- Qt 5.5
- Qt Widgets
- Drop Site Example
- droparea.cpp Example File
- Qt 5.5.1 Reference Documentation

# droparea.cpp Example File

draganddrop/dropsite/droparea.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the examples of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
    ** You may use this file under the terms of the BSD license as follows:
    **
    ** "Redistribution and use in source and binary forms, with or without
    ** modification, are permitted provided that the following conditions are
    ** met:
    **   * Redistributions of source code must retain the above copyright
    **     notice, this list of conditions and the following disclaimer.
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    **     notice, this list of conditions and the following disclaimer in
    **     the documentation and/or other materials provided with the
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    **     contributors may be used to endorse or promote products derived
    **     from this software without specific prior written permission.
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    #include "droparea.h"

    #include <QDragEnterEvent>
    #include <QMimeData>

    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::dragMoveEvent(QDragMoveEvent *event)
    {
        event->acceptProposedAction();
    }

    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 if (mimeData->hasUrls()) {
            QList<QUrl> urlList = mimeData->urls();
            QString text;
            for (int i = 0; i < urlList.size() && i < 32; ++i) {
                QString url = urlList.at(i).path();
                text += url + QString("\n");
            }
            setText(text);
        } 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();
    }