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droparea.cpp Example File
^{draganddrop/dropsite/droparea.cpp}

 /****************************************************************************
 **
 ** Copyright (C) 2005-2007 Trolltech ASA. All rights reserved.
 **
 ** This file is part of the example classes of the Qt Toolkit.
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 ** 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:
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 ** review the following information:
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 ****************************************************************************/

 #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;
 }