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# pieceslist.cpp Example File
draganddrop/puzzle/pieceslist.cpp

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        **
        ** This file is part of the documentation of the Qt Toolkit.
        **
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    ** as defined by Trolltech AS of Norway and appearing in the file
    ** LICENSE.QPL included in the packaging of this file.
    **
    ** This file may be distributed and/or modified under the terms of the
    ** GNU General Public License version 2 as published by the Free Software
    ** Foundation and appearing in the file LICENSE.GPL included in the
    ** packaging of this file.
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    **   information about Qt Commercial License Agreements.
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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::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));
        }