A Complete Application Window with Actions

The QAction class provides a way of associating user input from different user interface elements with abstract high level actions. This approach makes it easy to customize applications for different types of users.

This example program is just like the application example, but uses QAction to build the menu and the toolbar.

Header file:

/****************************************************************************
** $Id: qt/application.h   3.3.7   edited Aug 31 2005 $
**
** Copyright (C) 1992-2005 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 APPLICATION_H
#define APPLICATION_H

#include <qmainwindow.h>

class QTextEdit;

class ApplicationWindow: public QMainWindow
{
    Q_OBJECT

public:
    ApplicationWindow();
    ~ApplicationWindow();

protected:
    void closeEvent( QCloseEvent* );

private slots:
    void newDoc();
    void choose();
    void load( const QString &fileName );
    void save();
    void saveAs();
    void print();

    void about();
    void aboutQt();

private:
    QPrinter *printer;
    QTextEdit *e;
    QString filename;
};


#endif

Implementation:

/****************************************************************************
** $Id: qt/application.cpp   3.3.7   edited Aug 31 2005 $
**
** Copyright (C) 1992-2005 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 "application.h"

#include <qimage.h>
#include <qpixmap.h>
#include <qtoolbar.h>
#include <qtoolbutton.h>
#include <qpopupmenu.h>
#include <qmenubar.h>
#include <qtextedit.h>
#include <qfile.h>
#include <qfiledialog.h>
#include <qstatusbar.h>
#include <qmessagebox.h>
#include <qprinter.h>
#include <qapplication.h>
#include <qaccel.h>
#include <qtextstream.h>
#include <qpainter.h>
#include <qpaintdevicemetrics.h>
#include <qwhatsthis.h>
#include <qaction.h>
#include <qsimplerichtext.h>

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


ApplicationWindow::ApplicationWindow()
    : QMainWindow( 0, "example application main window", WDestructiveClose )
{
    printer = new QPrinter( QPrinter::HighResolution );

    QAction * fileNewAction;
    QAction * fileOpenAction;
    QAction * fileSaveAction, * fileSaveAsAction, * filePrintAction;
    QAction * fileCloseAction, * fileQuitAction;

    fileNewAction = new QAction( "&New", CTRL+Key_N, this, "new" );
    connect( fileNewAction, SIGNAL( activated() ) , this,
             SLOT( newDoc() ) );

    fileOpenAction = new QAction( QPixmap( fileopen ), "&Open...",
                                  CTRL+Key_O, this, "open" );
    connect( fileOpenAction, SIGNAL( activated() ) , this, SLOT( choose() ) );

    const char * fileOpenText = "<p><img source=\"fileopen\"> "
                     "Click this button to open a <em>new file</em>. <br>"
                     "You can also select the <b>Open</b> command "
                     "from the <b>File</b> menu.</p>";
    QMimeSourceFactory::defaultFactory()->setPixmap( "fileopen",
                          fileOpenAction->iconSet().pixmap() );
    fileOpenAction->setWhatsThis( fileOpenText );

    fileSaveAction = new QAction( QPixmap( filesave ),
                                  "&Save", CTRL+Key_S, this, "save" );
    connect( fileSaveAction, SIGNAL( activated() ) , this, SLOT( save() ) );

    const char * fileSaveText = "<p>Click this button to save the file you "
                     "are editing. You will be prompted for a file name.\n"
                     "You can also select the <b>Save</b> command "
                     "from the <b>File</b> menu.</p>";
    fileSaveAction->setWhatsThis( fileSaveText );

    fileSaveAsAction = new QAction( "Save File As", "Save &As...", 0,  this,
                                    "save as" );
    connect( fileSaveAsAction, SIGNAL( activated() ) , this,
             SLOT( saveAs() ) );
    fileSaveAsAction->setWhatsThis( fileSaveText );

    filePrintAction = new QAction( "Print File", QPixmap( fileprint ),
                                   "&Print...", CTRL+Key_P, this, "print" );
    connect( filePrintAction, SIGNAL( activated() ) , this,
             SLOT( print() ) );

    const char * filePrintText = "Click this button to print the file you "
                     "are editing.\n You can also select the Print "
                     "command from the File menu.";
    filePrintAction->setWhatsThis( filePrintText );

    fileCloseAction = new QAction( "Close", "&Close", CTRL+Key_W, this,
                                   "close" );
    connect( fileCloseAction, SIGNAL( activated() ) , this,
             SLOT( close() ) );

    fileQuitAction = new QAction( "Quit", "&Quit", CTRL+Key_Q, this,
                                  "quit" );
    connect( fileQuitAction, SIGNAL( activated() ) , qApp,
             SLOT( closeAllWindows() ) );

