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# Line Edits

This example shows how to work with single lineedit widgets, and how to use different echo modes and validators.

Header file:

    /****************************************************************************
    ** $Id:  qt/lineedits.h   3.0.0   edited Jun 22 13:24 $
    **
    ** Copyright (C) 1992-2000 Trolltech AS.  All rights reserved.
    **
    ** This file is part of an example program for Qt.  This example
    ** program may be used, distributed and modified without limitation.
    **
    *****************************************************************************/

    #ifndef LINEDITS_H
    #define LINEDITS_H

    #include <qgroupbox.h>

    class QLineEdit;
    class QComboBox;

    class LineEdits : public QGroupBox
    {
        Q_OBJECT

    public:
        LineEdits( QWidget *parent = 0, const char *name = 0 );

    protected:
        QLineEdit *lined1, *lined2, *lined3, *lined4;
        QComboBox *combo1, *combo2, *combo3, *combo4;

    protected slots:
        void slotEchoChanged( int );
        void slotValidatorChanged( int );
        void slotAlignmentChanged( int );
        void slotReadOnlyChanged( int );
    };

    #endif

Implementation:

    /****************************************************************************
    ** $Id:  qt/lineedits.cpp   3.0.0   edited Jun 22 13:24 $
    **
    ** Copyright (C) 1992-2000 Trolltech AS.  All rights reserved.
    **
    ** This file is part of an example program for Qt.  This example
    ** program may be used, distributed and modified without limitation.
    **
    *****************************************************************************/

    #include "lineedits.h"

    #include <qlineedit.h>
    #include <qcombobox.h>
    #include <qframe.h>
    #include <qvalidator.h>
    #include <qlabel.h>
    #include <qlayout.h>
    #include <qhbox.h>

    /*
     * Constructor
     *
     * Creates child widgets of the LineEdits widget
     */

    LineEdits::LineEdits( QWidget *parent, const char *name )
        : QGroupBox( 0, Horizontal, "Line edits", parent, name )
    {
        setMargin( 10 );

        QVBoxLayout* box = new QVBoxLayout( layout() );

        QHBoxLayout *row1 = new QHBoxLayout( box );
        row1->setMargin( 5 );

        // Create a Label
        QLabel* label = new QLabel( "Echo Mode: ", this);
        row1->addWidget( label );

        // Create a Combobox with three items...
        combo1 = new QComboBox( FALSE, this );
        row1->addWidget( combo1 );
        combo1->insertItem( "Normal", -1 );
        combo1->insertItem( "Password", -1 );
        combo1->insertItem( "No Echo", -1 );
        // ...and connect the activated() SIGNAL with the slotEchoChanged() SLOT to be able
        // to react when an item is selected
        connect( combo1, SIGNAL( activated( int ) ), this, SLOT( slotEchoChanged( int ) ) );

        // insert the first LineEdit
        lined1 = new QLineEdit( this );
        box->addWidget( lined1 );

        // another widget which is used for layouting
        QHBoxLayout *row2 = new QHBoxLayout( box );
        row2->setMargin( 5 );

        // and the second label
        label = new QLabel( "Validator: ", this );
        row2->addWidget( label );

        // A second Combobox with again three items...
        combo2 = new QComboBox( FALSE, this );
        row2->addWidget( combo2 );
        combo2->insertItem( "No Validator", -1 );
        combo2->insertItem( "Integer Validator", -1 );
        combo2->insertItem( "Double Validator", -1 );
        // ...and again the activated() SIGNAL gets connected with a SLOT
        connect( combo2, SIGNAL( activated( int ) ), this, SLOT( slotValidatorChanged( int ) ) );

        // and the second LineEdit
        lined2 = new QLineEdit( this );
        box->addWidget( lined2 );

        // yet another widget which is used for layouting
        QHBoxLayout *row3 = new QHBoxLayout( box );
        row3->setMargin( 5 );

        // we need a label for this too
        label = new QLabel( "Alignment: ", this );
        row3->addWidget( label );

        // A combo box for setting alignment
        combo3 = new QComboBox( FALSE, this );
        row3->addWidget( combo3 );
        combo3->insertItem( "Left", -1 );
        combo3->insertItem( "Centered", -1 );
        combo3->insertItem( "Right", -1 );
        // ...and again the activated() SIGNAL gets connected with a SLOT
        connect( combo3, SIGNAL( activated( int ) ), this, SLOT( slotAlignmentChanged( int ) ) );

