Question

将Dial Object添加到场景中。要移动对象，将QGraphicsRectitem设置为父对象，并通过sizegrip调整窗口小部件的大小。使用lamda函数更改小部件的几何形状并调整其父QGraphicsRectItem的大小。拨号对象之后我无法将其调整为某些大小。为什么发生这种情况？这是代码
Dial.h

    #include <QDial>

   class Dial : public QDial
   {
       Q_OBJECT
       public:
         Dial(QWidget * parent = nullptr);

       signals:
          void sizeChanged();
      protected:
         void resizeEvent(QResizeEvent *event);
   };

Dial.cpp

    #include "dial.h"
    Dial::Dial(QWidget *parent ) :
          QDial(parent)
    {
    }

    void Dial::resizeEvent(QResizeEvent *event)
    {
      QDial::resizeEvent(event);
      emit sizeChanged();
    }

mainWindow.cpp

 QGraphicsView *view = new QGraphicsView();
view->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
view->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
QGraphicsScene *scene = new QGraphicsScene();
scene->setBackgroundBrush(QBrush(Qt::cyan, Qt::SolidPattern));
view->setSceneRect(0,0,view->frameSize().width(),view->frameSize().height());
view->setScene(scene);
setCentralWidget(view);
     auto *dial= new Dial();      // The widget // Dial subclass of QDial
     auto *handle = new QGraphicsRectItem(QRect(0,0, 120, 120));    // Created to move and select on scene
     auto *proxy = new QGraphicsProxyWidget(handle); // Adding the widget through the proxy
     dial->setGeometry(10,10, 100, 100);
     proxy->setWidget(dial);
     QSizeGrip * sizeGrip = new QSizeGrip(dial);
     QHBoxLayout *layout = new QHBoxLayout(dial);
     layout->setContentsMargins(0, 0, 0, 0);
     layout->addWidget(sizeGrip, 0, Qt::AlignRight | Qt::AlignBottom);

     handle->setPen(QPen(Qt::transparent));
     handle->setBrush(Qt::gray);
     handle->setFlags(QGraphicsItem::ItemIsMovable |
     QGraphicsItem::ItemIsSelectable);

     scene->addItem(handle); // adding to scene

     connect(dial, &Dial::sizeChanged, [dial, handle](){ handle->setRect(dial->geometry().adjusted(-10, -10, 10, 10));});

在QGraphicscene中，为什么扩大窗口小部件后会受到限制？

0 个答案: