How to handle references to other entities

<?xml encoding=”UTF-8″>By Madhukar
Moogala

An example of handling some common operations for certain types of entities. This does not attempt to be a full-featured entity in the sense that it fills out every single function that it is supposed to. Its main purpose is to illustrate how to deal with pointing to a dictionary-resident”Style” object This sample is stripped out from Jim Awe’s classic ArxDBG, this mainly focus on establishing hard linkage to other entities, dealing copy with in and across database.

I received a query from ADN partner who is facing WBlock cloning issues i.e., when copying an entity with hard refererence to another entity

You need to be very cautious while copy and pasting entities, in below I have shown steps need to follow in both wblockclone and deepclone

Acad::ErrorStatus
ArxDbgDbEntity::subWblockClone(AcRxObject* pOwner, AcDbObject*& pClone,
AcDbIdMapping& idMap, Adesk::Boolean isPrimary) const
{
if (ArxDbgOptions::m_instance.m_showWblockCloneDetails) {
CString titleStr, tmpStr;
titleStr.Format(_T("Beginning -- wblockClone: %s"),
ArxDbgUtils::objToClassAndHandleStr(const_cast(this), tmpStr));
ArxDbgUiTdmIdMap dbox(&idMap, acedGetAcadDwgView(), titleStr);
dbox.DoModal();
}
AcDb::DeepCloneType type = idMap.deepCloneContext();
// if xrefInsert or xrefBind, we know everything will
// be cloned, so just let normal routine handle this
if ((type == AcDb::kDcXrefBind) || (type == AcDb::kDcXrefInsert)) {
return AcDbEntity::subWblockClone(pOwner, pClone, idMap, isPrimary);
}
// if we've already been cloned, just return
AcDbIdPair idPair(objectId(), AcDbObjectId::kNull, true);
if (idMap.compute(idPair) && (idPair.value() != AcDbObjectId::kNull)) {
return Acad::eOk;
}
// If isPrimary is kTrue, then override the default cloning
// within our own cloning, which would set it to kFalse,
// by cloning our referenced entity first.
if (isPrimary) {
// now ask derived classes what references they want cloned for them
AcDbObjectIdArray refEntIds;
AcDbIntArray refTypes;
getCloneReferences(type, refEntIds, refTypes);
ASSERT(refEntIds.length() == refTypes.length());
// clone each entity we reference first and change the value
// of isPrimary to fake it out.  Since we clone these first,
// when the normal wblockClone is called, it will see that
// they are already in the set of cloned objects and will not
// try to clone it again.
AcDbEntity* ent;
Acad::ErrorStatus es;
int len = refEntIds.length();
for (int i=0; iblockId()) {
// Use the same owner, and pass in the same isPrimary value
AcDbObject* pSubClone = NULL;
es = ent->wblockClone(pOwner, pSubClone, idMap, Adesk::kTrue);
if (pSubClone != NULL)
pSubClone->close();
if (es != Acad::eOk) {
ASSERT(0);
}
}
else {
ASSERT(0);
}
ent->close();
}
}
}
}
// Now we can clone ourselves via calling our parent's method.
Acad::ErrorStatus es =  AcDbEntity::subWblockClone(pOwner, pClone, idMap, isPrimary);
if (ArxDbgOptions::m_instance.m_showWblockCloneDetails) {
CString titleStr, tmpStr;
titleStr.Format(_T("End -- wblockClone: %s"),
ArxDbgUtils::objToClassAndHandleStr(const_cast(this), tmpStr));
ArxDbgUiTdmIdMap dbox(&idMap, acedGetAcadDwgView(), titleStr);
dbox.DoModal();
}
return es;
}
Acad::ErrorStatus
ArxDbgDbEntity::subDeepClone(AcDbObject* pOwner,
AcDbObject*& pClonedObject,
AcDbIdMapping& idMap,
Adesk::Boolean isPrimary) const
{
// You should always pass back pClonedObject == NULL
// if, for any reason, you do not actually clone it
// during this call.  The caller should pass it in
// as NULL, but to be safe, we set it here as well.
pClonedObject = NULL;
if (ArxDbgOptions::m_instance.m_showDeepCloneDetails) {
CString titleStr, tmpStr;
titleStr.Format(_T("Beginning -- deepClone: %s"),
ArxDbgUtils::objToClassAndHandleStr(const_cast(this), tmpStr));
ArxDbgUiTdmIdMap dbox(&idMap, acedGetAcadDwgView(), titleStr);
dbox.DoModal();
}
AcDb::DeepCloneType type = idMap.deepCloneContext();
// if we know everything will be cloned for us, just let
// the base class do everything for us.
if ((type == AcDb::kDcInsert) ||
(type == AcDb::kDcInsertCopy) ||
(type == AcDb::kDcExplode))
return AcDbEntity::subDeepClone(pOwner, pClonedObject, idMap, isPrimary);
// following case happens when doing a AcDbDatabase::deepCloneObjects()
// and the owner happens to be the same... then its really like a
// kDcCopy, otherwise deepCloneObjects() is like a kDcBlock
if (type == AcDb::kDcObjects) {
if (ownerId() == pOwner->objectId())
type = AcDb::kDcCopy;
else
type = AcDb::kDcBlock;
}
// now ask derived classes what references they want cloned for them
AcDbObjectIdArray refEntIds;
AcDbIntArray refTypes;
getCloneReferences(type, refEntIds, refTypes);
ASSERT(refEntIds.length() == refTypes.length());
// if derived class doesn't have any references to take care of, then
