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=An example of user login dialog=
[[Category:HowTo]]<br />[[Category:snippets]]


This code snippets shows how to implement a simple dialog window that allows the user to enter his username and password in order to make a login attempt. The dialog window will emit a signal in order to notify a listener for the login credentials. The login dialog can also presents a list of usernames to select one from.<br /> The dialog also allows for the proposal of a specified username/password as it could be loaded from a settings or a configuration file.
= An example of user login dialog =


==Header file==
This code snippets shows how to implement a simple dialog window that allows the user to enter his username and password in order to make a login attempt. The dialog window will emit a signal in order to notify a listener for the login credentials. The login dialog can also presents a list of usernames to select one from.<br />The dialog also allows for the proposal of a specified username/password as it could be loaded from a settings or a configuration file.


==Implementation==
== Header file ==


==Usage example==
<code><br />#include &lt;QDialog&amp;gt;<br />#include &lt;QLabel&amp;gt;<br />#include &lt;QPushButton&amp;gt;<br />#include &lt;QDialogButtonBox&amp;gt;<br />#include &lt;QLineEdit&amp;gt;<br />#include &lt;QComboBox&amp;gt;<br />#include &lt;QGridLayout&amp;gt;<br />#include &lt;QStringList&amp;gt;<br />#include &lt;QDebug&amp;gt;


===Categories:===
/*!<br /> '''Makes class LoginDialog a child to its parent, QDialog<br />'''/<br />class LoginDialog : public QDialog<br />{<br />/*!<br /> '''Turns Login Dialog into a QObject<br />'''/<br /> Q_OBJECT


* [[:Category:HowTo|HowTo]]
private:<br /> /*!<br /> * A label for the username component.<br /> '''/<br /> QLabel''' labelUsername;
* [[:Category:snippets|snippets]]
 
/*!<br /> * A label for the password.<br /> '''/<br /> QLabel''' labelPassword;
 
/*!<br /> * An editable combo box for allowing the user<br /> * to enter his username or select it from a list.<br /> '''/<br /> QComboBox''' comboUsername;
 
/*!<br /> * A field to let the user enters his password.<br /> '''/<br /> QLineEdit''' editPassword;
 
/*!<br /> * The standard dialog button box.<br /> '''/<br /> QDialogButtonBox''' buttons;
 
/*!<br /> * A method to set up all dialog components and<br /> * initialize them.<br /> */<br /> void setUpGUI();
 
public:<br /> explicit LoginDialog(QWidget '''parent = 0);
<br /> /'''!<br /> * Sets the proposed username, that can come for instance<br /> * from a shared setting.<br /> '''username the string that represents the current username<br />''' to display<br /> '''/<br /> void setUsername( QString&amp;amp; username );
<br /> /'''!<br /> * Sets the current password to propose to the user for the login.<br /> * password the password to fill into the dialog form<br /> '''/<br /> void setPassword( QString&amp;amp; password );
<br /> /'''!<br /> * Sets a list of allowed usernames from which the user<br /> * can pick one if he does not want to directly edit it.<br /> '''usernames a list of usernames<br />'''/<br /> void setUsernamesList( const QStringList&amp;amp; usernames );
 
signals:
 
/*!<br /> * A signal emitted when the login is performed.<br /> * username the username entered in the dialog<br /> * password the password entered in the dialog<br /> * index the number of the username selected in the combobox<br /> '''/<br /> void acceptLogin( QString&amp;amp; username, QString&amp;amp; password, int&amp;amp; indexNumber );
<br />public slots:<br /> /'''!<br /> * A lot to adjust the emitting of the signal.<br /> */<br /> void slotAcceptLogin();
 
};
 
#endif // LOGINDIALOG_H</code>
 
== Implementation ==
 
<code>LoginDialog::LoginDialog(QWidget '''parent) :<br /> QDialog(parent)<br />{<br /> setUpGUI();<br /> setWindowTitle( tr(&quot;User Login&amp;quot;) );<br /> setModal( true );<br />}
<br />void LoginDialog::setUpGUI(){<br /> // set up the layout<br /> QGridLayout''' formGridLayout = new QGridLayout( this );
 
