/// <summary>
/// Converts a string containing SVG path data to a sequence of <see cref="PathPiece"/> objects.</summary>
/// <param name="svgPath">
/// SVG path data to parse.</param>
public static IEnumerable <PathPiece> DecodePieces(string svgPath)
{
// Parse all the commands and coordinates
var numRegex = @"-?\d*(?:\.\d*)?\d(?:e-?\d+)?\s*,?\s*";
var prevPoint = new PointD(0, 0);
var prevStartPoint = (PointD?)null;
var prevControlPoint = new PointD(0, 0);
svgPath = svgPath.TrimStart();
while (!string.IsNullOrWhiteSpace(svgPath))
{
Match m;
if ((m = Regex.Match(svgPath, @"^[MLCHVS]\s*({0})*".Fmt(numRegex), RegexOptions.IgnoreCase)).Success)
{
PathPieceType type;
PointD[] points;
bool prevControlPointDetermined = false;
var numbers = m.Groups[1].Captures.Cast <Capture>().Select(c => double.Parse(c.Value.Trim().TrimEnd(',').Trim())).ToArray();
switch (m.Value[0])
{
case 'M':
type = PathPieceType.Move;
points = numbers.Split(2).Select(gr => new PointD(gr.First(), gr.Last())).ToArray();
prevPoint = points[points.Length - 1];
break;
case 'm':
type = PathPieceType.Move;
points = numbers.Split(2).Select(gr => new PointD(gr.First(), gr.Last())).ToArray();
for (int i = 0; i < points.Length; i++)
{
prevPoint = (points[i] += prevPoint);
}
break;
case 'L':
type = PathPieceType.Line;
points = numbers.Split(2).Select(gr => new PointD(gr.First(), gr.Last())).ToArray();
prevPoint = points[points.Length - 1];
break;
case 'l':
type = PathPieceType.Line;
points = numbers.Split(2).Select(gr => new PointD(gr.First(), gr.Last())).ToArray();
for (int i = 0; i < points.Length; i++)
{
prevPoint = (points[i] += prevPoint);
}
break;
case 'H':
type = PathPieceType.Line;
points = numbers.Select(x => new PointD(x, prevPoint.Y)).ToArray();
prevPoint = points.Last();
break;
case 'h':
type = PathPieceType.Line;
points = new PointD[numbers.Length];
for (int i = 0; i < numbers.Length; i++)
{
prevPoint = points[i] = new PointD(prevPoint.X + numbers[i], prevPoint.Y);
}
break;
case 'V':
type = PathPieceType.Line;
points = numbers.Select(y => new PointD(prevPoint.X, y)).ToArray();
prevPoint = points.Last();
break;
case 'v':
type = PathPieceType.Line;
points = new PointD[numbers.Length];
for (int i = 0; i < numbers.Length; i++)
{
prevPoint = points[i] = new PointD(prevPoint.X, prevPoint.Y + numbers[i]);
}
break;
case 'C':
type = PathPieceType.Curve;
points = numbers.Split(2).Select(x => new PointD(x.First(), x.Last())).ToArray();
prevPoint = points.Last();
prevControlPoint = points.SkipLast(1).Last();
prevControlPointDetermined = true;
break;
case 'c':
type = PathPieceType.Curve;
points = numbers.Split(2).Select(x => new PointD(x.First(), x.Last())).ToArray();
Ut.Assert(points.Length % 3 == 0);
for (int i = 0; i < points.Length; i += 3)
{
points[i] += prevPoint;
points[i + 1] += prevPoint;
prevPoint = (points[i + 2] += prevPoint);
}
prevPoint = points.Last();
prevControlPoint = points.SkipLast(1).Last();
prevControlPointDetermined = true;
break;
case 'S':
type = PathPieceType.Curve;
var pointsList1 = new List <PointD>();
foreach (var pair in numbers.Split(2).Select(x => new PointD(x.First(), x.Last())).Split(2))
{
Ut.Assert(pair.Count() == 2);
pointsList1.Add(prevPoint + (prevPoint - prevControlPoint));
pointsList1.Add(prevControlPoint = pair.First());
pointsList1.Add(prevPoint = pair.Last());
}
points = pointsList1.ToArray();
prevControlPointDetermined = true;
break;
case 's':
type = PathPieceType.Curve;
var pointsList2 = new List <PointD>();
foreach (var pair in numbers.Split(2).Select(x => new PointD(x.First(), x.Last())).Split(2))
{
Ut.Assert(pair.Count() == 2);
pointsList2.Add(prevPoint + (prevPoint - prevControlPoint));
pointsList2.Add(prevControlPoint = (pair.First() + prevPoint));
pointsList2.Add(prevPoint = (pair.Last() + prevPoint));
}
points = pointsList2.ToArray();
prevControlPointDetermined = true;
break;
default:
throw new InvalidOperationException();
}
if (prevStartPoint == null)
{
prevStartPoint = points[0];
}
if (!prevControlPointDetermined)
{
prevControlPoint = prevPoint;
}
yield return(new PathPiece(type, points));
}
else if ((m = Regex.Match(svgPath, @"^Z\s*", RegexOptions.IgnoreCase)).Success)
{
yield return(PathPiece.End);
prevPoint = prevStartPoint ?? new PointD(0, 0);
prevStartPoint = null;
}
else if ((m = Regex.Match(svgPath, @"^A\s*(({0})({0})({0})([01])[\s,]*([01])[\s,]*({0})({0}))+".Fmt(numRegex), RegexOptions.IgnoreCase)).Success)
{
for (var cp = 0; cp < m.Groups[1].Captures.Count; cp++)
{
double convert(int gr) => double.Parse(m.Groups[gr].Captures[cp].Value.Trim().TrimEnd(',').Trim());
var p = new PointD(convert(7), convert(8));
prevPoint = m.Value[0] == 'a' ? p + prevPoint : p;
yield return(new PathPieceArc(convert(2), convert(3), convert(4), m.Groups[5].Captures[cp].Value != "0", m.Groups[6].Captures[cp].Value != "0", prevPoint));
}
}
else
{
Debugger.Break();
throw new NotImplementedException();
}
svgPath = svgPath.Substring(m.Length);
}
}