Work with GPS Exchange Format GPX files in C#

Working with GPS Exchange File (GPX) Files

Aspose.GIS lets you open and read features from GPS Exchange File (GPX) files.

Reading Features from GPX File

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
using (var layer = Drivers.Gpx.OpenLayer(dataDir + "schiehallion.gpx"))
{
    foreach (var feature in layer)
    {
        switch (feature.Geometry.GeometryType)
        {
            // GPX waypoints are exported as features with point geometry.
            case GeometryType.Point:


                Console.WriteLine(feature.Geometry.Dimension);
                //HandleGpxWaypoint(feature);
                break;
            
            // GPX routes are exported as features with line string geometry.
            case GeometryType.LineString:

                //HandleGpxRoute(feature);
                LineString ls = (LineString)feature.Geometry;

                foreach (var point in ls)
                {
                    Console.WriteLine(point.AsText());
                }
                break;
            
                // GPX tracks are exported as features with multi line string geometry.
            // Every track segment is line string.
            case GeometryType.MultiLineString:

                //HandleGpxTrack(feature);
                Console.WriteLine(feature.Geometry.AsText());
                break;
            default: break;
        }
    }
}

Reading Features for each point in segment

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
// specify option
GpxOptions options = new GpxOptions()
{
    ReadNestedAttributes = true
};
            
// open GPX layer to read features
using (var layer = Drivers.Gpx.OpenLayer(dataDir + "nested_data.gpx", options))
{
    foreach (var feature in layer)
    {
        if (feature.Geometry.GeometryType == GeometryType.MultiLineString)
        {
            // read segment
            var lines = (MultiLineString) feature.Geometry;
            for (int i = 0; i < lines.Count; i++)
            {
                Console.WriteLine($"....segment({i})......");
                var segment = (LineString)lines[i];

                // read points in segment
                for (int j = 0; j < segment.Count; j++)
                {
                    // look for attribute
                    string attributeName = $"name__{i}__{j}";
                    if (layer.Attributes.Contains(attributeName) && feature.IsValueSet(attributeName))
                    {
                        // print a point and attribute
                        var value = feature.GetValue<string>(attributeName);
                        Console.WriteLine($"{segment[j].AsText()} - {attributeName}: {value}, ");
                    }
                    else
                    {
                        // print a point only
                        Console.WriteLine(segment[j].AsText());
                    }
                }
            }
            Console.WriteLine("..........");
        }
    }
}

Write Polygons As Lines to GPX File

GPX format does not support polygons and multipolygons. As result, sometime conversion is failed from other formats. You should apply the WritePolygonsAsLines option to resolve this issue.

// For complete examples and data files, please go to https://github.com/aspose-gis/Aspose.GIS-for-.NET
using (var layer = Drivers.Gpx.CreateLayer(dataDir + "lines_out.gpx", new GpxOptions()
{
    WritePolygonsAsLines = true
}))
{
    // The GPX format does not support polygons,
    // but we use the WritePolygonsAsLines options to resolve this issue.
    Feature feature = layer.ConstructFeature();
    feature.Geometry = Geometry.FromText("POLYGON((1 2, 1 4, 3 4, 3 2))");
    layer.Add(feature);
}