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+/****************************************************************************
+**
+** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: http://www.qt-project.org/
+**
+** 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 <QGraphicsScene>
+#include <QGraphicsSceneMouseEvent>
+#include <QPainter>
+#include <QStyleOption>
+
+#include "edge.h"
+#include "node.h"
+#include "graphwidget.h"
+
+//! [0]
+Node::Node(GraphWidget *graphWidget)
+ : graph(graphWidget)
+{
+ setFlag(ItemIsMovable);
+ setFlag(ItemSendsGeometryChanges);
+ setCacheMode(DeviceCoordinateCache);
+ setZValue(-1);
+}
+//! [0]
+
+//! [1]
+void Node::addEdge(Edge *edge)
+{
+ edgeList << edge;
+ edge->adjust();
+}
+
+QList<Edge *> Node::edges() const
+{
+ return edgeList;
+}
+//! [1]
+
+//! [2]
+void Node::calculateForces()
+{
+ if (!scene() || scene()->mouseGrabberItem() == this) {
+ newPos = pos();
+ return;
+ }
+//! [2]
+
+//! [3]
+ // Sum up all forces pushing this item away
+ qreal xvel = 0;
+ qreal yvel = 0;
+ foreach (QGraphicsItem *item, scene()->items()) {
+ Node *node = qgraphicsitem_cast<Node *>(item);
+ if (!node)
+ continue;
+
+ QPointF vec = mapToItem(node, 0, 0);
+ qreal dx = vec.x();
+ qreal dy = vec.y();
+ double l = 2.0 * (dx * dx + dy * dy);
+ if (l > 0) {
+ xvel += (dx * 150.0) / l;
+ yvel += (dy * 150.0) / l;
+ }
+ }
+//! [3]
+
+//! [4]
+ // Now subtract all forces pulling items together
+ double weight = (edgeList.size() + 1) * 10;
+ foreach (Edge *edge, edgeList) {
+ QPointF vec;
+ if (edge->sourceNode() == this)
+ vec = mapToItem(edge->destNode(), 0, 0);
+ else
+ vec = mapToItem(edge->sourceNode(), 0, 0);
+ xvel -= vec.x() / weight;
+ yvel -= vec.y() / weight;
+ }
+//! [4]
+
+//! [5]
+ if (qAbs(xvel) < 0.1 && qAbs(yvel) < 0.1)
+ xvel = yvel = 0;
+//! [5]
+
+//! [6]
+ 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));
+}
+//! [6]
+
+//! [7]
+bool Node::advance()
+{
+ if (newPos == pos())
+ return false;
+
+ setPos(newPos);
+ return true;
+}
+//! [7]
+
+//! [8]
+QRectF Node::boundingRect() const
+{
+ qreal adjust = 2;
+ return QRectF( -10 - adjust, -10 - adjust,
+ 23 + adjust, 23 + adjust);
+}
+//! [8]
+
+//! [9]
+QPainterPath Node::shape() const
+{
+ QPainterPath path;
+ path.addEllipse(-10, -10, 20, 20);
+ return path;
+}
+//! [9]
+
+//! [10]
+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);
+}
+//! [10]
+
+//! [11]
+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);
+}
+//! [11]
+
+//! [12]
+void Node::mousePressEvent(QGraphicsSceneMouseEvent *event)
+{
+ update();
+ QGraphicsItem::mousePressEvent(event);
+}
+
+void Node::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)
+{
+ update();
+ QGraphicsItem::mouseReleaseEvent(event);
+}
+//! [12]