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    41 

    42 #include <QGraphicsScene>

    43 #include <QGraphicsSceneMouseEvent>

    44 #include <QPainter>

    45 #include <QStyleOption>

    46 

    47 #include "edge.h"

    48 #include "node.h"

    49 #include "graphwidget.h"

    50 

    51 Node::Node(GraphWidget *graphWidget)

    52     : graph(graphWidget)

    53 {

    54     setFlag(ItemIsMovable);

    55     setFlag(ItemSendsGeometryChanges);

    56     setCacheMode(DeviceCoordinateCache);

    57     setZValue(-1);

    58 }

    59 

    60 void Node::addEdge(Edge *edge)

    61 {

    62     edgeList << edge;

    63     edge->adjust();

    64 }

    65 

    66 QList<Edge *> Node::edges() const

    67 {

    68     return edgeList;

    69 }

    70 

    71 void Node::calculateForces()

    72 {

    73     if (!scene() || scene()->mouseGrabberItem() == this) {

    74         newPos = pos();

    75         return;

    76     }

    77     

    78     // Sum up all forces pushing this item away

    79     qreal xvel = 0;

    80     qreal yvel = 0;

    81     foreach (QGraphicsItem *item, scene()->items()) {

    82         Node *node = qgraphicsitem_cast<Node *>(item);

    83         if (!node)

    84             continue;

    85 

    86         QLineF line(mapFromItem(node, 0, 0), QPointF(0, 0));

    87         qreal dx = line.dx();

    88         qreal dy = line.dy();

    89         double l = 2.0 * (dx * dx + dy * dy);

    90         if (l > 0) {

    91             xvel += (dx * 150.0) / l;

    92             yvel += (dy * 150.0) / l;

    93         }

    94     }

    95 

    96     // Now subtract all forces pulling items together

    97     double weight = (edgeList.size() + 1) * 10;

    98     foreach (Edge *edge, edgeList) {

    99         QPointF pos;

   100         if (edge->sourceNode() == this)

   101             pos = mapFromItem(edge->destNode(), 0, 0);

   102         else

   103             pos = mapFromItem(edge->sourceNode(), 0, 0);

   104         xvel += pos.x() / weight;

   105         yvel += pos.y() / weight;

   106     }

   107     

   108     if (qAbs(xvel) < 0.1 && qAbs(yvel) < 0.1)

   109         xvel = yvel = 0;

   110 

   111     QRectF sceneRect = scene()->sceneRect();

   112     newPos = pos() + QPointF(xvel, yvel);

   113     newPos.setX(qMin(qMax(newPos.x(), sceneRect.left() + 10), sceneRect.right() - 10));

   114     newPos.setY(qMin(qMax(newPos.y(), sceneRect.top() + 10), sceneRect.bottom() - 10));

   115 }

   116 

   117 bool Node::advance()

   118 {

   119     if (newPos == pos())

   120         return false;

   121 

   122     setPos(newPos);

   123     return true;

   124 }

   125 

   126 QRectF Node::boundingRect() const

   127 {

   128     qreal adjust = 2;

   129     return QRectF(-10 - adjust, -10 - adjust,

   130                   23 + adjust, 23 + adjust);

   131 }

   132 

   133 QPainterPath Node::shape() const

   134 {

   135     QPainterPath path;

   136     path.addEllipse(-10, -10, 20, 20);

   137     return path;

   138 }

   139 

   140 void Node::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *)

   141 {

   142     painter->setPen(Qt::NoPen);

   143     painter->setBrush(Qt::darkGray);

   144     painter->drawEllipse(-7, -7, 20, 20);

   145 

   146     QRadialGradient gradient(-3, -3, 10);

   147     if (option->state & QStyle::State_Sunken) {

   148         gradient.setCenter(3, 3);

   149         gradient.setFocalPoint(3, 3);

   150         gradient.setColorAt(1, QColor(Qt::yellow).light(120));

   151         gradient.setColorAt(0, QColor(Qt::darkYellow).light(120));

   152     } else {

   153         gradient.setColorAt(0, Qt::yellow);

   154         gradient.setColorAt(1, Qt::darkYellow);

   155     }

   156     painter->setBrush(gradient);

   157     painter->setPen(QPen(Qt::black, 0));

   158     painter->drawEllipse(-10, -10, 20, 20);

   159 }

   160 

   161 QVariant Node::itemChange(GraphicsItemChange change, const QVariant &value)

   162 {

   163     switch (change) {

   164     case ItemPositionHasChanged:

   165         foreach (Edge *edge, edgeList)

   166             edge->adjust();

   167         graph->itemMoved();

   168         break;

   169     default:

   170         break;

   171     };

   172 

   173     return QGraphicsItem::itemChange(change, value);

   174 }

   175 

   176 void Node::mousePressEvent(QGraphicsSceneMouseEvent *event)

   177 {

   178     update();

   179     QGraphicsItem::mousePressEvent(event);

   180 }

   181 

   182 void Node::mouseReleaseEvent(QGraphicsSceneMouseEvent *event)

   183 {

   184     update();

   185     QGraphicsItem::mouseReleaseEvent(event);

   186 }