Home | All Classes | Main Classes | Annotated | Grouped Classes | Functions |

# Using menus

This example demonstrates a menu bar with pull-down menus, sub-menus and custom menu items. It also demonstrates a pop-up context menu.

Header file:

    /****************************************************************************
    ** $Id: qt/menu.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 MENU_H
    #define MENU_H

    #include <qwidget.h>
    #include <qmenubar.h>
    #include <qlabel.h>

    class MenuExample : public QWidget
    {
        Q_OBJECT
    public:
        MenuExample( QWidget *parent=0, const char *name=0 );

    public slots:
        void open();
        void news();
        void save();
        void closeDoc();
        void undo();
        void redo();
        void normal();
        void bold();
        void underline();
        void about();
        void aboutQt();
        void printer();
        void file();
        void fax();
        void printerSetup();

    protected:
        void    resizeEvent( QResizeEvent * );

    signals:
        void    explain( const QString& );

    private:
        void contextMenuEvent ( QContextMenuEvent * );

        QMenuBar *menu;
        QLabel   *label;
        bool isBold;
        bool isUnderline;
        int boldID, underlineID;
    };

    #endif // MENU_H

Implementation:

    /****************************************************************************
    ** $Id: qt/menu.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 "menu.h"
    #include <qcursor.h>
    #include <qpopupmenu.h>
    #include <qapplication.h>
    #include <qmessagebox.h>
    #include <qpixmap.h>
    #include <qpainter.h>

    /* XPM */
    static const char * p1_xpm[] = {
    "16 16 3 1",
    "       c None",
    ".      c #000000000000",
    "X      c #FFFFFFFF0000",
    "                ",
    "                ",
    "         ....   ",
    "        .XXXX.  ",
    " .............. ",
    " .XXXXXXXXXXXX. ",
    " .XXXXXXXXXXXX. ",
    " .XXXXXXXXXXXX. ",
    " .XXXXXXXXXXXX. ",
    " .XXXXXXXXXXXX. ",
    " .XXXXXXXXXXXX. ",
    " .XXXXXXXXXXXX. ",
    " .XXXXXXXXXXXX. ",
    " .XXXXXXXXXXXX. ",
    " .............. ",
    "                "};

    /* XPM */
    static const char * p2_xpm[] = {
    "16 16 3 1",
    "       c None",
    ".      c #000000000000",
    "X      c #FFFFFFFFFFFF",
    "                ",
    "   ......       ",
    "   .XXX.X.      ",
    "   .XXX.XX.     ",
    "   .XXX.XXX.    ",
    "   .XXX.....    ",
    "   .XXXXXXX.    ",
    "   .XXXXXXX.    ",
    "   .XXXXXXX.    ",
    "   .XXXXXXX.    ",
    "   .XXXXXXX.    ",
    "   .XXXXXXX.    ",
    "   .XXXXXXX.    ",
    "   .........    ",
    "                ",
    "                "};

    /* XPM */
    static const char * p3_xpm[] = {
    "16 16 3 1",
    "       c None",
    ".      c #000000000000",
    "X      c #FFFFFFFFFFFF",
    "                ",
    "                ",
    "   .........    ",
    "  ...........   ",
    "  ........ ..   ",
    "  ...........   ",
    "  ...........   ",
    "  ...........   ",
    "  ...........   ",
    "  ...XXXXX...   ",
    "  ...XXXXX...   ",
    "  ...XXXXX...   ",
    "  ...XXXXX...   ",
    "   .........    ",
    "                ",
    "                "};

    /*
      Auxiliary class to provide fancy menu items with different
      fonts. Used for the "bold" and "underline" menu items in the options
      menu.
     */
    class MyMenuItem : public QCustomMenuItem
    {
    public:
        MyMenuItem( const QString& s, const QFont& f )
            : string( s ), font( f ){};
        ~MyMenuItem(){}

        void paint( QPainter* p, const QColorGroup& /*cg*/, bool /*act*/, bool /*enabled*/, int x, int y, int w, int h )
        {
            p->setFont ( font );
            p->drawText( x, y, w, h, AlignLeft | AlignVCenter | DontClip | ShowPrefix, string );
        }

