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droparea.cpp Example File
draganddrop/dropsite/droparea.cpp

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    **
    ** Copyright (C) 2005-2006 Trolltech ASA. All rights reserved.
    **
    ** This file is part of the example classes of the Qt Toolkit.
    **
    ** Licensees holding valid Qt Preview licenses may use this file in
    ** accordance with the Qt Preview License Agreement provided with the
    ** Software.
    **
    ** See http://www.trolltech.com/pricing.html or email sales@trolltech.com for
    ** information about Qt Commercial License Agreements.
    **
    ** Contact info@trolltech.com if any conditions of this licensing are
    ** not clear to you.
    **
    ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
    ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
    **
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    #include <QtGui>

    #include "droparea.h"

    DropArea::DropArea(QWidget *parent)
        : QLabel(parent)
    {
        setMinimumSize(200, 200);
        setFrameStyle(QFrame::Sunken | QFrame::StyledPanel);
        setAlignment(Qt::AlignCenter);
        setAcceptDrops(true);
        setAutoFillBackground(true);
        clear();
    }

    void DropArea::dragEnterEvent(QDragEnterEvent *event)
    {
        setText(tr("<drop content>"));
        setBackgroundRole(QPalette::Highlight);

        event->acceptProposedAction();
        emit changed(event->mimeData());
    }

    void DropArea::dropEvent(QDropEvent *event)
    {
        const QMimeData *mimeData = event->mimeData();

        if (mimeData->hasImage()) {
            setPixmap(qvariant_cast<QPixmap>(mimeData->imageData()));
        } else if (mimeData->hasHtml()) {
            setText(mimeData->html());
            setTextFormat(Qt::RichText);
        } else if (mimeData->hasText()) {
            setText(mimeData->text());
            setTextFormat(Qt::PlainText);
        } else {
            setText(tr("Cannot display data"));
        }

        setBackgroundRole(QPalette::Dark);
        event->acceptProposedAction();
    }

    void DropArea::dragLeaveEvent(QDragLeaveEvent *event)
    {
        clear();
        event->accept();
    }

    void DropArea::clear()
    {
        setText(tr("<drop content>"));
        setBackgroundRole(QPalette::Dark);

        emit changed();
    }

    QPixmap DropArea::extractPixmap(const QByteArray &data, const QString &format)
    {
        QList<QByteArray> imageFormats = QImageReader::supportedImageFormats();
        QPixmap pixmap;

        foreach (QByteArray imageFormat, imageFormats) {
            if (format.mid(6) == QString(imageFormat)) {
                pixmap.loadFromData(data, imageFormat);
                break;
            }
        }
        return pixmap;
    }


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Qt 4.2.0-tp1