Qt 5.11 | Qt Widgets | Diagram Scene Example | diagramitem.cpp Example File

Qt 5.11.3 Reference Documentation

# diagramitem.cpp Example File

graphicsview/diagramscene/diagramitem.cpp

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      #include "diagramitem.h"
      #include "arrow.h"

      #include <QGraphicsScene>
      #include <QGraphicsSceneContextMenuEvent>
      #include <QMenu>
      #include <QPainter>

      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, 25);
                  myPolygon = path.toFillPolygon();
                  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);
      }

      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;
      }

      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;
      }