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# Listviews

This examples shows how to work with listviews (hierarchical and multi-column). It also shows how to subclass listview items for special reasons. It looks and works like the main window of a mail client.

Header file:

    /****************************************************************************
    ** $Id: qt/listviews.h   3.3.3   edited May 27 2003 $
    **
    ** 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 LISTVIEWS_H
    #define LISTVIEWS_H

    #include <qsplitter.h>
    #include <qstring.h>
    #include <qobject.h>
    #include <qdatetime.h>
    #include <qptrlist.h>
    #include <qlistview.h>

    class QListView;
    class QLabel;
    class QPainter;
    class QColorGroup;
    class QObjectList;
    class QPopupMenu;

    // -----------------------------------------------------------------

    class MessageHeader
    {
    public:
        MessageHeader( const QString &_sender, const QString &_subject, const QDateTime &_datetime )
            : msender( _sender ), msubject( _subject ), mdatetime( _datetime )
        {}

        MessageHeader( const MessageHeader &mh );
        MessageHeader &operator=( const MessageHeader &mh );

        QString sender() { return msender; }
        QString subject() { return msubject; }
        QDateTime datetime() { return mdatetime; }

    protected:
        QString msender, msubject;
        QDateTime mdatetime;

    };

    // -----------------------------------------------------------------

    class Message
    {
    public:
        enum State { Read = 0,
                     Unread};

        Message( const MessageHeader &mh, const QString &_body )
            : mheader( mh ), mbody( _body ), mstate( Unread )
        {}

        Message( const Message &m )
            : mheader( m.mheader ), mbody( m.mbody ), mstate( m.mstate )
        {}

        MessageHeader header() { return mheader; }
        QString body() { return mbody; }

        void setState( const State &s ) { mstate = s; }
        State state() { return mstate; }

    protected:
        MessageHeader mheader;
        QString mbody;
        State mstate;

    };

    // -----------------------------------------------------------------

    class Folder : public QObject
    {
        Q_OBJECT

    public:
        Folder( Folder *parent, const QString &name );
        ~Folder()
        {}

        void addMessage( Message *m )
        { lstMessages.append( m ); }

        QString folderName() { return fName; }

        Message *firstMessage() { return lstMessages.first(); }
        Message *nextMessage() { return lstMessages.next(); }

    protected:
        QString fName;
        QPtrList<Message> lstMessages;

    };

    // -----------------------------------------------------------------

    class FolderListItem : public QListViewItem
    {
    public:
        FolderListItem( QListView *parent, Folder *f );
        FolderListItem( FolderListItem *parent, Folder *f );

        void insertSubFolders( const QObjectList *lst );

        Folder *folder() { return myFolder; }

    protected:
        Folder *myFolder;

    };

    // -----------------------------------------------------------------

    class MessageListItem : public QListViewItem
    {
    public:
        MessageListItem( QListView *parent, Message *m );

        virtual void paintCell( QPainter *p, const QColorGroup &cg,
                                int column, int width, int alignment );

        Message *message() { return myMessage; }

    protected:
        Message *myMessage;

    };

    // -----------------------------------------------------------------

    class ListViews : public QSplitter
    {
        Q_OBJECT

    public:
        ListViews( QWidget *parent = 0, const char *name = 0 );
        ~ListViews()
        {}

    protected:
        void initFolders();
        void initFolder( Folder *folder, unsigned int &count );
        void setupFolders();

        QListView *messages, *folders;
        QLabel *message;
        QPopupMenu* menu;

        QPtrList<Folder> lstFolders;

    protected slots:
        void slotFolderChanged( QListViewItem* );
        void slotMessageChanged();
        void slotRMB( QListViewItem*, const QPoint &, int );

    };

    #endif

Implementation:

    /****************************************************************************
    ** $Id: qt/listviews.cpp   3.3.3   edited May 27 2003 $
    **
    ** 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 "listviews.h"

    #include <qlabel.h>
    #include <qpainter.h>
    #include <qpalette.h>
    #include <qobjectlist.h>
    #include <qpopupmenu.h>
    #include <qheader.h>
    #include <qregexp.h>

