address book application is now half complete. We need to add some
+functions to navigate between contacts. But first, we have to decide
+what sort of a data structure we would like to use to hold these contacts.
+In Chapter 2, we used a QMap of key-value pairs with the contact's name
+as the \e key, and the contact's address as the \e value. This works well
+for our case. However, in order to navigate and display each entry, a
+little bit of enhancement is needed.
+We enhance the QMap by making it replicate a data structure similar to a
+circularly-linked list, where all elements are connected, including the
+first element and the last element. The figure below illustrates this data
+structure.
+\image addressbook-tutorial-part3-linkedlist.png
+\section1 Defining the AddressBook Class
+In order to add navigation functions to the address book application, we
+need to add two more slots to our \c AddressBook class: \c next() and
+\c previous(). These are added to our \c addressbook.h file:
+\snippet tutorials/addressbook/part3/addressbook.h navigation functions
+We also require another two QPushButton objects, so we declare \c nextButton
+and \c previousButton as private variables:
+\snippet tutorials/addressbook/part3/addressbook.h navigation pushbuttons
+\section1 Implementing the AddressBook Class
+In the \c AddressBook constructor in \c addressbook.cpp, we instantiate
+\c nextButton and \c previousButton and disable them by default. This is
+because navigation is only enabled when there is more than one contact
+in the address book.
+\snippet tutorials/addressbook/part3/addressbook.cpp navigation pushbuttons
+We then connect these push buttons to their respective slots:
+\snippet tutorials/addressbook/part3/addressbook.cpp connecting navigation signals
+The image below is our expected graphical user interface. Notice that it
+is getting closer to our final application.
+\image addressbook-tutorial-part3-screenshot.png
+We follow basic conventions for \c next() and \c previous() functions by
+placing the \c nextButton on the right and the \c previousButton on the
+left. In order to achieve this intuitive layout, we use QHBoxLayout to
+place the widgets side-by-side:
+\snippet tutorials/addressbook/part3/addressbook.cpp navigation layout
+The QHBoxLayout object, \c buttonLayout2, is then added to \c mainLayout.
+\snippet tutorials/addressbook/part3/addressbook.cpp adding navigation layout
+The figure below shows the coordinates of the widgets in \c mainLayout.
+\image addressbook-tutorial-part3-labeled-layout.png
+Within our \c addContact() function, we have to disable these buttons so
+that the user does not attempt to navigate while adding a contact.
+\snippet tutorials/addressbook/part3/addressbook.cpp disabling navigation
+Also, in our \c submitContact() function, we enable the navigation
+buttons, \c nextButton and \c previousButton, depending on the size
+of \c contacts. As mentioned earlier, navigation is only enabled when
+there is more than one contact in the address book. The following lines
+of code demonstrates how to do this:
+\snippet tutorials/addressbook/part3/addressbook.cpp enabling navigation
+We also include these lines of code in the \c cancel() function.
+Recall that we intend to emulate a circularly-linked list with our QMap
+object, \c contacts. So, in the \c next() function, we obtain an iterator
+for \c contacts and then:
+\list
+\o If the iterator is not at the end of \c contacts, we increment it
+by one.
+\o If the iterator is at the end of \c contacts, we move it to the
+beginning of \c contacts. This gives us the illusion that our QMap is
+working like a circularly-linked list.
+\endlist
+\snippet tutorials/addressbook/part3/addressbook.cpp next() function
+Once we have iterated to the correct object in \c contacts, we display
+its contents on \c nameLine and \c addressText.
+Similarly, for the \c previous() function, we obtain an iterator for
+\c contacts and then:
+\list
+\o If the iterator is at the end of \c contacts, we clear the
+display and return.
+\o If the iterator is at the beginning of \c contacts, we move it to
+the end.
+\o We then decrement the iterator by one.
+\endlist
+\snippet tutorials/addressbook/part3/addressbook.cpp previous() function
+Again, we display the contents of the current object in \c contacts.
+*/
+/*!