        QSize sizeHint()
        {
            return QFontMetrics( font ).size( AlignLeft | AlignVCenter | ShowPrefix | DontClip,  string );
        }
    private:
        QString string;
        QFont font;
    };

    MenuExample::MenuExample( QWidget *parent, const char *name )
        : QWidget( parent, name )
    {
        QPixmap p1( p1_xpm );
        QPixmap p2( p2_xpm );
        QPixmap p3( p3_xpm );
        QPopupMenu *print = new QPopupMenu( this );
        Q_CHECK_PTR( print );
        print->insertTearOffHandle();
        print->insertItem( "&Print to printer", this, SLOT(printer()) );
        print->insertItem( "Print to &file", this, SLOT(file()) );
        print->insertItem( "Print to fa&x", this, SLOT(fax()) );
        print->insertSeparator();
        print->insertItem( "Printer &Setup", this, SLOT(printerSetup()) );

        QPopupMenu *file = new QPopupMenu( this );
        Q_CHECK_PTR( file );
        file->insertItem( p1, "&Open",  this, SLOT(open()), CTRL+Key_O );
        file->insertItem( p2, "&New", this, SLOT(news()), CTRL+Key_N );
        file->insertItem( p3, "&Save", this, SLOT(save()), CTRL+Key_S );
        file->insertItem( "&Close", this, SLOT(closeDoc()), CTRL+Key_W );
        file->insertSeparator();
        file->insertItem( "&Print", print, CTRL+Key_P );
        file->insertSeparator();
        file->insertItem( "E&xit",  qApp, SLOT(quit()), CTRL+Key_Q );

        QPopupMenu *edit = new QPopupMenu( this );
        Q_CHECK_PTR( edit );
        int undoID = edit->insertItem( "&Undo", this, SLOT(undo()) );
        int redoID = edit->insertItem( "&Redo", this, SLOT(redo()) );
        edit->setItemEnabled( undoID, FALSE );
        edit->setItemEnabled( redoID, FALSE );

        QPopupMenu* options = new QPopupMenu( this );
        Q_CHECK_PTR( options );
        options->insertTearOffHandle();
        options->setCaption("Options");
        options->insertItem( "&Normal Font", this, SLOT(normal()) );
        options->insertSeparator();

        options->polish(); // adjust system settings
        QFont f = options->font();
        f.setBold( TRUE );
        boldID = options->insertItem( new MyMenuItem( "Bold", f ) );
        options->setAccel( CTRL+Key_B, boldID );
        options->connectItem( boldID, this, SLOT(bold()) );
        f = font();
        f.setUnderline( TRUE );
        underlineID = options->insertItem( new MyMenuItem( "Underline", f ) );
        options->setAccel( CTRL+Key_U, underlineID );
        options->connectItem( underlineID, this, SLOT(underline()) );

        isBold = FALSE;
        isUnderline = FALSE;
        options->setCheckable( TRUE );

        QPopupMenu *help = new QPopupMenu( this );
        Q_CHECK_PTR( help );
        help->insertItem( "&About", this, SLOT(about()), CTRL+Key_H );
        help->insertItem( "About &Qt", this, SLOT(aboutQt()) );

        // If we used a QMainWindow we could use its built-in menuBar().
        menu = new QMenuBar( this );
        Q_CHECK_PTR( menu );
        menu->insertItem( "&File", file );
        menu->insertItem( "&Edit", edit );
        menu->insertItem( "&Options", options );
        menu->insertSeparator();
        menu->insertItem( "&Help", help );
        menu->setSeparator( QMenuBar::InWindowsStyle );