// we will just let the AcDbEntity::deepClone() take care of things.
if (refEntIds.isEmpty())
return AcDbEntity::subDeepClone(pOwner, pClonedObject, idMap, isPrimary);
// If this object is in the idMap and is already
// cloned, then return.
bool tmpIsPrimary = isPrimary ? true : false;   // get around compiler performance warning
AcDbIdPair idPair(objectId(), AcDbObjectId::kNull, false, tmpIsPrimary);
if (idMap.compute(idPair) && (idPair.value() != NULL))
return Acad::eOk;
// STEP 1:
// Create the clone
//
AcDbObject *pClone = (AcDbObject*)isA()->create();
if (pClone != NULL)
pClonedObject = pClone;    // set the return value
else
return Acad::eOutOfMemory;
// STEP 2:
// Append the clone to its new owner.  In this example,
// we know that we are derived from AcDbEntity, so we
// can expect our owner to be an AcDbBlockTableRecord,
// unless we have set up an ownership relationship with
// another of our objects.  In that case, we need to
// establish how we connect to that owner in our own
// way.  This sample shows a generic method using
// setOwnerId().
//
AcDbBlockTableRecord *pBTR = AcDbBlockTableRecord::cast(pOwner);
if (pBTR != NULL) {
AcDbEntity* ent = AcDbEntity::cast(pClone);
pBTR->appendAcDbEntity(ent);
}
else {
if (isPrimary)
return Acad::eInvalidOwnerObject;
// Some form of this code is only necessary if
// anyone has set up an ownership for our object
// other than with an AcDbBlockTableRecord.
//
pOwner->database()->addAcDbObject(pClone);
pClone->setOwnerId(pOwner->objectId());
}
// STEP 3:
// Now we copy our contents to the clone.  This is done
// using an AcDbDeepCloneFiler.  This filer keeps a
// list of all AcDbHardOwnershipIds and
// AcDbSoftOwnershipIds we, and any classes we derive
// from,  have.  This list is then used to know what
// additional, "owned" objects need to be cloned below.
//
AcDbDeepCloneFiler filer;
dwgOut(&filer);
// STEP 4:
// Rewind the filer and read the data into the clone.
//
filer.seek(0L, AcDb::kSeekFromStart);
pClone->dwgIn(&filer);
// STEP 5:
// This must be called for all newly created objects
// in deepClone.  It is turned off by endDeepClone()
// after it has translated the references to their
// new values.
//
pClone->setAcDbObjectIdsInFlux();
// STEP 6:
// Add the new information to the idMap.  We can use
// the idPair started above.
//
idPair.setValue(pClonedObject->objectId());
idPair.setIsCloned(Adesk::kTrue);
idMap.assign(idPair);
// STEP 7:
// Using the filer list created above, find and clone
// any owned objects.
//
AcDbObject *pSubObject;
AcDbObject *pClonedSubObject;
AcDbObjectId id;
Acad::ErrorStatus es;
while (filer.getNextOwnedObject(id)) {
// Open the object and clone it.  Note that we now
// set "isPrimary" to kFalse here because the object
// is being cloned, not as part of the primary set,
// but because it is owned by something in the
// primary set.
es = acdbOpenAcDbObject(pSubObject, id, AcDb::kForRead);
if (es != Acad::eOk)
continue;   // could have been NULL or erased
pClonedSubObject = NULL;
pSubObject->deepClone(pClonedObject, pClonedSubObject, idMap, Adesk::kFalse);
// If this is a kDcInsert context, the objects
// may be "cheapCloned".  In this case, they are
// "moved" instead of cloned.  The result is that
// pSubObject and pClonedSubObject will point to
// the same object.  So, we only want to close
// pSubObject if it really is a different object
// than its clone.
if (pSubObject != pClonedSubObject)
pSubObject->close();
// The pSubObject may either already have been
// cloned, or for some reason has chosen not to be
// cloned.  In that case, the returned pointer will
// be NULL.  Otherwise, since we have no immediate
// use for it now, we can close the clone.
if (pClonedSubObject != NULL)
pClonedSubObject->close();
}
// clone the referenced entities
AcDbObject* ent;
int len = refEntIds.length();
for (int i=0; ideepClone(pOwner, pClonedSubObject, idMap, Adesk::kTrue);
if (es == Acad::eOk) {
// see comment above about cheap clone
if (ent != pClonedSubObject)
ent->close();
if (pClonedSubObject != NULL)
pClonedSubObject->close();
}
}
}
// this case is needed for RefEdit so we can pass its validation
// test when editing a blockReference.  We don't actually clone it
// but we add it to the map so it thinks it got cloned and is therefore
// a valid "Closed Set" of objects.
else if (refTypes[i] == kFakeClone) {
AcDbIdPair idPair(refEntIds[i], refEntIds[i], false, false, true);
idMap.assign(idPair);
}
}
if (ArxDbgOptions::m_instance.m_showDeepCloneDetails) {
CString titleStr, tmpStr;
titleStr.Format(_T("End -- deepClone: %s"),
ArxDbgUtils::objToClassAndHandleStr(const_cast(this), tmpStr));
ArxDbgUiTdmIdMap dbox(&idMap, acedGetAcadDwgView(), titleStr);
dbox.DoModal();
}
// Leave pClonedObject open for the caller
return Acad::eOk;
}

Complete Source

AdskLogo-Project