Qt 4.0: draglabel.cpp Example File (draganddrop/fridgemagnets/draglabel.cpp)

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

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        ** Copyright (C) 2005-2005 Trolltech AS. All rights reserved.
        **
        ** This file is part of the documentation of the Qt Toolkit.
        **
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    ** and appearing in the file LICENSE.GPL included in the packaging of
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        #include <QtGui>

        #include "draglabel.h"

        DragLabel::DragLabel(const QString &text, QWidget *parent)
            : QLabel(parent)
        {
            QFontMetrics fm(font());
            QSize size = fm.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->start(Qt::MoveAction) == Qt::MoveAction)
                close();
            else
                show();
        }