Question

This example implements a simple HTML help browser using Qt's richtext capabilities.

---

Header file:

/****************************************************************************
** $Id:  qt/helpwindow.h   3.0.5   edited Oct 12 2001 $
**
** 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 HELPWINDOW_H
#define HELPWINDOW_H

#include <qmainwindow.h>
#include <qtextbrowser.h>
#include <qstringlist.h>
#include <qmap.h>
#include <qdir.h>

class QComboBox;
class QPopupMenu;

class HelpWindow : public QMainWindow
{
    Q_OBJECT
public:
    HelpWindow( const QString& home_,  const QString& path, QWidget* parent = 0, const char *name=0 );
    ~HelpWindow();

private slots:
    void setBackwardAvailable( bool );
    void setForwardAvailable( bool );

    void textChanged();
    void about();
    void aboutQt();
    void openFile();
    void newWindow();
    void print();

    void pathSelected( const QString & );
    void histChosen( int );
    void bookmChosen( int );
    void addBookmark();

private:
    void readHistory();
    void readBookmarks();

    QTextBrowser* browser;
    QComboBox *pathCombo;
    int backwardId, forwardId;
    QString selectedURL;
    QStringList history, bookmarks;
    QMap<int, QString> mHistory, mBookmarks;
    QPopupMenu *hist, *bookm;

};





#endif

---

Implementation:

/****************************************************************************
** $Id:  qt/helpwindow.cpp   3.0.5   edited May 27 19:35 $
**
** 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 "helpwindow.h"
#include <qstatusbar.h>
#include <qpixmap.h>
#include <qpopupmenu.h>
#include <qmenubar.h>
#include <qtoolbar.h>
#include <qtoolbutton.h>
#include <qiconset.h>
#include <qfile.h>
#include <qtextstream.h>
#include <qstylesheet.h>
#include <qmessagebox.h>
#include <qfiledialog.h>
#include <qapplication.h>
#include <qcombobox.h>
#include <qevent.h>
#include <qlineedit.h>
#include <qobjectlist.h>
#include <qfileinfo.h>
#include <qfile.h>
#include <qdatastream.h>
#include <qprinter.h>
#include <qsimplerichtext.h>
#include <qpainter.h>
#include <qpaintdevicemetrics.h>

#include <ctype.h>

HelpWindow::HelpWindow( const QString& home_, const QString& _path,
                        QWidget* parent, const char *name )
    : QMainWindow( parent, name, WDestructiveClose ),
      pathCombo( 0 ), selectedURL()
{
    readHistory();
    readBookmarks();

    browser = new QTextBrowser( this );

    browser->mimeSourceFactory()->setFilePath( _path );
    browser->setFrameStyle( QFrame::Panel | QFrame::Sunken );
    connect( browser, SIGNAL( textChanged() ),
             this, SLOT( textChanged() ) );

    setCentralWidget( browser );

    if ( !home_.isEmpty() )
        browser->setSource( home_ );

    connect( browser, SIGNAL( highlighted( const QString&) ),
             statusBar(), SLOT( message( const QString&)) );

    resize( 640,700 );

    QPopupMenu* file = new QPopupMenu( this );
    file->insertItem( tr("&New Window"), this, SLOT( newWindow() ), CTRL+Key_N );
    file->insertItem( tr("&Open File"), this, SLOT( openFile() ), CTRL+Key_O );
    file->insertItem( tr("&Print"), this, SLOT( print() ), CTRL+Key_P );
    file->insertSeparator();
    file->insertItem( tr("&Close"), this, SLOT( close() ), CTRL+Key_Q );
    file->insertItem( tr("E&xit"), qApp, SLOT( closeAllWindows() ), CTRL+Key_X );

    // The same three icons are used twice each.
    QIconSet icon_back( QPixmap("back.xpm") );
    QIconSet icon_forward( QPixmap("forward.xpm") );
    QIconSet icon_home( QPixmap("home.xpm") );

    QPopupMenu* go = new QPopupMenu( this );
    backwardId = go->insertItem( icon_back,
                                 tr("&Backward"), browser, SLOT( backward() ),
                                 CTRL+Key_Left );
    forwardId = go->insertItem( icon_forward,
                                tr("&Forward"), browser, SLOT( forward() ),
                                CTRL+Key_Right );
    go->insertItem( icon_home, tr("&Home"), browser, SLOT( home() ) );