+\page tutorials-addressbook-part4.html
+\previouspage Address Book 3 - Navigating between Entries
+\contentspage {Address Book Tutorial}{Contents}
+\nextpage {tutorials/addressbook/part5}{Chapter 5}
+\example tutorials/addressbook/part4
+\title Address Book 4 - Editing and Removing Addresses
+In this chapter, we look at ways to modify the contents of contacts stored
+in the address book application.
+\image addressbook-tutorial-screenshot.png
+We now have an address book that not only holds contacts in an organized
+manner, but also allows navigation. It would be convenient to include
+edit and remove functions so that a contact's details can be changed
+when needed. However, this requires a little improvement, in the form of
+enums. In our previous chapters, we had two modes: \c{AddingMode} and
+\c{NavigationMode} - but they were not defined as enums. Instead, we
+enabled and disabled the corresponding buttons manually, resulting in
+multiple lines of repeated code.
+In this chapter, we define the \c Mode enum with three different values:
+\list
+\o \c{NavigationMode},
+\o \c{AddingMode}, and
+\o \c{EditingMode}.
+\endlist
+\section1 Defining the AddressBook Class
+The \c addressbook.h file is updated to contain the \c Mode enum:
+\snippet tutorials/addressbook/part4/addressbook.h Mode enum
+We also add two new slots, \c editContact() and \c removeContact(), to
+our current list of public slots.
+\snippet tutorials/addressbook/part4/addressbook.h edit and remove slots
+In order to switch between modes, we introduce the \c updateInterface() function
+to control the enabling and disabling of all QPushButton objects. We also
+add two new push buttons, \c editButton and \c removeButton, for the edit
+and remove functions mentioned earlier.
+\snippet tutorials/addressbook/part4/addressbook.h updateInterface() declaration
+\dots
+\snippet tutorials/addressbook/part4/addressbook.h buttons declaration
+\dots
+\snippet tutorials/addressbook/part4/addressbook.h mode declaration
+Lastly, we declare \c currentMode to keep track of the enum's current mode.
+\section1 Implementing the AddressBook Class
+We now have to implement the mode-changing features of the address book
+application. The \c editButton and \c removeButton are instantiated and
+disabled by default, as the address book starts up with zero contacts in
+memory.
+\snippet tutorials/addressbook/part4/addressbook.cpp edit and remove buttons
+These buttons are then connected to their respective slots, \c editContact()
+and \c removeContact(), and we add them to \c buttonLayout1.
+\snippet tutorials/addressbook/part4/addressbook.cpp connecting edit and remove
+\dots
+\snippet tutorials/addressbook/part4/addressbook.cpp adding edit and remove to the layout
+The \c editContact() function stores the contact's old details in
+\c oldName and \c oldAddress, before switching the mode to \c EditingMode.
+In this mode, the \c submitButton and \c cancelButton are both enabled,
+hence, the user can change the contact's details and click either button.
+\snippet tutorials/addressbook/part4/addressbook.cpp editContact() function
+The \c submitContact() function has been divided in two with an \c{if-else}
+statement. We check \c currentMode to see if it's in \c AddingMode. If it is,
+we proceed with our adding process.
+\snippet tutorials/addressbook/part4/addressbook.cpp submitContact() function beginning
+\dots
+\snippet tutorials/addressbook/part4/addressbook.cpp submitContact() function part1
+Otherwise, we check to see if \c currentMode is in \c EditingMode. If it
+is, we compare \c oldName with \c name. If the name has changed, we remove
+the old contact from \c contacts and insert the newly updated contact.
+\snippet tutorials/addressbook/part4/addressbook.cpp submitContact() function part2
+If only the address has changed (i.e., \c oldAddress is not the same as \c address),
+we update the contact's address. Lastly, we set \c currentMode to
+\c NavigationMode. This is an important step as it re-enables all the
+disabled push buttons.
+To remove a contact from the address book, we implement the
+\c removeContact() function. This function checks to see if the contact
+exists in \c contacts.
