diagramitem.cpp Example File

 /****************************************************************************
 **
 ** 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.
 **   * 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 The Qt Company Ltd 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 "diagramitem.h"
 #include "arrow.h"

 DiagramItem::DiagramItem(DiagramType diagramType, QMenu *contextMenu,
              QGraphicsItem *parent, QGraphicsScene *scene)
     : QGraphicsPolygonItem(parent, scene)
 {
     myDiagramType = diagramType;
     myContextMenu = contextMenu;

     QPainterPath path;
     switch (myDiagramType) {
         case StartEnd:
             path.moveTo(200, 50);
             path.arcTo(150, 0, 50, 50, 0, 90);
             path.arcTo(50, 0, 50, 50, 90, 90);
             path.arcTo(50, 50, 50, 50, 180, 90);
             path.arcTo(150, 50, 50, 50, 270, 90);
             path.lineTo(200, 25);
             myPolygon = path.toFillPolygon();
             break;
         case Conditional:
             myPolygon << QPointF(-100, 0) << QPointF(0, 100)
                       << QPointF(100, 0) << QPointF(0, -100)
                       << QPointF(-100, 0);
             break;
         case Step:
             myPolygon << QPointF(-100, -100) << QPointF(100, -100)
                       << QPointF(100, 100) << QPointF(-100, 100)
                       << QPointF(-100, -100);
             break;
         default:
             myPolygon << QPointF(-120, -80) << QPointF(-70, 80)
                       << QPointF(120, 80) << QPointF(70, -80)
                       << QPointF(-120, -80);
             break;
     }
     setPolygon(myPolygon);
     setFlag(QGraphicsItem::ItemIsMovable, true);
     setFlag(QGraphicsItem::ItemIsSelectable, true);
     setFlag(QGraphicsItem::ItemSendsGeometryChanges, true);
 }

 void DiagramItem::removeArrow(Arrow *arrow)
 {
     int index = arrows.indexOf(arrow);

     if (index != -1)
         arrows.removeAt(index);
 }

 void DiagramItem::removeArrows()
 {
     foreach (Arrow *arrow, arrows) {
         arrow->startItem()->removeArrow(arrow);
         arrow->endItem()->removeArrow(arrow);
         scene()->removeItem(arrow);
         delete arrow;
     }
 }

 void DiagramItem::addArrow(Arrow *arrow)
 {
     arrows.append(arrow);
 }

 QPixmap DiagramItem::image() const
 {
     QPixmap pixmap(250, 250);
     pixmap.fill(Qt::transparent);
     QPainter painter(&pixmap);
     painter.setPen(QPen(Qt::black, 8));
     painter.translate(125, 125);
     painter.drawPolyline(myPolygon);

     return pixmap;
 }

 void DiagramItem::contextMenuEvent(QGraphicsSceneContextMenuEvent *event)
 {
     scene()->clearSelection();
     setSelected(true);
     myContextMenu->exec(event->screenPos());
 }

 QVariant DiagramItem::itemChange(GraphicsItemChange change,
                      const QVariant &value)
 {
     if (change == QGraphicsItem::ItemPositionChange) {
         foreach (Arrow *arrow, arrows) {
             arrow->updatePosition();
         }
     }

     return value;
 }