Remove anonymous groups with ARX

By Xiaodong Liang 

When an end user creates a 'group' in AutoCAD, it may be an anonymous group. However, all group (anonymous or otherwise) are stored in the Named Objects Dictionary under the key 'ACAD_GROUP'. If the group is anonymous, AutoCAD assigns it a value such as 'A1', 'A2' and so on. Although to the end user it's anonymous, the group has a unique key name in the AutoCAD database.

Users may add or remove entities from groups so it is possible to have empty groups. The code below is a small demo to remove an anonymous group.

static void removeGroup()
{
 
Acad::ErrorStatus es;
AcDbDictionary *pGroupDict;
AcDbGroup *pGroup;
AcDbDictionaryIterator *pDictIter;
AcDbObjectId groupId;
long numItems;
AcDbObjectIdArray groupMembers;
 
es = 
acdbHostApplicationServices()->workingDatabase()->
   getGroupDictionary(pGroupDict,AcDb::kForWrite);
pDictIter = pGroupDict->newIterator();
 
for(; !pDictIter->done(); pDictIter->next())
{
    pDictIter->getObject(
        (AcDbObject*&)pGroup, AcDb::kForRead);
    // Is the group anonymous?
    if(pGroup->isAnonymous())
    {
        // Does the anonymous group have
        // any members associated with it?
        numItems = pGroup->numEntities();
        if(numItems > 0)
        {
            // Empty the group
            // Upgrade it first
            es = pGroup->upgradeOpen();
            es = pGroup->clear();
            es = pGroup->downgradeOpen();
 
            pGroup->close();
        }
 
        // Get the group ID and remove the
        // group from the dictionary
        groupId = pDictIter->objectId();
        es = pGroupDict->remove(groupId);
 
    } // if
 
    pGroup->close();
 
} // for
 
pGroupDict->close(); 
 
}