Qt 4.3: dragwidget.cpp Example File (draganddrop/fridgemagnets/dragwidget.cpp)

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# dragwidget.cpp Example File
draganddrop/fridgemagnets/dragwidget.cpp

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     #include <QtGui>

     #include "draglabel.h"
     #include "dragwidget.h"

     DragWidget::DragWidget(QWidget *parent)
         : QWidget(parent)
     {
         QFile dictionaryFile(":/dictionary/words.txt");
         dictionaryFile.open(QFile::ReadOnly);
         QTextStream inputStream(&dictionaryFile);

         int x = 5;
         int y = 5;

         while (!inputStream.atEnd()) {
             QString word;
             inputStream >> word;
             if (!word.isEmpty()) {
                 DragLabel *wordLabel = new DragLabel(word, this);
                 wordLabel->move(x, y);
                 wordLabel->show();
                 x += wordLabel->width() + 2;
                 if (x >= 245) {
                     x = 5;
                     y += wordLabel->height() + 2;
                 }
             }
         }

         QPalette newPalette = palette();
         newPalette.setColor(QPalette::Window, Qt::white);
         setPalette(newPalette);

         setMinimumSize(400, qMax(200, y));
         setWindowTitle(tr("Fridge Magnets"));
         setAcceptDrops(true);
     }

     void DragWidget::dragEnterEvent(QDragEnterEvent *event)
     {
         if (event->mimeData()->hasFormat("application/x-fridgemagnet")) {
             if (children().contains(event->source())) {
                 event->setDropAction(Qt::MoveAction);
                 event->accept();
             } else {
                 event->acceptProposedAction();
             }
         } else if (event->mimeData()->hasText()) {
             event->acceptProposedAction();
         } else {
             event->ignore();
         }
     }

     void DragWidget::dragMoveEvent(QDragMoveEvent *event)
     {
         if (event->mimeData()->hasFormat("application/x-fridgemagnet")) {
             if (children().contains(event->source())) {
                 event->setDropAction(Qt::MoveAction);
                 event->accept();
             } else {
                 event->acceptProposedAction();
             }
         } else if (event->mimeData()->hasText()) {
             event->acceptProposedAction();
         } else {
             event->ignore();
         }
     }

     void DragWidget::dropEvent(QDropEvent *event)
     {
         if (event->mimeData()->hasFormat("application/x-fridgemagnet")) {
             const QMimeData *mime = event->mimeData();
             QByteArray itemData = mime->data("application/x-fridgemagnet");
             QDataStream dataStream(&itemData, QIODevice::ReadOnly);

             QString text;
             QPoint offset;
             dataStream >> text >> offset;

             DragLabel *newLabel = new DragLabel(text, this);
             newLabel->move(event->pos() - offset);
             newLabel->show();

             if (children().contains(event->source())) {
                 event->setDropAction(Qt::MoveAction);
                 event->accept();
             } else {
                 event->acceptProposedAction();
             }
         } else if (event->mimeData()->hasText()) {
             QStringList pieces = event->mimeData()->text().split(QRegExp("\\s+"),
                                  QString::SkipEmptyParts);
             QPoint position = event->pos();

             foreach (QString piece, pieces) {
                 DragLabel *newLabel = new DragLabel(piece, this);
                 newLabel->move(position);
                 newLabel->show();

                 position += QPoint(newLabel->width(), 0);
             }

             event->acceptProposedAction();
         } else {
             event->ignore();
         }
     }