// initialize the username combo box so that it is editable<br /> comboUsername = new QComboBox( this );<br /> comboUsername-&gt;setEditable( true );<br /> // initialize the password field so that it does not echo<br /> // characters<br /> editPassword = new QLineEdit( this );<br /> editPassword-&gt;setEchoMode( QLineEdit::Password );
 
// initialize the labels<br /> labelUsername = new QLabel( this );<br /> labelPassword = new QLabel( this );<br /> labelUsername-&gt;setText( tr( &quot;Username&amp;quot; ) );<br /> labelUsername-&gt;setBuddy( comboUsername );<br /> labelPassword-&gt;setText( tr( &quot;Password&amp;quot; ) );<br /> labelPassword-&gt;setBuddy( editPassword );
 
// initialize buttons<br /> buttons = new QDialogButtonBox( this );<br /> buttons-&gt;addButton( QDialogButtonBox::Ok );<br /> buttons-&gt;addButton( QDialogButtonBox::Cancel );<br /> buttons-&gt;button( QDialogButtonBox::Ok )<s>&gt;setText( tr(&quot;Login&amp;quot;) );<br /> buttons</s>&gt;button( QDialogButtonBox::Cancel )<s>&gt;setText( tr(&quot;Abort&amp;quot;) );
<br /> // connects slots<br /> connect( buttons</s>&gt;button( QDialogButtonBox::Cancel ),<br /> SIGNAL (clicked()),<br /> this,<br /> SLOT (close())<br /> );
 
connect( buttons-&gt;button( QDialogButtonBox::Ok ),<br /> SIGNAL (clicked()),<br /> this,<br /> SLOT (slotAcceptLogin()) );
 
// place components into the dialog<br /> formGridLayout-&gt;addWidget( labelUsername, 0, 0 );<br /> formGridLayout-&gt;addWidget( comboUsername, 0, 1 );<br /> formGridLayout-&gt;addWidget( labelPassword, 1, 0 );<br /> formGridLayout-&gt;addWidget( editPassword, 1, 1 );<br /> formGridLayout-&gt;addWidget( buttons, 2, 0, 1, 2 );
 
setLayout( formGridLayout );
 
}
 
void LoginDialog::setUsername(QString &amp;username){<br /> bool found = false;<br /> for( int i = 0; i &lt; comboUsername-&gt;count() &amp;&amp; ! found ; i++ )<br /> if( comboUsername-&gt;itemText( i ) == username ){<br /> comboUsername-&gt;setCurrentIndex( i );<br /> found = true;<br /> }
 
if( ! found ){<br /> int index = comboUsername-&gt;count();<br /> qDebug() &lt;&lt; &quot;Select username &quot; &lt;&lt; index;<br /> comboUsername-&gt;addItem( username );
 
comboUsername-&gt;setCurrentIndex( index );<br /> }
 
// place the focus on the password field<br /> editPassword-&gt;setFocus();<br />}
 
void LoginDialog::setPassword(QString &amp;password){<br /> editPassword-&gt;setText( password );<br />}
 
void LoginDialog::slotAcceptLogin(){<br /> QString username = comboUsername-&gt;currentText();<br /> QString password = editPassword-&gt;text();<br /> int index = comboUsername-&gt;currentIndex();
 
emit acceptLogin( username, // current username<br /> password, // current password<br /> index // index in the username list<br /> );
 
// close this dialog<br /> close();<br />}
 
void LoginDialog::setUsernamesList(const QStringList &amp;usernames){<br /> comboUsername-&gt;addItems( usernames );<br />}
 
