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pieceslist.cpp Example File
^{draganddrop/puzzle/pieceslist.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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 ** 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
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 ** If you are unsure which license is appropriate for your use, please
 ** review the following information:
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 ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
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 ****************************************************************************/

 #include <QtGui>

 #include "pieceslist.h"

 PiecesList::PiecesList(QWidget *parent)
     : QListWidget(parent)
 {
     setDragEnabled(true);
     setViewMode(QListView::IconMode);
     setIconSize(QSize(60, 60));
     setSpacing(10);
     setAcceptDrops(true);
     setDropIndicatorShown(true);
 }

 void PiecesList::dragEnterEvent(QDragEnterEvent *event)
 {
     if (event->mimeData()->hasFormat("image/x-puzzle-piece"))
         event->accept();
     else
         event->ignore();
 }

 void PiecesList::dragMoveEvent(QDragMoveEvent *event)
 {
     if (event->mimeData()->hasFormat("image/x-puzzle-piece")) {
         event->setDropAction(Qt::MoveAction);
         event->accept();
     } else
         event->ignore();
 }

 void PiecesList::dropEvent(QDropEvent *event)
 {
     if (event->mimeData()->hasFormat("image/x-puzzle-piece")) {
         QByteArray pieceData = event->mimeData()->data("image/x-puzzle-piece");
         QDataStream dataStream(&pieceData, QIODevice::ReadOnly);
         QPixmap pixmap;
         QPoint location;
         dataStream >> pixmap >> location;

         addPiece(pixmap, location);

         event->setDropAction(Qt::MoveAction);
         event->accept();
     } else
         event->ignore();
 }

 void PiecesList::addPiece(QPixmap pixmap, QPoint location)
 {
     QListWidgetItem *pieceItem = new QListWidgetItem(this);
     pieceItem->setIcon(QIcon(pixmap));
     pieceItem->setData(Qt::UserRole, QVariant(pixmap));
     pieceItem->setData(Qt::UserRole+1, location);
     pieceItem->setFlags(Qt::ItemIsEnabled | Qt::ItemIsSelectable
                         | Qt::ItemIsDragEnabled);
 }

 void PiecesList::startDrag(Qt::DropActions supportedActions)
 {
     QListWidgetItem *item = currentItem();

     QByteArray itemData;
     QDataStream dataStream(&itemData, QIODevice::WriteOnly);
     QPixmap pixmap = qVariantValue<QPixmap>(item->data(Qt::UserRole));
     QPoint location = item->data(Qt::UserRole+1).toPoint();

     dataStream << pixmap << location;

     QMimeData *mimeData = new QMimeData;
     mimeData->setData("image/x-puzzle-piece", itemData);

     QDrag *drag = new QDrag(this);
     drag->setMimeData(mimeData);
     drag->setHotSpot(QPoint(pixmap.width()/2, pixmap.height()/2));
     drag->setPixmap(pixmap);

     if (drag->start(Qt::MoveAction) == Qt::MoveAction)
         delete takeItem(row(item));
 }