Home · All Classes · All Functions · Overviews

arrow.cpp Example File
graphicsview/diagramscene/arrow.cpp

 /****************************************************************************
 **
 ** Copyright (C) 2009 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.
 **
 ** $QT_BEGIN_LICENSE:LGPL$
 ** 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 1.1, 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 have questions regarding the use of this file, please contact
 ** Nokia at [email protected].
 ** $QT_END_LICENSE$
 **
 ****************************************************************************/

 #include <QtGui>

 #include "arrow.h"
 #include <math.h>

 const qreal Pi = 3.14;

 Arrow::Arrow(DiagramItem *startItem, DiagramItem *endItem,
          QGraphicsItem *parent, QGraphicsScene *scene)
     : QGraphicsLineItem(parent, scene)
 {
     myStartItem = startItem;
     myEndItem = endItem;
     setFlag(QGraphicsItem::ItemIsSelectable, true);
     myColor = Qt::black;
     setPen(QPen(myColor, 2, Qt::SolidLine, Qt::RoundCap, Qt::RoundJoin));
 }

 QRectF Arrow::boundingRect() const
 {
     qreal extra = (pen().width() + 20) / 2.0;

     return QRectF(line().p1(), QSizeF(line().p2().x() - line().p1().x(),
                                       line().p2().y() - line().p1().y()))
         .normalized()
         .adjusted(-extra, -extra, extra, extra);
 }

 QPainterPath Arrow::shape() const
 {
     QPainterPath path = QGraphicsLineItem::shape();
     path.addPolygon(arrowHead);
     return path;
 }

 void Arrow::updatePosition()
 {
     QLineF line(mapFromItem(myStartItem, 0, 0), mapFromItem(myEndItem, 0, 0));
     setLine(line);
 }

 void Arrow::paint(QPainter *painter, const QStyleOptionGraphicsItem *,
           QWidget *)
 {
     if (myStartItem->collidesWithItem(myEndItem))
         return;

     QPen myPen = pen();
     myPen.setColor(myColor);
     qreal arrowSize = 20;
     painter->setPen(myPen);
     painter->setBrush(myColor);

     QLineF centerLine(myStartItem->pos(), myEndItem->pos());
     QPolygonF endPolygon = myEndItem->polygon();
     QPointF p1 = endPolygon.first() + myEndItem->pos();
     QPointF p2;
     QPointF intersectPoint;
     QLineF polyLine;
     for (int i = 1; i < endPolygon.count(); ++i) {
     p2 = endPolygon.at(i) + myEndItem->pos();
     polyLine = QLineF(p1, p2);
     QLineF::IntersectType intersectType =
         polyLine.intersect(centerLine, &intersectPoint);
     if (intersectType == QLineF::BoundedIntersection)
         break;
         p1 = p2;
     }

     setLine(QLineF(intersectPoint, myStartItem->pos()));

     double angle = ::acos(line().dx() / line().length());
     if (line().dy() >= 0)
         angle = (Pi * 2) - angle;

         QPointF arrowP1 = line().p1() + QPointF(sin(angle + Pi / 3) * arrowSize,
                                         cos(angle + Pi / 3) * arrowSize);
         QPointF arrowP2 = line().p1() + QPointF(sin(angle + Pi - Pi / 3) * arrowSize,
                                         cos(angle + Pi - Pi / 3) * arrowSize);

         arrowHead.clear();
         arrowHead << line().p1() << arrowP1 << arrowP2;
         painter->drawLine(line());
         painter->drawPolygon(arrowHead);
         if (isSelected()) {
             painter->setPen(QPen(myColor, 1, Qt::DashLine));
         QLineF myLine = line();
         myLine.translate(0, 4.0);
         painter->drawLine(myLine);
         myLine.translate(0,-8.0);
         painter->drawLine(myLine);
     }
 }