+\snippet tutorials/addressbook/part4/addressbook.cpp removeContact() function
+If it does, we display a QMessageBox, to confirm the removal with the
+user. Once the user has confirmed, we call \c previous() to ensure that the
+user interface shows another contact, and we remove the contact using \l{QMap}'s
+\l{QMap::remove()}{remove()} function. As a courtesy, we display a QMessageBox
+to inform the user. Both the message boxes used in this function are shown below:
+\image addressbook-tutorial-part4-remove.png
+\section2 Updating the User Interface
+We mentioned the \c updateInterface() function earlier as a means to
+enable and disable the push buttons depending on the current mode.
+The function updates the current mode according to the \c mode argument
+passed to it, assigning it to \c currentMode before checking its value.
+Each of the push buttons is then enabled or disabled, depending on the
+current mode. The code for \c AddingMode and \c EditingMode is shown below:
+\snippet tutorials/addressbook/part4/addressbook.cpp update interface() part 1
+For \c NavigationMode, however, we include conditions within the parameters
+of the QPushButton::setEnabled() function. This is to ensure that
+\c editButton and \c removeButton are enabled when there is at least one
+contact in the address book; \c nextButton and \c previousButton are only
+enabled when there is more than one contact in the address book.
+\snippet tutorials/addressbook/part4/addressbook.cpp update interface() part 2
+By performing the task of setting the mode and updating the user interface in
+the same function, we avoid the possibility of the user interface getting "out
+of sync" with the internal state of the application.
+*/
+/*!
+\page tutorials-addressbook-part5.html
+\previouspage Address Book 4 - Editing and Removing Addresses
+\contentspage {Address Book Tutorial}{Contents}
+\nextpage {tutorials/addressbook/part6}{Chapter 6}
+\example tutorials/addressbook/part5
+\title Address Book 5 - Adding a Find Function
+In this chapter, we look at ways to locate contacts and addresses in
+the address book application.
+\image addressbook-tutorial-part5-screenshot.png
+As we keep adding contacts to our address book application, it becomes
+tedious to navigate them with the \e Next and \e Previous buttons. In this
+case, a \e Find function would be more efficient in looking up contacts.
+The screenshot above shows the \e Find button and its position on the panel
+of buttons.
+When the user clicks on the \e Find button, it is useful to display a
+dialog that can prompt the user for a contact's name. Qt provides QDialog,
+which we subclass in this chapter, to implement a \c FindDialog class.
+\section1 Defining the FindDialog Class
+\image addressbook-tutorial-part5-finddialog.png
+In order to subclass QDialog, we first include the header for QDialog in
+the \c finddialog.h file. Also, we use forward declaration to declare
+QLineEdit and QPushButton since we will be using those widgets in our
+dialog class.
+As in our \c AddressBook class, the \c FindDialog class includes
+the Q_OBJECT macro and its constructor is defined to accept a parent
+QWidget, even though the dialog will be opened as a separate window.
+\snippet tutorials/addressbook/part5/finddialog.h FindDialog header
+We define a public function, \c getFindText(), to be used by classes that
+instantiate \c FindDialog. This function allows these classes to obtain the
+search string entered by the user. A public slot, \c findClicked(), is also
+defined to handle the search string when the user clicks the \gui Find
+button.
+Lastly, we define the private variables, \c findButton, \c lineEdit
+and \c findText, corresponding to the \gui Find button, the line edit
+into which the user types the search string, and an internal string
+used to store the search string for later use.
+\section1 Implementing the FindDialog Class
+Within the constructor of \c FindDialog, we set up the private variables,
+\c lineEdit, \c findButton and \c findText. We use a QHBoxLayout to
+position the widgets.
+\snippet tutorials/addressbook/part5/finddialog.cpp constructor
+We set the layout and window title, as well as connect the signals to their
+respective slots. Notice that \c{findButton}'s \l{QPushButton::clicked()}
+{clicked()} signal is connected to to \c findClicked() and
+\l{QDialog::accept()}{accept()}. The \l{QDialog::accept()}{accept()} slot
+provided by QDialog hides the dialog and sets the result code to
+\l{QDialog::}{Accepted}. We use this function to help \c{AddressBook}'s
+\c findContact() function know when the \c FindDialog object has been
+closed. We will explain this logic in further detail when discussing the
+\c findContact() function.
