Saturday, January 01, 2022

C# code to generate a segment FIT file

Someone asked about getting hold of the code to generate FIT files from Strava segments. It's not possible to provide standalone code since it's has dependencies on the rest of my website and a Strava library, but here's what I use which may give people an idea of how to use the rather confusing Garmin FIT API


using System;
using System.Collections.Generic;
using System.IO;
using System.Web;
using Dynastream.Fit;
using Newtonsoft.Json.Linq;
using Strava.Common;
using Strava.Segments;
using Strava.Streams;
public static class FitGenerator { private static void AddLeaderEntry(SegmentPointMesg newRecord, int goal, float currentDistance, float totalDistance, byte goalIndex) { if (goal != 0) { var currentGoalTime = (float)Math.Floor(currentDistance / totalDistance * goal); newRecord.SetLeaderTime(goalIndex, currentGoalTime); } } private static SegmentLeaderboardEntryMesg GetLeaderboard(int goal, byte goalIndex, SegmentLeaderboardType type, string name) { var goalLeaderboard = new SegmentLeaderboardEntryMesg(); if (goal != 0) { goalLeaderboard.SetMessageIndex(goalIndex); goalLeaderboard.SetSegmentTime(goal); goalLeaderboard.SetType(type); if (!string.IsNullOrEmpty(name)) goalLeaderboard.SetName(name); } return goalLeaderboard; } private static int LatOrLngToSemicircle(double latOrLng) { return (int)(latOrLng * (Math.Pow(2, 31) / 180)); } private static bool HasPr(List<SegmentStream> pr, Segment seg) { if (pr != null) return true; if (seg.AthleteSegmentStats != null && seg.AthleteSegmentStats.PrElapsedTime != null) return true; return false; } public static byte[] Generate(Segment seg, int goal, string goalName, int rival, string rivalName, int challenger, string challengerName) { List<SegmentStream> altitude = null; try { StravaBaseHandler.TryStravaRequest((client) => { altitude = client.Streams.GetSegmentStream(seg.Id.ToString(), SegmentStreamType.Altitude | SegmentStreamType.LatLng); }); } catch (Exception ex) { throw new Exception("Failed to get stream for segment " + seg.Id, ex); } // get all the streams we are interested in SegmentStream locationStream = null; SegmentStream altitudeStream = null; SegmentStream distanceStream = null; locationStream = SegmentStream.GetStream(altitude, StreamType.LatLng); altitudeStream = SegmentStream.GetStream(altitude, StreamType.Altitude); distanceStream = SegmentStream.GetStream(altitude, StreamType.Distance); // grab user's best time List<SegmentStream> pr = null; var athlete = HttpContext.Current.Request.Cookies["athlete"]; if (athlete != null) { try { pr = StravaBaseHandler.GetSegmentPr(seg.Id.ToString(), athlete.Value); } catch { // do nothing } } // Generate some FIT messages // Every FIT file MUST contain a 'File ID' message as the first message var fileIdMesg = new FileIdMesg(); var records = new List<SegmentPointMesg>(); fileIdMesg.SetType(Dynastream.Fit.File.Segment); fileIdMesg.SetManufacturer(Manufacturer.Strava); // Types defined in the profile are available fileIdMesg.SetProduct(65534); fileIdMesg.SetTimeCreated(new Dynastream.Fit.DateTime(System.DateTime.Now)); fileIdMesg.SetSerialNumber(1); fileIdMesg.SetNumber(1); var fileCreator = new FileCreatorMesg(); fileCreator.SetHardwareVersion(0); fileCreator.SetSoftwareVersion(0); // segment ID var segmentId = new SegmentIdMesg(); segmentId.SetName(seg.Name); segmentId.SetEnabled(Bool.True); if (seg.ActivityType == "Run") segmentId.SetSport(Sport.Running); else segmentId.SetSport(Sport.Cycling); byte prIndex = 0; byte goalIndex = 1; byte rivalIndex = 2; byte challengerIndex = 3; byte komIndex = 4; byte qomIndex = 5; if (!HasPr(pr, seg)) { goalIndex--; rivalIndex--; challengerIndex--; komIndex--; qomIndex--; } if (goal == 0) { rivalIndex--; challengerIndex--; komIndex--; qomIndex--; } if (rival == 0) { challengerIndex--; komIndex--; qomIndex--; } if (challenger == 0) { komIndex--; qomIndex--; } if (seg.KOM() == 0) { qomIndex--; } segmentId.SetSelectionType(SegmentSelectionType.Starred); segmentId.SetUuid(Guid.NewGuid().ToByteArray()); if (HasPr(pr, seg)) segmentId.SetDefaultRaceLeader(prIndex); if (seg.Map.Polyline == "") throw new Exception("The segment has no map data (which is somewhat unexpected), " + "I can't generate the FIT file"); var points = PolylineDecoder.Decode(seg.Map.Polyline); // figure out SW and NE double swLat = 1000; double swLong = 1000; double neLat = -1000; double neLong = -1000; foreach (var pt in points) { swLat = Math.Min(swLat, pt.Latitude); swLong = Math.Min(swLong, pt.Longitude); neLat = Math.Max(neLat, pt.Latitude); neLong = Math.Max(neLong, pt.Longitude); } // segment info var lap = new