- Qt 5.5
- Qt Widgets
- Diagram Scene Example
- diagramitem.cpp Example File
- Qt 5.5.1 Reference Documentation

# diagramitem.cpp Example File

graphicsview/diagramscene/diagramitem.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** This file is part of the examples of the Qt Toolkit.
    **
    ** $QT_BEGIN_LICENSE:BSD$
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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;
    }