        QLabel *msg = new QLabel( this );
        Q_CHECK_PTR( msg );
        msg->setText( "A context menu is available.\n"
                      "Invoke it by right-clicking or by"
                      " pressing the 'context' button." );
        msg->setGeometry( 0, height() - 60, width(), 60 );
        msg->setAlignment( AlignCenter );

        label = new QLabel( this );
        Q_CHECK_PTR( label );
        label->setGeometry( 20, rect().center().y()-20, width()-40, 40 );
        label->setFrameStyle( QFrame::Box | QFrame::Raised );
        label->setLineWidth( 1 );
        label->setAlignment( AlignCenter );

        connect( this,  SIGNAL(explain(const QString&)),
                 label, SLOT(setText(const QString&)) );

        setMinimumSize( 100, 80 );
        setFocusPolicy( QWidget::ClickFocus );
    }

    void MenuExample::contextMenuEvent( QContextMenuEvent * )
    {
        QPopupMenu* contextMenu = new QPopupMenu( this );
        Q_CHECK_PTR( contextMenu );
        QLabel *caption = new QLabel( "<font color=darkblue><u><b>"
            "Context Menu</b></u></font>", this );
        caption->setAlignment( Qt::AlignCenter );
        contextMenu->insertItem( caption );
        contextMenu->insertItem( "&New",  this, SLOT(news()), CTRL+Key_N );
        contextMenu->insertItem( "&Open...", this, SLOT(open()), CTRL+Key_O );
        contextMenu->insertItem( "&Save", this, SLOT(save()), CTRL+Key_S );
        QPopupMenu *submenu = new QPopupMenu( this );
        Q_CHECK_PTR( submenu );
        submenu->insertItem( "&Print to printer", this, SLOT(printer()) );
        submenu->insertItem( "Print to &file", this, SLOT(file()) );
        submenu->insertItem( "Print to fa&x", this, SLOT(fax()) );
        contextMenu->insertItem( "&Print", submenu );
        contextMenu->exec( QCursor::pos() );
        delete contextMenu;
    }

    void MenuExample::open()
    {
        emit explain( "File/Open selected" );
    }

    void MenuExample::news()
    {
        emit explain( "File/New selected" );
    }

    void MenuExample::save()
    {
        emit explain( "File/Save selected" );
    }

    void MenuExample::closeDoc()
    {
        emit explain( "File/Close selected" );
    }

    void MenuExample::undo()
    {
        emit explain( "Edit/Undo selected" );
    }

    void MenuExample::redo()
    {
        emit explain( "Edit/Redo selected" );
    }

    void MenuExample::normal()
    {
        isBold = FALSE;
        isUnderline = FALSE;
        QFont font;
        label->setFont( font );
        menu->setItemChecked( boldID, isBold );
        menu->setItemChecked( underlineID, isUnderline );
        emit explain( "Options/Normal selected" );
    }

    void MenuExample::bold()
    {
        isBold = !isBold;
        QFont font;
        font.setBold( isBold );
        font.setUnderline( isUnderline );
        label->setFont( font );
        menu->setItemChecked( boldID, isBold );
        emit explain( "Options/Bold selected" );
    }

    void MenuExample::underline()
    {
        isUnderline = !isUnderline;
        QFont font;
        font.setBold( isBold );
        font.setUnderline( isUnderline );
        label->setFont( font );
        menu->setItemChecked( underlineID, isUnderline );
        emit explain( "Options/Underline selected" );
    }

    void MenuExample::about()
    {
        QMessageBox::about( this, "Qt Menu Example",
                            "This example demonstrates simple use of Qt menus.\n"
                            "You can cut and paste lines from it to your own\n"
                            "programs." );
    }

    void MenuExample::aboutQt()
    {
        QMessageBox::aboutQt( this, "Qt Menu Example" );
    }

    void MenuExample::printer()
    {
        emit explain( "File/Printer/Print selected" );
    }

    void MenuExample::file()
    {
        emit explain( "File/Printer/Print To File selected" );
    }

    void MenuExample::fax()
    {
        emit explain( "File/Printer/Print To Fax selected" );
    }

    void MenuExample::printerSetup()
    {
        emit explain( "File/Printer/Printer Setup selected" );
    }

    void MenuExample::resizeEvent( QResizeEvent * )
    {
        label->setGeometry( 20, rect().center().y()-20, width()-40, 40 );
    }

    int main( int argc, char ** argv )
    {
        QApplication a( argc, argv );
        MenuExample m;
        m.setCaption("Qt Examples - Menus");
        a.setMainWidget( &m );
        m.show();
        return a.exec();
    }

See also Examples.