This request came in a few weeks ago regarding the source code for the recently posted DGN clean-up tool:
Would you modify the tool so that it can be processed by the equivalent figure ObjectDBX (of course for AutoCAD, not RealDWG)? I would like to give the Database object to the function, and the tool would have to process them in batch (a tool for loading drawings on my side).
It seemed like a reasonable enough request, so I spent some time putting together a version of the code that can be used on non-editor resident drawings. I changed the existing DGNPURGE command to make use of a helper function that takes two arguments – the Database to work on and the Editor to display information to the user – and then used that same function to purge unwanted DGN linestyles from a drawing selected by the user.
I took some file selection code from this post and some bits and pieces from this post, as well as picking up this helpful tip from our friends at The Swamp to open the drawing for read in order for the thumbnail bitmap to be retained properly in the output drawing.
Here’s the resultant C# code. It should be trivial to either build this into a RealDWG app or simply extend it to work on a folder of drawings. As it stands the DGNPURGE command and its new sibling, DGNPURGEEXT, should be scriptable using ScriptPro 2.0 or a custom build of it (using either a full AutoCAD-based product or the Core Console).
using System;
using System.IO;
using System.Runtime.InteropServices;
using Autodesk.AutoCAD.ApplicationServices.Core;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.Runtime;
namespace DgnPurger
{
public class Commands
{
const string dgnLsDefName = "DGNLSDEF";
const string dgnLsDictName = "ACAD_DGNLINESTYLECOMP";
public struct ads_name
{
public IntPtr a;
public IntPtr b;
};
[DllImport("acdb19.dll",
CharSet = CharSet.Unicode,
CallingConvention = CallingConvention.Cdecl,
EntryPoint = "acdbHandEnt")]
public static extern int acdbHandEnt(string h, ref ads_name n);
[CommandMethod("DGNPURGE")]
public static void PurgeDgnLinetypes()
{
var doc =
Application.DocumentManager.MdiActiveDocument;
PurgeDgnLinetypesInDb(doc.Database, doc.Editor);
}
[CommandMethod("DGNPURGEEXT")]
public static void PurgeDgnLinetypesExt()
{
var doc =
Application.DocumentManager.MdiActiveDocument;
var ed = doc.Editor;
var pofo = new PromptOpenFileOptions("\nSelect file to purge");
// Use the command-line version if FILEDIA is 0 or
// CMDACTIVE indicates we're being called from a script
// or from LISP
short fd = (short)Application.GetSystemVariable("FILEDIA");
short ca = (short)Application.GetSystemVariable("CMDACTIVE");
pofo.PreferCommandLine = (fd == 0 || (ca & 36) > 0);
pofo.Filter = "DWG (*.dwg)|*.dwg|All files (*.*)|*.*";
// Ask the user to select a DWG file to purge
var pfnr = ed.GetFileNameForOpen(pofo);
if (pfnr.Status == PromptStatus.OK)
{
// Make sure the file exists
// (it should unless entered via the command-line)
if (!File.Exists(pfnr.StringResult))
{
ed.WriteMessage(
"\nCould not find file: \"{0}\".",
pfnr.StringResult
);
return;
}
try
{
// We'll just suffix the selected filename with "-purged"
// for the output location. This file will be overwritten
// if the command is called multiple times
var output =
Path.GetDirectoryName(pfnr.StringResult) + "\\" +
Path.GetFileNameWithoutExtension(pfnr.StringResult) +
"-purged" +
Path.GetExtension(pfnr.StringResult);
// Assume a post-R12 drawing
using (var db = new Database(false, true))
{
// Read the DWG file into our Database object
db.ReadDwgFile(
pfnr.StringResult,
FileOpenMode.OpenForReadAndReadShare,
false,
""
);
// No graphical changes, so we can keep the preview
// bitmap
db.RetainOriginalThumbnailBitmap = true;
// We'll store the current working database, to reset
// after the purge operation
var wdb = HostApplicationServices.WorkingDatabase;
HostApplicationServices.WorkingDatabase = db;
// Purge unused DGN linestyles from the drawing
// (returns false if nothing is erased)
if (PurgeDgnLinetypesInDb(db, ed))
{
// Check the version of the drawing to save back to
var ver =
(db.LastSavedAsVersion == DwgVersion.MC0To0 ?
