Example of Database Operations

The following example shows the createDwg() routine, which creates a new database, obtains the model space block table record, and creates two circles that are added to model space. It uses the AcDbDatabase::saveAs() function to save the drawing. The second routine, readDwg(), reads in the saved drawing, opens the model space block table record, and iterates through it, printing the class names of the entities it contains.

void
createDwg()
{
    AcDbDatabase *pDb = new AcDbDatabase();
    AcDbBlockTable *pBtbl;
    pDb->getSymbolTable(pBtbl, AcDb::kForRead);
    AcDbBlockTableRecord *pBtblRcd;
    pBtbl->getAt(ACDB_MODEL_SPACE, pBtblRcd,
        AcDb::kForWrite);
    pBtbl->close();
    AcDbCircle *pCir1 = new AcDbCircle(AcGePoint3d(1,1,1),
                                       AcGeVector3d(0,0,1),
                                       1.0),
               *pCir2 = new AcDbCircle(AcGePoint3d(4,4,4),
                                       AcGeVector3d(0,0,1),
                                       2.0);
    pBtblRcd->appendAcDbEntity(pCir1);
    pCir1->close();
    pBtblRcd->appendAcDbEntity(pCir2);
    pCir2->close();
    pBtblRcd->close();
    // AcDbDatabase::saveAs() does 
not
 automatically
    // append a DWG file extension, so it
    // must be specified.
    //
    pDb->saveAs(_T("c:\\test1.dwg"));
    delete pDb;
}
void
readDwg()
{
    // Set constructor parameter to kFalse so that the
    // database will be constructed empty.  This way only
    // what is read in will be in the database.
    //
    AcDbDatabase *pDb = new AcDbDatabase(Adesk::kFalse);
    // The AcDbDatabase::readDwgFile() function
    // automatically appends a DWG extension if it is not
    // specified in the filename parameter.
    //
    if(Acad::eOk != pDb->readDwgFile(_T("c:\\test1.dwg")))
	return;
    // Open the model space block table record.
    //
    AcDbBlockTable *pBlkTbl;
    pDb->getSymbolTable(pBlkTbl, AcDb::kForRead);
    AcDbBlockTableRecord *pBlkTblRcd;
    pBlkTbl->getAt(ACDB_MODEL_SPACE, pBlkTblRcd,
        AcDb::kForRead);
    pBlkTbl->close();
    AcDbBlockTableRecordIterator *pBlkTblRcdItr;
    pBlkTblRcd->newIterator(pBlkTblRcdItr);
    AcDbEntity *pEnt;
    for (pBlkTblRcdItr->start(); !pBlkTblRcdItr->done();
        pBlkTblRcdItr->step())
    {
        pBlkTblRcdItr->getEntity(pEnt,
            AcDb::kForRead);
        acutPrintf("classname: %s\n",
            (pEnt->isA())->name());
        pEnt->close();
    }
    pBlkTblRcd->close();
    delete pBlkTblRcdItr;
    delete pDb;
}