puzzlewidget.cpp Example File | Qt Widgets 5.12.10

- Qt 5.12
- Qt Widgets
- Drag and Drop Puzzle Example
- puzzlewidget.cpp Example File
- Qt 5.12.10 Reference Documentation

# puzzlewidget.cpp Example File

draganddrop/puzzle/puzzlewidget.cpp

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     #include "puzzlewidget.h"
     #include "pieceslist.h"

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

     PuzzleWidget::PuzzleWidget(int imageSize, QWidget *parent)
         : QWidget(parent), m_ImageSize(imageSize)
     {
         setAcceptDrops(true);
         setMinimumSize(m_ImageSize, m_ImageSize);
         setMaximumSize(m_ImageSize, m_ImageSize);
     }

     void PuzzleWidget::clear()
     {
         pieces.clear();
         highlightedRect = QRect();
         inPlace = 0;
         update();
     }

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

     void PuzzleWidget::dragLeaveEvent(QDragLeaveEvent *event)
     {
         QRect updateRect = highlightedRect;
         highlightedRect = QRect();
         update(updateRect);
         event->accept();
     }

     void PuzzleWidget::dragMoveEvent(QDragMoveEvent *event)
     {
         QRect updateRect = highlightedRect.united(targetSquare(event->pos()));

         if (event->mimeData()->hasFormat(PiecesList::puzzleMimeType())
             && findPiece(targetSquare(event->pos())) == -1) {

             highlightedRect = targetSquare(event->pos());
             event->setDropAction(Qt::MoveAction);
             event->accept();
         } else {
             highlightedRect = QRect();
             event->ignore();
         }

         update(updateRect);
     }

     void PuzzleWidget::dropEvent(QDropEvent *event)
     {
         if (event->mimeData()->hasFormat(PiecesList::puzzleMimeType())
             && findPiece(targetSquare(event->pos())) == -1) {

             QByteArray pieceData = event->mimeData()->data(PiecesList::puzzleMimeType());
             QDataStream dataStream(&pieceData, QIODevice::ReadOnly);
             Piece piece;
             piece.rect = targetSquare(event->pos());
             dataStream >> piece.pixmap >> piece.location;

             pieces.append(piece);

             highlightedRect = QRect();
             update(piece.rect);

             event->setDropAction(Qt::MoveAction);
             event->accept();

             if (piece.location == piece.rect.topLeft() / pieceSize()) {
                 inPlace++;
                 if (inPlace == 25)
                     emit puzzleCompleted();
             }
         } else {
             highlightedRect = QRect();
             event->ignore();
         }
     }

     int PuzzleWidget::findPiece(const QRect &pieceRect) const
     {
         for (int i = 0, size = pieces.size(); i < size; ++i) {
             if (pieces.at(i).rect == pieceRect)
                 return i;
         }
         return -1;
     }

     void PuzzleWidget::mousePressEvent(QMouseEvent *event)
     {
         QRect square = targetSquare(event->pos());
         const int found = findPiece(square);

         if (found == -1)
             return;

         Piece piece = pieces.takeAt(found);

         if (piece.location == square.topLeft() / pieceSize())
             inPlace--;

         update(square);

         QByteArray itemData;
         QDataStream dataStream(&itemData, QIODevice::WriteOnly);

         dataStream << piece.pixmap << piece.location;

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

         QDrag *drag = new QDrag(this);
         drag->setMimeData(mimeData);
         drag->setHotSpot(event->pos() - square.topLeft());
         drag->setPixmap(piece.pixmap);

         if (drag->exec(Qt::MoveAction) != Qt::MoveAction) {
             pieces.insert(found, piece);
             update(targetSquare(event->pos()));

             if (piece.location == square.topLeft() / pieceSize())
                 inPlace++;
         }
     }

     void PuzzleWidget::paintEvent(QPaintEvent *event)
     {
         QPainter painter(this);
         painter.fillRect(event->rect(), Qt::white);

         if (highlightedRect.isValid()) {
             painter.setBrush(QColor("#ffcccc"));
             painter.setPen(Qt::NoPen);
             painter.drawRect(highlightedRect.adjusted(0, 0, -1, -1));
         }

         for (const Piece &piece : pieces)
             painter.drawPixmap(piece.rect, piece.pixmap);
     }

     const QRect PuzzleWidget::targetSquare(const QPoint &position) const
     {
         return QRect(position / pieceSize() * pieceSize(),
                      QSize(pieceSize(), pieceSize()));
     }

     int PuzzleWidget::pieceSize() const
     {
         return m_ImageSize / 5;
     }

     int PuzzleWidget::imageSize() const
     {
         return m_ImageSize;
     }