    // -----------------------------------------------------------------

    MessageHeader::MessageHeader( const MessageHeader &mh )
    {
        msender = mh.msender;
        msubject = mh.msubject;
        mdatetime = mh.mdatetime;
    }

    MessageHeader &MessageHeader::operator=( const MessageHeader &mh )
    {
        msender = mh.msender;
        msubject = mh.msubject;
        mdatetime = mh.mdatetime;

        return *this;
    }

    // -----------------------------------------------------------------

    Folder::Folder( Folder *parent, const QString &name )
        : QObject( parent, name ), fName( name )
    {
        lstMessages.setAutoDelete( TRUE );
    }

    // -----------------------------------------------------------------

    FolderListItem::FolderListItem( QListView *parent, Folder *f )
        : QListViewItem( parent )
    {
        myFolder = f;
        setText( 0, f->folderName() );

        if ( myFolder->children() )
            insertSubFolders( myFolder->children() );
    }

    FolderListItem::FolderListItem( FolderListItem *parent, Folder *f )
        : QListViewItem( parent )
    {
        myFolder = f;

        setText( 0, f->folderName() );

        if ( myFolder->children() )
            insertSubFolders( myFolder->children() );
    }

    void FolderListItem::insertSubFolders( const QObjectList *lst )
    {
        Folder *f;
        for ( f = ( Folder* )( ( QObjectList* )lst )->first(); f; f = ( Folder* )( ( QObjectList* )lst )->next() )
            (void)new FolderListItem( this, f );
    }

    // -----------------------------------------------------------------

    MessageListItem::MessageListItem( QListView *parent, Message *m )
        : QListViewItem( parent )
    {
        myMessage = m;
        setText( 0, myMessage->header().sender() );
        setText( 1, myMessage->header().subject() );
        setText( 2, myMessage->header().datetime().toString() );
    }

    void MessageListItem::paintCell( QPainter *p, const QColorGroup &cg,
                                     int column, int width, int alignment )
    {
        QColorGroup _cg( cg );
        QColor c = _cg.text();

        if ( myMessage->state() == Message::Unread )
            _cg.setColor( QColorGroup::Text, Qt::red );

        QListViewItem::paintCell( p, _cg, column, width, alignment );

        _cg.setColor( QColorGroup::Text, c );
    }

    // -----------------------------------------------------------------

    ListViews::ListViews( QWidget *parent, const char *name )
        : QSplitter( Qt::Horizontal, parent, name )
    {
        lstFolders.setAutoDelete( TRUE );

        folders = new QListView( this );
        folders->header()->setClickEnabled( FALSE );
        folders->addColumn( "Folder" );

        initFolders();
        setupFolders();

        folders->setRootIsDecorated( TRUE );
        setResizeMode( folders, QSplitter::KeepSize );

        QSplitter *vsplitter = new QSplitter( Qt::Vertical, this );

        messages = new QListView( vsplitter );
        messages->addColumn( "Sender" );
        messages->addColumn( "Subject" );
        messages->addColumn( "Date" );
        messages->setColumnAlignment( 1, Qt::AlignRight );
        messages->setAllColumnsShowFocus( TRUE );
        messages->setShowSortIndicator( TRUE );
        menu = new QPopupMenu( messages );
        for( int i = 1; i <= 10; i++ )
            menu->insertItem( QString( "Context Item %1" ).arg( i ) );
        connect(messages, SIGNAL( contextMenuRequested( QListViewItem *, const QPoint& , int ) ),
                this, SLOT( slotRMB( QListViewItem *, const QPoint &, int ) ) );
        vsplitter->setResizeMode( messages, QSplitter::KeepSize );

        message = new QLabel( vsplitter );
        message->setAlignment( Qt::AlignTop );
        message->setBackgroundMode( PaletteBase );

        connect( folders, SIGNAL( selectionChanged( QListViewItem* ) ),
                 this, SLOT( slotFolderChanged( QListViewItem* ) ) );
        connect( messages, SIGNAL( selectionChanged() ),
                 this, SLOT( slotMessageChanged() ) );
        connect( messages, SIGNAL( currentChanged( QListViewItem * ) ),
                 this, SLOT( slotMessageChanged() ) );

        messages->setSelectionMode( QListView::Extended );
        // some preparations
        folders->firstChild()->setOpen( TRUE );
        folders->firstChild()->firstChild()->setOpen( TRUE );
        folders->setCurrentItem( folders->firstChild()->firstChild()->firstChild() );
        folders->setSelected( folders->firstChild()->firstChild()->firstChild(), TRUE );

        messages->setSelected( messages->firstChild(), TRUE );
        messages->setCurrentItem( messages->firstChild() );
        message->setMargin( 5 );

