Simple editor that can load encodings

Header file:

/****************************************************************************
** $Id: qt/qwerty.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 QWERTY_H
#define QWERTY_H

#include <qwidget.h>
#include <qmenubar.h>
#include <qmultilineedit.h>
#include <qprinter.h>

class Editor : public QWidget
{
    Q_OBJECT
public:
    Editor( QWidget *parent=0, const char *name="qwerty" );
   ~Editor();

    void load( const QString& fileName, int code=-1 );

public slots:
    void newDoc();
    void load();
    bool save();
    void print();
    void addEncoding();
    void toUpper();
    void toLower();
    void font();
protected:
    void resizeEvent( QResizeEvent * );
    void closeEvent( QCloseEvent * );

private slots:
    void saveAsEncoding( int );
    void openAsEncoding( int );
    void textChanged();

private:
    bool saveAs( const QString& fileName, int code=-1 );
    void rebuildCodecList();
    QMenuBar       *m;
    QMultiLineEdit *e;
#ifndef QT_NO_PRINTER
    QPrinter        printer;
#endif
    QPopupMenu     *save_as;
    QPopupMenu     *open_as;
    bool changed;
};

#endif // QWERTY_H

Implementation:

/****************************************************************************
** $Id: qt/qwerty.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 "qwerty.h"
#include <qapplication.h>
#include <qfile.h>
#include <qfiledialog.h>
#include <qpopupmenu.h>
#include <qtextstream.h>
#include <qpainter.h>
#include <qmessagebox.h>
#include <qpaintdevicemetrics.h>
#include <qptrlist.h>
#include <qfontdialog.h>

#include <qtextcodec.h>

const bool no_writing = FALSE;

static QPtrList<QTextCodec> *codecList = 0;

enum { Uni = 0, MBug = 1, Lat1 = 2, Local = 3, Guess = 4, Codec = 5 };


Editor::Editor( QWidget * parent , const char * name )
    : QWidget( parent, name, WDestructiveClose )
{
    m = new QMenuBar( this, "menu" );

    QPopupMenu * file = new QPopupMenu();
    Q_CHECK_PTR( file );
    m->insertItem( "&File", file );

    file->insertItem( "&New",   this, SLOT(newDoc()),   ALT+Key_N );
    file->insertItem( "&Open...",  this, SLOT(load()),     ALT+Key_O );
    file->insertItem( "&Save...",  this, SLOT(save()),     ALT+Key_S );
    file->insertSeparator();
    open_as = new QPopupMenu();
    file->insertItem( "Open &As",  open_as );
    save_as = new QPopupMenu();
    file->insertItem( "Sa&ve As",  save_as );
    file->insertItem( "Add &Encoding", this, SLOT(addEncoding()) );
#ifndef QT_NO_PRINTER
    file->insertSeparator();
    file->insertItem( "&Print...", this, SLOT(print()),    ALT+Key_P );
#endif
    file->insertSeparator();
    file->insertItem( "&Close", this, SLOT(close()),ALT+Key_W );
    file->insertItem( "&Quit",  qApp, SLOT(closeAllWindows()),     ALT+Key_Q );

    connect( save_as, SIGNAL(activated(int)), this, SLOT(saveAsEncoding(int)) );
    connect( open_as, SIGNAL(activated(int)), this, SLOT(openAsEncoding(int)) );
    rebuildCodecList();

    QPopupMenu * edit = new QPopupMenu();
    Q_CHECK_PTR( edit );
    m->insertItem( "&Edit", edit );

    edit->insertItem( "To &Uppercase",   this, SLOT(toUpper()),   ALT+Key_U );
    edit->insertItem( "To &Lowercase",   this, SLOT(toLower()),   ALT+Key_L );
#ifndef QT_NO_FONTDIALOG
    edit->insertSeparator();
    edit->insertItem( "&Select Font" ,   this, SLOT(font()),     ALT+Key_T );
#endif
    changed = FALSE;
    e = new QMultiLineEdit( this, "editor" );
    connect( e, SIGNAL( textChanged() ), this, SLOT( textChanged() ) );

