By Barbara Han
You can use the ownerId() method of sub entities in an block reference (INSERT) entity to get the object id of the block table record (block definition) that the INSERT references to, and then get the block’s information, i.e. name. The following code shows how to do this. The function acedNEntSelP() is used to get a sub entity in a INSERT block.
void getBlockNameFromItsSubentity()
{
Acad::ErrorStatus es;
ads_name ent;
ads_point pt;
ads_matrix xform;
struct resbuf* pRb = NULL;
if( acedNEntSelP(L"\nSelect an subentity inside an INSERT: ",
ent, pt, FALSE, xform, &pRb) != RTNORM )
{
acutPrintf(L"\acedNEntSelP failed");
return;
}
AcDbObjectId subEntId;
AcDbEntity* pSubEnt = NULL;
if( (es = acdbGetObjectId(subEntId, ent)) != Acad::eOk ||
(es = acdbOpenAcDbEntity(pSubEnt, subEntId,
AcDb::kForRead)) !=
Acad::eOk )
{
acutPrintf(L"\nFailure: %s", acadErrorStatusText(es));
acutRelRb(pRb);
return;
}
acutRelRb(pRb);
// Output the class name of the sub entity
acutPrintf(L"\nThe sub entity is of type %s",
pSubEnt->isA()->name());
// Get the object id of the owner block
AcDbObjectId mainId = pSubEnt->ownerId();
pSubEnt->close();
pSubEnt = NULL;
AcDbObject* pOwner = NULL;
if((es = acdbOpenObject(pOwner, mainId, AcDb::kForRead)) !=
Acad::eOk )
{
acutPrintf(L"\nFailure: %s", acadErrorStatusText(es));
return;
}
// Output the class name of the owner block
acutPrintf(L"\nThe owner is of type %s",
pOwner->isA()->name());
// Output the information of the block definition
AcDbBlockTableRecord *pBTR = NULL;
pBTR = AcDbBlockTableRecord::cast(pOwner);
if( pBTR != NULL )
{
const ACHAR* pBlkName;
pBTR->getName(pBlkName);
acutPrintf(L"\nBlock name is %s", pBlkName);
}
pOwner->close();
pOwner = NULL;
}
Not only the sub entities, the similar method can also apply to almost all entities, e.g. line segments of 3d polylines, old style 2d polylines, mesh face of 3d meshes, simple entities, and even viewports.
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