    QPopupMenu* help = new QPopupMenu( this );
    help->insertItem( tr("&About ..."), this, SLOT( about() ) );
    help->insertItem( tr("About &Qt ..."), this, SLOT( aboutQt() ) );

    hist = new QPopupMenu( this );
    QStringList::Iterator it = history.begin();
    for ( ; it != history.end(); ++it )
        mHistory[ hist->insertItem( *it ) ] = *it;
    connect( hist, SIGNAL( activated( int ) ),
             this, SLOT( histChosen( int ) ) );

    bookm = new QPopupMenu( this );
    bookm->insertItem( tr( "Add Bookmark" ), this, SLOT( addBookmark() ) );
    bookm->insertSeparator();

    QStringList::Iterator it2 = bookmarks.begin();
    for ( ; it2 != bookmarks.end(); ++it2 )
        mBookmarks[ bookm->insertItem( *it2 ) ] = *it2;
    connect( bookm, SIGNAL( activated( int ) ),
             this, SLOT( bookmChosen( int ) ) );

    menuBar()->insertItem( tr("&File"), file );
    menuBar()->insertItem( tr("&Go"), go );
    menuBar()->insertItem( tr( "History" ), hist );
    menuBar()->insertItem( tr( "Bookmarks" ), bookm );
    menuBar()->insertSeparator();
    menuBar()->insertItem( tr("&Help"), help );

    menuBar()->setItemEnabled( forwardId, FALSE);
    menuBar()->setItemEnabled( backwardId, FALSE);
    connect( browser, SIGNAL( backwardAvailable( bool ) ),
             this, SLOT( setBackwardAvailable( bool ) ) );
    connect( browser, SIGNAL( forwardAvailable( bool ) ),
             this, SLOT( setForwardAvailable( bool ) ) );


    QToolBar* toolbar = new QToolBar( this );
    addToolBar( toolbar, "Toolbar");
    QToolButton* button;

    button = new QToolButton( icon_back, tr("Backward"), "", browser, SLOT(backward()), toolbar );
    connect( browser, SIGNAL( backwardAvailable(bool) ), button, SLOT( setEnabled(bool) ) );
    button->setEnabled( FALSE );
    button = new QToolButton( icon_forward, tr("Forward"), "", browser, SLOT(forward()), toolbar );
    connect( browser, SIGNAL( forwardAvailable(bool) ), button, SLOT( setEnabled(bool) ) );
    button->setEnabled( FALSE );
    button = new QToolButton( icon_home, tr("Home"), "", browser, SLOT(home()), toolbar );

    toolbar->addSeparator();

    pathCombo = new QComboBox( TRUE, toolbar );
    connect( pathCombo, SIGNAL( activated( const QString & ) ),
             this, SLOT( pathSelected( const QString & ) ) );
    toolbar->setStretchableWidget( pathCombo );
    setRightJustification( TRUE );
    setDockEnabled( DockLeft, FALSE );
    setDockEnabled( DockRight, FALSE );

    pathCombo->insertItem( home_ );
    browser->setFocus();

}


void HelpWindow::setBackwardAvailable( bool b)
{
    menuBar()->setItemEnabled( backwardId, b);
}

void HelpWindow::setForwardAvailable( bool b)
{
    menuBar()->setItemEnabled( forwardId, b);
}


void HelpWindow::textChanged()
{
    if ( browser->documentTitle().isNull() )
        setCaption( "Qt Example - Helpviewer - " + browser->context() );
    else
        setCaption( "Qt Example - Helpviewer - " + browser->documentTitle() ) ;

    selectedURL = browser->context();

    if ( !selectedURL.isEmpty() && pathCombo ) {
        bool exists = FALSE;
        int i;
        for ( i = 0; i < pathCombo->count(); ++i ) {
            if ( pathCombo->text( i ) == selectedURL ) {
                exists = TRUE;
                break;
            }
        }
        if ( !exists ) {
            pathCombo->insertItem( selectedURL, 0 );
            pathCombo->setCurrentItem( 0 );
            mHistory[ hist->insertItem( selectedURL ) ] = selectedURL;
        } else
            pathCombo->setCurrentItem( i );
        selectedURL = QString::null;
    }
}

HelpWindow::~HelpWindow()
{
    history.clear();
    QMap<int, QString>::Iterator it = mHistory.begin();
    for ( ; it != mHistory.end(); ++it )
        history.append( *it );

    QFile f( QDir::currentDirPath() + "/.history" );
    f.open( IO_WriteOnly );
    QDataStream s( &f );
    s << history;
    f.close();

    bookmarks.clear();
    QMap<int, QString>::Iterator it2 = mBookmarks.begin();
    for ( ; it2 != mBookmarks.end(); ++it2 )
        bookmarks.append( *it2 );

