TMSFNCGoogleMaps Marker are drawn several times

FNC TMS FNC Maps
1

I create around 8000 markers.
After "EndUpdate", all markers are drawn individually but than this is repeated one or more times.

2

Please specify the map service you are using as each service might have a different behavior. If possible, switch between mapping services and see if there is a difference.

As the service provider updates and refreshes sometimes, you might not be able to prevent this from happening.

As a suggestion, in case you use Google, please have a look at Google Maps clustering. It might resolve your issue. The topic is covered in detail in the documentation and also in my book with a detailed example using a database with hundreds of records.

Something else coming to mind. There has been significant development wrt to performance of markers. Please make sure you use the latest version.

3

8000 markers are quite significant. Please show us the code snippet you are using to add the markers.

4

I use the TMSFNCGoogleMaps komponent (1.0.4.1) and add all (German) ZIP Codes from a table to a cluster.

procedure TMapIt.DBtoMAP;
begin
  TMSFNCMaps1.BeginUpdate;

  with MarkerTable do begin
    First;
    while not MarkerTable.EOF do begin
      // TMSFNCMaps1.AddMarker(FieldByName('LAT').Value, FieldByName('LON').Value, FieldByName('ZipCode').Value, '');
      CreateClusterMarker(FieldByName('ZipCode').Value, FieldByName('LAT').Value, FieldByName('LON').Value, eu,'');
      Next
    end;
  end;

  TMSFNCMaps1.EndUpdate;
end;

procedure TMapIt.CreateClusterMarker(ATitle: string; ALatitude,
  ALongitude: Double; AGroup: TTMSFNCGoogleMapsCluster; AIconName: string);
var
  m: TTMSFNCGoogleMapsMarker;
begin
  m := TMSFNCMaps1.Markers.Add;
  m.Longitude := ALongitude;
  m.Latitude := ALatitude;
  m.Title := ATitle;
  m.Cluster := AGroup;

  AGroup.Markers.Add(m);
end;

procedure TMapIt.InitGroups;
begin
  TMSFNCMaps1.BeginUpdate;

  TMSFNCMaps1.Markers.Clear;
  TMSFNCMaps1.Clusters.Clear;


  eu := TMSFNCMaps1.Clusters.Add;
  eu.Title := 'Europe';
  af := TMSFNCMaps1.Clusters.Add;
  af.Title := 'Africa';
  asia := TMSFNCMaps1.Clusters.Add;
  asia.Title := 'Asia';
  na := TMSFNCMaps1.Clusters.Add;
  na.Title := 'North-America';
  sa := TMSFNCMaps1.Clusters.Add;
  sa.Title := 'South-America';
  oc := TMSFNCMaps1.Clusters.Add;
  oc.Title := 'Oceania';


  TMSFNCMaps1.EndUpdate;
end;
```[MontPos.zip|attachment](upload://i02Ijyc9jzRClEI5JjBMBtv5yi2.zip) (377.9 KB) 

The source code is included as a zip file.

When I call INIGroups and DBtoMAP in one Step, the markers are drawn twice.
If I call INIGroups first and then the DBtoMAP, everything is ok.
I guess it is better to send the data as a JSON-file.
5

Hi,

Can you please try the following?

Move the BeginUpdate and EndUpdate call outside of the InitGroups and DBToMap procedures.

Example:

procedure TForm1.Button1Click(Sender: TObject);
begin
  TMSFNCMaps1.BeginUpdate;
  InitGroups;
  DBToMap;
  TMSFNCMaps1.EndUpdate;
end;