+\image addressbook-tutorial-part5-signals-and-slots.png
+In \c findClicked(), we validate \c lineEdit to ensure that the user
+did not click the \gui Find button without entering a contact's name. Then, we set
+\c findText to the search string, extracted from \c lineEdit. After that,
+we clear the contents of \c lineEdit and hide the dialog.
+\snippet tutorials/addressbook/part5/finddialog.cpp findClicked() function
+The \c findText variable has a public getter function, \c getFindText(),
+associated with it. Since we only ever set \c findText directly in both the
+constructor and in the \c findClicked() function, we do not create a
+setter function to accompany \c getFindText().
+Because \c getFindText() is public, classes instantiating and using
+\c FindDialog can always access the search string that the user has
+entered and accepted.
+\snippet tutorials/addressbook/part5/finddialog.cpp getFindText() function
+\section1 Defining the AddressBook Class
+To ensure we can use \c FindDialog from within our \c AddressBook class, we
+include \c finddialog.h in the \c addressbook.h file.
+\snippet tutorials/addressbook/part5/addressbook.h include finddialog's header
+So far, all our address book features have a QPushButton and a
+corresponding slot. Similarly, for the \gui Find feature we have
+\c findButton and \c findContact().
+The \c findButton is declared as a private variable and the
+\c findContact() function is declared as a public slot.
+\snippet tutorials/addressbook/part5/addressbook.h findContact() declaration
+\dots
+\snippet tutorials/addressbook/part5/addressbook.h findButton declaration
+Lastly, we declare the private variable, \c dialog, which we will use to
+refer to an instance of \c FindDialog.
+\snippet tutorials/addressbook/part5/addressbook.h FindDialog declaration
+Once we have instantiated a dialog, we will want to use it more than once;
+using a private variable allows us to refer to it from more than one place
+in the class.
+\section1 Implementing the AddressBook Class
+Within the \c AddressBook class's constructor, we instantiate our private
+objects, \c findButton and \c findDialog:
+\snippet tutorials/addressbook/part5/addressbook.cpp instantiating findButton
+\dots
+\snippet tutorials/addressbook/part5/addressbook.cpp instantiating FindDialog
+Next, we connect the \c{findButton}'s
+\l{QPushButton::clicked()}{clicked()} signal to \c findContact().
+\snippet tutorials/addressbook/part5/addressbook.cpp signals and slots for find
+Now all that is left is the code for our \c findContact() function:
+\snippet tutorials/addressbook/part5/addressbook.cpp findContact() function
+We start out by displaying the \c FindDialog instance, \c dialog. This is
+when the user enters a contact name to look up. Once the user clicks
+the dialog's \c findButton, the dialog is hidden and the result code is
+set to QDialog::Accepted. This ensures that
+our \c if statement is always true.
+We then proceed to extract the search string, which in this case is
+\c contactName, using \c{FindDialog}'s \c getFindText() function. If the
+contact exists in our address book, we display it immediately. Otherwise,
+we display the QMessageBox shown below to indicate that their search
+failed.
+\image addressbook-tutorial-part5-notfound.png
+*/
+/*!
+\page tutorials-addressbook-part6.html
+\previouspage Address Book 5 - Adding a Find Function
+\contentspage {Address Book Tutorial}{Contents}
+\nextpage {tutorials/addressbook/part7}{Chapter 7}
+\example tutorials/addressbook/part6
+\title Address Book 6 - Loading and Saving
+This chapter covers the file handling features of Qt that we use to write
+loading and saving routines for the address book application.
+\image addressbook-tutorial-part6-screenshot.png
+Although browsing and searching for contacts are useful features, our
+address book is not ready for use until we can save existing contacts and
+load them again at a later time.
+Qt provides a number of classes for \l{Input/Output and Networking}
+{input and output}, but we have chosen to use two which are simple to use
+in combination: QFile and QDataStream.
