Commit bd16eeef authored by Oswald Buddenhagen's avatar Oswald Buddenhagen
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Merge branch 'docs'

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	doc/qtcreator.qdoc
parents 14fc6e93 16f7ed26
......@@ -42,7 +42,7 @@
\image addressbook-tutorial-screenshot.png
In the process, we will learn about some basic technologies provided by
In the process, you will learn about some basic technologies provided by
Qt, such as:
\list
......@@ -88,21 +88,22 @@
\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) we use for the Address Book application.
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, our goal is to set up the labels and input fields needed
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
We begin by launching Qt Creator and use it to generate a new project. To
do this, select \gui{New File or Project...} from the \gui File menu. In
the \gui{New...} dialog, select \gui{Projects -> Qt4 Gui Application} and
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 \bold part1 with the QtCore and
QtGui modules checked. Ensure that you select QWidget as your base class
and name it \c AddressBook.
......@@ -122,12 +123,11 @@
\o \c{part1.pro} - the project file.
\endlist
Now that we have all the files we need, click \gui Finish so can start
designing the user interface.
\note For more information on how to create a \gui Project, see
\l {Creating a project}.
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
......@@ -139,21 +139,26 @@
\image addressbook-tutorial-part1-designer-screenshot.png
We require two \l{QLabel}s to label the input fields as well as a QLineEdit
and a QTextEdit for the input fields. So, drag those widgets from the
\gui{Widget Box} to your form. In the \gui{Property Editor}, set their
\gui{objectName} property to \c nameLabel and \c addressLabel for the
\l{QLabel}s, \c nameLine for the QLineEdit and finally, \c addressText for
the QTextEdit.
Next, we have to position the widgets properly, according to the screenshot
earlier. We use a QGridLayout to position our labels and input fields in a
structured manner. QGridLayout divides the available space into a grid and
places widgets in the cells we specify with row and column numbers. To place
the caption of the \c addressLabel on the top, change the vertical alignment
property to \c AlignTop. The diagram below shows the layout cells and the
position of our widgets. Place your widgets accordingly and save the form by
choosing \gui{File -> Save} or using the \key{Ctrl+S} shortcut.
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
\o Drag those widgets from the \gui{Widget Box} to your form.
\o 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.
\o Position the widgets properly, according to the screenshot above.
\o 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.
\o 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
......@@ -162,19 +167,15 @@
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{Ctrl+Alt+R} now. To correct it, simply click
can try this out by pressing \key{Ctrl+Alt+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.
\table
\row
\o \bold{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.
\endtable
\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
......@@ -191,7 +192,7 @@
\snippet examples/addressbook-sdk/part1/addressbook.h class definition
Qt Creator's \gui{Project Wizard} provides us with the \c Ui object as a
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}
......@@ -223,23 +224,24 @@
\section1 Running the Application
To run your application with Qt Creator, simply click on the Play button
(image). A bare bones Address Book will be displayed. Click on the X button
to close it.
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, we usually subclass Qt objects to add
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
\o We can write implementations of virtual or pure virtual functions
to obtain exactly what we need, falling back on the base class's
\o 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.
\o It allows us to encapsulate parts of the user interface within a
\o 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.
\o The subclass can be used to create multiple custom widgets in the
......@@ -247,10 +249,12 @@
reused in other projects.
\endlist
Since Qt does not provided a specific address book widget, we subclass a
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
we create in this tutorial can be reused in situations where a basic
you create in this tutorial can be reused in situations where a basic
address book is needed.
*/
......@@ -267,56 +271,58 @@
\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.
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
We shall continue with the form we had from the last chapter; we have the
labels and input fields set up, but we need to add push buttons to complete
the process of adding a contact. So, we begin by breaking the existing
layouts: select \gui{Break Layout} from the context menu. You might have to
do a \gui{Select All} with \key{Ctrl+A} first.. Then, we add three push
buttons. Double-click on each of them to set their text to "Add", "Submit",
and "Cancel". Next, set the \c objectName of the buttons to \c addButton,
\c submitButton and \c cancelButton respectively.
We now require a vertical spacer to ensure that the push buttons will be laid
out neatly; drag one from the \gui{Widget Box}.
