FNC Maps FNCElevation GetElevation() - C++ Builder

FNC TMS FNC Maps
1

How do I access Location Elevation through the TTMSFNCElevation component?
I dont seem to find the GetElevation() function.

2

With this code you should be able to achieve this:

var
  coord: TTMSFNCMapsCoordinateRec;
begin
  TMSFNCElevation1.GetElevationResult(coord,
  procedure(const AResult: TTMSFNCElevationRequest)
  var
    el: Single;
  begin
    if AResult.Items.Count > 0 then
    begin
      //elevation
      el := AResult.Items[0].Elevation;
    end;
  end);
3

Thanks for that, can you perhaps provide code in C++ also?

4

Hi,

I am also having difficulty implementing code to get the elevation for map coordinates. I have tried implementing your suggested code Pieter, but cannot get it to retrieve coordinates. My code is:

var
  Lat,Lng  : double;
  Elev     : single;
  ACoord   : TTMSFNCMapsCoordinateRec;
begin
...
  ACoord := CreateCoordinate(Lat,Lng)
  Elev   := 0;
  FNCElevation.GetElevationResult(ACoord,
    procedure(const AResult: TTMSFNCElevationRequest)
      begin
        if AResult.Items.Count > 0 then
          Elev := AResult.Items[0].Elevation;
      end);
...
end;

I then try to use the value assigned to Elev after your nested GetElevationResult procedure, but it always returns with a 0.

This code is actually in a loop with other code (...) which is creating additional information for each coordinate as well as the elevation. I am assigning valid Lat and Lng before the code example here.

If I examine values in debug mode the GetElevationResult procedure is called, and Elev gets elevation values, but these values are not available after the call is completed, Elev is a 0.

Any suggestions why I am not getting any values for Elev outside your nested procedure? I am a newbie to using nested procedures, keen to learn what I am doing wrong.

Jonathan

5

Hi,

The anonymous callback is asynchronous, so the callback will be triggered at a later time, after the method has finished, that's why Elev is 0 at the end of the method.

6

Thanks Pieter

I have now changed my code to

  • build up a TTMSFNCMapsCoordinateRecArray (ACoordRecArray) of all coordinates (over 800 of them)
  • use .GetElevationResult(ACoordRecArray,nil) to request elevations for all these coordinates at once
  • wait for the OnGetElevation event which signals when all the elevation data is ready
  • then extract the elevations from the .ElevationData array (provided as part of the TTMSFNCElevation component). I use the .Elevation value that comes with each TTMSFNCMapsCoordinateRec in this array of results.

This works well, and I am able to get lots of elevations.

Thanks for your help. I would be interested if anyone has found better ways to do this.

Jonathan

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