        QValueList<int> lst;
        lst.append( 170 );
        setSizes( lst );
    }

    void ListViews::initFolders()
    {
        unsigned int mcount = 1;

        for ( unsigned int i = 1; i < 20; i++ ) {
            QString str;
            str = QString( "Folder %1" ).arg( i );
            Folder *f = new Folder( 0, str );
            for ( unsigned int j = 1; j < 5; j++ ) {
                QString str2;
                str2 = QString( "Sub Folder %1" ).arg( j );
                Folder *f2 = new Folder( f, str2 );
                for ( unsigned int k = 1; k < 3; k++ ) {
                    QString str3;
                    str3 = QString( "Sub Sub Folder %1" ).arg( k );
                    Folder *f3 = new Folder( f2, str3 );
                    initFolder( f3, mcount );
                }
            }
            lstFolders.append( f );
        }
    }

    void ListViews::initFolder( Folder *folder, unsigned int &count )
    {
        for ( unsigned int i = 0; i < 15; i++, count++ ) {
            QString str;
            str = QString( "Message %1  " ).arg( count );
            QDateTime dt = QDateTime::currentDateTime();
            dt = dt.addSecs( 60 * count );
            MessageHeader mh( "Trolltech <info@trolltech.com>  ", str, dt );

            QString body;
            body = QString( "This is the message number %1 of this application, \n"
                            "which shows how to use QListViews, QListViewItems, \n"
                            "QSplitters and so on. The code should show how easy\n"
                            "this can be done in Qt." ).arg( count );
            Message *msg = new Message( mh, body );
            folder->addMessage( msg );
        }
    }

    void ListViews::setupFolders()
    {
        folders->clear();

        for ( Folder* f = lstFolders.first(); f; f = lstFolders.next() )
            (void)new FolderListItem( folders, f );
    }

    void ListViews::slotRMB( QListViewItem* Item, const QPoint & point, int )
    {
        if( Item )
            menu->popup( point );
    }

    void ListViews::slotFolderChanged( QListViewItem *i )
    {
        if ( !i )
            return;
        messages->clear();
        message->setText( "" );

        FolderListItem *item = ( FolderListItem* )i;

        for ( Message* msg = item->folder()->firstMessage(); msg;
              msg = item->folder()->nextMessage() )
            (void)new MessageListItem( messages, msg );
    }

    void ListViews::slotMessageChanged()
    {
        QListViewItem *i = messages->currentItem();
        if ( !i )
            return;

        if ( !i->isSelected() ) {
            message->setText( "" );
            return;
        }

        MessageListItem *item = ( MessageListItem* )i;
        Message *msg = item->message();

        QString text;
        QString tmp = msg->header().sender();
        tmp = tmp.replace( "<", "&lt;" );
        tmp = tmp.replace( ">", "&gt;" );
        text = QString( "<b><i>From:</i></b> <a href=\"mailto:info@trolltech.com\">%1</a><br>"
                        "<b><i>Subject:</i></b> <big><big><b>%2</b></big></big><br>"
                        "<b><i>Date:</i></b> %3<br><br>"
                        "%4" ).
               arg( tmp ).arg( msg->header().subject() ).
               arg( msg->header().datetime().toString() ).arg( msg->body() );

        message->setText( text );

        msg->setState( Message::Read );
    }

Main:

    /****************************************************************************
    ** $Id: qt/main.cpp   3.3.3   edited May 27 2003 $
    **
    ** 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 "listviews.h"
    #include <qapplication.h>

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

        ListViews listViews;
        listViews.resize( 640, 480 );
        listViews.setCaption( "Qt Example - Listview" );
        a.setMainWidget( &listViews );
        listViews.show();

        return a.exec();
    }

See also Examples.