public override bool HandleGeometry(IGeometryHandler handler)
{
var decoder = new GeometryDecoder(feature, layer);
// From https://github.com/mapbox/vector-tile-spec/tree/master/2.1
//
// The POINT geometry type encodes a point or multipoint geometry. The geometry command sequence for a point
// geometry MUST consist of a single MoveTo command with a command count greater than 0.
//
// The LINESTRING geometry type encodes a linestring or multilinestring geometry. The geometry command sequence
// for a linestring geometry MUST consist of one or more repetitions of the following sequence:
// 1. A MoveTo command with a command count of 1
// 2. A LineTo command with a command count greater than 0
//
// The POLYGON geometry type encodes a polygon or multipolygon geometry, each polygon consisting of exactly one
// exterior ring that contains zero or more interior rings. The geometry command sequence for a polygon consists
// of one or more repetitions of the following sequence:
// 1. An ExteriorRing
// 2. Zero or more InteriorRings
// Each ExteriorRing and InteriorRing MUST consist of the following sequence:
// 1. A MoveTo command with a command count of 1
// 2. A LineTo command with a command count greater than 1
// 3. A ClosePath command
switch (feature.Type)
{
case PbfGeomType.Point:
while (decoder.HasData())
{
decoder.AdvanceCommand();
Debug.Assert(decoder.Command == CommandType.MoveTo && decoder.Repeat > 0);
for (int i = decoder.Repeat; i > 0; i--)
{
handler.OnPoint(decoder.AdvanceCursor());
}
}
break;
case PbfGeomType.LineString:
while (decoder.HasData())
{
handler.OnBeginLineString();
decoder.AdvanceCommand();
Debug.Assert(decoder.Command == CommandType.MoveTo && decoder.Repeat == 1);
handler.OnPoint(decoder.AdvanceCursor());
decoder.AdvanceCommand();
Debug.Assert(decoder.Command == CommandType.LineTo && decoder.Repeat > 0);
for (int i = decoder.Repeat; i > 0; i--)
{
handler.OnPoint(decoder.AdvanceCursor());
}
handler.OnEndLineString();
}
break;
case PbfGeomType.Polygon:
// Create temporary storage to hold rings until we determine whether they are interior or exterior.
var ring = new List <Point>();
var isPolygonStarted = false;
while (decoder.HasData())
{
// Read out the coordinates of the next ring.
decoder.AdvanceCommand();
Debug.Assert(decoder.Command == CommandType.MoveTo && decoder.Repeat == 1);
ring.Add(decoder.AdvanceCursor());
decoder.AdvanceCommand();
for (int i = decoder.Repeat; i > 0; i--)
{
ring.Add(decoder.AdvanceCursor());
}
ring.Add(ring.First());
decoder.AdvanceCommand();
Debug.Assert(decoder.Command == CommandType.ClosePath && decoder.Repeat == 1);
// If ring is exterior, end the current polygon, start a new one, add ring to new polygon.
// If ring is interior, add the ring to current polygon.
var area = SignedArea(ring);
if (area > 0)
{
if (isPolygonStarted)
{
handler.OnEndPolygon();
}
handler.OnBeginPolygon();
isPolygonStarted = true;
}
handler.OnBeginLinearRing();
foreach (var point in ring)
{
handler.OnPoint(point);
}
handler.OnEndLinearRing();
ring.Clear();
}
handler.OnEndPolygon();
break;
case PbfGeomType.Unknown:
return(false);
}
return(true);
}
public override bool HandleGeometry(IGeometryHandler handler)
{
var decoder = new GeometryDecoder(feature, layer);
// From https://github.com/mapbox/vector-tile-spec/tree/master/2.1
//
// The POINT geometry type encodes a point or multipoint geometry. The geometry command sequence for a point
// geometry MUST consist of a single MoveTo command with a command count greater than 0.
//
// The LINESTRING geometry type encodes a linestring or multilinestring geometry. The geometry command sequence
// for a linestring geometry MUST consist of one or more repetitions of the following sequence:
// 1. A MoveTo command with a command count of 1
// 2. A LineTo command with a command count greater than 0
//
// The POLYGON geometry type encodes a polygon or multipolygon geometry, each polygon consisting of exactly one
// exterior ring that contains zero or more interior rings. The geometry command sequence for a polygon consists
// of one or more repetitions of the following sequence:
// 1. An ExteriorRing
// 2. Zero or more InteriorRings
// Each ExteriorRing and InteriorRing MUST consist of the following sequence:
// 1. A MoveTo command with a command count of 1
// 2. A LineTo command with a command count greater than 1
// 3. A ClosePath command
switch (feature.Type)
{
case PbfGeomType.Point:
if (decoder.AdvanceCommand() && decoder.Command == CommandType.MoveTo)
{
for (int i = 0; i < decoder.Repeat; i++)
{
decoder.AdvanceCursor();
handler.OnPoint(decoder.CurrentPoint());
}
}
break;
case PbfGeomType.LineString:
while (decoder.AdvanceCommand() && (decoder.Command == CommandType.MoveTo && decoder.Repeat == 1))
{
decoder.AdvanceCursor();
if (decoder.AdvanceCommand() && (decoder.Command == CommandType.LineTo && decoder.Repeat > 0))
{
handler.OnBeginLineString();
handler.OnPoint(decoder.CurrentPoint());
for (int i = 0; i < decoder.Repeat; i++)
{
decoder.AdvanceCursor();
handler.OnPoint(decoder.CurrentPoint());
}
handler.OnEndLineString();
}
}
break;
case PbfGeomType.Polygon:
while (decoder.AdvanceCommand() && (decoder.Command == CommandType.MoveTo && decoder.Repeat == 1))
{
handler.OnBeginPolygon();
decoder.AdvanceCursor();
if (decoder.AdvanceCommand() && (decoder.Command == CommandType.LineTo && decoder.Repeat > 0))
{
handler.OnBeginLinearRing();
var start = decoder.CurrentPoint();
handler.OnPoint(start);
for (int i = 0; i < decoder.Repeat; i++)
{
decoder.AdvanceCursor();
handler.OnPoint(decoder.CurrentPoint());
}
handler.OnPoint(start);
handler.OnEndLinearRing();
}
if (decoder.AdvanceCommand() && decoder.Command == CommandType.ClosePath)
{
// We should assert that this condition holds.
}
handler.OnEndPolygon();
}
break;
case PbfGeomType.Unknown:
break;
}
return(true);
}
