Commit a7d33406 authored by Leena Miettinen's avatar Leena Miettinen
Browse files

Doc: remove the Address Book Tutorial



The screenshots and instructions are partly outdated and the
tutorial has not been built as part of the Manual since 2.x.

Change-Id: I311f80d1d449ab82ebc65207686faeb0739f9d5e
Reviewed-by: default avatarFriedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: default avatarhjk <hjk121@nokiamail.com>
Reviewed-by: default avatarDavid Schulz <david.schulz@digia.com>
Reviewed-by: default avatarEike Ziller <eike.ziller@digia.com>
parent 13468fc1
/**************************************************************************
**
** Copyright (c) 2014 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
**
** This file is part of Qt Creator
**
**
** GNU Free Documentation License
**
** Alternatively, this file may be used under the terms of the GNU Free
** Documentation License version 1.3 as published by the Free Software
** Foundation and appearing in the file included in the packaging of this
** file.
**
**
**************************************************************************/
/*!
\page tutorials-addressbook-sdk.html
\startpage {index.html}{Qt Reference Documentation}
\nextpage {examples/addressbook-sdk/part1}{Chapter 1}
\title Address Book Tutorial
\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.
\image addressbook-tutorial-screenshot.png
In the process, you will learn about some basic technologies provided by
Qt, such as:
\list
\li Widgets and layout managers
\li Container classes
\li Signals and slots
\li Input and output devices
\endlist
All these technologies will be introduced via the Qt Creator Integrated
Development Environment (IDE).
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
\li \l{examples/addressbook-sdk/part1}{Designing the User Interface}
\li \l{examples/addressbook-sdk/part2}{Adding Addresses}
\li \l{examples/addressbook-sdk/part3}{Navigating between Entries}
\li \l{examples/addressbook-sdk/part4}{Editing and Removing Addresses}
\li \l{examples/addressbook-sdk/part5}{Adding a Find Function}
\li \l{examples/addressbook-sdk/part6}{Loading and Saving}
\li \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 {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) you use for the Address Book application.
The first step to creating a GUI program is to design the user interface.
In this chapter, your 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
Begin by launching Qt Creator and use it to generate a new project. To
do this, select \gui{File} > \gui{New File or Project...} >
\gui{Qt Application Project} > \gui{Qt Gui Application} and
click \gui OK. Set your project name to \b part1 with the QtCore and
QtGui modules checked. Ensure that you select QWidget as your base class
and name it \c AddressBook.
When you click \gui Next, \e five files will be generated in this
\gui{Project}:
\list
\li \c{main.cpp} - the file containing a \c main() function, with an
instance of \c AddressBook,
\li \c{addressbook.cpp} - the implementation file for the
\c AddressBook class,
\li \c{addressbook.h} - the definition file for the \c AddressBook
class,
\li \c{addressbook.ui} - the user interface file created with \QD,
and
\li \c{part1.pro} - the project file.
\endlist
Now that you have all the files you need, click \gui Finish so you can
start designing the user interface.
\note For more details on how to create a \gui Project with Qt Creator,
refer to \l{Creating a Project}.
\section1 Placing Widgets on The Form
\image addressbook-tutorial-part1-creator-screenshot.png
In the \gui{Projects} sidebar, double-click on the \c{addressbook.ui} file.
The \QD plugin will be launched, allowing you to design your program's user
interface.
\image addressbook-tutorial-part1-designer-screenshot.png
You require two \l{QLabel}s to label the input fields as well as a
QLineEdit and a QTextEdit for the input fields. To create this follow the
steps mentioned below:
\list
\li Drag those widgets from the \gui{Widget Box} to your form.
\li 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.
\li Position the widgets properly, according to the screenshot above.
\li 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 you specify with row and
column numbers.
\li Place the caption of the \c addressLabel on the top, change the
vertical alignment property to \c AlignTop.
\endlist
The figure below shows the layout cells and the position of our widgets.
Place your widgets accordingly and save the form by choosing
\gui{File} > \gui{Save} or use the shortcut key \key{Ctrl+S}.
