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[[Category:HowTo]]<br />[[Category:snippets]]
[[Category:HowTo]]
[[Category:snippets]]


= An example of user login dialog =
= 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.<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.
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 ==
== Header file ==


<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;
<code>
#include <QDialog>
#include <QLabel>
#include <QPushButton>
#include <QDialogButtonBox>
#include <QLineEdit>
#include <QComboBox>
#include <QGridLayout>
#include <QStringList>
#include <QDebug>


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


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


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


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


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


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


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


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


};
};
Line 39: Line 109:
== Implementation ==
== Implementation ==


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


// 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 );
void LoginDialog::setUpGUI(){
// set up the layout
QGridLayout''' formGridLayout = new QGridLayout( this );


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


// 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;) );
// initialize the labels
<br /> // connects slots<br /> connect( buttons</s>&gt;button( QDialogButtonBox::Cancel ),<br /> SIGNAL (clicked()),<br /> this,<br /> SLOT (close())<br /> );
labelUsername = new QLabel( this );
labelPassword = new QLabel( this );
labelUsername->setText( tr( "Username" ) );
labelUsername->setBuddy( comboUsername );
labelPassword->setText( tr( "Password" ) );
labelPassword->setBuddy( editPassword );


connect( buttons-&gt;button( QDialogButtonBox::Ok ),<br /> SIGNAL (clicked()),<br /> this,<br /> SLOT (slotAcceptLogin()) );
// initialize buttons
buttons = new QDialogButtonBox( this );
buttons->addButton( QDialogButtonBox::Ok );
buttons->addButton( QDialogButtonBox::Cancel );
buttons->button( QDialogButtonBox::Ok )->setText( tr("Login") );
buttons->button( QDialogButtonBox::Cancel )->setText( tr("Abort") );


// 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 );
// connects slots
connect( buttons->button( QDialogButtonBox::Cancel ),
SIGNAL (clicked()),
this,
SLOT (close())
);
 
connect( buttons->button( QDialogButtonBox::Ok ),
SIGNAL (clicked()),
this,
SLOT (slotAcceptLogin()) );
 
// place components into the dialog
formGridLayout->addWidget( labelUsername, 0, 0 );
formGridLayout->addWidget( comboUsername, 0, 1 );
formGridLayout->addWidget( labelPassword, 1, 0 );
formGridLayout->addWidget( editPassword, 1, 1 );
formGridLayout->addWidget( buttons, 2, 0, 1, 2 );


setLayout( formGridLayout );
setLayout( formGridLayout );
Line 57: Line 167:
}
}


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


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


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


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


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


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


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


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


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


</code>
</code>
Line 79: Line 213:
== Usage example ==
== 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>LoginDialog* loginDialog = new LoginDialog( this );
loginDialog->setUsername( "Luca" ); // optional
connect( loginDialog,
SIGNAL (acceptLogin(QString&amp;amp;,QString&amp;amp;,int&amp;amp;)),
this,
SLOT (slotAcceptUserLogin(QString&amp;amp;,QString&amp;amp;)));
loginDialog->exec();


</code>
</code>

Revision as of 08:57, 25 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

#include <QDialog>
#include <QLabel>
#include <QPushButton>
#include <QDialogButtonBox>
#include <QLineEdit>
#include <QComboBox>
#include <QGridLayout>
#include <QStringList>
#include <QDebug>

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

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

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

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

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

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

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

public:
 explicit LoginDialog(QWidget '''parent = 0);

 /*!
 * Sets the proposed username, that can come for instance
 * from a shared setting.
 '''username the string that represents the current username
''' to display
 */
 void setUsername( QString&amp;amp; username );

 /*!
 * Sets the current password to propose to the user for the login.
 * password the password to fill into the dialog form
 */
 void setPassword( QString&amp;amp; password );

 /*!
 * Sets a list of allowed usernames from which the user
 * can pick one if he does not want to directly edit it.
 '''usernames a list of usernames
*/
 void setUsernamesList( const QStringList&amp;amp; usernames );

signals:

/*!
 * A signal emitted when the login is performed.
 * username the username entered in the dialog
 * password the password entered in the dialog
 * index the number of the username selected in the combobox
 */
 void acceptLogin( QString&amp;amp; username, QString&amp;amp; password, int&amp;amp; indexNumber );

public slots:
 /*!
 * A lot to adjust the emitting of the signal.
 */
 void slotAcceptLogin();

};

#endif // LOGINDIALOG_H

Implementation

LoginDialog::LoginDialog(QWidget '''parent) :
 QDialog(parent)
{
 setUpGUI();
 setWindowTitle( tr("User Login") );
 setModal( true );
}

void LoginDialog::setUpGUI(){
 // set up the layout
 QGridLayout''' formGridLayout = new QGridLayout( this );

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

// initialize the labels
 labelUsername = new QLabel( this );
 labelPassword = new QLabel( this );
 labelUsername->setText( tr( "Username" ) );
 labelUsername->setBuddy( comboUsername );
 labelPassword->setText( tr( "Password" ) );
 labelPassword->setBuddy( editPassword );

// initialize buttons
 buttons = new QDialogButtonBox( this );
 buttons->addButton( QDialogButtonBox::Ok );
 buttons->addButton( QDialogButtonBox::Cancel );
 buttons->button( QDialogButtonBox::Ok )->setText( tr("Login") );
 buttons->button( QDialogButtonBox::Cancel )->setText( tr("Abort") );

 // connects slots
 connect( buttons->button( QDialogButtonBox::Cancel ),
 SIGNAL (clicked()),
 this,
 SLOT (close())
 );

connect( buttons->button( QDialogButtonBox::Ok ),
 SIGNAL (clicked()),
 this,
 SLOT (slotAcceptLogin()) );

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

setLayout( formGridLayout );

}

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

if( ! found ){
 int index = comboUsername->count();
 qDebug() << "Select username " << index;
 comboUsername->addItem( username );

comboUsername->setCurrentIndex( index );
 }

// place the focus on the password field
 editPassword->setFocus();
}

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

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

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

// close this dialog
 close();
}

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

Usage example

LoginDialog* loginDialog = new LoginDialog( this );
loginDialog->setUsername( "Luca" ); // optional
connect( loginDialog,
 SIGNAL (acceptLogin(QString&amp;amp;,QString&amp;amp;,int&amp;amp;)),
 this,
 SLOT (slotAcceptUserLogin(QString&amp;amp;,QString&amp;amp;)));
loginDialog->exec();