    // populate a tool bar with some actions

    QToolBar * fileTools = new QToolBar( this, "file operations" );
    fileTools->setLabel( "File Operations" );
    fileOpenAction->addTo( fileTools );
    fileSaveAction->addTo( fileTools );
    filePrintAction->addTo( fileTools );
    (void)QWhatsThis::whatsThisButton( fileTools );


    // populate a menu with all actions

    QPopupMenu * file = new QPopupMenu( this );
    menuBar()->insertItem( "&File", file );
    fileNewAction->addTo( file );
    fileOpenAction->addTo( file );
    fileSaveAction->addTo( file );
    fileSaveAsAction->addTo( file );
    file->insertSeparator();
    filePrintAction->addTo( file );
    file->insertSeparator();
    fileCloseAction->addTo( file );
    fileQuitAction->addTo( file );


    menuBar()->insertSeparator();

    // add a help menu

    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 );


    // create and define the central widget

    e = new QTextEdit( this, "editor" );
    e->setFocus();
    setCentralWidget( e );
    statusBar()->message( "Ready", 2000 );

    resize( 450, 600 );
}


ApplicationWindow::~ApplicationWindow()
{
    delete printer;
}



void ApplicationWindow::newDoc()
{
    ApplicationWindow *ed = new ApplicationWindow;
    ed->show();
}

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


void ApplicationWindow::load( const QString &fileName )
{
    QFile f( fileName );
    if ( !f.open( IO_ReadOnly ) )
        return;

    QTextStream ts( &f );
    e->setText( ts.read() );
    e->setModified( FALSE );
    setCaption( fileName );
    statusBar()->message( "Loaded document " + fileName, 2000 );
}


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

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

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

    e->setModified( FALSE );

    setCaption( filename );

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


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


void ApplicationWindow::print()
{
    printer->setFullPage( TRUE );
    if ( printer->setup(this) ) {               // printer dialog
        statusBar()->message( "Printing..." );
        QPainter p;
        if( !p.begin( printer ) ) {               // paint on printer
            statusBar()->message( "Printing aborted", 2000 );
            return;
        }

        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(e->text()),
                                  QFont(),
                                  e->context(),
                                  e->styleSheet(),
                                  e->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;
            printer->newPage();
            page++;
        } while (TRUE);

        statusBar()->message( "Printing completed", 2000 );
    } else {
        statusBar()->message( "Printing aborted", 2000 );
    }
}

void ApplicationWindow::closeEvent( QCloseEvent* ce )
{
    if ( !e->isModified() ) {
        ce->accept();
        return;
    }

    switch( QMessageBox::information( this, "Qt Application Example",
                                      "The document has been changed since "
                                      "the last save.",
                                      "Save Now", "Cancel", "Leave Anyway",
                                      0, 1 ) ) {
    case 0:
        save();
        ce->accept();
        break;
    case 1:
    default: // just for sanity
        ce->ignore();
        break;
    case 2:
        ce->accept();
        break;
    }
}


void ApplicationWindow::about()
{
    QMessageBox::about( this, "Qt Application Example",
                        "This example demonstrates simple use of "
                        "QMainWindow,\nQMenuBar and QToolBar.");
}


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

Main:

/****************************************************************************
** $Id: qt/main.cpp   3.3.7   edited Aug 31 2005 $
**
** Copyright (C) 1992-2005 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 <qapplication.h>
#include "application.h"

int main( int argc, char ** argv ) {
    QApplication a( argc, argv );
    ApplicationWindow * mw = new ApplicationWindow();
    mw->setCaption( "Document 1" );
    mw->show();
    a.connect( &a, SIGNAL(lastWindowClosed()), &a, SLOT(quit()) );
    return a.exec();
}

See also QAction Examples.