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# Listbox Example

This example shows how to use the different modes (single columns, multiple columns, fixed number of rows, etc.) of QListBox.

Header file:

    /****************************************************************************
    ** $Id:  qt/listbox.h   3.0.3   edited Oct 12 12:18 $
    **
    ** 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 LISTBOX_H
    #define LISTBOX_H

    class QSpinBox;
    class QListBox;
    class QButtonGroup;

    #include <qwidget.h>

    class ListBoxDemo: public QWidget
    {
        Q_OBJECT
    public:
        ListBoxDemo();
        ~ListBoxDemo();

    private slots:
        void setNumRows();
        void setNumCols();
        void setRowsByHeight();
        void setColsByWidth();
        void setVariableWidth( bool );
        void setVariableHeight( bool );
        void setMultiSelection( bool );
        void sortAscending();
        void sortDescending();

    private:
        QListBox * l;
        QSpinBox * columns;
        QSpinBox * rows;
        QButtonGroup * bg;
    };

    #endif

Implementation:

    /****************************************************************************
    ** $Id:  qt/listbox.cpp   3.0.3   edited Oct 12 12:18 $
    **
    ** 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 "listbox.h"

    #include <qlabel.h>
    #include <qradiobutton.h>
    #include <qcheckbox.h>
    #include <qspinbox.h>
    #include <qlistbox.h>
    #include <qbuttongroup.h>
    #include <qlayout.h>
    #include <qpushbutton.h>

    ListBoxDemo::ListBoxDemo()
        : QWidget( 0, 0 )
    {
        QGridLayout * g = new QGridLayout( this, 2, 2, 6 );

        g->addWidget( new QLabel( "<b>Configuration:</b>", this ), 0, 0 );
        g->addWidget( new QLabel( "<b>Result:</b>", this ), 0, 1 );

        l = new QListBox( this );
        g->addWidget( l, 1, 1 );
        l->setFocusPolicy( QWidget::StrongFocus );

        QVBoxLayout * v = new QVBoxLayout;
        g->addLayout( v, 1, 0 );

        QRadioButton * b;
        bg = new QButtonGroup( 0 );

        b = new QRadioButton( "Fixed number of columns,\n"
                              "as many rows as needed.",
                              this );
        bg->insert( b );
        v->addWidget( b );
        b->setChecked( TRUE );
        connect( b, SIGNAL(clicked()), this, SLOT(setNumCols()) );
        QHBoxLayout * h = new QHBoxLayout;
        v->addLayout( h );
        h->addSpacing( 30 );
        h->addSpacing( 100 );
        h->addWidget( new QLabel( "Columns:", this ) );
        columns = new QSpinBox( this );
        h->addWidget( columns );

        v->addSpacing( 12 );

        b = new QRadioButton( "As many columns as fit on-screen,\n"
                              "as many rows as needed.",
                              this );
        bg->insert( b );
        v->addWidget( b );
        connect( b, SIGNAL(clicked()), this, SLOT(setColsByWidth()) );

        v->addSpacing( 12 );

        b = new QRadioButton( "Fixed number of rows,\n"
                              "as many columns as needed.",
                              this );
        bg->insert( b );
        v->addWidget( b );
        connect( b, SIGNAL(clicked()), this, SLOT(setNumRows()) );
        h = new QHBoxLayout;
        v->addLayout( h );
        h->addSpacing( 30 );
        h->addSpacing( 100 );
        h->addWidget( new QLabel( "Rows:", this ) );
        rows = new QSpinBox( this );
        rows->setEnabled( FALSE );
        h->addWidget( rows );

        v->addSpacing( 12 );

        b = new QRadioButton( "As many rows as fit on-screen,\n"
                              "as many columns as needed.",
                              this );
        bg->insert( b );
        v->addWidget( b );
        connect( b, SIGNAL(clicked()), this, SLOT(setRowsByHeight()) );

        v->addSpacing( 12 );

        QCheckBox * cb = new QCheckBox( "Variable-height rows", this );
        cb->setChecked( TRUE );
        connect( cb, SIGNAL(toggled(bool)), this, SLOT(setVariableHeight(bool)) );
        v->addWidget( cb );
        v->addSpacing( 6 );

        cb = new QCheckBox( "Variable-width columns", this );
        connect( cb, SIGNAL(toggled(bool)), this, SLOT(setVariableWidth(bool)) );
        v->addWidget( cb );

        cb = new QCheckBox( "Extended-Selection", this );
        connect( cb, SIGNAL(toggled(bool)), this, SLOT(setMultiSelection(bool)) );
        v->addWidget( cb );

        QPushButton *pb = new QPushButton( "Sort ascending", this );
        connect( pb, SIGNAL( clicked() ), this, SLOT( sortAscending() ) );
        v->addWidget( pb );

        pb = new QPushButton( "Sort descending", this );
        connect( pb, SIGNAL( clicked() ), this, SLOT( sortDescending() ) );
        v->addWidget( pb );

        v->addStretch( 100 );

        int i = 0;
        while( ++i <= 2560 )
            l->insertItem( QString::fromLatin1( "Item " ) + QString::number( i ),
                           i );
        columns->setRange( 1, 256 );
        columns->setValue( 1 );
        rows->setRange( 1, 256 );
        rows->setValue( 256 );

        connect( columns, SIGNAL(valueChanged(int)), this, SLOT(setNumCols()) );
        connect( rows, SIGNAL(valueChanged(int)), this, SLOT(setNumRows()) );
    }

    ListBoxDemo::~ListBoxDemo()
    {
        delete bg;
    }

    void ListBoxDemo::setNumRows()
    {
        columns->setEnabled( FALSE );
        rows->setEnabled( TRUE );
        l->setRowMode( rows->value() );
    }

    void ListBoxDemo::setNumCols()
    {
        columns->setEnabled( TRUE );
        rows->setEnabled( FALSE );
        l->setColumnMode( columns->value() );
    }

    void ListBoxDemo::setRowsByHeight()
    {
        columns->setEnabled( FALSE );
        rows->setEnabled( FALSE );
        l->setRowMode( QListBox::FitToHeight );
    }

    void ListBoxDemo::setColsByWidth()
    {
        columns->setEnabled( FALSE );
        rows->setEnabled( FALSE );
        l->setColumnMode( QListBox::FitToWidth );
    }

    void ListBoxDemo::setVariableWidth( bool b )
    {
        l->setVariableWidth( b );
    }

    void ListBoxDemo::setVariableHeight( bool b )
    {
        l->setVariableHeight( b );
    }

    void ListBoxDemo::setMultiSelection( bool b )
    {
        l->clearSelection();
        l->setSelectionMode( b ? QListBox::Extended : QListBox::Single );
    }

    void ListBoxDemo::sortAscending()
    {
        l->sort( TRUE );
    }

    void ListBoxDemo::sortDescending()
    {
        l->sort( FALSE );
    }

Main:

    /****************************************************************************
    ** $Id:  qt/main.cpp   3.0.3   edited Oct 12 12:18 $
    **
    ** 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 "listbox.h"
    #include <qapplication.h>

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

        ListBoxDemo t;
        t.setCaption( "Qt Example - Listbox" );
        a.setMainWidget( &t );
        t.show();

        return a.exec();
    }

See also Examples.