+A QFile object represents a file on disk that can be read from and written
+to. QFile is a subclass of the more general QIODevice class which
+represents many different kinds of devices.
+A QDataStream object is used to serialize binary data so that it can be
+stored in a QIODevice and retrieved again later. Reading from a QIODevice
+and writing to it is as simple as opening the stream - with the respective
+device as a parameter - and reading from or writing to it.
+\section1 Defining the AddressBook Class
+We declare two public slots, \c saveToFile() and \c loadFromFile(), as well
+as two QPushButton objects, \c loadButton and \c saveButton.
+\snippet tutorials/addressbook/part6/addressbook.h save and load functions declaration
+\dots
+\snippet tutorials/addressbook/part6/addressbook.h save and load buttons declaration
+\section1 Implementing the AddressBook Class
+In our constructor, we instantiate \c loadButton and \c saveButton.
+Ideally, it would be more user-friendly to set the push buttons' labels
+to "Load contacts from a file" and "Save contacts to a file". However, due
+to the size of our other push buttons, we set the labels to \gui{Load...}
+and \gui{Save...}. Fortunately, Qt provides a simple way to set tooltips with
+\l{QWidget::setToolTip()}{setToolTip()} and we use it in the following way
+for our push buttons:
+\snippet tutorials/addressbook/part6/addressbook.cpp tooltip 1
+\dots
+\snippet tutorials/addressbook/part6/addressbook.cpp tooltip 2
+Although it is not shown here, just like the other features we implemented,
+we add the push buttons to the layout panel on the right, \c button1Layout,
+and we connect the push buttons' \l{QPushButton::clicked()}{clicked()}
+signals to their respective slots.
+For the saving feature, we first obtain \c fileName using
+QFileDialog::getSaveFileName(). This is a convenience function provided
+by QFileDialog, which pops up a modal file dialog and allows the user to
+enter a file name or select any existing \c{.abk} file. The \c{.abk} file
+is our Address Book extension that we create when we save contacts.
+\snippet tutorials/addressbook/part6/addressbook.cpp saveToFile() function part1
+The file dialog that pops up is displayed in the screenshot below:
+\image addressbook-tutorial-part6-save.png
+If \c fileName is not empty, we create a QFile object, \c file, with
+\c fileName. QFile works with QDataStream as QFile is a QIODevice.
+Next, we attempt to open the file in \l{QIODevice::}{WriteOnly} mode.
+If this is unsuccessful, we display a QMessageBox to inform the user.
+\snippet tutorials/addressbook/part6/addressbook.cpp saveToFile() function part2
+Otherwise, we instantiate a QDataStream object, \c out, to write the open
+file. QDataStream requires that the same version of the stream is used
+for reading and writing. We ensure that this is the case by setting the
+version used to the \l{QDataStream::Qt_4_5}{version introduced with Qt 4.5}
+before serializing the data to \c file.
+\snippet tutorials/addressbook/part6/addressbook.cpp saveToFile() function part3
+For the loading feature, we also obtain \c fileName using
+QFileDialog::getOpenFileName(). This function, the counterpart to
+QFileDialog::getSaveFileName(), also pops up the modal file dialog and
+allows the user to enter a file name or select any existing \c{.abk} file
+to load it into the address book.
+\snippet tutorials/addressbook/part6/addressbook.cpp loadFromFile() function part1
+On Windows, for example, this function pops up a native file dialog, as
+shown in the following screenshot.
+\image addressbook-tutorial-part6-load.png
+If \c fileName is not empty, again, we use a QFile object, \c file, and
+attempt to open it in \l{QIODevice::}{ReadOnly} mode. Similar to our
+implementation of \c saveToFile(), if this attempt is unsuccessful, we
+display a QMessageBox to inform the user.
+\snippet tutorials/addressbook/part6/addressbook.cpp loadFromFile() function part2
+Otherwise, we instantiate a QDataStream object, \c in, set its version as
+above and read the serialized data into the \c contacts data structure.
