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# An MDI Application

This example program is just like the application example, except that it provides a Multiple Document Interface (MDI).

Header file:

    /****************************************************************************
    ** $Id: qt/application.h   3.3.8   edited Jan 11 14:37 $
    **
    ** Copyright (C) 1992-2007 Trolltech ASA.  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 APPLICATION_H
    #define APPLICATION_H

    #include <qmainwindow.h>
    #include <qptrlist.h>

    class QTextEdit;
    class QToolBar;
    class QPopupMenu;
    class QWorkspace;
    class QPopupMenu;
    class QMovie;

    class MDIWindow: public QMainWindow
    {
        Q_OBJECT
    public:
        MDIWindow( QWidget* parent, const char* name, int wflags );
        ~MDIWindow();

        void load( const QString& fn );
        void save();
        void saveAs();
        void print( QPrinter* );

    protected:
        void closeEvent( QCloseEvent * );

    signals:
        void message(const QString&, int );

    private:
        QTextEdit* medit;
        QMovie * mmovie;
        QString filename;
    };

    class ApplicationWindow: public QMainWindow
    {
        Q_OBJECT
    public:
        ApplicationWindow();
        ~ApplicationWindow();

    protected:
        void closeEvent( QCloseEvent * );

    private slots:
        MDIWindow* newDoc();
        void load();
        void save();
        void saveAs();
        void print();
        void closeWindow();
        void tileHorizontal();

        void about();
        void aboutQt();

        void windowsMenuAboutToShow();
        void windowsMenuActivated( int id );

    private:
        QPrinter *printer;
        QWorkspace* ws;
        QToolBar *fileTools;
        QPopupMenu* windowsMenu;
    };

    #endif

Implementation:

    /****************************************************************************
    ** $Id: qt/application.cpp   3.3.8   edited Jan 11 14:37 $
    **
    ** Copyright (C) 1992-2007 Trolltech ASA.  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 "application.h"
    #include <qworkspace.h>
    #include <qimage.h>
    #include <qpixmap.h>
    #include <qtoolbar.h>
    #include <qtoolbutton.h>
    #include <qpopupmenu.h>
    #include <qmenubar.h>
    #include <qmovie.h>
    #include <qfile.h>
    #include <qfiledialog.h>
    #include <qlabel.h>
    #include <qstatusbar.h>
    #include <qmessagebox.h>
    #include <qprinter.h>
    #include <qapplication.h>
    #include <qpushbutton.h>
    #include <qaccel.h>
    #include <qtextstream.h>
    #include <qtextedit.h>
    #include <qpainter.h>
    #include <qpaintdevicemetrics.h>
    #include <qwhatsthis.h>
    #include <qobjectlist.h>
    #include <qvbox.h>
    #include <qsimplerichtext.h>

    #include "filesave.xpm"
    #include "fileopen.xpm"
    #include "fileprint.xpm"

    const char * fileOpenText = "Click this button to open a <em>new file</em>. <br><br>"
    "You can also select the <b>Open command</b> from the File menu.";
    const char * fileSaveText = "Click this button to save the file you are "
    "editing.  You will be prompted for a file name.\n\n"
    "You can also select the Save command from the File menu.\n\n"
    "Note that implementing this function is left as an exercise for the reader.";
    const char * filePrintText = "Click this button to print the file you "
    "are editing.\n\n"
    "You can also select the Print command from the File menu.";

    ApplicationWindow::ApplicationWindow()
        : QMainWindow( 0, "example application main window", WDestructiveClose )
    {
        int id;

        QPixmap openIcon, saveIcon;

        fileTools = new QToolBar( this, "file operations" );
        addToolBar( fileTools, tr( "File Operations" ), DockTop, TRUE );

        openIcon = QPixmap( fileopen );
        QToolButton * fileOpen
            = new QToolButton( openIcon, "Open File", QString::null,
                               this, SLOT(load()), fileTools, "open file" );

        saveIcon = QPixmap( filesave );
        QToolButton * fileSave
            = new QToolButton( saveIcon, "Save File", QString::null,
                               this, SLOT(save()), fileTools, "save file" );

