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  ** This file is part of the examples of the Qt Toolkit.
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  #include "diagramitem.h"
  #include "arrow.h"
  
  #include <QGraphicsScene>
  #include <QGraphicsSceneContextMenuEvent>
  #include <QMenu>
  #include <QPainter>
  #include <QDebug>
  #include <QStyleOptionGraphicsItem>
  
  //! [0]
  DiagramItem::DiagramItem(DiagramType diagramType, QMenu *contextMenu,
               QGraphicsItem *parent)
      : QGraphicsPolygonItem(parent)
  {
      myDiagramType = diagramType;
      myContextMenu = contextMenu;
  
      QPainterPath path;
      switch (myDiagramType) {
          case StartEnd:
              path.moveTo(200, 50);
              path.arcTo(150, 0, 50, 50, 0, 90);
              path.arcTo(50, 0, 50, 50, 90, 90);
              path.arcTo(50, 50, 50, 50, 180, 90);
              path.arcTo(150, 50, 50, 50, 270, 90);
              path.lineTo(200, 50);
              myPolygon = path.toFillPolygon().translated(-125, -50);
              break;
          case Conditional:
              myPolygon << QPointF(-100, 0) << QPointF(0, 100)
                        << QPointF(100, 0) << QPointF(0, -100)
                        << QPointF(-100, 0);
              break;
          case Step:
              myPolygon << QPointF(-100, -100) << QPointF(100, -100)
                        << QPointF(100, 100) << QPointF(-100, 100)
                        << QPointF(-100, -100);
              break;
          default:
              myPolygon << QPointF(-120, -80) << QPointF(-70, 80)
                        << QPointF(120, 80) << QPointF(70, -80)
                        << QPointF(-120, -80);
              break;
      }
      setPolygon(myPolygon);
      setFlag(QGraphicsItem::ItemIsMovable, true);
      setFlag(QGraphicsItem::ItemIsSelectable, true);
      setFlag(QGraphicsItem::ItemSendsGeometryChanges, true);
      setAcceptHoverEvents(true);
  }
  
  
  void DiagramItem::removeArrow(Arrow *arrow)
  {
      int index = arrows.indexOf(arrow);
  
      if (index != -1)
          arrows.removeAt(index);
  }
  
  void DiagramItem::removeArrows()
  {
      foreach (Arrow *arrow, arrows) {
          arrow->startItem()->removeArrow(arrow);
          arrow->endItem()->removeArrow(arrow);
          scene()->removeItem(arrow);
          delete arrow;
      }
  }
  
  void DiagramItem::addArrow(Arrow *arrow)
  {
      arrows.append(arrow);
  }
  
  QPixmap DiagramItem::image() const
  {
      QPixmap pixmap(250, 250);
      pixmap.fill(Qt::transparent);
      QPainter painter(&pixmap);
      painter.setPen(QPen(Qt::black, 8));
      painter.translate(125, 125);
      painter.drawPolyline(myPolygon);
  
      return pixmap;
  }
  
  QList<QPointF> DiagramItem::resizeHandlePoints() {
      qreal width = resizeHandlePointWidth;
      QRectF rf = QRectF(boundingRect().topLeft() + QPointF(width/2, width/2),
                             boundingRect().bottomRight() - QPointF(width/2, width/2));
      qreal centerX = rf.center().x();
      qreal centerY = rf.center().y();
      return QList<QPointF>{rf.topLeft(), QPointF(centerX, rf.top()), rf.topRight(),
                           QPointF(rf.left(), centerY), QPointF(rf.right(), centerY),
                  rf.bottomLeft(), QPointF(centerX, rf.bottom()), rf.bottomRight()};
  }
  
  bool DiagramItem::isCloseEnough(QPointF const& p1, QPointF const& p2) {
      qreal delta = std::abs(p1.x() - p2.x()) + std::abs(p1.y() - p2.y());
      return delta < closeEnoughDistance;
  }
  
  DiagramItem* DiagramItem::clone() {
      DiagramItem* cloned = new DiagramItem(myDiagramType, myContextMenu, nullptr);
      cloned->myPolygon = myPolygon;
      cloned->setPos(scenePos());
      cloned->setPolygon(myPolygon);
      cloned->setBrush(brush());
      cloned->setZValue(zValue());
      return cloned;
  }
  
  
  void DiagramItem::mousePressEvent(QGraphicsSceneMouseEvent* event) {
      resizeMode = false;
      int index = 0;
      foreach (QPointF const& p, resizeHandlePoints()) {
          if (isCloseEnough(event->pos(), p)) {
              resizeMode = true;
              break;
          }
          index++;
      }
      scaleDirection = static_cast<Direction>(index);
      setFlag(GraphicsItemFlag::ItemIsMovable, !resizeMode);
      if (resizeMode) {
          qDebug() << "begin resizing";
          previousPolygon = polygon();
          event->accept();
      } else {
          qDebug() << "item type " << this->type() << " start moving from" << scenePos();
          movingStartPosition = scenePos();
          QGraphicsItem::mousePressEvent(event);
      }
  }
  
