Open CASCADE Technology: Inspector


Open CASCADE Technology  7.2.0


This manual explains how to use Inspector.


Inspector is a Qt-based library that provides functionality to interactively inspect low-level content of the OCAF data model, OCCT viewer and Modelisation Data. This component is aimed to assist the developers of OCCT-based applications to debug the problematic situations that occur in their applications.

Inspector has a plugin-oriented architecture. The current release contains the following plugins:

Plugin OCCT component Root class of OCCT investigated component
DFBrowserOCAF TDocStd_Application
VInspectorVisualization AIS_InteractiveContext
ShapeViewModelisation Data TopoDS_Shape

Each plugin implements logic of a corresponding OCCT component.

Each of the listed plugins is embeded in the common framework. The user is able to manage which plugins should be loaded by Inspector. Also he can extend number of plugins by implementing a new plugin.

Getting started

There are two launch modes:

  1. Launch TInspectorEXE executable sample. For more details see TInspectorEXE section;
  2. Launch DRAW, load plugin INSPECTOR, and use tinspector command. For more details see Launch in DRAW Test Harness section.

Note. If you have no Inspector library in your build directory, please make sure that OCCT is compiled with BUILD_Inspector option ON. For more details see Build procedure.



Inspector consists of the following components:

  • buttons to activate the corresponding plugin;
  • view area to visualize the plugin content.
Plugins placement in Inspector

DFBrowser Plugin



This plugin visualizes content of TDocStd_Application in a tree view. It shows documents of the application, hierarchy of TDF_Labels, content of TDF_Attributes and interconnection between attributes (e.g. references). Additionally it has 3D view to visualize TopoDS_Shape elements stored in the document.


DFBrowser Elements

OCAF tree view

Each OCAF element has own tree view item:

Type Tree item Text Description
TDocStd_Application Application TDocStd_Application It is the root of tree view. Children are documents.
TDocStd_Document Document entry : name It is a child of Application item. Children are Labels and Attributes items.
Text view is an entry of the root label and the value of TDataStd_Name attribute for the label if it exists.
TDF_Label Label entry : name It is a child of a Document or another Label item. Children and text view are the same as for Document item.
TDF_Attribute Attribute attribute type [additional information] It is a child of a Label. It has no children.
Text view is the attribute type (DynamicType()->Name() of TDF_Attribute) and additional information (a combination of attribute values)

Additional information of TDF_Attributes:

Type Text
TDocStd_Owner [storage format]
other Simple types
other List types
[value_1 ... value_n]
other Array types
[value_1 ... value_n]
TDataStd_TreeNode [tree node ID ==> Father()->Label()] (if it has father) or
[tree node ID <== First()->Label()] (if it has NO father)
TDataStd_TreeNode(XDE) [XDE tree node ID ==> Father()->Label()] (if it has father),
[XDE tree Node ID <== label_1, ..., label_n] (if it has NO father)
TNaming_NamedShape [shape type : evolution]
TNaming_UsedShapes [map extent]

Custom color of items:

OCAF element Type Color
TDF_Label dark green, if the label has TDataStd_Name attribute,
light grey if the label is empty (has no attributes on all levels of hierarchy),
black otherwise
TNaming_NamedShape dark gray for TopAbs_FORWARD orientation of TopoDS_Shape,
gray for TopAbs_REVERSED orientation of TopoDS_Shape,
black for other orientation

Context popup menu:

Action Functionality
Expand Expands the next two levels under the selected item
Expand All Expands the whole tree of the selected item
Collapse All Collapses the whole tree of the selected item

Property Panel

Property panel is used to display content of Label or Attribute tree view items. This control is used for content of Label or Attribute tree view items or Search result view. Information is usually shown in one or several tables.

TDF_Attribute has the following content in Property Panel:

TDF_Label a table of [entry or attribute name, value]
Simple types,
List types
a table of [method name, value]
other Array types
2 controls:
* a table of [array bound, value],
* table of [method name, value]
TDataStd_TreeNode 2 controls:
* a table of [Tree ID, value] (visible only if Tree ID() != ID()),
* a tree view of tree nodes starting from Root() of the tree node. The current tree node has dark blue text.
TDataStd_NamedData tab bar of attribute elements, each tab has a table of [name, value]
TNaming_UsedShapes a table of all the shapes handled by the framework
TNaming_NamedShape 2 controls:
* a table of [method name, value] including CurrentShape/OriginalShape methods result of TNaming_Tools,
* an evolution table.
Tables contain buttons for TopoDS_Shape export.
TNaming_Naming 2 controls:
* a table of TNaming_Name vlaues,
* a table of [method name, value]

Dump view

Dump of TDF_Attribute

Dump view shows result of TDF_Attribute::Dump() or TDF_Label::Dump() of selected tree view item.

