coloritem.cpp Example File

 /****************************************************************************
 **
 ** Copyright (C) 2011 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 "coloritem.h"

 ColorItem::ColorItem()
     : color(qrand() % 256, qrand() % 256, qrand() % 256)
 {
     setToolTip(QString("QColor(%1, %2, %3)\n%4")
               .arg(color.red()).arg(color.green()).arg(color.blue())
               .arg("Click and drag this color onto the robot!"));
     setCursor(Qt::OpenHandCursor);
     setAcceptedMouseButtons(Qt::LeftButton);
 }

 QRectF ColorItem::boundingRect() const
 {
     return QRectF(-15.5, -15.5, 34, 34);
 }

 void ColorItem::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
 {
     Q_UNUSED(option);
     Q_UNUSED(widget);
     painter->setPen(Qt::NoPen);
     painter->setBrush(Qt::darkGray);
     painter->drawEllipse(-12, -12, 30, 30);
     painter->setPen(QPen(Qt::black, 1));
     painter->setBrush(QBrush(color));
     painter->drawEllipse(-15, -15, 30, 30);
 }

 void ColorItem::mousePressEvent(QGraphicsSceneMouseEvent *)
 {
     setCursor(Qt::ClosedHandCursor);
 }

 void ColorItem::mouseMoveEvent(QGraphicsSceneMouseEvent *event)
 {
     if (QLineF(event->screenPos(), event->buttonDownScreenPos(Qt::LeftButton))
         .length() < QApplication::startDragDistance()) {
         return;
     }

     QDrag *drag = new QDrag(event->widget());
     QMimeData *mime = new QMimeData;
     drag->setMimeData(mime);

     static int n = 0;
     if (n++ > 2 && (qrand() % 3) == 0) {
         QImage image(":/images/head.png");
         mime->setImageData(image);

         drag->setPixmap(QPixmap::fromImage(image).scaled(30, 40));
         drag->setHotSpot(QPoint(15, 30));
     } else {
         mime->setColorData(color);
         mime->setText(QString("#%1%2%3")
                       .arg(color.red(), 2, 16, QLatin1Char('0'))
                       .arg(color.green(), 2, 16, QLatin1Char('0'))
                       .arg(color.blue(), 2, 16, QLatin1Char('0')));

         QPixmap pixmap(34, 34);
         pixmap.fill(Qt::white);

         QPainter painter(&pixmap);
         painter.translate(15, 15);
         painter.setRenderHint(QPainter::Antialiasing);
         paint(&painter, 0, 0);
         painter.end();

         pixmap.setMask(pixmap.createHeuristicMask());

         drag->setPixmap(pixmap);
         drag->setHotSpot(QPoint(15, 20));
     }

     drag->exec();
     setCursor(Qt::OpenHandCursor);
 }

 void ColorItem::mouseReleaseEvent(QGraphicsSceneMouseEvent *)
 {
     setCursor(Qt::OpenHandCursor);
 }