Widgets within a QGraphicsScene

Question

I'm trying to add a QgraphicsView(QColorDialog) widget onto a Palette dialog, but the QGraphicsScene corresponding to the QColorDialog widget is always blank and it would be of great help if readers could help me correct my mistake.

Qt-4.8.4-Linux(CentOS)

1. The GraphicsView widget which will be included in the PalletteDialog

   ClrWidget::ClrWidget(QWidget *parent) :
     QGraphicsView(parent)
   {
     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
     setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
     setFrameStyle(QFrame::NoFrame);
   
     setScene(new QGraphicsScene(this));
   
     _dialog = new QColorDialog();
     _dialog->setOption(QColorDialog::NoButtons, true);
     setMinimumSize(_dialog->size());
     setMaximumSize(_dialog->size());
   
     QGraphicsProxyWidget *proxyWidget = new QGraphicsProxyWidget();
     proxyWidget->setWidget(_dialog);
     //scene()->addItem(proxyWidget);
     //scene()->setSceneRect(proxyWidget->geometry());
   
     scene()->addWidget(_dialog);
     scene()->setSceneRect(_dialog->geometry());
   }
   

2. PaletteDialog Constructor

   PaletteDialog::PaletteDialog(QWidget *parent)
     : QDialog(parent),
     ui(new Ui::PaletteDialog),
   {
     //PaletteDialog sets up the ClrWidget
     ui->setupUi(this);
     ...
   }
   

Answer 1

Try something like this:

setScene(new QGraphicsScene);
QColorDialog *_dialog = new QColorDialog();
_dialog->setOption(QColorDialog::NoButtons, true);
_dialog->show();
QGraphicsProxyWidget *proxyWidget = scene()->addWidget(_dialog);

And remove this line:

proxyWidget->setWidget(_dialog);

What you did wrong was set a widget to a QGraphicsProxyWidget and then called QGraphicsScene::addWidget(..) which does the same thing, and that doesn't work. You can add your QGraphicsProxyWidget to the scene though by calling QGraphicsScene::addItem().

Example:

setScene(new QGraphicsScene(this));
QColorDialog *_dialog = new QColorDialog;
_dialog->setOption(QColorDialog::NoButtons, true);
QGraphicsProxyWidget *proxyWidget = new QGraphicsProxyWidget;
proxyWidget->setWidget(_dialog);
scene()->addItem(proxyWidget);