3D view

3D View visualizes TopoDS_Shape elements of OCAF attribute via AIS facilities.

DFBrowser creates two kinds presentations depending on the selection place:

KindSource objectVisualization propetiesView
Main presentation Tree view item:
Color: a default color for shape type of the current TopoDS_Shape
Additional presentation References in Property panel Color: white

Tree Navigation

Tree Navigation shows a path to the item selected in the tree view. The path is a sequence of label entries and attribute type name. Each element in the path is selectable - the user can click on it to select the corresponding tree view item.

Navigation control has buttons to go to the previous and the next selected tree view items.

Update Button

Update button synchronizes content of tree view to the current content of OCAF document that could be modified outside.


The user can search OCAF element by typing:

  • TDF_Label entry,
  • TDF_Attribute name,
  • TDataStd_Name and TDataStd_Comment attributes value.

As soon as the user confirms the typed criteria, the Property panel is filled by all satisfied values. The user can click a value to hightligt the corresponding tree view item. By double click the item will be selected.

Elements cooperation

Tree item selection

Selection of tree view item updates content of the following controls:

  • Navigation line
  • Property Panel
  • 3D View (if it is possible to create an interactive presentation)
  • Dump View

Property Panel item selection

If property panel shows content of TDF_Label:

  • selection of the table row hightlights the corresponding item in tree view,
  • double click on the table row selects this item in tree view.

If property panel shows content of TDF_Attribute that has reference to another attribute, selection of this reference:

  • highlights the referenced item in TreeView,
  • displays additional presentation in 3D view if it can be created.

Attributes having references:

Type Reference Additional presentation
TDF_Reference TDF_Label
one or several TDF_Label in a container
TDataStd_TreeNode TDF_Label
TNaming_NamedShape TDF_Label in Evolution table selected TopoDS_Shapes in property panel tables
TNaming_UsedShapes one or several TNaming_NamedShape TopoDS_Shapes of selected TNaming_NamedShape

TopoDS_Shape export

Property panel of TNaming_NamedShape attribute has controls to export TopoDS_Shape to:

  • BREP. The save file dialog is started to enter the result file name,
  • ShapeView plugin. Dialog about exporting element to ShapeView is shown with a possibility to activate this plugin immediatelly.

VInspector Plugin



It visualizes interactive objects displayed in AIS_InteractiveContext in a tree view with columputed selection components for each presentation. It shows the selected elements in the context and allows to select these elements.


VInspector Elements

Presentations tree view

It shows presentations and selection computed of them. Also, the view has columns with information about state of visualization elements.

VInspector tree items.

Type Description
AIS_InteractiveContext It is the root of tree view. Children are interactive objects obtained by DisplayedObjects and ErasedObjects methods.
AIS_InteractiveObject It is a child of AIS_InteractiveContext item. Children are SelectMgr_Selection obtained by iteration on CurrentSelection
SelectMgr_Selection It is a child of AIS_InteractiveObject. Children are SelectMgr_SensitiveEntity obtaining by iteration on Sensitive
SelectMgr_SensitiveEntity It is a child of SelectMgr_Selection. Children are SelectMgr_SensitiveEntity obtaining by iteration on OwnerId
SelectBasics_EntityOwner It is a child SelectMgr_SensitiveEntity. It has no children.

Custom color of tree view items:

OCAF element Type Column What Color
AIS_InteractiveObject 0 Text dark gray, it is in ErasedObjects list of AIS_InteractiveContext,
black otherwise
1 Background dark blue, if there is a selected owner under the item,
black otherwise
all Text dark gray, if SelectionState of SelectMgr_Selection is not SelectMgr_SOS_Activated,
black otherwise

Context popup menu in tree view:

Action Item Functionality
Export to ShapeView AIS_InteractiveObject Exports TopoDS_Shape of AIS_Interactive presentation to ShapeView plugin.
It should be AIS_Shape presentation and ShapeView plugin should be registered in Inspector
Dialog about exporting element to ShapeView is shown with a possibility to activate this plugin immediatelly.
Show AIS_InteractiveObject Display presentation in AIS_InteractiveContext
Hide AIS_InteractiveObject Erase presentation from AIS_InteractiveContext


It synchronizes content of the plugin to the current state of AIS_InteractiveContext. It updates the presence of items and the current selection for the items.

