Important: Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

How to use a QPixmap as an object in DiagramScene?



  • I'm kind of adapting the DiagramScene example(it's on qt the site)
    But in the project it uses a QPolygon as an object, but i want to use a Pixmap instead.
    It's a program composed by some classes:
    diagramitem is responsible fot the items that we will place on the screen
    diagramscene handles the act of placing an object on the screen

    I thought that it is i little bit confusing the that qt did it, but ok

    diagramitem.cpp

    DiagramItem::DiagramItem(DiagramType diagramType, QMenu *contextMenu,
                 QGraphicsItem *parent)
        : QGraphicsPolygonItem(parent)
    {
        QPainter *painter=new QPainter;
        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:
                path.addEllipse(QPoint(0,0),50,50);
                path.addEllipse(QPoint(50,0),50,50);
                myPolygon=path.toFillPolygon();
    
                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::contextMenuEvent(QGraphicsSceneContextMenuEvent *event)
    {
        scene()->clearSelection();
        setSelected(true);
        myContextMenu->exec(event->screenPos());
    } //i didn't understand what this function means
    

    diagramscene.cpp

    DiagramScene::DiagramScene(QMenu *itemMenu, QObject *parent)
        : QGraphicsScene(parent)
    {
        myItemMenu = itemMenu;
        myMode = MoveItem;
        myItemType = DiagramItem::Step;
        line = 0;
        textItem = 0;
        myItemColor = Qt::white;
        myTextColor = Qt::black;
        myLineColor = Qt::black;
    }
    
    void DiagramScene::mousePressEvent(QGraphicsSceneMouseEvent *mouseEvent)
    {
        if (mouseEvent->button() != Qt::LeftButton)
            return;
    
        DiagramItem *item;
        switch (myMode) {
            case InsertItem:
                
                item = new DiagramItem(myItemType, myItemMenu);
                item->setBrush(myItemColor);
                addItem(item);
                item->setPos(mouseEvent->scenePos());
                emit itemInserted(item);
                break;
      ...
      }
    

    how can i create a myitemtype object with a pixmap instead of a polygon?


  • Lifetime Qt Champion

    Hi,

    In that case, why not use a QGraphicsPixmapItem ?



  • I did this but i don't know if i'm right

    diagramitem.h

    class DiagramItem : public QGraphicsPixmapItem 
    //now its from QGraphicsPixmapItem
    {
    public:
    ....
    QPixmap polygon() const { return myPolygon; }
    ....
    private:
        DiagramType myDiagramType;
        QPixmap myPolygon;
        QMenu *myContextMenu;
        QList<Line *> arrows;
    };
    

    now i'm using a pixmap as "myPolygon" instead of using QPolygonF

    diagramitem.cpp

    DiagramItem::DiagramItem(DiagramType diagramType, QMenu *contextMenu,
                 QGraphicsItem *parent)
        : QGraphicsPixmapItem(parent)
    {
        myDiagramType = diagramType;
        myContextMenu = contextMenu;
    
        QPainterPath path;
        switch (myDiagramType) {
            case StartEnd:{
                QPixmap pixmap("C:/Users/ILHA4/Desktop/diagrama_unifilar/trafo");
                myPolygon = pixmap;
                break;
        }
        case Conditional:{
                QPixmap pixmap2("C:/Users/ILHA4/Desktop/diagrama_unifilar/gerador");
                myPolygon=pixmap2;
                break;
        }
        case Step:{
                QPixmap pixmap3("C:/Users/ILHA4/Desktop/diagrama_unifilar/barramento");
                myPolygon=pixmap3;
                break;
        }
        default:{
                QPixmap pixmap4("C:/Users/ILHA4/Desktop/diagrama_unifilar/carga");
                myPolygon=pixmap4;
                break;
        }
        }
       setPixmap(myPolygon);
        setFlag(QGraphicsItem::ItemIsMovable, true);
        setFlag(QGraphicsItem::ItemIsSelectable, true);
        setFlag(QGraphicsItem::ItemSendsGeometryChanges, true);
    }
    

    that's it, am i doing something wrong?


Log in to reply