\image addressbook-tutorial-part1-labeled-screenshot.png
A common mistake when designing user interfaces with \QD is overlooking the
top level widget's layout. Unlike sub-layouts, which \QD displays with a
red border, top level layouts have no graphical representation. Layouts are
necessary for top level widgets, in this case QWidget, to ensure that when
the window is resized, the widgets on the form will resize accordingly. You
can try this out by pressing \key{Alt+Shift+R} now. To correct it, click
anywhere on the form and select \gui{Lay out Horizontally} or
\gui{Lay out Vertically}. The output will be the same. Now your widgets
will resize correctly.
\note Refer to the \l{Layout Classes} document for more
details on Qt's layout management classes. In addition, the
\l{Getting to Know Qt Designer} document explains how to use
layouts with \QD.
\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 as well as Qt's signals and slots features.
Although the macro implements some of Qt's more advanced features, 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 you 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 stack 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. This is done by calling the application's
\l{QApplication::}{exec()} function. Finally, the result returned by
\l{QApplication::}{exec()} is used as the \c main() function's return
value.
\section1 Running the Application
To run your application with Qt Creator, simply click,
\inlineimage qtcreator-run.png.
A bare bones Address Book will be displayed.
\section1 Qt Programming - Subclassing
When writing Qt programs, you 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 You can write implementations of virtual or pure virtual functions
to obtain exactly what you need, falling back on the base class's
implementation when necessary.
\li It allows you 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.
\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 provided a specific address book widget, you subclass a
standard Qt widget class and add features to it. The \c AddressBook class
you 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 {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
You 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
You can continue with the form from the last chapter; you have the
labels and input fields set up, but you need to add push buttons to
complete the process of adding a contact. Break the existing layouts by
following the steps below:
\list
\li Select, \gui{Break Layout} from the context menu. You might have to
do a \gui{Select All} with \key{Ctrl+A} first..
\li Add three push buttons and double-click on each of them to set
their text to "Add", "Submit", and "Cancel".
\li Set the \c objectName of the buttons to \c addButton,
\c submitButton and \c cancelButton respectively.
\li A \gui{Vertical Spacer} is required to ensure that the push buttons
will be laid out neatly; drag one from the \gui{Widget Box}.
\li Lay out these three push buttons and the spacer vertically, by
selecting all three of them using \key{Ctrl + click} and selecting
\gui{Lay out Vertically} from the context menu. Alternatively you
can use the \key{Ctrl+L} shortcut key.
\note Use the spacer as you do not want the buttons to be evenly
spaced, but arranged closer to the top of the widget.
\li The figure below shows the difference between using the spacer and
not using it.
\image addressbook-tutorial-part2-stretch-effects.png
\li Select all the objects on the form using, \key{Ctrl+A} and lay them
out in a grid.
\li Lastly, set the top level widget's layout by right-clicking anywhere
on the widget and selecting \gui{Lay out Horizontally} or
\gui{Lay out Vertically}.
\endlist
The final design of the form is shown in the screenshot below:
\image addressbook-tutorial-part2-form-design.png
\section1 The AddressBook Class
To ensure that the Address Book reacts to user interaction, you need to
write slots for each push button that you added earlier. A slot is a
function that responds to a particular signal. This concept will be
discussed further in detail below. However, for an overview of Qt's signals
and slots concept, you can refer to the \l{Signals and Slots} document.
In the \l{examples/addressbook-sdk/part2/addressbook.h}{\c addressbook.h}
file, add the following code:
\snippet examples/addressbook-sdk/part2/addressbook.h slot definition
Since the \c AddressBook class is a subclass of QWidget, Qt Creator
includes QWidget in the header file.
\snippet examples/addressbook-sdk/part2/addressbook.h include
You need a container to store our address book contacts, so that you 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 examples/addressbook-sdk/part2/addressbook.h members
You 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 you click \gui Add. So, when you
click \gui Cancel, you can revert to displaying the details of the last
contact.
Let's move on to implementing the slots defined earlier. Within the
constructor of \c AddressBook, you set up our fields by ensuring that
\c nameLine and \c addressText are read-only, so that you can only display
but not edit existing contact details.
\note In order to prevent crashes, you need make sure that the
autogenerated \c setupUi() call is always first in the constructor.
\snippet examples/addressbook-sdk/part2/addressbook.cpp setup fields
You also hide both \c submitButton and \c cancelButton as they will only be
displayed when you click \gui Add, and this is handled by the
\c addContact() function discussed below.
