Fix docs for scene, selectedSeries, and selectedElement

Pick-to: 6.8 6.8.1
Task-number: QTBUG-131131
Change-Id: Ia1ad7eac5b5e2a33ea3844202262e53535082480
Reviewed-by: Sami Varanka <sami.varanka@qt.io>
Reviewed-by: Tomi Korpipää <tomi.korpipaa@qt.io>

src/graphs3d/qml/qquickgraphsbars.cpp

@@ -107,6 +107,8 @@
 
 /*!
  * \qmlproperty Bar3DSeries Bars3D::selectedSeries
+ * \readonly
+ *
  * The selected series or \c null. If \l {GraphsItem3D::selectionMode}{selectionMode} has
  * the \c SelectionMultiSeries flag set, this property holds the series that
  * owns the selected bar.

src/graphs3d/qml/qquickgraphsitem.cpp

@@ -226,6 +226,8 @@ constexpr float polarRoundness = 64.0f;
 
 /*!
  * \qmlproperty Scene3D GraphsItem3D::scene
+ * \readonly
+ *
  * The Scene3D pointer that can be used to manipulate the scene and access the
  * scene elements.
  *
@@ -430,6 +432,7 @@ constexpr float polarRoundness = 64.0f;
 
 /*!
  * \qmlproperty Graphs3D.ElementType GraphsItem3D::selectedElement
+ * \readonly
  *
  * The element selected in the graph.
  *

src/graphs3d/qml/qquickgraphsscatter.cpp

@@ -78,6 +78,8 @@ static const int insertRemoveRecordReserveSize = 31;
 
 /*!
  * \qmlproperty Scatter3DSeries Scatter3D::selectedSeries
+ * \readonly
+ *
  * The selected series or null.
  */
 

src/graphs3d/qml/qquickgraphssurface.cpp

@@ -75,6 +75,8 @@ QT_BEGIN_NAMESPACE
 
 /*!
  * \qmlproperty Surface3DSeries Surface3D::selectedSeries
+ * \readonly
+ *
  * The selected series or null. If \l {GraphsItem3D::selectionMode}{selectionMode}
  * has the \c MultiSeries flag set, this property holds the series
  * which owns the selected point.

src/graphs3d/widget/q3dbarswidgetitem.cpp

@@ -359,6 +359,7 @@ QValue3DAxis *Q3DBarsWidgetItem::valueAxis() const
 
 /*!
  * \property Q3DBarsWidgetItem::selectedSeries
+ * \readonly
  *
  * \brief The selected series or a null value.
  *

src/graphs3d/widget/q3dgraphswidgetitem.cpp

@@ -181,6 +181,7 @@ void Q3DGraphsWidgetItem::setShadowQuality(const QtGraphs3D::ShadowQuality &shad
 
 /*!
  * \property Q3DGraphsWidgetItem::scene
+ * \readonly
  *
  * \brief The Q3DScene pointer that can be used to manipulate the scene and
  * access the scene elements.
@@ -347,6 +348,7 @@ QCustom3DItem *Q3DGraphsWidgetItem::selectedCustomItem() const
 
 /*!
  * \property Q3DGraphsWidgetItem::selectedElement
+ * \readonly
  *
  * \brief The element selected in the graph.
  *

src/graphs3d/widget/q3dscatterwidgetitem.cpp

@@ -195,6 +195,7 @@ QValue3DAxis *Q3DScatterWidgetItem::axisZ() const
 
 /*!
  * \property Q3DScatterWidgetItem::selectedSeries
+ * \readonly
  *
  * \brief The selected series or null.
  */

src/graphs3d/widget/q3dsurfacewidgetitem.cpp

@@ -214,6 +214,7 @@ QValue3DAxis *Q3DSurfaceWidgetItem::axisZ() const
 
 /*!
  * \property Q3DSurfaceWidgetItem::selectedSeries
+ * \readonly
  *
  * \brief The selected series or null.
  *