Categories: Symbian C++ | Location Based Services | How To | Code Examples

This page was last modified 19:59, 10 April 2008.

From Forum Nokia Wiki

All local landmark databases are stored in files. As a result of some data changes ( for example: the addition of new landmarks ), it could happens that the size of database files will be greater then the necessary minimum.

The following code snippet demonstrates how to compress all local databases and calculate the count of the released bytes.

It is necessary to include the following headers:

• epos_cposlmdatabasemanager.h
• epos_cposlandmarkdatabase.h
• aknnotewrappers.h - for the information note

And link against:

• eposlmdbmanlib.lib
• eposlandmarks.lib
• avkon.lib eikcdlg.lib eikctl.lib - for the information note

// db manager
CPosLmDatabaseManager* dbManager = CPosLmDatabaseManager :: NewL();
CleanupStack :: PushL( dbManager );
	 
// protocol for the local DB
_LIT( KFileProto, "file" );
	 
// array, that contains URI of the local DBs	
CDesCArray* dbUriList = dbManager->ListDatabasesLC( KFileProto );		   
	
TInt delta = 0;	// delta of the total size
for(TInt i = 0; i < dbUriList->Count(); i++ )
{
   // open database
   CPosLandmarkDatabase* db = CPosLandmarkDatabase :: OpenL( (*dbUriList)[i] );
   CleanupStack :: PushL( db );
	   
   // initialize if necessary
   if( db->IsInitializingNeeded() )
   ExecuteAndDeleteLD( db->InitializeL() );	   
 
   // get size before compact
   CPosLandmarkDatabase :: TSize oldSize = db->SizeL();
	   
   // execute compact in batch mode
   ExecuteAndDeleteLD( db->CompactL() );
	   
   // get size after compact
   CPosLandmarkDatabase :: TSize newSize = db->SizeL();
	   
   // inc delta
   delta += oldSize.iFileSize - newSize.iFileSize;
   CleanupStack :: PopAndDestroy(); // db
}		               
CleanupStack :: PopAndDestroy( 2 ); // iDbList dbManager	
	
// create message
_LIT( KMess, "Released bytes: " );
TBuf<32> mess( KMess );
mess.AppendNum( delta );
	
// show message
CAknInformationNote* informationNote;
informationNote = new ( ELeave ) CAknInformationNote;
informationNote->ExecuteLD( mess );