node.cpp Example File

graphicsview/elasticnodes/node.cpp
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#include "edge.h" #include "node.h" #include "graphwidget.h" #include <QGraphicsScene> #include <QGraphicsSceneMouseEvent> #include <QPainter> #include <QStyleOption> 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; } // 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; } } // 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; } 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::advancePosition() { 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); }