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<pre> /****************************************************************************
**
** Copyright (C) 2006-2006 Trolltech ASA. All rights reserved.
**
** This file is part of the example classes of the Qt Toolkit.
**
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** License version 2.0 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 GNU
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#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);
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 ItemPositionChange:
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>
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