Selection controls

Selection controls switch on/off the posibility to set selection in the context from VInspector plugin.

Action Tree view item Functionality
Select Presentations AIS_InteractiveObject Calls AddOrRemoveSelected of interactive object for the selected item
Select Owners SelectMgr_EntityOwner or
Calls AddOrRemoveSelected of SelectMgr_EntityOwner for the selected item

Please note, that the initial selection in context will be cleared. If the button is toggled, the button selection is active. Only one button may be toggled at the moment.

History view

At present the History view is under implementation and may be used only in a custom application where Inspector is loaded.

To fill this view, VInspectorAPI_CallBack should be redefined in the application and send signals about some actions applyed to context. After, the call back should be given as parameter in the plugin. If done, new items will be created in the history view for each action.

Elements cooperation

Vinspector markes current selected presentations in AIS_InteractiveContext with blue background in tree items. Use "Update" button to synchronize VInspector selected items state to the context.

It is also possible to perform selection in context using "Selection controls" VInspector. However, it should be performed carefully as it clears the current selection in AIS_InteractiveContext.

Selection change:

From To Action Result
AIS_InteractiveContext VInspector perform selection in AIS_InteractiveContext Click "Update" button in VInspector and check "Selection" column:
AIS_InteractiveContext item has anount of selected objects,
some of AIS_InteractiveObject have filled value if it selection happens for this presentation or entity owner of it
VInspector AIS_InteractiveContext activate one of Selection controls and select one or several elements in tree view The objects become selected in AIS_InteractiveContext

ShapeView Plugin



This plugin visualizes content of TopoDS_Shape in a tree view.


ShapeView Elements

TopoDS_Shape View

Elements of the view are TopoDS_Shape objects. This shape is exploded into sub-shapes using TopoDS_Iterator of the TopoDS_Shape. Child sub-shapes are presented in the view as children of the initial shape. Iterating recursively by all shapes we obtain a tree view of items shown in the ShapeView.

Columns of the View show some information about TopoDS_Shape of the item. The most informative column is the last column of TopoDS_Vertex and TopoDS_Edge shape types.

For TopoDS_Vertex it contains the point coordinates,

for TopoDS_Edge it contains the first and the last point coordinates, the edge length and some other parameters.

Context popup menu in tree view:

Action Functionality
Load BREP file Opens selected file and appends the result TopoDS_Shape into tree view
Remove all shape items Clears tree view
BREP view Shows text view with BREP content of the selected item. It creates BREP file in temporary directory of the plugin.
Close All BREP views Closes all opened text views
BREP directory Displays folder where temporary BREP files have been stored.

Elements cooperation

Selection of one or several items in TopoDS_Shape View creates AIS_Shape presentation for it and displays it in the 3D View.

Common controls

3D View


3D View

Control for OCCT 3D viewer. It creates visualization view components with possibilities to perform some user actions for the view.


3DView Elements

3D View contains:

Element Functionality
3D view V3d viewer with mouse events processing
Context choice of another context that should be used in the plugin.
It is possible to use the next contexts:
Own - context of this view,
External - context come in parameters which intializes plugin,
None - do not perform visualization at all
Multi/Single Buttons defined what to do with the previous displayed objects:
Multi displays new presentations in additional to already displayed,
Single removes all previuos displayed presentations
Clean Removes all displayed presentations
Fit All,
Fit Area,
Scene manipulation actions
Display Mode Sets AIS_Shading or AIS_WireFrame display mode for all presentations

TInspectorEXE sample

Inspector functionality can be tried using this sample.

Use inspector.bat script file placed in binary directory of OCCT to launch it.

This script accepts the names of plugin's DLL that should be loaded. By default it loads all described above plugins.


Click on the Open button shows the dialog to select a file. The user is able to select one of the sample files or load own one.


Depending on the active plugin, the following files should be selected in the dialog: OCAF document or STEP files for DFBRowser and BREP files for VInspector and ShapeView plugins.

It is possible to click the file name in the proposed directory, enter it manually or using Browser button. The last Loading icon becomes enabled if file name is correct.

By default TInspectorEXE opens the next files for plugins:

Plugin DLL library name Files
TKDFBrowser step/screw.step
TKVInspector occ/hammer.brep
TKShapeView occ/face1.brep,

These files are found relatively CSF_OCCTDataPath.

