Home · All Namespaces · All Classes · Main Classes · Grouped Classes · Modules · Functions

dragwidget.cpp Example File
draganddrop/draggableicons/dragwidget.cpp

 /****************************************************************************
 **
 ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
 ** Contact: Qt Software Information ([email protected])
 **
 ** This file is part of the examples of the Qt Toolkit.
 **
 ** $QT_BEGIN_LICENSE:LGPL$
 ** Commercial Usage
 ** Licensees holding valid Qt Commercial licenses may use this file in
 ** accordance with the Qt Commercial License Agreement provided with the
 ** Software or, alternatively, in accordance with the terms contained in
 ** a written agreement between you and Nokia.
 **
 ** GNU Lesser General Public License Usage
 ** Alternatively, this file may be used under the terms of the GNU Lesser
 ** General Public License version 2.1 as published by the Free Software
 ** Foundation and appearing in the file LICENSE.LGPL included in the
 ** packaging of this file.  Please review the following information to
 ** ensure the GNU Lesser General Public License version 2.1 requirements
 ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
 **
 ** In addition, as a special exception, Nokia gives you certain
 ** additional rights. These rights are described in the Nokia Qt LGPL
 ** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
 ** package.
 **
 ** GNU General Public License Usage
 ** Alternatively, this file may be used under the terms of the GNU
 ** General Public License version 3.0 as published by the Free Software
 ** Foundation and appearing in the file LICENSE.GPL included in the
 ** packaging of this file.  Please review the following information to
 ** ensure the GNU General Public License version 3.0 requirements will be
 ** met: http://www.gnu.org/copyleft/gpl.html.
 **
 ** If you are unsure which license is appropriate for your use, please
 ** contact the sales department at [email protected].
 ** $QT_END_LICENSE$
 **
 ****************************************************************************/

 #include <QtGui>

 #include "dragwidget.h"

 DragWidget::DragWidget(QWidget *parent)
     : QFrame(parent)
 {
     setMinimumSize(200, 200);
     setFrameStyle(QFrame::Sunken | QFrame::StyledPanel);
     setAcceptDrops(true);

     QLabel *boatIcon = new QLabel(this);
     boatIcon->setPixmap(QPixmap(":/images/boat.png"));
     boatIcon->move(20, 20);
     boatIcon->show();
     boatIcon->setAttribute(Qt::WA_DeleteOnClose);

     QLabel *carIcon = new QLabel(this);
     carIcon->setPixmap(QPixmap(":/images/car.png"));
     carIcon->move(120, 20);
     carIcon->show();
     carIcon->setAttribute(Qt::WA_DeleteOnClose);

     QLabel *houseIcon = new QLabel(this);
     houseIcon->setPixmap(QPixmap(":/images/house.png"));
     houseIcon->move(20, 120);
     houseIcon->show();
     houseIcon->setAttribute(Qt::WA_DeleteOnClose);
 }

 void DragWidget::dragEnterEvent(QDragEnterEvent *event)
 {
     if (event->mimeData()->hasFormat("application/x-dnditemdata")) {
         if (event->source() == this) {
             event->setDropAction(Qt::MoveAction);
             event->accept();
         } else {
             event->acceptProposedAction();
         }
     } else {
         event->ignore();
     }
 }

 void DragWidget::dragMoveEvent(QDragMoveEvent *event)
 {
     if (event->mimeData()->hasFormat("application/x-dnditemdata")) {
         if (event->source() == this) {
             event->setDropAction(Qt::MoveAction);
             event->accept();
         } else {
             event->acceptProposedAction();
         }
     } else {
         event->ignore();
     }
 }

 void DragWidget::dropEvent(QDropEvent *event)
 {
     if (event->mimeData()->hasFormat("application/x-dnditemdata")) {
         QByteArray itemData = event->mimeData()->data("application/x-dnditemdata");
         QDataStream dataStream(&itemData, QIODevice::ReadOnly);

         QPixmap pixmap;
         QPoint offset;
         dataStream >> pixmap >> offset;

         QLabel *newIcon = new QLabel(this);
         newIcon->setPixmap(pixmap);
         newIcon->move(event->pos() - offset);
         newIcon->show();
         newIcon->setAttribute(Qt::WA_DeleteOnClose);

         if (event->source() == this) {
             event->setDropAction(Qt::MoveAction);
             event->accept();
         } else {
             event->acceptProposedAction();
         }
     } else {
         event->ignore();
     }
 }

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

     QPixmap pixmap = *child->pixmap();

     QByteArray itemData;
     QDataStream dataStream(&itemData, QIODevice::WriteOnly);
     dataStream << pixmap << QPoint(event->pos() - child->pos());

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

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

     QPixmap tempPixmap = pixmap;
     QPainter painter;
     painter.begin(&tempPixmap);
     painter.fillRect(pixmap.rect(), QColor(127, 127, 127, 127));
     painter.end();

     child->setPixmap(tempPixmap);

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