Understanding DGN File

DGN File

DgnFile format is used by Microstation or MicroStation based applications like OpenRoadsDesigner etc.
It is an in-memory representation of a physical file, regardless of its format.
A DgnFile contains one or more models. One model may reference another. A DgnAttachment captures a reference between models.
Every DgnFile holds one Dictionary Model which stores data common to all elements in file.
Elements in Design Models refer to levels, fonts, color definitions, line styles, etc. defined in their containing DgnFile.

Classes to access Dgn File

Document

Container of information - Could be a .dgn, .dwg, .dxf, .fbx file etc.
A DgnFile document is organized as a series of Models, there is a single dictionary model and one or more Graphic models. Models contain Elements.
Represented by the DgnDocument class in the C# API

Session

Documents are edited within a session
Starting a session, a document and its references will be opened
The document which is loaded is the called the Master File & the model which is displayed is called the Active Model throughout the API’s
On file open the default views are displayed, required mdl applications loaded and other settings initialized
Application developers can monitor events like file open events
ISessionMgr is the C# class associated with a session

Transactions

Enables application to save changes during a session
Transactions are made upon elements & models
A single Transaction is a set of modifications, adds & deletes
Transactions are journaled and can be reversed or reinstated as a unit, this is undo/redo
Changes are in the context of a current transaction.
API’s exist to monitor transactions.
ITxnManager is implemented for C#

Classes to access Models

DgnModelRef: provides access to a model that may be a direct reference to a root model or an indirect reference to an attachment model - Is base class of DgnModel & DgnAttachment.

DgnModel: represents a (root) model in memory. A DgnModel consists of:

- One or more elements

- Two ElementLists :Control ElementList and Graphic ElementList

- One or more attachments

DgnAttachment: represents an attachment from one model to another

Examples of accessing objects in DGN

DGN /DGNLib

Get active DGN /DGNLib

Bentley.DgnPlatformNET.DgnFile activeDGNFile = Bentley.MstnPlatformNET.Session.Instance.GetActiveDgnFile();

References/Attachments

Get all attachements to current DGN file

  DgnAttachmentCollection dgnAttachments = Session.Instance.GetActiveDgnModel().GetDgnAttachments();
  foreach (DgnAttachment dgnAttachment in dgnAttachments)
    {
      string referenceFileName = dgnAttachment.AttachFileName;
    }

Model

Get active model

Bentley.DgnPlatformNET.DgnModel activeDgnModel = Bentley.MstnPlatformNET.Session.Instance.GetActiveDgnModel();

Levels

Get levels

  FileLevelCache fileLevelCache = activeDgnModel.GetFileLevelCache();

Elements

Get all elements

ModelElementsCollection modelElementsCollection = dgnModel.GetElements();

Sheets

Get all sheets

 Bentley.DgnPlatformNET.DgnFile activeDGNFile = Bentley.MstnPlatformNET.Session.Instance.GetActiveDgnFile();
 ModelIndexCollection modelIndexCollection = activeDGNFile.GetModelIndexCollection();
 foreach (ModelIndex modelIndex in modelIndexCollection)
   {
     DgnModel dgnModel = activeDGNFile.LoadRootModelById(out StatusInt status, modelIndex.Id);

     if (dgnModel.ModelType == Bentley.DgnPlatformNET.DgnModelType.Sheet)
        {
        }
   }

Annotation

Get all annotations

Bentley.DgnPlatformNET.DgnModel dgnModel = Session.Instance.GetActiveDgnModel();
Bentley.DgnPlatformNET.ModelElementsCollection modelElementsCollection = dgnModel.GetElements();    
foreach(Bentley.DgnPlatformNET.Elements.Element el in modelElementsCollection)
 {
  if(el.ElementType == MSElementType.Text)
  {
   Bentley.Interop.MicroStationDGN.TextElement textNodeElement = (Bentley.Interop.MicroStationDGN.TextElement)el;          
  }
 }

Cells

Get cells

Bentley.Interop.MicroStationDGN.ElementCache elementCache = Bentley.MstnPlatformNET.InteropServices.Utilities.ComApp.ActiveModelReference.GraphicalElementCache; 
Bentley.Interop.MicroStationDGN.ElementEnumerator elementEnumerator = elementCache.Scan();

while (elementEnumerator.MoveNext())
 {
   Bentley.Interop.MicroStationDGN.Element currentElement = elementEnumerator.Current;
   if (currentElement.IsCellElement())
   {
     Bentley.Interop.MicroStationDGN.CellElement cellElement = (Bentley.Interop.MicroStationDGN.CellElement)currentElement;
   }
 }

Feature Definitions

Get feature definitions

Bentley.DgnPlatformNET.DgnModel dgnModel = Session.Instance.GetActiveDgnModel();
Bentley.CifNET.SDK.ConsensusConnection con = new ConsensusConnection(dgnModel);
Bentley.CifNET.GeometryModel.SDK.GeometricModel activeGM = con.GetActiveGeometricModel();
IEnumerable<Bentley.CifNET.GeometryModel.SDK.FeatureDefinition> featureDefinitions = activeGM.FeatureDefinitions;