<?xml version="1.0" encoding="iso-8859-1"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <title>Qt 4.6: node.cpp Example File (graphicsview/elasticnodes/node.cpp)</title> <link href="classic.css" rel="stylesheet" type="text/css" /> </head> <body> <table border="0" cellpadding="0" cellspacing="0" width="100%"> <tr> <td align="left" valign="top" width="32"><a href="http://qt.nokia.com/"><img src="images/qt-logo.png" align="left" border="0" /></a></td> <td width="1"> </td><td class="postheader" valign="center"><a href="index.html"><font color="#004faf">Home</font></a> · <a href="classes.html"><font color="#004faf">All Classes</font></a> · <a href="functions.html"><font color="#004faf">All Functions</font></a> · <a href="overviews.html"><font color="#004faf">Overviews</font></a></td></tr></table><h1 class="title">node.cpp Example File<br /><span class="small-subtitle">graphicsview/elasticnodes/node.cpp</span> </h1> <pre><span class="comment"> /**************************************************************************** ** ** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies). ** All rights reserved. ** Contact: Nokia Corporation (qt-info@nokia.com) ** ** 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 qt-info@nokia.com. ** $QT_END_LICENSE$ ** ****************************************************************************/</span> #include <QGraphicsScene> #include <QGraphicsSceneMouseEvent> #include <QPainter> #include <QStyleOption> #include "edge.h" #include "node.h" #include "graphwidget.h" Node::Node(GraphWidget *graphWidget) : graph(graphWidget) { setFlag(ItemIsMovable); setFlag(ItemSendsGeometryChanges); setCacheMode(DeviceCoordinateCache); setZValue(-1); } void Node::addEdge(Edge *edge) { edgeList << edge; edge->adjust(); } QList<Edge *> Node::edges() const { return edgeList; } void Node::calculateForces() { if (!scene() || scene()->mouseGrabberItem() == this) { newPos = pos(); return; } <span class="comment">// Sum up all forces pushing this item away</span> qreal xvel = 0; qreal yvel = 0; foreach (QGraphicsItem *item, scene()->items()) { Node *node = qgraphicsitem_cast<Node *>(item); if (!node) continue; QLineF line(mapFromItem(node, 0, 0), QPointF(0, 0)); qreal dx = line.dx(); qreal dy = line.dy(); double l = 2.0 * (dx * dx + dy * dy); if (l > 0) { xvel += (dx * 150.0) / l; yvel += (dy * 150.0) / l; } } <span class="comment">// Now subtract all forces pulling items together</span> double weight = (edgeList.size() + 1) * 10; foreach (Edge *edge, edgeList) { QPointF pos; if (edge->sourceNode() == this) pos = mapFromItem(edge->destNode(), 0, 0); else pos = mapFromItem(edge->sourceNode(), 0, 0); xvel += pos.x() / weight; yvel += pos.y() / weight; } if (qAbs(xvel) < 0.1 && qAbs(yvel) < 0.1) xvel = yvel = 0; QRectF sceneRect = scene()->sceneRect(); newPos = pos() + QPointF(xvel, yvel); newPos.setX(qMin(qMax(newPos.x(), sceneRect.left() + 10), sceneRect.right() - 10)); newPos.setY(qMin(qMax(newPos.y(), sceneRect.top() + 10), sceneRect.bottom() - 10)); } bool Node::advance() { if (newPos == pos()) return false; setPos(newPos); return true; } QRectF Node::boundingRect() const { qreal adjust = 2; return QRectF(-10 - adjust, -10 - adjust, 23 + adjust, 23 + adjust); } QPainterPath Node::shape() const { QPainterPath path; path.addEllipse(-10, -10, 20, 20); return path; } void Node::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *) { painter->setPen(Qt::NoPen); painter->setBrush(Qt::darkGray); painter->drawEllipse(-7, -7, 20, 20); QRadialGradient gradient(-3, -3, 10); if (option->state & QStyle::State_Sunken) { gradient.setCenter(3, 3); gradient.setFocalPoint(3, 3); gradient.setColorAt(1, QColor(Qt::yellow).light(120)); gradient.setColorAt(0, QColor(Qt::darkYellow).light(120)); } else { gradient.setColorAt(0, Qt::yellow); gradient.setColorAt(1, Qt::darkYellow); } painter->setBrush(gradient); painter->setPen(QPen(Qt::black, 0)); painter->drawEllipse(-10, -10, 20, 20); } QVariant Node::itemChange(GraphicsItemChange change, const QVariant &value) { switch (change) { case ItemPositionHasChanged: foreach (Edge *edge, edgeList) edge->adjust(); graph->itemMoved(); break; default: break; }; return QGraphicsItem::itemChange(change, value); } void Node::mousePressEvent(QGraphicsSceneMouseEvent *event) { update(); QGraphicsItem::mousePressEvent(event); } void Node::mouseReleaseEvent(QGraphicsSceneMouseEvent *event) { update(); QGraphicsItem::mouseReleaseEvent(event); }</pre> <p /><address><hr /><div align="center"> <table width="100%" cellspacing="0" border="0"><tr class="address"> <td width="40%" align="left">Copyright © 2010 Nokia Corporation and/or its subsidiary(-ies)</td> <td width="20%" align="center"><a href="trademarks.html">Trademarks</a></td> <td width="40%" align="right"><div align="right">Qt 4.6.3</div></td> </tr></table></div></address></body> </html>