public static bool TryParseArcPath(string ArcPath, out SvgArcPath arc)
{
string[] strArray = ArcPath.Split(' ');
if (strArray[0] == "M" && strArray[3] == "A")
{
double.TryParse(strArray[1], out arc.x1); //x1
double.TryParse(strArray[2], out arc.y1); //y1
double.TryParse(strArray[4], out arc.rx); //rx
double.TryParse(strArray[5], out arc.ry); //ry
double.TryParse(strArray[6], out arc.phi); //x-axis-rotation
int.TryParse(strArray[7], out int fA); //large-arc-flag
arc.fA = fA == 1;
int.TryParse(strArray[8], out int fS); //sweep-flag
arc.fS = fS == 1;
double.TryParse(strArray[9], out arc.x2); //x2
double.TryParse(strArray[10], out arc.y2); //y2
return(true);
}
else if (strArray[0].StartsWith("M") && strArray[2].StartsWith("A"))
{
double.TryParse(strArray[0][1..], out arc.x1); //x1
//conversion_from_endpoint_to_center_parameterization
//sample : svgArcToCenterParam(200,200,50,50,0,1,1,300,200)
// x1 y1 rx ry φ fA fS x2 y2
private static ArcParams SvgArcToArcParam(SvgArcPath svgArc)
{
double cx, cy, startAngle, deltaAngle, endAngle;
var PIx2 = Math.PI * 2.0;
if (svgArc.rx < 0)
{
svgArc.rx = -svgArc.rx;
}
if (svgArc.ry < 0)
{
svgArc.ry = -svgArc.ry;
}
if (svgArc.rx == 0.0 || svgArc.ry == 0.0)
{ // invalid arguments
throw new Exception("rx and ry can not be 0");
}
var s_phi = Math.Sin(svgArc.phi);
var c_phi = Math.Cos(svgArc.phi);
var hd_x = (svgArc.x1 - svgArc.x2) / 2.0; // half diff of x
var hd_y = (svgArc.y1 - svgArc.y2) / 2.0; // half diff of y
var hs_x = (svgArc.x1 + svgArc.x2) / 2.0; // half sum of x
var hs_y = (svgArc.y1 + svgArc.y2) / 2.0; // half sum of y
// F6.5.1
var x1_ = c_phi * hd_x + s_phi * hd_y;
var y1_ = c_phi * hd_y - s_phi * hd_x;
// F.6.6 Correction of out-of-range radii
// Step 3: Ensure radii are large enough
var lambda = (x1_ * x1_) / (svgArc.rx * svgArc.rx) + (y1_ * y1_) / (svgArc.ry * svgArc.ry);
if (lambda > 1)
{
svgArc.rx *= Math.Sqrt(lambda);
svgArc.ry *= Math.Sqrt(lambda);
}
var rxry = svgArc.rx * svgArc.ry;
var rxy1_ = svgArc.rx * y1_;
var ryx1_ = svgArc.ry * x1_;
var sum_of_sq = rxy1_ * rxy1_ + ryx1_ * ryx1_; // sum of square
if (sum_of_sq == 0)
{
throw new Exception("start point can not be same as end point");
}
var coe = Math.Sqrt(Math.Abs((rxry * rxry - sum_of_sq) / sum_of_sq));
if (svgArc.fA == svgArc.fS)
{
coe = -coe;
}
// F6.5.2
var cx_ = coe * rxy1_ / svgArc.ry;
var cy_ = -coe * ryx1_ / svgArc.rx;
// F6.5.3
cx = c_phi * cx_ - s_phi * cy_ + hs_x;
cy = s_phi * cx_ + c_phi * cy_ + hs_y;
var xcr1 = (x1_ - cx_) / svgArc.rx;
var xcr2 = (x1_ + cx_) / svgArc.rx;
var ycr1 = (y1_ - cy_) / svgArc.ry;
var ycr2 = (y1_ + cy_) / svgArc.ry;
// F6.5.5
startAngle = Radian(1.0, 0.0, xcr1, ycr1);
// F6.5.6
deltaAngle = Radian(xcr1, ycr1, -xcr2, -ycr2);
while (deltaAngle > PIx2)
{
deltaAngle -= PIx2;
}
while (deltaAngle < 0.0)
{
deltaAngle += PIx2;
}
if (!svgArc.fS)
{
deltaAngle -= PIx2;
}
endAngle = startAngle + deltaAngle;
while (endAngle > PIx2)
{
endAngle -= PIx2;
}
while (endAngle < 0.0)
{
endAngle += PIx2;
}
ArcParams outputObj = new ArcParams()
{ /* cx, cy, startAngle, deltaAngle */
center_x = cx,
center_y = cy,
startAngle = startAngle * (180 / Math.PI),
endAngle = endAngle * (180 / Math.PI),
radius = svgArc.rx
};
return(outputObj);
}
