public override void AddToPath(Path graphicsPath)
{
if (Start == End)
{
return;
}
if (RadiusX == 0.0f && RadiusY == 0.0f)
{
graphicsPath.LineTo(Start, End);
return;
}
var sinPhi = Math.Sin(Angle*RadiansPerDegree);
var cosPhi = Math.Cos(Angle*RadiansPerDegree);
var x1dash = cosPhi*(Start.X - End.X)/2.0 + sinPhi*(Start.Y - End.Y)/2.0;
var y1dash = -sinPhi*(Start.X - End.X)/2.0 + cosPhi*(Start.Y - End.Y)/2.0;
double root;
var numerator = RadiusX*RadiusX*RadiusY*RadiusY - RadiusX*RadiusX*y1dash*y1dash -
RadiusY*RadiusY*x1dash*x1dash;
var rx = RadiusX;
var ry = RadiusY;
if (numerator < 0.0)
{
var s = (float) Math.Sqrt(1.0 - numerator/(RadiusX*RadiusX*RadiusY*RadiusY));
rx *= s;
ry *= s;
root = 0.0;
}
else
{
root = ((Size == SvgArcSize.Large && Sweep == SvgArcSweep.Positive) ||
(Size == SvgArcSize.Small && Sweep == SvgArcSweep.Negative)
? -1.0
: 1.0)*Math.Sqrt(numerator/(RadiusX*RadiusX*y1dash*y1dash + RadiusY*RadiusY*x1dash*x1dash));
}
var cxdash = root*rx*y1dash/ry;
var cydash = -root*ry*x1dash/rx;
var cx = cosPhi*cxdash - sinPhi*cydash + (Start.X + End.X)/2.0;
var cy = sinPhi*cxdash + cosPhi*cydash + (Start.Y + End.Y)/2.0;
var theta1 = CalculateVectorAngle(1.0, 0.0, (x1dash - cxdash)/rx, (y1dash - cydash)/ry);
var dtheta = CalculateVectorAngle((x1dash - cxdash)/rx, (y1dash - cydash)/ry, (-x1dash - cxdash)/rx,
(-y1dash - cydash)/ry);
if (Sweep == SvgArcSweep.Negative && dtheta > 0)
{
dtheta -= 2.0*Math.PI;
}
else if (Sweep == SvgArcSweep.Positive && dtheta < 0)
{
dtheta += 2.0*Math.PI;
}
var segments = (int) Math.Ceiling(Math.Abs(dtheta/(Math.PI/2.0)));
var delta = dtheta/segments;
var t = 8.0/3.0*Math.Sin(delta/4.0)*Math.Sin(delta/4.0)/Math.Sin(delta/2.0);
var startX = Start.X;
var startY = Start.Y;
for (var i = 0; i < segments; ++i)
{
var cosTheta1 = Math.Cos(theta1);
var sinTheta1 = Math.Sin(theta1);
var theta2 = theta1 + delta;
var cosTheta2 = Math.Cos(theta2);
var sinTheta2 = Math.Sin(theta2);
var endpointX = cosPhi*rx*cosTheta2 - sinPhi*ry*sinTheta2 + cx;
var endpointY = sinPhi*rx*cosTheta2 + cosPhi*ry*sinTheta2 + cy;
var dx1 = t*(-cosPhi*rx*sinTheta1 - sinPhi*ry*cosTheta1);
var dy1 = t*(-sinPhi*rx*sinTheta1 + cosPhi*ry*cosTheta1);
var dxe = t*(cosPhi*rx*sinTheta2 + sinPhi*ry*cosTheta2);
var dye = t*(sinPhi*rx*sinTheta2 - cosPhi*ry*cosTheta2);
graphicsPath.CurveTo(new Point(startX, startY), new Point((startX + dx1), (startY + dy1)),
new Point((endpointX + dxe), (endpointY + dye)), new Point(endpointX, endpointY));
theta1 = theta2;
startX = (float) endpointX;
startY = (float) endpointY;
}
}
public override void AddToPath(Path graphicsPath)
{
graphicsPath.LineTo(Start, End);
}