DwgVersion.Current :
db.LastSavedAsVersion
);
// Now we can save
db.SaveAs(output, ver);
ed.WriteMessage(
"\nSaved purged file to \"{0}\".",
output
);
}
// Still need to reset the working database
HostApplicationServices.WorkingDatabase = wdb;
}
}
catch (Autodesk.AutoCAD.Runtime.Exception ex)
{
ed.WriteMessage("\nException: {0}", ex.Message);
}
}
}
// Helper function to be shared between our command
// implementations
private static bool PurgeDgnLinetypesInDb(Database db, Editor ed)
{
using (var tr = db.TransactionManager.StartTransaction())
{
// Start by getting all the "complex" DGN linetypes
// from the linetype table
var linetypes = CollectComplexLinetypeIds(db, tr);
// Store a count before we start removing the ones
// that are referenced
var ltcnt = linetypes.Count;
// Remove any from the "to remove" list that need to be
// kept (as they have references from objects other
// than anonymous blocks)
var ltsToKeep =
PurgeLinetypesReferencedNotByAnonBlocks(db, tr, linetypes);
// Now we collect the DGN stroke entries from the NOD
var strokes = CollectStrokeIds(db, tr);
// Store a count before we start removing the ones
// that are referenced
var strkcnt = strokes.Count;
// Open up each of the "keeper" linetypes, and go through
// their data, removing any NOD entries from the "to
// remove" list that are referenced
PurgeStrokesReferencedByLinetypes(tr, ltsToKeep, strokes);
// Erase each of the NOD entries that are safe to remove
int erasedStrokes = 0;
foreach (ObjectId id in strokes)
{
try
{
var obj = tr.GetObject(id, OpenMode.ForWrite);
obj.Erase();
if (
obj.GetRXClass().Name.Equals("AcDbLSSymbolComponent")
)
{
EraseReferencedAnonBlocks(tr, obj);
}
erasedStrokes++;
}
catch (System.Exception ex)
{
ed.WriteMessage(
"\nUnable to erase stroke ({0}): {1}",
id.ObjectClass.Name,
ex.Message
);
}
}
// And the same for the complex linetypes
int erasedLinetypes = 0;
foreach (ObjectId id in linetypes)
{
try
{
var obj = tr.GetObject(id, OpenMode.ForWrite);
obj.Erase();
erasedLinetypes++;
}
catch (System.Exception ex)
{
ed.WriteMessage(
"\nUnable to erase linetype ({0}): {1}",
id.ObjectClass.Name,
ex.Message
);
}
}
// Remove the DGN stroke dictionary from the NOD if empty
bool erasedDict = false;
var nod =
(DBDictionary)tr.GetObject(
db.NamedObjectsDictionaryId, OpenMode.ForRead
);
ed.WriteMessage(
"\nPurged {0} unreferenced complex linetype records" +
" (of {1}).",
erasedLinetypes, ltcnt
);
ed.WriteMessage(
"\nPurged {0} unreferenced strokes (of {1}).",
erasedStrokes, strkcnt
);
if (nod.Contains(dgnLsDictName))
{
var dgnLsDict =
(DBDictionary)tr.GetObject(
(ObjectId)nod[dgnLsDictName],
OpenMode.ForRead
);
if (dgnLsDict.Count == 0)
{
dgnLsDict.UpgradeOpen();
dgnLsDict.Erase();
ed.WriteMessage(
"\nRemoved the empty DGN linetype stroke dictionary."
);
erasedDict = true;
}
}
tr.Commit();
// Return whether we have actually found anything to erase
return (
erasedLinetypes > 0 || erasedStrokes > 0 || erasedDict
);
}
}
// Collect the complex DGN linetypes from the linetype table
private static ObjectIdCollection CollectComplexLinetypeIds(
Database db, Transaction tr
)
{
var ids = new ObjectIdCollection();
var lt =
(LinetypeTable)tr.GetObject(
db.LinetypeTableId, OpenMode.ForRead
);
foreach (var ltId in lt)
{
// Complex DGN linetypes have an extension dictionary
// with a certain record inside
var obj = tr.GetObject(ltId, OpenMode.ForRead);
if (obj.ExtensionDictionary != ObjectId.Null)
{
var exd =
(DBDictionary)tr.GetObject(
obj.ExtensionDictionary, OpenMode.ForRead
);
if (exd.Contains(dgnLsDefName))
{
ids.Add(ltId);
}
}
}
return ids;
}
// Collect the DGN stroke entries from the NOD
private static ObjectIdCollection CollectStrokeIds(
Database db, Transaction tr
)
{
var ids = new ObjectIdCollection();
var nod =
(DBDictionary)tr.GetObject(
db.NamedObjectsDictionaryId, OpenMode.ForRead
);
// Strokes are stored in a particular dictionary
if (nod.Contains(dgnLsDictName))
{
var dgnDict =
(DBDictionary)tr.GetObject(
(ObjectId)nod[dgnLsDictName],
OpenMode.ForRead
);
foreach (var item in dgnDict)
{
ids.Add(item.Value);
}
}
return ids;
}
// Remove the linetype IDs that have references from objects
// other than anonymous blocks from the list passed in,
// returning the ones removed in a separate list
private static ObjectIdCollection