    #ifndef QT_NO_PRINTER
        printer = new QPrinter( QPrinter::HighResolution );
        QPixmap printIcon;

        printIcon = QPixmap( fileprint );
        QToolButton * filePrint
            = new QToolButton( printIcon, "Print File", QString::null,
                               this, SLOT(print()), fileTools, "print file" );
        QWhatsThis::add( filePrint, filePrintText );
    #endif

        (void)QWhatsThis::whatsThisButton( fileTools );

        QWhatsThis::add( fileOpen, fileOpenText );
        QWhatsThis::add( fileSave, fileSaveText );

        QPopupMenu * file = new QPopupMenu( this );
        menuBar()->insertItem( "&File", file );

        file->insertItem( "&New", this, SLOT(newDoc()), CTRL+Key_N );

        id = file->insertItem( openIcon, "&Open...",
                               this, SLOT(load()), CTRL+Key_O );
        file->setWhatsThis( id, fileOpenText );

        id = file->insertItem( saveIcon, "&Save",
                               this, SLOT(save()), CTRL+Key_S );
        file->setWhatsThis( id, fileSaveText );
        id = file->insertItem( "Save &As...", this, SLOT(saveAs()) );
        file->setWhatsThis( id, fileSaveText );
    #ifndef QT_NO_PRINTER
        file->insertSeparator();
        id = file->insertItem( printIcon, "&Print...",
                               this, SLOT(print()), CTRL+Key_P );
        file->setWhatsThis( id, filePrintText );
    #endif
        file->insertSeparator();
        file->insertItem( "&Close", this, SLOT(closeWindow()), CTRL+Key_W );
        file->insertItem( "&Quit", qApp, SLOT( closeAllWindows() ), CTRL+Key_Q );

        windowsMenu = new QPopupMenu( this );
        windowsMenu->setCheckable( TRUE );
        connect( windowsMenu, SIGNAL( aboutToShow() ),
                 this, SLOT( windowsMenuAboutToShow() ) );
        menuBar()->insertItem( "&Windows", windowsMenu );

        menuBar()->insertSeparator();
        QPopupMenu * help = new QPopupMenu( this );
        menuBar()->insertItem( "&Help", help );

        help->insertItem( "&About", this, SLOT(about()), Key_F1);
        help->insertItem( "About &Qt", this, SLOT(aboutQt()));
        help->insertSeparator();
        help->insertItem( "What's &This", this, SLOT(whatsThis()), SHIFT+Key_F1);

        QVBox* vb = new QVBox( this );
        vb->setFrameStyle( QFrame::StyledPanel | QFrame::Sunken );
        ws = new QWorkspace( vb );
        ws->setScrollBarsEnabled( TRUE );
        setCentralWidget( vb );

        statusBar()->message( "Ready", 2000 );
    }

    ApplicationWindow::~ApplicationWindow()
    {
    #ifndef QT_NO_PRINTER
        delete printer;
    #endif
    }

    MDIWindow* ApplicationWindow::newDoc()
    {
        MDIWindow* w = new MDIWindow( ws, 0, WDestructiveClose );
        connect( w, SIGNAL( message(const QString&, int) ), statusBar(), SLOT( message(const QString&, int )) );
        w->setCaption("unnamed document");
        w->setIcon( QPixmap("document.xpm") );
        // show the very first window in maximized mode
        if ( ws->windowList().isEmpty() )
            w->showMaximized();
        else
            w->show();
        return w;
    }

    void ApplicationWindow::load()
    {
        QString fn = QFileDialog::getOpenFileName( QString::null, QString::null, this );
        if ( !fn.isEmpty() ) {
            MDIWindow* w = newDoc();
            w->load( fn );
        }  else {
            statusBar()->message( "Loading aborted", 2000 );
        }
    }

    void ApplicationWindow::save()
    {
        MDIWindow* m = (MDIWindow*)ws->activeWindow();
        if ( m )
            m->save();
    }

    void ApplicationWindow::saveAs()
    {
        MDIWindow* m = (MDIWindow*)ws->activeWindow();
        if ( m )
            m->saveAs();
    }