</code>
 
== Usage example ==
 
<code>LoginDialog* loginDialog = new LoginDialog( this );<br />loginDialog-&gt;setUsername( &quot;Luca&amp;quot; ); // optional<br />connect( loginDialog,<br /> SIGNAL (acceptLogin(QString&amp;amp;,QString&amp;amp;,int&amp;amp;)),<br /> this,<br /> SLOT (slotAcceptUserLogin(QString&amp;amp;,QString&amp;amp;)));<br />loginDialog-&gt;exec&amp;amp;#40;&amp;#41;;
 
</code>

Revision as of 14:33, 23 February 2015


An example of user login dialog

This code snippets shows how to implement a simple dialog window that allows the user to enter his username and password in order to make a login attempt. The dialog window will emit a signal in order to notify a listener for the login credentials. The login dialog can also presents a list of usernames to select one from.
The dialog also allows for the proposal of a specified username/password as it could be loaded from a settings or a configuration file.

Header file

<br />#include &lt;QDialog&amp;gt;<br />#include &lt;QLabel&amp;gt;<br />#include &lt;QPushButton&amp;gt;<br />#include &lt;QDialogButtonBox&amp;gt;<br />#include &lt;QLineEdit&amp;gt;<br />#include &lt;QComboBox&amp;gt;<br />#include &lt;QGridLayout&amp;gt;<br />#include &lt;QStringList&amp;gt;<br />#include &lt;QDebug&amp;gt;

/*!<br /> '''Makes class LoginDialog a child to its parent, QDialog<br />'''/<br />class LoginDialog : public QDialog<br />{<br />/*!<br /> '''Turns Login Dialog into a QObject<br />'''/<br /> Q_OBJECT

private:<br /> /*!<br /> * A label for the username component.<br /> '''/<br /> QLabel''' labelUsername;

/*!<br /> * A label for the password.<br /> '''/<br /> QLabel''' labelPassword;

/*!<br /> * An editable combo box for allowing the user<br /> * to enter his username or select it from a list.<br /> '''/<br /> QComboBox''' comboUsername;

/*!<br /> * A field to let the user enters his password.<br /> '''/<br /> QLineEdit''' editPassword;

/*!<br /> * The standard dialog button box.<br /> '''/<br /> QDialogButtonBox''' buttons;

/*!<br /> * A method to set up all dialog components and<br /> * initialize them.<br /> */<br /> void setUpGUI();

public:<br /> explicit LoginDialog(QWidget '''parent = 0);
<br /> /'''!<br /> * Sets the proposed username, that can come for instance<br /> * from a shared setting.<br /> '''username the string that represents the current username<br />''' to display<br /> '''/<br /> void setUsername( QString&amp;amp; username );
<br /> /'''!<br /> * Sets the current password to propose to the user for the login.<br /> * password the password to fill into the dialog form<br /> '''/<br /> void setPassword( QString&amp;amp; password );
<br /> /'''!<br /> * Sets a list of allowed usernames from which the user<br /> * can pick one if he does not want to directly edit it.<br /> '''usernames a list of usernames<br />'''/<br /> void setUsernamesList( const QStringList&amp;amp; usernames );

signals:

/*!<br /> * A signal emitted when the login is performed.<br /> * username the username entered in the dialog<br /> * password the password entered in the dialog<br /> * index the number of the username selected in the combobox<br /> '''/<br /> void acceptLogin( QString&amp;amp; username, QString&amp;amp; password, int&amp;amp; indexNumber );
<br />public slots:<br /> /'''!<br /> * A lot to adjust the emitting of the signal.<br /> */<br /> void slotAcceptLogin();

};

#endif // LOGINDIALOG_H

Implementation

LoginDialog::LoginDialog(QWidget '''parent) :<br /> QDialog(parent)<br />{<br /> setUpGUI();<br /> setWindowTitle( tr(&quot;User Login&amp;quot;) );<br /> setModal( true );<br />}
<br />void LoginDialog::setUpGUI(){<br /> // set up the layout<br /> QGridLayout''' formGridLayout = new QGridLayout( this );