## image for button missing
Next, lay out these three push buttons and the spacer vertically, by
selecting all three of them (using the \key{Ctrl + click}) and choosing
\gui{Lay out Vertically} from the context menu. Alternatively you can click
on the ... button or use the \key{Ctrl+L} shortcut. We use the spacer as we
do not want the buttons to be evenly spaced, but arranged closer to the top
of the widget. The figure below shows the difference between using the
spacer and not using it.
\image addressbook-tutorial-part2-stretch-effects.png
Select all the objects on the form (use \key{Ctrl+A}) and lay them out in a
grid. 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}.
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
\o Select, \gui{Break Layout} from the context menu. You might have to
do a \gui{Select All} with \key{Ctrl+A} first..
\o Add three push buttons and double-click on each of them to set
their text to "Add", "Submit", and "Cancel".
\o Set the \c objectName of the buttons to \c addButton,
\c submitButton and \c cancelButton respectively.
\o A \gui{Vertical Spacer} is required to ensure that the push buttons
will be laid out neatly; drag one from the \gui{Widget Box}.
\o 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.
\o The figure below shows the difference between using the spacer and
not using it.
\image addressbook-tutorial-part2-stretch-effects.png
\o Select all the objects on the form using, \key{Ctrl+A} and lay them
out in a grid.
\o 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
\image addressbook-tutorial-part2-form-design.png
\section1 The AddressBook Class
To ensure that the Address Book reacts to user interaction, we need to
write slots for each push button that we added earlier. A slot is a
function that responds to a particular signal. We will discuss this
concept in further detail below. However, for an overview of Qt's signals
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, we add the following code:
file, add the following code:
\snippet examples/addressbook-sdk/part2/addressbook.h slot definition
......@@ -325,53 +331,54 @@
\snippet examples/addressbook-sdk/part2/addressbook.h include
We need a container to store our address book contacts, so that we can
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
We also declare two private QString objects, \c oldName and \c oldAddress.
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 the user clicked \gui Add. So, when the user
clicks \gui Cancel, we can revert to displaying the details of the last
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.
## this is a bit confusing, as the ctor was not defined by us nor is a slot
Let's move on to implementing the slots we defined earlier. Within the
constructor of \c AddressBook, we set up our fields by ensuring that
\c nameLine and \c addressText are read-only, so that we can only display
but not edit existing contact details. Note that in order to prevent
crashes, you need make sure that the autogenerated \c setupUi() call
is always first in the constructor.
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
We also hide both \c submitButton and \c cancelButton as they will only be
displayed when the user clicks \gui Add, and this is handled by the
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
We connect the push buttons' \l{QAbstractButton::}{clicked()} signal to
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, we set the window title to "Simple Address Book" using the
Finally, set the window title to "Simple Address Book" using the
\l{QWidget::}{setWindowTitle()} function. The tr() method allows us
to translate user interface strings. Refer to ###.
to translate user interface strings.
\snippet examples/addressbook-sdk/part2/addressbook.cpp window title
\section2 The \c addContact() Function
In this function, we begin by storing 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; but we disable \c addButton.
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
......@@ -380,30 +387,30 @@
This function can be divided into three parts:
\list 1
\o We extract the contact's detail from \c nameLine and \c addressText
and store them in QString objects. We also validate to ensure that
the user did not click \gui Submit with empty input fields;
otherwise, a QMessageBox is displayed to remind the user for a name
\o 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
\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 about this, preventing the user from
\o 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, we want to ensure that
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
\o Once we have handled both cases mentioned above, we restore the
\o 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 we use to display
The screenshot below shows the QMessageBox object used to display
information messages to the user.
\image addressbook-tutorial-part2-add-successful.png
......@@ -415,7 +422,7 @@
\snippet examples/addressbook-sdk/part2/addressbook.cpp cancel
The general idea behind adding a contact is to give the user the
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:
......@@ -438,115 +445,121 @@
\example examples/addressbook-sdk/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.
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, we used a QMap of key-value pairs with the contact's name as
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
our case. However, in order to navigate and display each entry, a little
your 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
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;
structure.
\image addressbook-tutorial-part3-linkedlist.png
\section1 Placing Widgets on The Form
So far, our application allows us to add new contacts. However, we also
need to traverse the existing contacts. To do so, we add two push buttons
at the bottom of our application and name them: \gui Next and
\gui Previous. The buttons' \c objectName should be \c nextButton and
\c previousButton, respectively. Then, we break our top level layout.
