SVG

SVG (Scalable Vector Graphics) read/write support for Geometry<Point> and Feature<Point>. Coordinates are written directly into element attributes (points, d, cx/cy) — the viewBox is calculated for display only and never transforms them — so geometries round-trip through SVG at the configured coordinate precision. Ships in the IRI.Maptor.Core.Spatial package; the EPS support in ../Eps mirrors this API for PostScript output.

Supported capabilities

Capability	Supported	Implemented in
Read (SVG → geometry/feature)	Yes	SvgReader, SvgReaderExtensions
Write (geometry/feature → SVG)	Yes	SvgWriter, ToSvg/SaveAsSvg extensions
Styling on write (stroke, fill, width, opacity)	Yes	SvgOptions
Feature attributes (id, class, data-*)	Yes	SvgWriter/SvgReader (PreserveFeatureAttributes, preserveAttributes)

All geometry types are handled: Point, LineString, Polygon (including holes), MultiPoint, MultiLineString, MultiPolygon, and GeometryCollection.

Usage

Writing

ToSvg/SaveAsSvg live in the IRI.Maptor.Extensions namespace; SvgOptions in IRI.Maptor.Core.Spatial.IO.Svg; RgbColor in IRI.Maptor.Core.Spatial.IO.Dxf.

using IRI.Maptor.Extensions;
using IRI.Maptor.Core.Spatial.IO.Svg;
using IRI.Maptor.Core.Spatial.IO.Dxf;      // RgbColor
using IRI.Maptor.Core.Spatial.Primitives;
using IRI.Maptor.Core.Common.Primitives;

var point = Geometry<Point>.Create(100.5, 200.3, srid: 4326);

string svg = point.ToSvg();        // SVG text
point.SaveAsSvg("point.svg");      // write to file

// With styling
var styled = new SvgOptions(
    strokeColor: new RgbColor(255, 0, 0),
    fillColor: new RgbColor(255, 255, 0, 200),
    strokeWidth: 2.0,
    opacity: 0.8);
point.SaveAsSvg("styled.svg", styled);

Features carry their attributes into the output:

var feature = new Feature<Point>(point, new Dictionary<string, object>
{
    { "id", "point-1" },
    { "class", "marker" },
    { "name", "Sample" }
});

string svg = feature.ToSvg();
// <circle id="point-1" class="marker" data-name="Sample" ... />
feature.SaveAsSvg("feature.svg");

Reading

Reader extensions live in IRI.Maptor.Core.Spatial.IO.Svg (SvgReaderExtensions); the underlying static methods are SvgReader.Read, SvgReader.ReadFromFile, SvgReader.ReadFeature, and SvgReader.ReadFeatureFromFile.

using IRI.Maptor.Core.Spatial.IO.Svg;

// From string
string svgContent = File.ReadAllText("geometry.svg");
var geometry = svgContent.FromSvg(srid: 4326);

// From file
var fileInfo = new FileInfo("geometry.svg");
var geometry2 = fileInfo.ReadSvg(srid: 4326);

// With attributes
var feature = svgContent.FromSvgFeature(srid: 4326, preserveAttributes: true);
var feature2 = fileInfo.ReadSvgFeature(srid: 4326, preserveAttributes: true);

if (feature.Attributes.ContainsKey("id"))
    Console.WriteLine($"Feature ID: {feature.Attributes["id"]}");

A document with several top-level elements parses to a GeometryCollection:

string svgContent = @"
<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 200 200'>
  <circle cx='50' cy='50' r='3'/>
  <polyline points='100,50 150,100 200,50'/>
  <polygon points='50,150 100,200 150,150'/>
</svg>";

var collection = svgContent.FromSvg(srid: 4326);
// GeometryCollection containing Point, LineString, and Polygon

Options

var options = new SvgOptions
{
    StrokeColor = new RgbColor(0, 0, 255),
    FillColor = new RgbColor(255, 255, 255),
    StrokeWidth = 1.5,                 // default 1.0
    Opacity = 0.9,                     // default 1.0
    IncludeViewBox = true,             // default true
    ViewBoxPadding = 0.1,              // fraction of bbox, default 0.05
    CoordinatePrecision = 8,           // decimal places, default 6
    PreserveFeatureAttributes = true,  // default true
    PointCircleRadius = 5.0            // default 3.0
};

Element mapping

Geometry type	SVG element	Notes
Point	<circle>	cx, cy, r attributes
LineString	<polyline>	points attribute
Polygon (single ring)	<polygon>	points attribute
Polygon (with holes)	<path>	d attribute with M/L/Z commands
MultiPoint	<g> + circles	group of <circle> elements
MultiLineString	<g> + polylines	group of <polyline> elements
MultiPolygon	<g> + polygons	group of <polygon>/<path> elements
GeometryCollection	<g> + mixed	group of the above

Feature attributes map to SVG attributes: id → id, class → class, existing data-* keys are kept as-is, and every other attribute is stored as data-{key}.

Limitations

• Only circle, polyline, polygon, path, and g elements are parsed; rect, ellipse, line, text, and transforms are ignored.
• The path parser handles M/L/Z commands; curve and arc commands are approximated as line segments.
• Round-trip fidelity is bounded by CoordinatePrecision (default 6 decimal places).
• Styling applies on write only; stroke/fill attributes are not read back into options.
• Empty geometries produce an empty SVG document.

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