How to use Assembly Tree

After enabling readers you want to use, then starting the Dtk_API, you can call the OpenDocument method of the Dtk_API class to get a Dtk_MainDoc. It contains a root representing the Assembly Tree based on Dtk_Component.
Dtk_API contains a file search engine to set your preferences for searching for files that are part of an assembly : How to use Search File Engine

Here is a model sample and its corresponding representation in Dtk_Component :

Each Dtk_Component has a type, a name and children.
There are 4 different types:

• Virtual Component contains only children
  
• A Prototype represents a model that can have 0 or several children. It must be referenced by an instance or a catalog (except if he is root).
• An Instance has only one child which is the prototype and a placement matrix.
• A Catalog has one or several children representing the different possibilities for an Assembly Tree (such as Scene in CatiaV5). Default is given by method GetDefaultChildInCatalog();.
  
  
  
  
  From Dtk_Component you have to call ReadComponent to get corresponding Construction Tree.
  
  
  

  Dtk_Node RootNode;
  Dtk_API *inAPI = Dtk_API::GetAPI();
   
  Dtk_string ComponentName = inComponent->Name();
   
  /*Get the Construction tree for this prototype */
  err = inAPI->ReadComponent( inComponent, RootNode );
  if (err == dtkNoError && RootNode.IsNotNULL())
  {
      user_WriteNode(RootNode);
  }
   
  /*We close the opened Component and free his construction tree*/
  err = inAPI->EndComponent(inComponent);

If you need only data for visualisation you can call ReadComponentGraphic();
This method gives you a set of meshes for 3D files and a set of drawing for 2D files. Not all files contains such information so result may be empty : In this case you have to call ReadComponent to get all data.

You can also get a corresponding image preview with GetPreview() method.

Dtk_GraphicalData GraphData;
Dtk_API *inAPI = Dtk_API::GetAPI();
 
Dtk_string ComponentName = inComponent->Name();
/*Get the Image Preview for this prototype */
Dtk_Preview Preview = inComponent->GetPreview();
                                                                                                                               
/*Get the Graphical data for this prototype */
err = inAPI->ReadComponentGraphic( inObject, GraphData );
if (err == dtkNoError && GraphData.IsNotNULL())
{
            user_WriteGraphicalData(GraphData);
}                                                                                                                 
/*We close the opened Component and free his construction tree*/
err = inAPI->EndComponent(inComponent);

Note about how to use colors in Assembly Tree :

Dtk_Component colors should prevail on any other defined colors A single blue Cube could be instantiated as green and red :

• Green and red colors are stored at Dtk_Component upper level(Instance type)
• Blue is stored in Dtk_Component child (Prototype type) or in Construction Tree (Dtk_Node). At screen, you'll see one red cube and one green cube.