Qt 4.2: droparea.cpp Example File (draganddrop/dropsite/droparea.cpp)

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# droparea.cpp Example File
draganddrop/dropsite/droparea.cpp

     /****************************************************************************
     **
     ** Copyright (C) 2005-2006 Trolltech ASA. All rights reserved.
     **
     ** This file is part of the example classes of the Qt Toolkit.
     **
     ** This file may be used under the terms of the GNU General Public
     ** License version 2.0 as published by the Free Software Foundation
     ** and appearing in the file LICENSE.GPL included in the packaging of
     ** this file.  Please review the following information to ensure GNU
     ** General Public Licensing requirements will be met:
     ** http://www.trolltech.com/products/qt/opensource.html
     **
     ** If you are unsure which license is appropriate for your use, please
     ** review the following information:
     ** http://www.trolltech.com/products/qt/licensing.html or contact the
     ** sales department at sales@trolltech.com.
     **
     ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
     ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
     **
     ****************************************************************************/

     #include <QtGui>

     #include "droparea.h"

     DropArea::DropArea(QWidget *parent)
         : QLabel(parent)
     {
         setMinimumSize(200, 200);
         setFrameStyle(QFrame::Sunken | QFrame::StyledPanel);
         setAlignment(Qt::AlignCenter);
         setAcceptDrops(true);
         setAutoFillBackground(true);
         clear();
     }

     void DropArea::dragEnterEvent(QDragEnterEvent *event)
     {
         setText(tr("<drop content>"));
         setBackgroundRole(QPalette::Highlight);

         event->acceptProposedAction();
         emit changed(event->mimeData());
     }

     void DropArea::dragMoveEvent(QDragMoveEvent *event)
     {
         event->acceptProposedAction();
     }

     void DropArea::dropEvent(QDropEvent *event)
     {
         const QMimeData *mimeData = event->mimeData();

         if (mimeData->hasImage()) {
             setPixmap(qvariant_cast<QPixmap>(mimeData->imageData()));
         } else if (mimeData->hasHtml()) {
             setText(mimeData->html());
             setTextFormat(Qt::RichText);
         } else if (mimeData->hasText()) {
             setText(mimeData->text());
             setTextFormat(Qt::PlainText);
         } else {
             setText(tr("Cannot display data"));
         }

         setBackgroundRole(QPalette::Dark);
         event->acceptProposedAction();
     }

     void DropArea::dragLeaveEvent(QDragLeaveEvent *event)
     {
         clear();
         event->accept();
     }

     void DropArea::clear()
     {
         setText(tr("<drop content>"));
         setBackgroundRole(QPalette::Dark);

         emit changed();
     }

     QPixmap DropArea::extractPixmap(const QByteArray &data, const QString &format)
     {
         QList<QByteArray> imageFormats = QImageReader::supportedImageFormats();
         QPixmap pixmap;

         foreach (QByteArray imageFormat, imageFormats) {
             if (format.mid(6) == QString(imageFormat)) {
                 pixmap.loadFromData(data, imageFormat);
                 break;
             }
         }
         return pixmap;
     }