    QFile f2( QDir::currentDirPath() + "/.bookmarks" );
    f2.open( IO_WriteOnly );
    QDataStream s2( &f2 );
    s2 << bookmarks;
    f2.close();
}

void HelpWindow::about()
{
    QMessageBox::about( this, "HelpViewer Example",
                        "<p>This example implements a simple HTML help viewer "
                        "using Qt's rich text capabilities</p>"
                        "<p>It's just about 100 lines of C++ code, so don't expect too much :-)</p>"
                        );
}


void HelpWindow::aboutQt()
{
    QMessageBox::aboutQt( this, "QBrowser" );
}

void HelpWindow::openFile()
{
#ifndef QT_NO_FILEDIALOG
    QString fn = QFileDialog::getOpenFileName( QString::null, QString::null, this );
    if ( !fn.isEmpty() )
        browser->setSource( fn );
#endif
}

void HelpWindow::newWindow()
{
    ( new HelpWindow(browser->source(), "qbrowser") )->show();
}

void HelpWindow::print()
{
#ifndef QT_NO_PRINTER
    QPrinter printer;
    printer.setFullPage(TRUE);
    if ( printer.setup( this ) ) {
        QPainter p( &printer );
        QPaintDeviceMetrics metrics(p.device());
        int dpix = metrics.logicalDpiX();
        int dpiy = metrics.logicalDpiY();
        const int margin = 72; // pt
        QRect body(margin*dpix/72, margin*dpiy/72,
                   metrics.width()-margin*dpix/72*2,
                   metrics.height()-margin*dpiy/72*2 );
        QFont font( "times", 10 );
        QSimpleRichText richText( browser->text(), font,
                                  browser->context(),
                                  browser->styleSheet(),
                                  browser->mimeSourceFactory(),
                                  body.height() );
        richText.setWidth( &p, body.width() );
        QRect view( body );
        int page = 1;
        do {
            richText.draw( &p, body.left(), body.top(), view, colorGroup() );
            view.moveBy( 0, body.height() );
            p.translate( 0 , -body.height() );
            p.setFont( font );
            p.drawText( view.right() - p.fontMetrics().width( QString::number(page) ),
                        view.bottom() + p.fontMetrics().ascent() + 5, QString::number(page) );
            if ( view.top()  >= body.top() + richText.height() )
                break;
            printer.newPage();
            page++;
        } while (TRUE);
    }
#endif
}

void HelpWindow::pathSelected( const QString &_path )
{
    browser->setSource( _path );
    QMap<int, QString>::Iterator it = mHistory.begin();
    bool exists = FALSE;
    for ( ; it != mHistory.end(); ++it ) {
        if ( *it == _path ) {
            exists = TRUE;
            break;
        }
    }
    if ( !exists )
        mHistory[ hist->insertItem( _path ) ] = _path;
}

void HelpWindow::readHistory()
{
    if ( QFile::exists( QDir::currentDirPath() + "/.history" ) ) {
        QFile f( QDir::currentDirPath() + "/.history" );
        f.open( IO_ReadOnly );
        QDataStream s( &f );
        s >> history;
        f.close();
        while ( history.count() > 20 )
            history.remove( history.begin() );
    }
}

void HelpWindow::readBookmarks()
{
    if ( QFile::exists( QDir::currentDirPath() + "/.bookmarks" ) ) {
        QFile f( QDir::currentDirPath() + "/.bookmarks" );
        f.open( IO_ReadOnly );
        QDataStream s( &f );
        s >> bookmarks;
        f.close();
    }
}

void HelpWindow::histChosen( int i )
{
    if ( mHistory.contains( i ) )
        browser->setSource( mHistory[ i ] );
}

void HelpWindow::bookmChosen( int i )
{
    if ( mBookmarks.contains( i ) )
        browser->setSource( mBookmarks[ i ] );
}

void HelpWindow::addBookmark()
{
    mBookmarks[ bookm->insertItem( caption() ) ] = browser->context();
}

---

Main:

/****************************************************************************
** $Id:  qt/main.cpp   3.0.5   edited Oct 12 2001 $
**
** 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 "helpwindow.h"
#include <qapplication.h>
#include <qwindowsstyle.h>
#include <qstylesheet.h>
#include <stdlib.h>


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

    QString home;
    if (argc > 1)
        home = argv[1];
    else
        home = QString(getenv("QTDIR")) + "/doc/html/index.html";


    HelpWindow *help = new HelpWindow(home, ".", 0, "help viewer");
    help->setCaption("Qt Example - Helpviewer");
    if ( QApplication::desktop()->width() > 400
         && QApplication::desktop()->height() > 500 )
        help->show();
    else
        help->showMaximized();

    QObject::connect( &a, SIGNAL(lastWindowClosed()),
                      &a, SLOT(quit()) );

    return a.exec();
}

See also Examples.