Generating thumbnails problem

Beginner

Sunday, January 20th 2008, 1:16am

I am writing a program to render NFO files, and I want to write a thumbnail viewer so that you can select or mouse over NFO files in Konqueror and see them rendered correctly. To this end, I wrote a text codec for Qt3 for the CP/IBM 437 encoding. It works in the program.

I copied the code for the HTML file preview in Konqueror. It works as is for NFO files, but the moment I try to add code to open and decode the file it doesn't work.

Source code

/***************************************************************************
 *   Copyright (C) 2007 by Lawrence Lee   *
 *   valheru@facticius.net   *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/
#include <kstandarddirs.h>
#include <kapplication.h>
#include <kmimetype.h>
#include <time.h>
#include <qpixmap.h>
#include <qimage.h>
#include <qpainter.h>
#include <khtml_part.h>
#include <qfile.h>
#include <qimage.h>
#include <qtextstream.h>
#include "knfoviewerthumbnail.h"
#include "cp437codec.h"

extern "C"
{
    ThumbCreator *new_creator()
    {
        return new KNfoViewerThumbnail();
    }
}

/*
 * This code is taken nearly verbatim from htmlcreator.cpp
 * in kdebase/kioslave/thumbnail/ with minor changes to
 * ensure the correct rendering of CP437 encoded characters.
 */
KNfoViewerThumbnail::KNfoViewerThumbnail() : m_html( 0 )
{
}

KNfoViewerThumbnail::~KNfoViewerThumbnail()
{
    delete m_html;
}

bool KNfoViewerThumbnail::create( const QString &path, int width, int height, QImage &img )
{
    if (!m_html)
    {
        m_html = new KHTMLPart;
        connect(m_html, SIGNAL(completed()), SLOT(slotCompleted()));
        m_html->setJScriptEnabled(false);
        m_html->setJavaEnabled(false);
        m_html->setPluginsEnabled(false);
        m_html->setMetaRefreshEnabled(false);
        m_html->setOnlyLocalReferences(true);
    }
    KURL url;
    url.setPath( path );
//     QFile file( url.url() );

//     if( !file.open( IO_ReadOnly ) )
//         return false;

//     QString text;
//     QTextStream stream( &file );
//     CP437Codec codec;
//     stream.setCodec( &codec );
// 
//     while( !stream.atEnd() ){
//         text += stream.readLine() + "\n";
//     }

//     m_html->begin();
//     m_html->write( htmlCode( text ) );
//     m_html->end();

    m_html->openURL(url);

    int t = startTimer(5000);

    qApp->enter_loop();

    killTimer(t);

    // render the HTML page on a bigger pixmap and use smoothScale,
    // looks better than directly scaling with the QPainter (malte)
    QPixmap pix;
    if (width > 400 || height > 600)
    {
        if (height * 3 > width * 4)
            pix.resize(width, width * 4 / 3);
        else
            pix.resize(height * 3 / 4, height);
    }
    else
        pix.resize(400, 600);

    // light-grey background, in case loadind the page failed
    pix.fill( QColor( 245, 245, 245 ) );

    int borderX = pix.width() / width, borderY = pix.height() / height;
    QRect rc(borderX, borderY, pix.width() - borderX * 2,
             pix.height() - borderY * 2);

    QPainter p;
    p.begin(&pix);
    m_html->paint(&p, rc);
    p.end();

    img = pix.convertToImage();

    m_html->closeURL();

    return true;
}

const QString KNfoViewerThumbnail::htmlCode( const QString &text )
{
    QString code = "<!DOCTYPE html PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">\n\
            <html>\n\
            <head>\n\
            <meta http-equiv=\"Content-Type\" content=\"text/html; charset=ISO-8859-1\" />\n\
            <style type=\"text/css\" media=\"screen\"><!--\n\
            body {\n \
                color : #000000;\n\
                background-color: #ffffff;\n\
                margin: 0px;\n\
            }\n\
            #nfo {\n\
                color: #000000;\n\
                background-color: transparent;\n\
                text-align: center;\n\
                position: absolute;\n\
                top: 0px;\n\
                left: 0px;\n\
                width: 100%;\n\
                height: 100%;\n\
                overflow: visible;\n\
                visibility: visible;\n\
                display: block\n\
            }\n\
            #data {\n\
                font-size: 11px;\n\
                font-family: \"Andale Mono\";\n\
                line-height: 11px;\n\
                background-color: #ffffff;\n\
                color: #000000;\n\
                position: relative;\n\
                white-space: pre;\n\
                visibility : visible;\n\
            }\n\
            a {\n\
                color: #000000;\n\
                text-decoration: none;\n\
            }\n\
            a:hover {\n\
                color: #000000;\n\
                text-decoration: none;\n\
}\n\
            --></style>\n\
            </head>\n\
            <body>\n\
            <div id\"nfo\">\n\
            <div id=\"data\">\n";

    code += text;
    code += "<br></div></div><br/></body></html>";

    return code;
}

void KNfoViewerThumbnail::timerEvent(QTimerEvent *)
{
    qApp->exit_loop();
}

void KNfoViewerThumbnail::slotCompleted()
{
    qApp->exit_loop();
}

ThumbCreator::Flags KNfoViewerThumbnail::flags() const
{
    return DrawFrame;
}

#include "knfoviewerthumbnail.moc"

If I uncomment the lines:

	Source code
1 2 3 4	QFile file( url.url() ); if( !file.open( IO_ReadOnly ) ) return false;

It doesn't generate a preview, so obviously it is returning false there. My question is why?

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CamilleM

Beginner

Posts: 5

2

Wednesday, May 15th 2013, 8:36am

What language u are using ?I do want to creat thumbnails in C#.NET . I found some sample codes and follow the tutorails ,but haven't worked out yet.Does it mean I have to download their thmbnail creating sdk ?Is there any other way to create thumbnail generator?

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adlike

Beginner

Posts: 2

3

Monday, April 21st 2014, 9:03am

right now, i am testing this image viewer control , it has useful thumbnail preview support . it enable you to use the thumbnail preview window to load and save file. besides you can process and zoom image as well.

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