    void ApplicationWindow::print()
    {
    #ifndef QT_NO_PRINTER
        MDIWindow* m = (MDIWindow*)ws->activeWindow();
        if ( m )
            m->print( printer );
    #endif
    }

    void ApplicationWindow::closeWindow()
    {
        MDIWindow* m = (MDIWindow*)ws->activeWindow();
        if ( m )
            m->close();
    }

    void ApplicationWindow::about()
    {
        QMessageBox::about( this, "Qt Application Example",
                            "This example demonstrates simple use of\n "
                            "Qt's Multiple Document Interface (MDI).");
    }

    void ApplicationWindow::aboutQt()
    {
        QMessageBox::aboutQt( this, "Qt Application Example" );
    }

    void ApplicationWindow::windowsMenuAboutToShow()
    {
        windowsMenu->clear();
        int cascadeId = windowsMenu->insertItem("&Cascade", ws, SLOT(cascade() ) );
        int tileId = windowsMenu->insertItem("&Tile", ws, SLOT(tile() ) );
        int horTileId = windowsMenu->insertItem("Tile &Horizontally", this, SLOT(tileHorizontal() ) );
        if ( ws->windowList().isEmpty() ) {
            windowsMenu->setItemEnabled( cascadeId, FALSE );
            windowsMenu->setItemEnabled( tileId, FALSE );
            windowsMenu->setItemEnabled( horTileId, FALSE );
        }
        windowsMenu->insertSeparator();
        QWidgetList windows = ws->windowList();
        for ( int i = 0; i < int(windows.count()); ++i ) {
            int id = windowsMenu->insertItem(windows.at(i)->caption(),
                                             this, SLOT( windowsMenuActivated( int ) ) );
            windowsMenu->setItemParameter( id, i );
            windowsMenu->setItemChecked( id, ws->activeWindow() == windows.at(i) );
        }
    }

    void ApplicationWindow::windowsMenuActivated( int id )
    {
        QWidget* w = ws->windowList().at( id );
        if ( w )
            w->showNormal();
        w->setFocus();
    }

    void ApplicationWindow::tileHorizontal()
    {
        // primitive horizontal tiling
        QWidgetList windows = ws->windowList();
        if ( !windows.count() )
            return;

        if (ws->activeWindow())
            ws->activeWindow()->showNormal();

        int heightForEach = ws->height() / windows.count();
        int y = 0;
        for ( int i = 0; i < int(windows.count()); ++i ) {
            QWidget *window = windows.at(i);
            int preferredHeight = window->minimumHeight()+window->parentWidget()->baseSize().height();
            int actHeight = QMAX(heightForEach, preferredHeight);

            window->parentWidget()->setGeometry( 0, y, ws->width(), actHeight );
            y += actHeight;
        }
    }

    void ApplicationWindow::closeEvent( QCloseEvent *e )
    {
        QWidgetList windows = ws->windowList();
        if ( windows.count() ) {
            for ( int i = 0; i < int(windows.count()); ++i ) {
                QWidget *window = windows.at( i );
                if ( !window->close() ) {
                    e->ignore();
                    return;
                }
            }
        }

        QMainWindow::closeEvent( e );
    }

    MDIWindow::MDIWindow( QWidget* parent, const char* name, int wflags )
        : QMainWindow( parent, name, wflags )
    {
        mmovie = 0;
        medit = new QTextEdit( this );
        setFocusProxy( medit );
        setCentralWidget( medit );
    }