\snippet examples/addressbook-sdk/part2/addressbook.cpp signal slot
You connect the push buttons' \l{QAbstractButton::}{clicked()} signal to
their respective slots. The figure below illustrates this.
\image addressbook-tutorial-part2-signals-and-slots.png
Finally, set the window title to "Simple Address Book" using the
\l{QWidget::}{setWindowTitle()} function. The tr() function allows us
to translate user interface strings.
\snippet examples/addressbook-sdk/part2/addressbook.cpp window title
\section2 The \c addContact() Function
In this function, begin by storing the last displayed contact details
in \c oldName and \c oldAddress. Then clear these input fields and turn
off the read-only mode. The focus is set on \c nameLine and display
\c submitButton and \c cancelButton; but disable \c addButton.
\snippet examples/addressbook-sdk/part2/addressbook.cpp addContact
\section2 The \c submitContact() Function
This function can be divided into three parts:
\list 1
\li Extract the contact's detail from \c nameLine and \c addressText
and store them in QString objects. Also validate to ensure that
you did not click \gui Submit with empty input fields;
otherwise, a QMessageBox is displayed to remind you for a name
and address.
\snippet examples/addressbook-sdk/part2/addressbook.cpp submitContact part1
\li Then proceed to check if the contact already exists. If it does
not exist, add the contact to \c contacts and display a
QMessageBox to inform you about this, preventing you from
adding duplicate contacts. Our \c contacts object is based on
key-value pairs or name and address, hence, you want to ensure that
\e key is unique.
\snippet examples/addressbook-sdk/part2/addressbook.cpp submitContact part2
\li Once you have handled both cases mentioned above, restore the
push buttons to their normal state with the following code:
\snippet examples/addressbook-sdk/part2/addressbook.cpp submitContact part3
\endlist
The screenshot below shows the QMessageBox object used to display
information messages to the user.
\image addressbook-tutorial-part2-add-successful.png
\section2 The \c cancel() Function
This function restores the last displayed contact details and enables
\c addButton, as well as hides \c submitButton and \c cancelButton.
\snippet examples/addressbook-sdk/part2/addressbook.cpp cancel
The general idea behind adding a contact is to give you 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
\section1 Running the Application
Run your application now. You will be able to add as many unique contacts
as you like.
*/
/*!
\page tutorials-addressbook-sdk-part3.html
\previouspage Address Book 2 - Adding Addresses
\contentspage {Address Book Tutorial}{Contents}
\nextpage {examples/addressbook-sdk/part4}{Chapter 4}
\example examples/addressbook-sdk/part3
\title Address Book 3 - Navigating between Entries
The address book application is now half complete. You need to add some
functions to navigate between contacts. But first, you have to decide what
sort of a data structure you would like to use to hold these contacts.
In Chapter 2, you 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
your case. However, in order to navigate and display each entry, a little
bit of enhancement is needed.
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 Placing Widgets on The Form
So far, your application allows us to add new contacts. However, you also
need to traverse the existing contacts. To do so follow the steps
mentioned below:
\list
\li Add two push buttons at the bottom of your application and name
them: \gui Next and \gui Previous.
\li The buttons' \c objectName should be \c nextButton and
\c previousButton, respectively.
\li Break your top level layout by right-clicking on \c AddressBook in
the \gui{Object Inspector} and then select \gui{Lay out|Break Layout}.
\li Place the \gui Next and \gui Previous buttons in a horizontal
layout.
\li Drag and drop the buttons together with their layout into the
existing grid layout.
\li Set a top level layout for the widget again.
\endlist
The screenshot below illustrates what you will see as the button layout
approaches the grid layout; drop it then.
\image addressbook-tutorial-part3-drop-in-gridlayout.png
\note 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.
\section1 The AddressBook Class
In order to add navigation functions to the address book application,
you need to add two more slots to our \c AddressBook class: \c next() and
\c previous().
\snippet examples/addressbook-sdk/part3/addressbook.h slot definition
In the \c AddressBook constructor, you setup your fields and disable them
by default. This is because navigation is only enabled when there is more
than one contact in the address book.
