Qt Reference Documentation

dragwidget.cpp Example File

draganddrop/fridgemagnets/dragwidget.cpp
 /****************************************************************************
 **
 ** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
 ** All rights reserved.
 ** Contact: Nokia Corporation ([email protected])
 **
 ** 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.
 **   * Redistributions in binary form must reproduce the above copyright
 **     notice, this list of conditions and the following disclaimer in
 **     the documentation and/or other materials provided with the
 **     distribution.
 **   * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor
 **     the names of its contributors may be used to endorse or promote
 **     products derived from this software without specific prior written
 **     permission.
 **
 ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
 ** $QT_END_LICENSE$
 **
 ****************************************************************************/

 #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();
             wordLabel->setAttribute(Qt::WA_DeleteOnClose);
             x += wordLabel->width() + 2;
             if (x >= 245) {
                 x = 5;
                 y += wordLabel->height() + 2;
             }
         }
     }

     #ifndef Q_WS_S60
     //Fridge magnets is used for demoing Qt on S60 and themed backgrounds look better than white
     QPalette newPalette = palette();
     newPalette.setColor(QPalette::Window, Qt::white);
     setPalette(newPalette);
     #endif

     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();
         newLabel->setAttribute(Qt::WA_DeleteOnClose);

         if (event->source() == this) {
             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();
             newLabel->setAttribute(Qt::WA_DeleteOnClose);

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

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

 void DragWidget::mousePressEvent(QMouseEvent *event)
 {
     DragLabel *child = static_cast<DragLabel*>(childAt(event->pos()));
     if (!child)
         return;

     QPoint hotSpot = event->pos() - child->pos();

     QByteArray itemData;
     QDataStream dataStream(&itemData, QIODevice::WriteOnly);
     dataStream << child->labelText() << QPoint(hotSpot);

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

     QDrag *drag = new QDrag(this);
     drag->setMimeData(mimeData);
     drag->setPixmap(*child->pixmap());
     drag->setHotSpot(hotSpot);

     child->hide();

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

Thank you for giving your feedback.

Make sure it is related to this specific page. For more general bugs and requests, please use the Qt Bug Tracker.