    // We use Unifont - if you have it installed you'll see all
    // Unicode character glyphs.
    //
    // Unifont only comes in one pixel size, so we cannot let
    // it change pixel size as the display DPI changes.
    //
    QFont unifont("unifont",16,50); unifont.setPixelSize(16);
    e->setFont( unifont );

    e->setFocus();
}

Editor::~Editor()
{
}

void Editor::font()
{
#ifndef QT_NO_FONTDIALOG
    bool ok;
    QFont f = QFontDialog::getFont( &ok, e->font() );
    if ( ok ) {
        e->setFont( f );
    }
#endif
}



void Editor::rebuildCodecList()
{
    delete codecList;
    codecList = new QPtrList<QTextCodec>;
    QTextCodec *codec;
    int i;
    for (i = 0; (codec = QTextCodec::codecForIndex(i)); i++)
        codecList->append( codec );
    int n = codecList->count();
    for (int pm=0; pm<2; pm++) {
        QPopupMenu* menu = pm ? open_as : save_as;
        menu->clear();
        QString local = "Local (";
        local += QTextCodec::codecForLocale()->name();
        local += ")";
        menu->insertItem( local, Local );
        menu->insertItem( "Unicode", Uni );
        menu->insertItem( "Latin1", Lat1 );
        menu->insertItem( "Microsoft Unicode", MBug );
        if ( pm )
            menu->insertItem( "[guess]", Guess );
        for ( i = 0; i < n; i++ )
            menu->insertItem( codecList->at(i)->name(), Codec + i );
    }
}

void Editor::newDoc()
{
    Editor *ed = new Editor;
    if ( qApp->desktop()->size().width() < 450
         || qApp->desktop()->size().height() < 450 ) {
        ed->showMaximized();
    } else {
        ed->resize( 400, 400 );
        ed->show();
    }
}


void Editor::load()
{
#ifndef QT_NO_FILEDIALOG
    QString fn = QFileDialog::getOpenFileName( QString::null, QString::null, this );
    if ( !fn.isEmpty() )
        load( fn, -1 );
#endif
}

void Editor::load( const QString& fileName, int code )
{
    QFile f( fileName );
    if ( !f.open( IO_ReadOnly ) )
        return;

    e->setAutoUpdate( FALSE );

    QTextStream t(&f);
    if ( code >= Codec )
        t.setCodec( codecList->at(code-Codec) );
    else if ( code == Uni )
        t.setEncoding( QTextStream::Unicode );
    else if ( code == MBug )
        t.setEncoding( QTextStream::UnicodeReverse );
    else if ( code == Lat1 )
        t.setEncoding( QTextStream::Latin1 );
    else if ( code == Guess ) {
        QFile f(fileName);
        f.open(IO_ReadOnly);
        char buffer[256];
        int l = 256;
        l=f.readBlock(buffer,l);
        QTextCodec* codec = QTextCodec::codecForContent(buffer, l);
        if ( codec ) {
            QMessageBox::information(this,"Encoding",QString("Codec: ")+codec->name());
            t.setCodec( codec );
        }
    }
    e->setText( t.read() );
    f.close();

    e->setAutoUpdate( TRUE );
    e->repaint();
    setCaption( fileName );

    changed = FALSE;
}

void Editor::openAsEncoding( int code )
{
#ifndef QT_NO_FILEDIALOG
    //storing filename (proper save) is left as an exercise...
    QString fn = QFileDialog::getOpenFileName( QString::null, QString::null, this );
    if ( !fn.isEmpty() )
        (void) load( fn, code );
#endif
}

bool Editor::save()
{
#ifndef QT_NO_FILEDIALOG
    //storing filename (proper save) is left as an exercise...
    QString fn = QFileDialog::getSaveFileName( QString::null, QString::null, this );
    if ( !fn.isEmpty() )
        return saveAs( fn );
    return FALSE;
#endif
}

void Editor::saveAsEncoding( int code )
{
#ifndef QT_NO_FILEDIALOG
    //storing filename (proper save) is left as an exercise...
    QString fn = QFileDialog::getSaveFileName( QString::null, QString::null, this );
    if ( !fn.isEmpty() )
        (void) saveAs( fn, code );
#endif
}