\snippet examples/addressbook-sdk/part3/addressbook.cpp setup fields
Next, connect the buttons to their respective slots:
\snippet examples/addressbook-sdk/part3/addressbook.cpp signal slot
The screenshot below is your expected graphical user interface. Notice that
it is getting closer to your final application.
\image addressbook-tutorial-part3-screenshot.png
Within your \c addContact() function, you have to disable the \gui Next and
\gui Previous buttons so that you do not attempt to navigate while
adding a contact.
\snippet examples/addressbook-sdk/part3/addressbook.cpp disable navigation
Also, in your \c submitContact() function, enable the navigation buttons,
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 examples/addressbook-sdk/part3/addressbook.cpp enable navigation
Also include these lines of code in the \c cancel() function.
Recall that you intend to emulate a circularly-linked list with your QMap
object, \c contacts. So in the \c next() function, obtain an iterator
for \c contacts and then:
\list
\li If the iterator is not at the end of \c contacts, increment it by
one.
\li If the iterator is at the end of \c contacts, move it to the
beginning of \c contacts. This gives an illusion that our QMap
is working like a circularly-linked list.
\endlist
\snippet examples/addressbook-sdk/part3/addressbook.cpp next
Once you have iterated to the current object in \c contacts, display its
contents on \c nameLine and \c addressText.
Similarly, for the \c previous() function, obtain an iterator for
\c contacts and then:
\list
\li If the iterator is at the end of \c contacts, clear the display
and return.
\li If the iterator is at the beginning of \c contacts, move it to
the end.
\li Then decrement the iterator by one.
\endlist
\snippet examples/addressbook-sdk/part3/addressbook.cpp previous
Again, display the contents of the current object in \c contacts.
*/
/*!
\page tutorials-addressbook-sdk-part4.html
\previouspage Address Book 3 - Navigating between Entries
\contentspage {Address Book Tutorial}{Contents}
\nextpage {examples/addressbook-sdk/part5}{Chapter 5}
\example examples/addressbook-sdk/part4
\title Address Book 4 - Editing and Removing Addresses
This chapter looks at ways to modify the contents of contacts stored
in the address book application.
\image addressbook-tutorial-part4-screenshot.png
You 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, you had two modes: \c AddingMode and
\c NavigationMode - but they were not defined as enums. Instead, you
enabled and disabled the corresponding buttons manually, resulting in
multiple lines of repeated code.
In this chapter, define the \c Mode enum with three different values:
\list
\li \c{NavigationMode}
\li \c{AddingMode}
\li \c{EditingMode}
\endlist
\section1 Placing Widgets on The Form
To edit and remove contacts, you need two push buttons. Drag them and name
them accordingly. Their \c objectName properties should be \c editButton
and \c removeButton, respectively. The quickest way to place these two
buttons into our existing layout, is to simply drag and drop them. Use the
screenshot below as a guide:
\image addressbook-tutorial-part4-drop-in-gridlayout.png
\section1 The AddressBook Class
Update the header file to contain the \c Mode enum:
\snippet examples/addressbook-sdk/part4/addressbook.h enum
Also add two new slots, \c editContact() and \c removeContact(), to your
current list of public slots.
\snippet examples/addressbook-sdk/part4/addressbook.h slot definition
In order to switch between modes, introduce the \c updateInterface()
function to control the enabling and disabling of all push buttons.
\snippet examples/addressbook-sdk/part4/addressbook.h updateInterface
Lastly, declare \c currentMode to keep track of the enum's current mode.
\snippet examples/addressbook-sdk/part4/addressbook.h current mode
Let's begin by implementing the mode-changing features of the address book
application. The \c editButton and \c removeButton are disabled by default,
as the address book starts up with zero contacts in memory.
\snippet examples/addressbook-sdk/part4/addressbook.cpp extract objects
These buttons are then connected to their respective slots,
\c editContact() and \c removeContact.
\snippet examples/addressbook-sdk/part4/addressbook.cpp signal slot
Now look at the \c editContact() and \c removeContact() functions in
detail.
\section2 The \c editContact() Function
This 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 examples/addressbook-sdk/part4/addressbook.cpp editContact
Since you will reuse the \c submitButton for both: adding a new contact and
editing an existing contact, you need to modify our existing
\c submitContact() function. So, divide it in two with an \c{if-else}
statement.
First, check \c currentMode to see if it is in \c AddingMode. If it is,