/// <summary>
/// Gets the <see cref="GraphicsPath"/> for this element.
/// </summary>
/// <value></value>
public override GraphicsPath Path(ISvgRenderer renderer)
{
if (this._path == null || this.IsPathDirty)
{
var halfStrokeWidth = base.StrokeWidth / 2;
// If it is to render, don't need to consider stroke width.
// i.e stroke width only to be considered when calculating boundary
if (renderer != null)
{
halfStrokeWidth = 0;
this.IsPathDirty = false;
}
var center = SvgUnit.GetDevicePoint(this.CenterX, this.CenterY, renderer, this);
var radiusX = this.RadiusX.ToDeviceValue(renderer, UnitRenderingType.Other, this) + halfStrokeWidth;
var radiusY = this.RadiusY.ToDeviceValue(renderer, UnitRenderingType.Other, this) + halfStrokeWidth;
this._path = new GraphicsPath();
_path.StartFigure();
_path.AddElement(new EllipseElement(center, radiusX, radiusY));
_path.CloseFigure();
}
return(_path);
}
public override void AddToPath(GraphicsPath graphicsPath)
{
graphicsPath.AddElement(new BezierElement(Start, FirstControlPoint, SecondControlPoint, End));
}
public override void AddToPath(GraphicsPath graphicsPath)
{
graphicsPath.AddElement(new LineElement(Start, End));
}
public static void AddToPath(GraphicsPath graphicsPath, Vector2 Start, Vector2 End, float RadiusX, float RadiusY, float Angle, SvgArcSize Size, SvgArcSweep Sweep)
{
if (Start == End)
{
return;
}
if (RadiusX == 0.0f && RadiusY == 0.0f)
{
graphicsPath.AddElement(new LineElement(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((double)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.AddElement(new BezierElement(
startX, startY,
(float)(startX + dx1), (float)(startY + dy1),
(float)(endpointX + dxe), (float)(endpointY + dye),
(float)endpointX, (float)endpointY));
theta1 = theta2;
startX = (float)endpointX;
startY = (float)endpointY;
}
}