  void DiagramItem::mouseMoveEvent(QGraphicsSceneMouseEvent* event) {
      if (resizeMode) {
          prepareGeometryChange();
          myPolygon = scaledPolygon(myPolygon, scaleDirection, event->pos());
          setPolygon(myPolygon);
      }
      QGraphicsItem::mouseMoveEvent(event);
  }
  
  void DiagramItem::mouseReleaseEvent(QGraphicsSceneMouseEvent* event) {
      if (resizeMode) {
          qDebug() << "after resizing";
          if (polygon() != previousPolygon) {
              isResized = true;
          }
      } else {
          qDebug() << "\tend moving in" << scenePos();
          if (scenePos() != movingStartPosition) {
              isMoved = true;
              qDebug() << "-- " << scenePos() << movingStartPosition;
          }
      }
      resizeMode = false;
      QGraphicsItem::mouseReleaseEvent(event);
  }
  
  void DiagramItem::hoverMoveEvent(QGraphicsSceneHoverEvent* event) {
      setCursor(Qt::ArrowCursor);
      int index = 0;
      foreach (QPointF const& p, resizeHandlePoints()) {
          if (isCloseEnough(p, event->pos())) {
              switch (static_cast<Direction>(index)) {
              case TopLeft:
              case BottomRight: setCursor(Qt::SizeFDiagCursor); break;
              case Top:
              case Bottom: setCursor(Qt::SizeVerCursor); break;
              case TopRight:
              case BottomLeft: setCursor(Qt::SizeBDiagCursor); break;
              case Left:
              case Right: setCursor(Qt::SizeHorCursor); break;
              }
              break;
          }
          index++;
      }
      QGraphicsItem::hoverMoveEvent(event);
  }
  
  void DiagramItem::paint(QPainter* painter, const QStyleOptionGraphicsItem* option,
                          QWidget* widget) {
      // remove build-in selected state
      QStyleOptionGraphicsItem myOption(*option);
      myOption.state &= ~QStyle::State_Selected;
      QGraphicsPolygonItem::paint(painter, &myOption, widget);
  
      // add resize handles
      if (this->isSelected()) {
          qreal width = resizeHandlePointWidth;
          foreach(QPointF const& point, resizeHandlePoints()) {
              painter->drawEllipse(QRectF(point.x() - width/2, point.y() - width/2, width, width));
          }
      }
  }
  
  void DiagramItem::contextMenuEvent(QGraphicsSceneContextMenuEvent *event)
  {
      scene()->clearSelection();
      setSelected(true);
      myContextMenu->exec(event->screenPos());
  }
  
  QVariant DiagramItem::itemChange(GraphicsItemChange change, const QVariant &value)
  {
      if (change == QGraphicsItem::ItemPositionChange) {
          foreach (Arrow *arrow, arrows) {
              arrow->updatePosition();
          }
      }
  
      return value;
  }
  
  QPolygonF DiagramItem::scaledPolygon(const QPolygonF& old, DiagramItem::Direction direction,
                                      const QPointF& newPos) {
      qreal oldWidth = old.boundingRect().width();
      qreal oldHeight = old.boundingRect().height();
      qreal scaleWidth, scaleHeight;
      switch(direction) {
      case TopLeft: {
          QPointF fixPoint = old.boundingRect().bottomRight();
          scaleWidth = (fixPoint.x() - newPos.x()) / oldWidth;
          scaleHeight = (fixPoint.y() - newPos.y()) / oldHeight;
          break;
      }
      case Top: {
          QPointF fixPoint = old.boundingRect().bottomLeft();
          scaleWidth = 1;
          scaleHeight = (fixPoint.y() - newPos.y()) / oldHeight;
          break;
      }
      case TopRight: {
          QPointF fixPoint = old.boundingRect().bottomLeft();
          scaleWidth = (newPos.x() - fixPoint.x()) / oldWidth;
          scaleHeight = (fixPoint.y() - newPos.y() ) / oldHeight;
          break;
      }
      case Right: {
          QPointF fixPoint = old.boundingRect().bottomLeft();
          scaleWidth = (newPos.x() - fixPoint.x()) / oldWidth;
          scaleHeight = 1;
          break;
      }
      case BottomRight: {
          QPointF fixPoint = old.boundingRect().topLeft();
          scaleWidth = (newPos.x() - fixPoint.x()) / oldWidth;
          scaleHeight = (newPos.y() - fixPoint.y()) / oldHeight;
          break;
      }
      case Bottom: {
          QPointF fixPoint = old.boundingRect().topLeft();
          scaleWidth = 1;
          scaleHeight = (newPos.y() - fixPoint.y()) / oldHeight;
          break;
      }
      case BottomLeft: {
          QPointF fixPoint = old.boundingRect().topRight();
          scaleWidth = (fixPoint.x() - newPos.x()) / oldWidth;
          scaleHeight = (newPos.y() - fixPoint.y()) / oldHeight;
          break;
      }
      case Left: {
          QPointF fixPoint = old.boundingRect().bottomRight();
          scaleWidth = (fixPoint.x() - newPos.x()) / oldWidth;
          scaleHeight = 1;
          break;
      }
      }
      QTransform trans;
      trans.scale(scaleWidth, scaleHeight);
      return trans.map(old);
  }
  
  
  //! [6]
  