void Editor::addEncoding()
{
#ifndef QT_NO_FILEDIALOG
    QString fn = QFileDialog::getOpenFileName( QString::null, "*.map", this );
    if ( !fn.isEmpty() ) {
        QFile f(fn);
        if (f.open(IO_ReadOnly)) {
            if (QTextCodec::loadCharmap(&f)) {
                rebuildCodecList();
            } else {
                QMessageBox::warning(0,"Charmap error",
                    "The file did not contain a valid charmap.\n\n"
                    "A charmap file should look like this:\n"
                       "  <code_set_name> thename\n"
                       "  <escape_char> /\n"
                       "  % alias thealias\n"
                       "  CHARMAP\n"
                       "  <tokenname> /x12 <U3456>\n"
                       "  <tokenname> /xAB/x12 <U0023>\n"
                       "  ...\n"
                       "  END CHARMAP\n"
                );
            }
        }
    }
#endif
}


bool Editor::saveAs( const QString& fileName, int code )
{
    QFile f( fileName );
    if ( no_writing || !f.open( IO_WriteOnly ) ) {
        QMessageBox::warning(this,"I/O Error",
                    QString("The file could not be opened.\n\n")
                        +fileName);
        return FALSE;
    }
    QTextStream t(&f);
    if ( code >= Codec )
        t.setCodec( codecList->at(code-Codec) );
    else if ( code == Uni )
        t.setEncoding( QTextStream::Unicode );
    else if ( code == MBug )
        t.setEncoding( QTextStream::UnicodeReverse );
    else if ( code == Lat1 )
        t.setEncoding( QTextStream::Latin1 );
    t << e->text();
    f.close();
    setCaption( fileName );
    changed = FALSE;
    return TRUE;
}

void Editor::print()
{
#ifndef QT_NO_PRINTER
    if ( printer.setup(this) ) {                // opens printer dialog
        printer.setFullPage(TRUE);              // we'll set our own margins
        QPainter p;
        p.begin( &printer );                    // paint on printer
        p.setFont( e->font() );
        QFontMetrics fm = p.fontMetrics();
        QPaintDeviceMetrics metrics( &printer ); // need width/height
                                                 // of printer surface
        const int MARGIN = metrics.logicalDpiX() / 2; // half-inch margin
        int yPos        = MARGIN;               // y position for each line

        for( int i = 0 ; i < e->numLines() ; i++ ) {
            if ( printer.aborted() )
                break;
            if ( yPos + fm.lineSpacing() > metrics.height() - MARGIN ) {
                // no more room on this page
                if ( !printer.newPage() )          // start new page
                    break;                           // some error
                yPos = MARGIN;                   // back to top of page
            }
            p.drawText( MARGIN, yPos, metrics.width() - 2*MARGIN,
                        fm.lineSpacing(), ExpandTabs, e->textLine( i ) );
            yPos += fm.lineSpacing();
        }
        p.end();                                // send job to printer
    }
#endif
}

void Editor::resizeEvent( QResizeEvent * )
{
    if ( e && m )
        e->setGeometry( 0, m->height(), width(), height() - m->height() );
}

void Editor::closeEvent( QCloseEvent *event )
{
    event->accept();

    if ( changed ) { // the text has been changed
        switch ( QMessageBox::warning( this, "Qwerty",
                                        "Save changes to Document?",
                                        tr("&Yes"),
                                        tr("&No"),
                                        tr("Cancel"),
                                        0, 2) ) {
        case 0: // yes
            if ( save() )
                event->accept();
            else
                event->ignore();
            break;
        case 1: // no
            event->accept();
            break;
        default: // cancel
            event->ignore();
            break;
        }
    }
}

void Editor::toUpper()
{
    e->setText(e->text().upper());
}

void Editor::toLower()
{
    e->setText(e->text().lower());
}

void Editor::textChanged()
{
    changed = TRUE;
}

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 "qwerty.h"


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


    bool isSmall =  qApp->desktop()->size().width() < 450
                  || qApp->desktop()->size().height() < 450;

    int i;
    for ( i= argc <= 1 ? 0 : 1; i<argc; i++ ) {
        Editor *e = new Editor;
        e->setCaption("Qt Example - QWERTY");
        if ( i > 0 )
            e->load( argv[i] );
        if ( isSmall ) {
            e->showMaximized();
        } else {
            e->resize( 400, 400 );
            e->show();
        }
    }
    a.connect( &a, SIGNAL(lastWindowClosed()), &a, SLOT(quit()) );
    return a.exec();
}

See also Examples.