Qt 4.6: piecesmodel.cpp Example File (itemviews/puzzle/piecesmodel.cpp)

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# piecesmodel.cpp Example File
itemviews/puzzle/piecesmodel.cpp

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     #include <QtGui>

     #include "piecesmodel.h"

     PiecesModel::PiecesModel(QObject *parent)
         : QAbstractListModel(parent)
     {
     }

     QVariant PiecesModel::data(const QModelIndex &index, int role) const
     {
         if (!index.isValid())
             return QVariant();

         if (role == Qt::DecorationRole)
             return QIcon(pixmaps.value(index.row()).scaled(60, 60,
                              Qt::KeepAspectRatio, Qt::SmoothTransformation));
         else if (role == Qt::UserRole)
             return pixmaps.value(index.row());
         else if (role == Qt::UserRole + 1)
             return locations.value(index.row());

         return QVariant();
     }

     void PiecesModel::addPiece(const QPixmap &pixmap, const QPoint &location)
     {
         int row;
         if (int(2.0*qrand()/(RAND_MAX+1.0)) == 1)
             row = 0;
         else
             row = pixmaps.size();

         beginInsertRows(QModelIndex(), row, row);
         pixmaps.insert(row, pixmap);
         locations.insert(row, location);
         endInsertRows();
     }

     Qt::ItemFlags PiecesModel::flags(const QModelIndex &index) const
     {
         if (index.isValid())
             return (Qt::ItemIsEnabled | Qt::ItemIsSelectable | Qt::ItemIsDragEnabled);

         return Qt::ItemIsDropEnabled;
     }

     bool PiecesModel::removeRows(int row, int count, const QModelIndex &parent)
     {
         if (parent.isValid())
             return false;

         if (row >= pixmaps.size() || row + count <= 0)
             return false;

         int beginRow = qMax(0, row);
         int endRow = qMin(row + count - 1, pixmaps.size() - 1);

         beginRemoveRows(parent, beginRow, endRow);

         while (beginRow <= endRow) {
             pixmaps.removeAt(beginRow);
             locations.removeAt(beginRow);
             ++beginRow;
         }

         endRemoveRows();
         return true;
     }

     QStringList PiecesModel::mimeTypes() const
     {
         QStringList types;
         types << "image/x-puzzle-piece";
         return types;
     }

     QMimeData *PiecesModel::mimeData(const QModelIndexList &indexes) const
     {
         QMimeData *mimeData = new QMimeData();
         QByteArray encodedData;

         QDataStream stream(&encodedData, QIODevice::WriteOnly);

         foreach (QModelIndex index, indexes) {
             if (index.isValid()) {
                 QPixmap pixmap = qVariantValue<QPixmap>(data(index, Qt::UserRole));
                 QPoint location = data(index, Qt::UserRole+1).toPoint();
                 stream << pixmap << location;
             }
         }

         mimeData->setData("image/x-puzzle-piece", encodedData);
         return mimeData;
     }

     bool PiecesModel::dropMimeData(const QMimeData *data, Qt::DropAction action,
                                    int row, int column, const QModelIndex &parent)
     {
         if (!data->hasFormat("image/x-puzzle-piece"))
             return false;

         if (action == Qt::IgnoreAction)
             return true;

         if (column > 0)
             return false;

         int endRow;

         if (!parent.isValid()) {
             if (row < 0)
                 endRow = pixmaps.size();
             else
                 endRow = qMin(row, pixmaps.size());
         } else
             endRow = parent.row();

         QByteArray encodedData = data->data("image/x-puzzle-piece");
         QDataStream stream(&encodedData, QIODevice::ReadOnly);

         while (!stream.atEnd()) {
             QPixmap pixmap;
             QPoint location;
             stream >> pixmap >> location;

             beginInsertRows(QModelIndex(), endRow, endRow);
             pixmaps.insert(endRow, pixmap);
             locations.insert(endRow, location);
             endInsertRows();

             ++endRow;
         }

         return true;
     }

     int PiecesModel::rowCount(const QModelIndex &parent) const
     {
         if (parent.isValid())
             return 0;
         else
             return pixmaps.size();
     }

     Qt::DropActions PiecesModel::supportedDropActions() const
     {
         return Qt::CopyAction | Qt::MoveAction;
     }

     void PiecesModel::addPieces(const QPixmap& pixmap)
     {
         beginRemoveRows(QModelIndex(), 0, 24);
         pixmaps.clear();
         locations.clear();
         endRemoveRows();
         for (int y = 0; y < 5; ++y) {
             for (int x = 0; x < 5; ++x) {
                 QPixmap pieceImage = pixmap.copy(x*80, y*80, 80, 80);
                 addPiece(pieceImage, QPoint(x, y));
             }
         }
     }