pieceslist.cpp Example File

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  #include "pieceslist.h"

  #include <QDrag>
  #include <QDragEnterEvent>
  #include <QMimeData>

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

  void PiecesList::dragEnterEvent(QDragEnterEvent *event)
  {
      if (event->mimeData()->hasFormat(PiecesList::puzzleMimeType()))
          event->accept();
      else
          event->ignore();
  }

  void PiecesList::dragMoveEvent(QDragMoveEvent *event)
  {
      if (event->mimeData()->hasFormat(PiecesList::puzzleMimeType())) {
          event->setDropAction(Qt::MoveAction);
          event->accept();
      } else {
          event->ignore();
      }
  }

  void PiecesList::dropEvent(QDropEvent *event)
  {
      if (event->mimeData()->hasFormat(PiecesList::puzzleMimeType())) {
          QByteArray pieceData = event->mimeData()->data(PiecesList::puzzleMimeType());
          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 = qvariant_cast<QPixmap>(item->data(Qt::UserRole));
      QPoint location = item->data(Qt::UserRole+1).toPoint();

      dataStream << pixmap << location;

      QMimeData *mimeData = new QMimeData;
      mimeData->setData(PiecesList::puzzleMimeType(), itemData);

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

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