从QGraphicsItem获取QGraphicsView的大小

Question

问：如何从我graphicsview的{​​{1}}子类中获取width height和graphicsItem？< / p>

Answer 1

假设您的场景只有一个视图：

#include <QtWidgets>

class SimpleItem : public QGraphicsItem
{
public:
    QRectF boundingRect() const
    {
        qreal penWidth = 1;
        return QRectF(-10 - penWidth / 2, -10 - penWidth / 2, 20 + penWidth, 20 + penWidth);
    }

    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
    {
        QGraphicsView *view = scene()->views().first();
        qDebug() << "View width:" << view->width() << "height:" << view->height();
        painter->drawRect(-10, -10, 20, 20);
    }
};

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QGraphicsView view;
    QGraphicsScene *scene = new QGraphicsScene;
    scene->addItem(new SimpleItem());
    view.setScene(scene);
    view.show();
    return app.exec();
}

请参阅QGraphicsItem::scene()和QGraphicsScene::views()。