+The \c contacts object is emptied before data is read into it to simplify
+the file reading process. A more advanced method would be to read the
+contacts into a temporary QMap object, and copy over non-duplicate contacts
+into \c contacts.
+\snippet tutorials/addressbook/part6/addressbook.cpp loadFromFile() function part3
+To display the contacts that have been read from the file, we must first
+validate the data obtained to ensure that the file we read from actually
+contains address book contacts. If it does, we display the first contact;
+otherwise, we display a QMessageBox to inform the user about the problem.
+Lastly, we update the interface to enable and disable the push buttons
+accordingly.
+*/
+/*!
+\page tutorials-addressbook-part7.html
+\previouspage Address Book 6 - Loading and Saving
+\contentspage {Address Book Tutorial}{Contents}
+\example tutorials/addressbook/part7
+\title Address Book 7 - Additional Features
+This chapter covers some additional features that make the address book
+application more convenient for everyday use.
+\image addressbook-tutorial-part7-screenshot.png
+Although our address book application is useful in its own right, it would
+be useful if we could exchange contact data with other applications.
+The vCard format is a popular file format that can be used for this purpose.
+In this chapter, we extend our address book client to allow contacts to
+be exported to vCard \c{.vcf} files.
+\section1 Defining the AddressBook Class
+We add a QPushButton object, \c exportButton, and a corresponding public
+slot, \c exportAsVCard() to our \c AddressBook class in the
+\c addressbook.h file.
+\snippet tutorials/addressbook/part7/addressbook.h exportAsVCard() declaration
+\dots
+\snippet tutorials/addressbook/part7/addressbook.h exportButton declaration
+\section1 Implementing the AddressBook Class
+Within the \c AddressBook constructor, we connect \c{exportButton}'s
+\l{QPushButton::clicked()}{clicked()} signal to \c exportAsVCard().
+We also add this button to our \c buttonLayout1, the layout responsible
+for our panel of buttons on the right.
+In our \c exportAsVCard() function, we start by extracting the contact's
+name into \c name. We declare \c firstName, \c lastName and \c nameList.
+Next, we look for the index of the first white space in \c name. If there
+is a white space, we split the contact's name into \c firstName and
+\c lastName. Then, we replace the space with an underscore ("_").
+Alternately, if there is no white space, we assume that the contact only
+has a first name.
+\snippet tutorials/addressbook/part7/addressbook.cpp export function part1
+As with the \c saveToFile() function, we open a file dialog to let the user
+choose a location for the file. Using the file name chosen, we create an
+instance of QFile to write to.
+We attempt to open the file in \l{QIODevice::}{WriteOnly} mode. If this
+process fails, we display a QMessageBox to inform the user about the
+problem and return. Otherwise, we pass the file as a parameter to a
+QTextStream object, \c out. Like QDataStream, the QTextStream class
+provides functionality to read and write plain text to files. As a result,
+the \c{.vcf} file generated can be opened for editing in a text editor.
+\snippet tutorials/addressbook/part7/addressbook.cpp export function part2
+We then write out a vCard file with the \c{BEGIN:VCARD} tag, followed by
+the \c{VERSION:2.1} tag. The contact's name is written with the \c{N:}
+tag. For the \c{FN:} tag, which fills in the "File as" property of a vCard,
+we have to check whether the contact has a last name or not. If the contact
+does, we use the details in \c nameList to fill it. Otherwise, we write
+\c firstName only.
+\snippet tutorials/addressbook/part7/addressbook.cpp export function part3
+We proceed to write the contact's address. The semicolons in the address
+are escaped with "\\", the newlines are replaced with semicolons, and the
+commas are replaced with spaces. Lastly, we write the \c{ADR;HOME:;}
+tag, followed by \c address and then the \c{END:VCARD} tag.
+\snippet tutorials/addressbook/part7/addressbook.cpp export function part4
+In the end, a QMessageBox is displayed to inform the user that the vCard
+has been successfully exported.
+\e{vCard is a trademark of the \l{http://www.imc.org}
+{Internet Mail Consortium}}.
+*/

branch	RCL_3
changeset 7	3f74d0d4af4c