PurgeLinetypesReferencedNotByAnonBlocks(
Database db, Transaction tr, ObjectIdCollection ids
)
{
var keepers = new ObjectIdCollection();
// To determine the references from objects in the database,
// we need to open every object. One reasonably efficient way
// to do so is to loop through all handles in the possible
// handle space for this drawing (starting with 1, ending with
// the value of "HANDSEED") and open each object we can
// Get the last handle in the db
var handseed = db.Handseed;
// Copy the handseed total into an efficient raw datatype
var handseedTotal = handseed.Value;
// Loop from 1 to the last handle (could be a big loop)
var ename = new ads_name();
for (long i = 1; i < handseedTotal; i++)
{
// Get a handle from the counter
var handle = Convert.ToString(i, 16);
// Get the entity name using acdbHandEnt()
var res = acdbHandEnt(handle, ref ename);
if (res != 5100) // RTNORM
continue;
// Convert the entity name to an ObjectId
var id = new ObjectId(ename.a);
// Open the object and check its linetype
var obj = tr.GetObject(id, OpenMode.ForRead, true);
var ent = obj as Entity;
if (ent != null && !ent.IsErased)
{
if (ids.Contains(ent.LinetypeId))
{
// If the owner does not belong to an anonymous
// block, then we take it seriously as a reference
var owner =
(BlockTableRecord)tr.GetObject(
ent.OwnerId, OpenMode.ForRead
);
if (
!owner.Name.StartsWith("*") ||
owner.Name.ToUpper() == BlockTableRecord.ModelSpace ||
owner.Name.ToUpper().StartsWith(
BlockTableRecord.PaperSpace
)
)
{
// Move the linetype ID from the "to remove" list
// to the "to keep" list
ids.Remove(ent.LinetypeId);
keepers.Add(ent.LinetypeId);
}
}
}
}
return keepers;
}
// Remove the stroke objects that have references from
// complex linetypes (or from other stroke objects, as we
// recurse) from the list passed in
private static void PurgeStrokesReferencedByLinetypes(
Transaction tr,
ObjectIdCollection tokeep,
ObjectIdCollection nodtoremove
)
{
foreach (ObjectId id in tokeep)
{
PurgeStrokesReferencedByObject(tr, nodtoremove, id);
}
}
// Remove the stroke objects that have references from this
// particular complex linetype or stroke object from the list
// passed in
private static void PurgeStrokesReferencedByObject(
Transaction tr, ObjectIdCollection nodIds, ObjectId id
)
{
var obj = tr.GetObject(id, OpenMode.ForRead);
if (obj.ExtensionDictionary != ObjectId.Null)
{
// Get the extension dictionary
var exd =
(DBDictionary)tr.GetObject(
obj.ExtensionDictionary, OpenMode.ForRead
);
// And the "DGN Linestyle Definition" object
if (exd.Contains(dgnLsDefName))
{
var lsdef =
tr.GetObject(
exd.GetAt(dgnLsDefName), OpenMode.ForRead
);
// Use a DWG filer to extract the references
var refFiler = new ReferenceFiler();
lsdef.DwgOut(refFiler);
// Loop through the references and remove any from the
// list passed in
foreach (ObjectId refid in refFiler.HardPointerIds)
{
if (nodIds.Contains(refid))
{
nodIds.Remove(refid);
}
// We need to recurse, as linetype strokes can reference
// other linetype strokes
PurgeStrokesReferencedByObject(tr, nodIds, refid);
}
}
}
else if (
obj.GetRXClass().Name.Equals("AcDbLSCompoundComponent") ||
obj.GetRXClass().Name.Equals("AcDbLSPointComponent")
)
{
// We also need to consider compound components, which
// don't use objects in their extension dictionaries to
// manage references to strokes...
// Use a DWG filer to extract the references from the
// object itself
var refFiler = new ReferenceFiler();
obj.DwgOut(refFiler);
// Loop through the references and remove any from the
// list passed in
foreach (ObjectId refid in refFiler.HardPointerIds)
{
if (nodIds.Contains(refid))
{
nodIds.Remove(refid);
}
// We need to recurse, as linetype strokes can reference
// other linetype strokes
PurgeStrokesReferencedByObject(tr, nodIds, refid);
}
}
}
// Erase the anonymous blocks referenced by an object
private static void EraseReferencedAnonBlocks(
Transaction tr, DBObject obj
)
{
var refFiler = new ReferenceFiler();
obj.DwgOut(refFiler);
// Loop through the references and erase any
// anonymous block definitions
//
foreach (ObjectId refid in refFiler.HardPointerIds)
{
BlockTableRecord btr =
tr.GetObject(refid, OpenMode.ForRead) as BlockTableRecord;
if (btr != null && btr.IsAnonymous)
{
btr.UpgradeOpen();
btr.Erase();
}
}
}
}
}
