public List <CoordinateStructure> ExtractCoordinates(List <string> listPathNodes)
{
// an array of arrays (which contain point coordinates, which are constructed from the list of offsets in the SVG
List <CoordinateStructure> listCoordinateStructures = new List <CoordinateStructure>();
Console.WriteLine($"Parsing nodes...");
foreach (var pathNode in listPathNodes)
{
var coordinateStructure = new CoordinateStructure();
var listWords = pathNode.Split(" ");
// extract start coordinates
int coordStartX = int.Parse(Regex.Replace(listWords[0], "[^0-9.+-]", ""));
int coordStartY = int.Parse(Regex.Replace(listWords[1], "[^0-9.+-]", ""));
coordinateStructure.ListPoints.Add(new Point(coordStartX, coordStartY));
int i = 2; // don't start at very beginning, skip over the first pair of values as these are always the "starting position"
SvgPathVariantEnum currentSvgPathVariantEnum = SvgPathVariantEnum.Unset;
while (i < listWords.Length)
{
//check to see if the "variant" has changed (is this a line or curve, or are we carrying on from the last previously set variant?)
var newPathVariant = GetCurrentPathVariant(listWords, i);
if (newPathVariant != SvgPathVariantEnum.Unset)
{
currentSvgPathVariantEnum = newPathVariant;
}
// depending on the "variant" extract the appropriate coordinates and add this to "coordinateStructure.ListPoints" collection.
Point previousPoint = coordinateStructure.ListPoints[coordinateStructure.ListPoints.Count - 1];
Point?nextPoint = ExtractCoordinate(previousPoint, listWords, i, currentSvgPathVariantEnum);
if (nextPoint is null)
{
// skip over, as point was a "MoveTo" command.
}
else
{
coordinateStructure.ListPoints.Add((Point)nextPoint);
}
//depending on the current variant, increment the current index appropriately (either by 2 for a line, or 6 for a curve)
i = i + IncrementCurrentPathIndex(currentSvgPathVariantEnum);
}
listCoordinateStructures.Add(coordinateStructure);
}
return(listCoordinateStructures);
}
/// <summary>
/// Selectively return an int, , which is used to increment the index used to parse the
/// </summary>
/// <param name="i"></param>
/// <param name="currentSvgPathVariantEnum"></param>
/// <returns></returns>
public int IncrementCurrentPathIndex(SvgPathVariantEnum currentSvgPathVariantEnum)
{
// in an SVG path, this code accounts for two "variants".
// a "line variant" has coordinate values that come in just pairs, therefore we increment the index by 2
// a "curve variant" has coordinate values that comprise of 3 pairs. The first two pairs are "bezier control points", whilst the last is the coordinate of wherethe curve ends. So we increment by 6.
// push the "index" forward, depending on the current variant
switch (currentSvgPathVariantEnum)
{
case SvgPathVariantEnum.Line:
return(2);
case SvgPathVariantEnum.Curve:
return(6);
case SvgPathVariantEnum.MoveTo:
return(2);
default:
throw new Exception("Encountered 'SvgPathVariantEnum.Unset'");
}
}
/// <summary>
/// Extracts the appropriate coordinates from a list SVG path string values
/// Coordinate to use, changes depending on the SvgPathVariant (i.e. line or curve)
/// adds extracted coordinate to previous trailing value (because coordinates are not absolutes, but instead deltas)
/// </summary>
/// <param name="previousPoint"></param>
/// <param name="listWords"></param>
/// <param name="i"></param>
/// <param name="currentSvgPathVariantEnum"></param>
/// <returns>
/// Nullable Point, which represents the next *Absolute* coordinate.
/// </returns>
public Point?ExtractCoordinate(Point previousPoint, string[] listWords, int i, SvgPathVariantEnum currentSvgPathVariantEnum)
{
string coordX;
string coordY;
switch (currentSvgPathVariantEnum)
{
case SvgPathVariantEnum.Line:
coordX = Regex.Replace(listWords[i], "[^0-9.+-]", "");
coordY = Regex.Replace(listWords[i + 1], "[^0-9.+-]", "");
break;
case SvgPathVariantEnum.Curve:
// n.b. in an SVG curve, there are 3 pairs of coordinates (the first two are bezier control points), where the last pair is the coordinates where the curve ends (we want these coordinates!)
coordX = Regex.Replace(listWords[i + 4], "[^0-9.+-]", "");
coordY = Regex.Replace(listWords[i + 5], "[^0-9.+-]", "");
break;
case SvgPathVariantEnum.MoveTo:
// we simply don't need to deal with a move-to command in this code (because we're not drawing proper curves)
return(null);
default:
throw new Exception("Encountered 'SvgPathVariantEnum.Unset'");
}
int offsetX = int.Parse(coordX);
int offsetY = int.Parse(coordY);
return(new Point(previousPoint.X + offsetX, previousPoint.Y + offsetY));
}