        // and the third lineedit
        lined3 = new QLineEdit( this );
        box->addWidget( lined3 );

        // last widget used for layouting
        QHBox *row4 = new QHBox( this );
        box->addWidget( row4 );
        row4->setMargin( 5 );

        // last label
        (void)new QLabel( "Read-Only: ", row4 );

        // A combo box for setting alignment
        combo4 = new QComboBox( FALSE, row4 );
        combo4->insertItem( "False", -1 );
        combo4->insertItem( "True", -1 );
        // ...and again the activated() SIGNAL gets connected with a SLOT
        connect( combo4, SIGNAL( activated( int ) ), this, SLOT( slotReadOnlyChanged( int ) ) );

        // and the last lineedit
        lined4 = new QLineEdit( this );
        box->addWidget( lined4 );

        // give the first LineEdit the focus at the beginning
        lined1->setFocus();
    }

    /*
     * SLOT slotEchoChanged( int i )
     *
     * i contains the number of the item which the user has been chosen in the
     * first Combobox. According to this value, we set the Echo-Mode for the
     * first LineEdit.
     */

    void LineEdits::slotEchoChanged( int i )
    {
        switch ( i ) {
        case 0:
            lined1->setEchoMode( QLineEdit::Normal );
            break;
        case 1:
            lined1->setEchoMode( QLineEdit::Password );
            break;
        case 2:
            lined1->setEchoMode( QLineEdit::NoEcho );
            break;
        }

        lined1->setFocus();
    }

    /*
     * SLOT slotValidatorChanged( int i )
     *
     * i contains the number of the item which the user has been chosen in the
     * second Combobox. According to this value, we set a validator for the
     * second LineEdit. A validator checks in a LineEdit each character which
     * the user enters and accepts it if it is valid, else the character gets
     * ignored and not inserted into the lineedit.
     */

    void LineEdits::slotValidatorChanged( int i )
    {
        switch ( i ) {
        case 0:
            lined2->setValidator( 0 );
            break;
        case 1:
            lined2->setValidator( new QIntValidator( lined2 ) );
            break;
        case 2:
            lined2->setValidator( new QDoubleValidator( -999.0, 999.0, 2,
                                                        lined2 ) );
            break;
        }

        lined2->setText( "" );
        lined2->setFocus();
    }

    /*
     * SLOT slotAlignmentChanged( int i )
     *
     * i contains the number of the item which the user has been chosen in
     * the third Combobox.  According to this value, we set an alignment
     * third LineEdit.
     */

    void LineEdits::slotAlignmentChanged( int i )
    {
        switch ( i ) {
        case 0:
            lined3->setAlignment( QLineEdit::AlignLeft );
            break;
        case 1:
            lined3->setAlignment( QLineEdit::AlignCenter );
            break;
        case 2:
            lined3->setAlignment( QLineEdit::AlignRight );
            break;
        }

        lined3->setFocus();
    }

    /*
     * SLOT slotReadOnlyChanged( int i )
     *
     * i contains the number of the item which the user has been chosen in
     * the fourth Combobox.  According to this value, we toggle read-only.
     */

    void LineEdits::slotReadOnlyChanged( int i )
    {
        switch ( i ) {
        case 0:
            lined4->setReadOnly( FALSE );
            break;
        case 1:
            lined4->setReadOnly( TRUE );
            break;
        }

        lined4->setFocus();
    }

Main:

    /****************************************************************************
    ** $Id:  qt/main.cpp   3.0.0   edited Jun 22 13:24 $
    **
    ** Copyright (C) 1992-2000 Trolltech AS.  All rights reserved.
    **
    ** This file is part of an example program for Qt.  This example
    ** program may be used, distributed and modified without limitation.
    **
    *****************************************************************************/

    #include "lineedits.h"
    #include <qapplication.h>

    int main( int argc, char **argv )
    {
        QApplication a( argc, argv );

        LineEdits lineedits;
        lineedits.setCaption( "Qt Example - Lineedits" );
        a.setMainWidget( &lineedits );
        lineedits.show();

        return a.exec();
    }

See also Examples.