SegmentLapMesg(); lap.SetUuid(Guid.NewGuid().ToByteArray()); lap.SetTotalDistance(seg.Distance); lap.SetTotalAscent((ushort)seg.TotalElevationGain); lap.SetSwcLat(LatOrLngToSemicircle(swLat)); lap.SetSwcLong(LatOrLngToSemicircle(swLong)); lap.SetNecLat(LatOrLngToSemicircle(neLat)); lap.SetNecLong(LatOrLngToSemicircle(neLong)); lap.SetMessageIndex(1); lap.SetStartPositionLat(LatOrLngToSemicircle(points[0].Latitude)); lap.SetStartPositionLong(LatOrLngToSemicircle(points[0].Longitude)); lap.SetEndPositionLat(LatOrLngToSemicircle(points[points.Count - 1].Latitude)); lap.SetEndPositionLong(LatOrLngToSemicircle(points[points.Count - 1].Longitude)); // goal entry var goalLeaderboard = GetLeaderboard(goal, goalIndex, SegmentLeaderboardType.Goal, goalName); var rivalLeaderboard = GetLeaderboard(rival, rivalIndex, SegmentLeaderboardType.Rival, rivalName); var challengerLeaderboard = GetLeaderboard(challenger, challengerIndex, SegmentLeaderboardType.Challenger, challengerName); var komLeaderboard = GetLeaderboard(seg.KOM(), komIndex, SegmentLeaderboardType.Kom, ""); var qomLeaderboard = GetLeaderboard(seg.QOM(), qomIndex, SegmentLeaderboardType.Qom, ""); SegmentStream prDistanceStream = null; SegmentStream prTimeStream = null; if (pr != null) { prDistanceStream = SegmentStream.GetStream(pr, StreamType.Distance); prTimeStream = SegmentStream.GetStream(pr, StreamType.Time); } SegmentLeaderboardEntryMesg prLeaderboard = null; if (HasPr(pr, seg)) { prLeaderboard = new SegmentLeaderboardEntryMesg(); prLeaderboard.SetMessageIndex(prIndex); var prTime = seg.AthleteSegmentStats.PrElapsedTime; prLeaderboard.SetSegmentTime(prTime); prLeaderboard.SetType(SegmentLeaderboardType.Pr); } for (var i = 0; i < locationStream.Data.Count; i++) { var newRecord = new SegmentPointMesg(); var latLng = locationStream.Data[i]; if (latLng != null) { var intLat = LatOrLngToSemicircle(Convert.ToDouble(((JArray)(latLng)).First)); newRecord.SetPositionLat(intLat); var intLng = LatOrLngToSemicircle(Convert.ToDouble(((JArray)(latLng)).Last)); newRecord.SetPositionLong(intLng); } if (altitudeStream != null) newRecord.SetAltitude(Convert.ToSingle(altitudeStream.Data[i])); var currentDistance = Convert.ToSingle(distanceStream.Data[i]); newRecord.SetDistance(currentDistance); newRecord.SetMessageIndex((ushort)i); if (HasPr(pr, seg)) { if (pr != null) { // add PR time // find index of the PR item that is at or beyond current distance var pos = prDistanceStream.Data.Count - 1; for (var j = 0; j < prDistanceStream.Data.Count; j++) { if (Convert.ToSingle(prDistanceStream.Data[j]) - Convert.ToSingle(prDistanceStream.Data[0]) >= currentDistance) { pos = j; break; } } // find time at that distance if (pos > 0) { var prStartDistance = Convert.ToSingle(prDistanceStream.Data[pos - 1]) - Convert.ToSingle(prDistanceStream.Data[0]); var prEndDistance = Convert.ToSingle(prDistanceStream.Data[pos]) - Convert.ToSingle(prDistanceStream.Data[0]); var fraction = (currentDistance - prStartDistance) / (prEndDistance - prStartDistance); var prTime = Convert.ToSingle(prTimeStream.Data[pos - 1]) + fraction * (Convert.ToSingle(prTimeStream.Data[pos]) - Convert.ToSingle(prTimeStream.Data[pos - 1])); newRecord.SetLeaderTime(prIndex, (float)Math.Floor(prTime - Convert.ToSingle(prTimeStream.Data[0]))); } else { newRecord.SetLeaderTime(prIndex, 0); } } else { AddLeaderEntry(newRecord, seg.AthleteSegmentStats.PrElapsedTime.Value, currentDistance, seg.Distance, prIndex); } } // add goal time AddLeaderEntry(newRecord, goal, currentDistance, seg.Distance, goalIndex); AddLeaderEntry(newRecord, rival, currentDistance, seg.Distance, rivalIndex); AddLeaderEntry(newRecord, challenger, currentDistance, seg.Distance, challengerIndex); AddLeaderEntry(newRecord, seg.KOM(), currentDistance, seg.Distance, komIndex); AddLeaderEntry(newRecord, seg.QOM(), currentDistance, seg.Distance, qomIndex); records.Add(newRecord); } // Create file encode object var encodeDemo = new Encode(ProtocolVersion.V20); using (var fitDest = new MemoryStream()) { // Write our header encodeDemo.Open(fitDest); // Encode each message, a definition message is automatically generated and output if necessary encodeDemo.Write(fileIdMesg); encodeDemo.Write(fileCreator); encodeDemo.Write(segmentId); if (prLeaderboard != null) encodeDemo.Write(prLeaderboard); if (goal != 0) encodeDemo.Write(goalLeaderboard); if (rival != 0) encodeDemo.Write(rivalLeaderboard); if (challenger != 0) encodeDemo.Write(challengerLeaderboard); if (seg.KOM() != 0) encodeDemo.Write(komLeaderboard); if (seg.QOM() != 0) encodeDemo.Write(qomLeaderboard); encodeDemo.Write(lap); encodeDemo.Write(records); encodeDemo.Close(); fitDest.Flush(); fitDest.Position = 0; return fitDest.ToArray(); } } }

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