Create virtual-functions.md

_docs/virtual-functions.md

@@ -0,0 +1,55 @@
+---
+title: Virtual functions
+permalink: /object/virtual-functions
+layout: default
+---
+
+## Overview of virtual functions
+
+A PDM object inherits PdmObject which inherits PdmUiObjectHandle. This documents gives an overview of virtual functions that can be overridden with short examples of usage.
+[cafPdmUiObjectHandle()](https://github.com/OPM/ResInsight/blob/dev/Fwk/AppFwk/cafProjectDataModel/cafPdmUiCore/cafPdmUiObjectHandle.h)
+
+## appendMenuItems
+Used to append menu items to the right click menu of an object. Previous pattern created these menus centralized in RimContextCommandBuilder which will be obsoleted.
+
+void RimPolygon::appendMenuItems( caf::CmdFeatureMenuBuilder& menuBuilder ) const
+{
+    menuBuilder << "RicDuplicatePolygonFeature";
+    menuBuilder << "Separator";
+    menuBuilder << "RicExportPolygonCsvFeature";
+}
+
+## userDescriptionField
+If defined, the string defined by this field will be used when displaying object text in the Property Tree.
+
+caf::PdmFieldHandle* RimNamedObject::userDescriptionField()
+{
+    return nameField();
+}
+
+## objectToggleField
+If defined, displays a checkbox next to the object in the Project Tree. The field must be of the boolean type.
+
+caf::PdmField<bool>                         m_isActive;
+caf::PdmFieldHandle* RimCellFilter::objectToggleField()
+{
+    return &m_isActive;
+}
+
+## fieldChangedByUi
+Use this method to react on user interaction in the user interface. A pointer to the field being changed, old and new value is available.
+
+## objectToggleField
+If defined, displays a checkbox next to the object in the Project Tree. The field must be of the boolean type.
+
+void RimPolygon::fieldChangedByUi( const caf::PdmFieldHandle* changedField, const QVariant& oldValue, const QVariant& newValue )
+{
+    if ( changedField == &m_pointsInDomainCoords )
+    {
+        coordinatesChanged.send();
+        objectChanged.send();
+    }
+}
+
+
+