Source code of TIspectorEXE is a good sample for Using Inspector in a custom application.

Launch in DRAW Test Harness

TKToolsDraw plugin is created to provide DRAW commands for Qt tools. Use INSPECTOR parameter of pload command to download commands of this library. It contains tinspector command to start Inspector under DRAW. See more detailed description of the tinspector command.

The simple code to start Inspector with all plugins loaded:


Result of this command is the next:

  • all available Plugins are presented in the Inspector. These are DFBrowser, VInspector and ShapeView.
  • DFBrowser is an active plugin
  • tree of OCAF is empty.

After, we should create objects in DRAW and update tinspector.

Using in a custom application

To use Inspector in an application, the next steps should be done:

  • Set dependencies to OCCT and Qt in application (Header and Link)
  • Create an instance of TInspector_Communicator.
  • Register plugins of interest in the communicator by DLL library name
  • Initialize communicator with objects that will be investigated
  • Set visible true for commumicator

C++ code is similar:

#include <inspector/TInspector_Communicator.hxx>
static TInspector_Communicator* MyTCommunicator;
void CreateInspector()
NCollection_List<Handle(Standard_Transient)> aParameters;
//... append parameters in the list
if (!MyTCommunicator)
MyTCommunicator = new TInspector_Communicator();
MyTCommunicator->RegisterPlugin ("TKDFBrowser");
MyTCommunicator->RegisterPlugin ("TKVInspector");
MyTCommunicator->RegisterPlugin ("TKShapeView");
MyTCommunicator->Init (aParameters);
MyTCommunicator->Activate ("TKDFBrowser");
MyTCommunicator->SetVisible (true);
Plugin to be initialized by
TKDFBrowser TDocStd_Application
TKVInspector AIS_InteractiveContext
TKShapeView TopoDS_TShape

Build procedure

By default the Inspector compilation is off. To compile it, set the BUILD_Inspector flag to "ON". See Configuration process.

When this option is switched On, MS Visual Studio project has an additional tree of folders:

Inspector packages in MS Visual Studio

Sources and packaging

OCCT sources are extended by the /tools directory.

Distribution of packages participated in plugins:

Sources packagesPlugin

Other packages:

Sources packagesUsed in
Iterface for connection to plugin.
Items-oriented model to simplify work with GUI tree control.
3D View component
Inspector window where plugins are placed
Plugin for DRAW to start Inspector

In MSVC studio the separate folder contains Inspector projects.


  • Component – OCCT part, e.g. OCAF, VISUALIZATION, MODELING and others.
  • Plugin – library that is loaded in some executable/library. Here, the plugins are:
    • DFBrowser,
    • ShapeView,
    • VInspector.

TDF_Attribute Simple types

Types where the content is a single value

Type Kind of value
TDataStd_AsciiString TDataStd_AsciiString
TDataStd_Comment TCollection_ExtendedString
TDataStd_Integer Standard_Integer
TDataStd_Name TCollection_ExtendedString
TDataStd_Real Standard_Real
TDF_Reference TDF_Label
TDF_TagSource Standard_Integer

TDF_Attribute List types

Type Kind of value (container of)
TDataStd_BooleanList Standard_Boolean
TDataStd_ExtStringList TCollection_ExtendedString
TDataStd_IntegerList Standard_Integer
TDataStd_RealList Standard_Real
TDataStd_ReferenceList TDF_Label

TDF_Attribute Array types

Type Kind of value (container of)
TDataStd_BooleanArray Standard_Boolean
TDataStd_ByteArray Standard_Byte
TDataStd_ExtStringArray TCollection_ExtendedString
TDataStd_IntegerArray Standard_Integer
TDataStd_RealArray Standard_Real
TDataStd_ReferenceArray TDF_Label

XDE tree node ID description

XCAFDoc::ShapeRefGUID() Shape Instance Link
XCAFDoc::ColorRefGUID (XCAFDoc_ColorGen) Generic Color Link
XCAFDoc::ColorRefGUID (XCAFDoc_ColorSurf) Surface Color Link
XCAFDoc::ColorRefGUID (XCAFDoc_ColorCurv) Curve Color Link
XCAFDoc::DimTolRefGUID() DGT Link
XCAFDoc::DatumRefGUID() Datum Link
XCAFDoc::MaterialRefGUID() Material Link
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