从的QGraphicsItem

Question

Q得到的QGraphicsView的大小：我怎样才能得到graphicsviewwidth和height从我自己的graphicsItem从QGraphicsItem继承？

Answer 1

假设只有一个看你的场景：

#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(); 
} 

见QGraphicsItem::scene()和QGraphicsScene::views()。