Distinguish between Activate and Open a DGN File

From a user perspective, opening and activating a new DGN file appear the same. For programmers, those are distinct operations …

• Opening a DGN file means locating that file and then obtaining a file pointer. The programmer can do what she wants with that pointer, but a user cannot see it
• Activating a DGN file means first opening it and then using the file pointer to display the graphical contents of that file in MicroStation's view windows

Open and Activate a New DGN File

ISessionMgr

This example uses two methods provided by ISessionMgr …

• ISessionMgr.FindDesignFile() This function works with MSDocumentManager to locate and manage files. In stand-alone MicroStation, if inFilename is not a complete file path, this function will look for it in the directories defined by configuration variable MS_DEF.
• ISessionMgr.SwitchToNewFile() This function closes the current Master DGN, if any, and ends the previous session. It then begins a new session. See SessionManager for a description of what happens when a session ends and starts

Example Python Code

from MSPyBentley import *
from MSPyBentleyGeom import *
from MSPyDgnPlatform import *
from MSPyMstnPlatform import *

def  activate_dgn_file(file_path: str, open_mode: DgnFileOpenMode = DgnFileOpenMode.ePreferablyReadWrite)->bool:
    '''
    Opening and activating a DGN file requires two steps...
    1  Use ISessionMgr.FindDesignFile to find a file using a specified path
    2  Switch to the new file using ISessionMgr.SwitchToNewFile

    '''
    _session_mgr = ISessionMgr.GetManager()
    _dgn_model_name = None
    _ALLOW_CANCEL = True
    dgn_file, status = _session_mgr.FindDesignFile(file_path,
                                                  _dgn_model_name,
                                                   GraphicsFileType.eGRAPHICSFILE_CAD,
                                                  _ALLOW_CANCEL)

    _UPDATE_ALL = True
    _RELEASE_REFERENCES = False
    status = _session_mgr.SwitchToNewFile         (dgn_file.GetDocument(),
                                                  _dgn_model_name,
                                                   GraphicsFileType.eGRAPHICSFILE_UStn,
                                                  _UPDATE_ALL,
                                                  _RELEASE_REFERENCES)

    retVal = status == DgnFileStatus.eDGNFILE_STATUS_Success
    return retVal

if __name__ == "__main__":  # check if this script is being run directly (not imported as a module)
    # Choose a file from the same workset as the one you have open in MicroStation.
    # Otherwise MicroStation will pop a modal dialog about the file being from a different workset.
    FILE_PATH = r"L:\ full path to the DGN file you want to activate"
    activate_dgn_file (FILE_PATH)

Copy the above code to a new .py file. Edit the file name and change FILE_PATH to a valid DGN file. Execute the code!

MicroStation Session Manager

The following paragraphs are copied from the C++ MicroStationAPI help manual.

The MicroStation user interface focuses on one design file and one model within that file at a time.

The design file whose views are displayed is called the "MasterFile" and the model is called the "Active Model". A new session begins when a file becomes the MasterFile. When a session begins, the session manager does the following:

• Loads the selected model of the new file into memory.
• Loads models referenced by the new file (if not carried over).
• Opens and displays the default views
• Sets default symbology and reinitializes the rest of the system. Sets the workmode, based on the file format.
• Attaches default cell libraries
• Loads DGNAPPs
• Calls SessionMonitor::_OnMasterFileStart and SYSTEM_NEWFILE_COMPLETE hooks

A session ends when the Master DGN is closed, a new file is to become the master, or when MicroStation shuts down. When ending a session, the session manager does the following:

• Closes views associated with the current Master DGN.
• Closes and unloads the current master DGN.
• Unloads models referenced by the file (unless they carry over to the new file). May close referenced files.
• Calls SessionMonitor::_OnMasterFileStop and SYSTEM_NEWFILE_CLOSE hooks

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Questions

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