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

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

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     #include <QtGui>

     #include "draglabel.h"

     DragLabel::DragLabel(const QString &text, QWidget *parent)
         : QLabel(parent)
     {
         QFontMetrics metric(font());
         QSize size = metric.size(Qt::TextSingleLine, text);

         QImage image(size.width() + 12, size.height() + 12,
                      QImage::Format_ARGB32_Premultiplied);
         image.fill(qRgba(0, 0, 0, 0));

         QFont font;
         font.setStyleStrategy(QFont::ForceOutline);

         QPainter painter;
         painter.begin(&image);
         painter.setRenderHint(QPainter::Antialiasing);
         painter.setBrush(Qt::white);
         painter.drawRoundRect(QRectF(0.5, 0.5, image.width()-1, image.height()-1),
                               25, 25);

         painter.setFont(font);
         painter.setBrush(Qt::black);
         painter.drawText(QRect(QPoint(6, 6), size), Qt::AlignCenter, text);
         painter.end();

         setPixmap(QPixmap::fromImage(image));
         labelText = text;
     }

     void DragLabel::mousePressEvent(QMouseEvent *event)
     {
         QByteArray itemData;
         QDataStream dataStream(&itemData, QIODevice::WriteOnly);
         dataStream << labelText << QPoint(event->pos() - rect().topLeft());

         QMimeData *mimeData = new QMimeData;
         mimeData->setData("application/x-fridgemagnet", itemData);
         mimeData->setText(labelText);

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

         hide();

         if (drag->exec(Qt::MoveAction | Qt::CopyAction, Qt::CopyAction) == Qt::MoveAction)
             close();
         else
             show();
     }