// initialize the username combo box so that it is editable<br /> comboUsername = new QComboBox( this );<br /> comboUsername-&gt;setEditable( true );<br /> // initialize the password field so that it does not echo<br /> // characters<br /> editPassword = new QLineEdit( this );<br /> editPassword-&gt;setEchoMode( QLineEdit::Password );

// initialize the labels<br /> labelUsername = new QLabel( this );<br /> labelPassword = new QLabel( this );<br /> labelUsername-&gt;setText( tr( &quot;Username&amp;quot; ) );<br /> labelUsername-&gt;setBuddy( comboUsername );<br /> labelPassword-&gt;setText( tr( &quot;Password&amp;quot; ) );<br /> labelPassword-&gt;setBuddy( editPassword );

// initialize buttons<br /> buttons = new QDialogButtonBox( this );<br /> buttons-&gt;addButton( QDialogButtonBox::Ok );<br /> buttons-&gt;addButton( QDialogButtonBox::Cancel );<br /> buttons-&gt;button( QDialogButtonBox::Ok )<s>&gt;setText( tr(&quot;Login&amp;quot;) );<br /> buttons</s>&gt;button( QDialogButtonBox::Cancel )<s>&gt;setText( tr(&quot;Abort&amp;quot;) );
<br /> // connects slots<br /> connect( buttons</s>&gt;button( QDialogButtonBox::Cancel ),<br /> SIGNAL (clicked()),<br /> this,<br /> SLOT (close())<br /> );

connect( buttons-&gt;button( QDialogButtonBox::Ok ),<br /> SIGNAL (clicked()),<br /> this,<br /> SLOT (slotAcceptLogin()) );

// place components into the dialog<br /> formGridLayout-&gt;addWidget( labelUsername, 0, 0 );<br /> formGridLayout-&gt;addWidget( comboUsername, 0, 1 );<br /> formGridLayout-&gt;addWidget( labelPassword, 1, 0 );<br /> formGridLayout-&gt;addWidget( editPassword, 1, 1 );<br /> formGridLayout-&gt;addWidget( buttons, 2, 0, 1, 2 );

setLayout( formGridLayout );

}

void LoginDialog::setUsername(QString &amp;username){<br /> bool found = false;<br /> for( int i = 0; i &lt; comboUsername-&gt;count() &amp;&amp; ! found ; i++ )<br /> if( comboUsername-&gt;itemText( i ) == username ){<br /> comboUsername-&gt;setCurrentIndex( i );<br /> found = true;<br /> }

if( ! found ){<br /> int index = comboUsername-&gt;count();<br /> qDebug() &lt;&lt; &quot;Select username &quot; &lt;&lt; index;<br /> comboUsername-&gt;addItem( username );

comboUsername-&gt;setCurrentIndex( index );<br /> }

// place the focus on the password field<br /> editPassword-&gt;setFocus();<br />}

void LoginDialog::setPassword(QString &amp;password){<br /> editPassword-&gt;setText( password );<br />}

void LoginDialog::slotAcceptLogin(){<br /> QString username = comboUsername-&gt;currentText();<br /> QString password = editPassword-&gt;text();<br /> int index = comboUsername-&gt;currentIndex();

emit acceptLogin( username, // current username<br /> password, // current password<br /> index // index in the username list<br /> );

// close this dialog<br /> close();<br />}

void LoginDialog::setUsernamesList(const QStringList &amp;usernames){<br /> comboUsername-&gt;addItems( usernames );<br />}

Usage example

LoginDialog* loginDialog = new LoginDialog( this );<br />loginDialog-&gt;setUsername( &quot;Luca&amp;quot; ); // optional<br />connect( loginDialog,<br /> SIGNAL (acceptLogin(QString&amp;amp;,QString&amp;amp;,int&amp;amp;)),<br /> this,<br /> SLOT (slotAcceptUserLogin(QString&amp;amp;,QString&amp;amp;)));<br />loginDialog-&gt;exec&amp;amp;#40;&amp;#41;;