Simply right-click on \c AddressBook in the \gui{Object Inspector} and
then select \gui{Lay out|Break Layout}. Place the \gui Next and
\gui Previous buttons in a horizontal layout. Now drag and drop the buttons
together with their layout into the existing grid layout. The screenshot
below illustrates what you will see as the button layout approaches the
grid layout; drop it then.
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
\o Add two push buttons at the bottom of your application and name
them: \gui Next and \gui Previous.
\o The buttons' \c objectName should be \c nextButton and
\c previousButton, respectively.
\o Break your top level layout by right-clicking on \c AddressBook in
the \gui{Object Inspector} and then select \gui{Lay out|Break Layout}.
\o Place the \gui Next and \gui Previous buttons in a horizontal
layout.
\o Drag and drop the buttons together with their layout into the
existing grid layout.
\o Set a top level layout for the widget again.
\endlist
\image addressbook-tutorial-part3-drop-in-gridlayout.png
The screenshot below illustrates what you will see as the button layout
approaches the grid layout; drop it then.
Finally, set a top level layout for the widget again.
\image addressbook-tutorial-part3-drop-in-gridlayout.png
\note We follow basic conventions for \c next() and \c previous() functions
\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
Let's move on to the code. 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().
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, we setup our fields and disable them by
default. This is because navigation is only enabled when there is more than
one contact in the address book.
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, we connect the buttons to their respective slots:
Next, connect the buttons to their respective slots:
\snippet examples/addressbook-sdk/part3/addressbook.cpp signal slot
The screenshot below is our expected graphical user interface. Notice that
it is getting closer to our final application.
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 our \c addContact() function, we have to disable the \gui Next and
\gui Previous buttons so that the user does not attempt to navigate while
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 our \c submitContact() function, we enable the navigation buttons,
depending on the size of \c contacts. Asmentioned earlier, navigation is
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
We also include these lines of code in the \c cancel() function.
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
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
\o If the iterator is not at the end of \c contacts, we increment it by
\o If the iterator is not at the end of \c contacts, 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
\o 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 we have iterated to the current object in \c contacts, we display its
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,we obtain an iterator for
Similarly, for the \c previous() function, obtain an iterator for
\c contacts and then:
\list
\o If the iterator is at the end of \c contacts, we clear the display
\o If the iterator is at the end of \c contacts, clear the display
and return.
\o If the iterator is at the beginning of \c contacts, we move it to
\o If the iterator is at the beginning of \c contacts, move it to
the end.
\o We then decrement the iterator by one.
\o Then decrement the iterator by one.
\endlist
\snippet examples/addressbook-sdk/part3/addressbook.cpp previous
Again, we display the contents of the current object in \c contacts.
Again, display the contents of the current object in \c contacts.
*/
......@@ -559,31 +572,31 @@
\example examples/addressbook-sdk/part4
\title Address Book 4 - Editing and Removing Addresses
In this chapter, we look at ways to modify the contents of contacts stored
This chapter looks at ways to modify the contents of contacts stored
in the address book application.
#screenshot
\image addressbook-tutorial-part4-screenshot.png
We now have an address book that not only holds contacts in an organized
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, 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 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, we define the \c Mode enum with three different values:
In this chapter, define the \c Mode enum with three different values:
\list
\o \c{NavigationMode},
\o \c{AddingMode}, and
\o \c{EditingMode}.
\o \c{NavigationMode}
\o \c{AddingMode}
\o \c{EditingMode}
\endlist
\section1 Placing Widgets on The Form
To edit and remove contacts, we need two push buttons. Drag them and name
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
......@@ -594,21 +607,21 @@
\section1 The AddressBook Class
We update the header file to contain the \c Mode enum:
Update the header file to contain the \c Mode enum:
\snippet examples/addressbook-sdk/part4/addressbook.h enum
We also add two new slots, \c editContact() and \c removeContact(), to our
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, we introduce the \c updateInterface()
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, we declare \c currentMode to keep track of the enum's current mode.
Lastly, declare \c currentMode to keep track of the enum's current mode.
\snippet examples/addressbook-sdk/part4/addressbook.h current mode
......@@ -623,10 +636,9 @@
\snippet examples/addressbook-sdk/part4/addressbook.cpp signal slot
Now we look at the \c editContact() and \c removeContact() functions in
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
......@@ -636,58 +648,58 @@
\snippet examples/addressbook-sdk/part4/addressbook.cpp editContact
Since we will reuse the \c submitButton for both: adding a new contact and
editing an existing contact, we need to modify our existing