    MDIWindow::~MDIWindow()
    {
        delete mmovie;
    }

    void MDIWindow::closeEvent( QCloseEvent *e )
    {
        if ( medit->isModified() ) {
            switch( QMessageBox::warning( this, "Save Changes",
                tr("Save changes to %1?").arg( caption() ),
                tr("Yes"), tr("No"), tr("Cancel") ) ) {
            case 0:
                {
                    save();
                    if ( !filename.isEmpty() )
                        e->accept();
                    else
                        e->ignore();
                }
                break;
            case 1:
                e->accept();
                break;
            default:
                e->ignore();
                break;
            }
        } else {
            e->accept();
        }
    }

    void MDIWindow::load( const QString& fn )
    {
        filename  = fn;
        QFile f( filename );
        if ( !f.open( IO_ReadOnly ) )
            return;

        if(fn.contains(".gif")) {
            QWidget * tmp=new QWidget(this);
            setFocusProxy(tmp);
            setCentralWidget(tmp);
            medit->hide();
            delete medit;
            QMovie * qm=new QMovie(fn);
    #ifdef Q_WS_QWS // temporary speed-test hack
            qm->setDisplayWidget(tmp);
    #endif
            tmp->setBackgroundMode(QWidget::NoBackground);
            tmp->show();
            mmovie=qm;
        } else {
            mmovie = 0;

            QTextStream t(&f);
            QString s = t.read();
            medit->setText( s );
            f.close();

        }
        setCaption( filename );
        emit message( QString("Loaded document %1").arg(filename), 2000 );
    }

    void MDIWindow::save()
    {
        if ( filename.isEmpty() ) {
            saveAs();
            return;
        }

        QString text = medit->text();
        QFile f( filename );
        if ( !f.open( IO_WriteOnly ) ) {
            emit message( QString("Could not write to %1").arg(filename),
                          2000 );
            return;
        }

        QTextStream t( &f );
        t << text;
        f.close();

        setCaption( filename );

        emit message( QString( "File %1 saved" ).arg( filename ), 2000 );
    }

    void MDIWindow::saveAs()
    {
        QString fn = QFileDialog::getSaveFileName( filename, QString::null, this );
        if ( !fn.isEmpty() ) {
            filename = fn;
            save();
        } else {
            emit message( "Saving aborted", 2000 );
        }
    }

    void MDIWindow::print( QPrinter* printer)
    {
    #ifndef QT_NO_PRINTER
        int pageNo = 1;

        if ( printer->setup(this) ) {               // printer dialog
            printer->setFullPage( TRUE );
            emit message( "Printing...", 0 );
            QPainter p;
            if ( !p.begin( printer ) )
                return;                             // paint on printer
            QPaintDeviceMetrics metrics( p.device() );
            int dpiy = metrics.logicalDpiY();
            int margin = (int) ( (2/2.54)*dpiy ); // 2 cm margins
            QRect view( margin, margin, metrics.width() - 2*margin, metrics.height() - 2*margin );
            QSimpleRichText richText( QStyleSheet::convertFromPlainText(medit->text()),
                                      QFont(),
                                      medit->context(),
                                      medit->styleSheet(),
                                      medit->mimeSourceFactory(),
                                      view.height() );
            richText.setWidth( &p, view.width() );
            int page = 1;
            do {
                richText.draw( &p, margin, margin, view, colorGroup() );
                view.moveBy( 0, view.height() );
                p.translate( 0 , -view.height() );
                p.drawText( view.right() - p.fontMetrics().width( QString::number( page ) ),
                            view.bottom() + p.fontMetrics().ascent() + 5, QString::number( page ) );
                if ( view.top() - margin >= richText.height() )
                    break;
                QString msg( "Printing (page " );
                msg += QString::number( ++pageNo );
                msg += ")...";
                emit message( msg, 0 );
                printer->newPage();
                page++;
            } while (TRUE);
        }
    #endif
    }

Main:

    /****************************************************************************
    ** $Id: qt/main.cpp   3.3.8   edited Jan 11 14:37 $
    **
    ** Copyright (C) 1992-2007 Trolltech ASA.  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 <qapplication.h>
    #include "application.h"

    int main( int argc, char ** argv ) {
        QApplication a( argc, argv );
        ApplicationWindow * mw = new ApplicationWindow();
        a.setMainWidget(mw);
        mw->setCaption( "Qt Example - Multiple Documents Interface (MDI)" );
        mw->show();
        a.connect( &a, SIGNAL(lastWindowClosed()), &a, SLOT(quit()) );
        int res = a.exec();
        return res;
    }

See also Examples.