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-// Copyright (C) 2016 The Qt Company Ltd.
-// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
-
-/*!
- \page tutorials-addressbook.html
-
- \title Address Book Tutorial
- \ingroup examples-layout
- \brief An introduction to GUI programming, showing how to put together a
- simple yet fully-functioning application.
-
- This tutorial is an introduction to GUI programming with 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 this tutorial, you will learn about some of the basic
- components of Qt, including:
-
- \list
- \li Widgets and layout managers
- \li Container classes
- \li Signals and slots
- \li Input and output devices
- \endlist
-
- Tutorial contents:
-
- \list 1
- \li \l{tutorials/addressbook/part1}{Designing the User Interface}
- \li \l{tutorials/addressbook/part2}{Adding Addresses}
- \li \l{tutorials/addressbook/part3}{Navigating between Entries}
- \li \l{tutorials/addressbook/part4}{Editing and Removing Addresses}
- \li \l{tutorials/addressbook/part5}{Adding a Find Function}
- \li \l{tutorials/addressbook/part6}{Loading and Saving}
- \li \l{tutorials/addressbook/part7}{Additional Features}
- \endlist
-
- The tutorial source code is located in \c{tutorials/addressbook}.
-
- Although this little application does not look much like a
- fully-fledged modern GUI application, it uses many of the basic
- elements that are used in more complex applications. After you
- have worked through this tutorial, we recommend reading the
- \l{mainwindows/application}{Application} example, which presents a
- small GUI application, with menus, toolbars, a status bar, and so
- on.
-*/
-
-/*!
- \example tutorials/addressbook/part1
- \title Part 1 - Designing the User Interface
- \brief Describes how to code the user interface of the Address Book Example.
- This first part covers the design of the basic graphical user
- interface (GUI) for our address book application.
-
- The first step in creating a GUI program is to design the user
- interface. Here the our goal is to set up the labels and input
- fields to implement a basic address book. The figure below is a
- screenshot of the 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
- \li \c{addressbook.h} - the definition file for the \c AddressBook
- class,
- \li \c{addressbook.cpp} - the implementation file for the
- \c AddressBook class, and
- \li \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
- \li 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.
- \li 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.
- \li 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 \c{tutorials/addressbook/part1/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. The data stored in \c nameLine and \c addressText will
- be needed for many of the address book functions.
-
- We don't 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
-
- In this constructor, the QLabel objects \c nameLabel and \c
- addressLabel are instantiated, as well as \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. This function
- marks its QString parameter as one that should be translated into
- other languages. It should be used wherever a translatable string
- appears.
-
- 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.
-*/
-
-/*!
- \example tutorials/addressbook/part2
- \title Part 2 - Adding Addresses
- \brief Describes the code for inserting records in the Address Book Example.
-
- The next step in creating the address book is to implement some
- user interactions.
-
- \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.
-
- \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 \uicontrol Add. So, when the user clicks
- \uicontrol 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 \uicontrol 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
- \li 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 \uicontrol 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
-
- \li 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.
-
- \li 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 \uicontrol Submit or \uicontrol Cancel at any time. The flowchart below
- further explains this concept:
-
- \image addressbook-tutorial-part2-add-flowchart.png
-*/
-
-/*!
- \example tutorials/addressbook/part3
- \title Part 3 - Navigating between Entries
- \brief Explains the code that enables navigating the contacts.
-
- The address book is now about half complete. We should add the
- capability to navigate the contacts, but first we must
- decide what sort of a data structure we need for containing these
- contacts.
-
- In the previous section, 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
-
- To add navigation functions to the address book, we must add two
- more slots to the \c AddressBook class: \c next() and \c
- previous() to the \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 the expected graphical user interface.
-
- \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
- \li If the iterator is not at the end of \c contacts, we increment it
- by one.
- \li 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
- \li If the iterator is at the end of \c contacts, we clear the
- display and return.
- \li If the iterator is at the beginning of \c contacts, we move it to
- the end.
- \li 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.
-
-*/
-
-/*!
- \example tutorials/addressbook/part4
- \title Part 4 - Editing and Removing Addresses
- \brief Explains how to add edit and remove functionality.
-
- Now we look at ways to modify the contents of contacts stored in
- the address book.
-
- \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. We defined
- two modes: \c{AddingMode} and \c{NavigationMode}, but they were
- not defined as enum values. Instead, we enabled and disabled the
- corresponding buttons manually, resulting in multiple lines of
- repeated code.
-
- Here we define the \c Mode enum with three different values:
-
- \list
- \li \c{NavigationMode},
- \li \c{AddingMode}, and
- \li \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 implement the mode-changing features of the address
- book. The \c editButton and \c removeButton are instantiated and
- disabled by default. The address book starts 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 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.
- */
-
-/*!
- \example tutorials/addressbook/part5
- \title Part 5 - Adding a Find Function
- \brief Describes how to add a find function.
-
- Here we look at ways to locate contacts and addresses in the
- address book.
-
- \image addressbook-tutorial-part5-screenshot.png
-
- As we add contacts to our address book, it becomes tedious to
- navigate the list with the \e Next and \e Previous buttons. A \e
- Find function would be more efficient. 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 prompts for a contact's name. Qt provides
- QDialog, which we subclass here 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 \uicontrol Find
- button.
-
- Lastly, we define the private variables, \c findButton, \c lineEdit
- and \c findText, corresponding to the \uicontrol 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 \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 \uicontrol 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 \uicontrol 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
-*/
-
-/*!
- \example tutorials/addressbook/part6
- \title Part 6 - Loading and Saving
- \brief Describes how to add save and load functionality.
-
- This part covers the Qt file handling features we use to write
- loading and saving routines for the address book.
-
- \image addressbook-tutorial-part6-screenshot.png
-
- Although browsing and searching the contact list are useful
- features, our address book is not complete 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 \uicontrol{Load...}
- and \uicontrol{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 buttonLayout1,
- 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{QIODeviceBase::}{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{QIODeviceBase::}{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.
-*/
-
-/*!
- \example tutorials/addressbook/part7
- \title Part 7 - Additional Features
- \brief Describes how to export data in VCard format.
-
- This part covers some additional features that make the address
- book more convenient for the frequent user.
-
- \image addressbook-tutorial-part7-screenshot.png
-
- Although our address book is useful in isolation, it would be
- better if we could exchange contact data with other applications.
- The vCard format is a popular file format that can be used for
- this purpose. Here 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{QIODeviceBase::}{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}}.
-*/