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

/****************************************************************************
**
** Copyright (C) 2005-2006 Trolltech ASA. All rights reserved.
**
** This file is part of the example classes of the Qt Toolkit.
**
** Licensees holding valid Qt Preview licenses may use this file in
** accordance with the Qt Preview License Agreement provided with the
** Software.
**
** See http://www.trolltech.com/pricing.html or email sales@trolltech.com for
** information about Qt Commercial License Agreements.
**
** Contact info@trolltech.com if any conditions of this licensing are
** not clear to you.
**
** 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 "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));
}


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Qt 4.2.0-rc1