// THIS FILE IS PART OF SVG PROJECT
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// THE SVG PROJECT IS AN OPENSOURCE LIBRARY LICENSED UNDER THE MS-PL License.
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// COPYRIGHT (C) svg-net. ALL RIGHTS RESERVED.
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// GITHUB: https://github.com/svg-net/SVG
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using System;
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using System.Drawing;
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using System.Drawing.Drawing2D;
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namespace AntdUI.Svg.Pathing
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{
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public sealed class SvgArcSegment : SvgPathSegment
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{
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private const double RadiansPerDegree = Math.PI / 180.0;
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private const double DoublePI = Math.PI * 2;
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public float RadiusX { get; set; }
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public float RadiusY { get; set; }
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public float Angle { get; set; }
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public SvgArcSweep Sweep { get; set; }
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public SvgArcSize Size { get; set; }
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public SvgArcSegment(PointF start, float radiusX, float radiusY, float angle, SvgArcSize size, SvgArcSweep sweep, PointF end)
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: base(start, end)
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{
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RadiusX = Math.Abs(radiusX);
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RadiusY = Math.Abs(radiusY);
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Angle = angle;
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Sweep = sweep;
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Size = size;
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}
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private static double CalculateVectorAngle(double ux, double uy, double vx, double vy)
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{
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double ta = Math.Atan2(uy, ux);
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double tb = Math.Atan2(vy, vx);
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if (tb >= ta) return tb - ta;
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return DoublePI - (ta - tb);
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}
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public override void AddToPath(GraphicsPath graphicsPath)
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{
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if (Start == End) return;
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if (RadiusX == 0.0f && RadiusY == 0.0f)
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{
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graphicsPath.AddLine(Start, End);
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return;
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}
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double sinPhi = Math.Sin(Angle * RadiansPerDegree);
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double cosPhi = Math.Cos(Angle * RadiansPerDegree);
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double x1dash = cosPhi * (Start.X - End.X) / 2.0 + sinPhi * (Start.Y - End.Y) / 2.0;
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double y1dash = -sinPhi * (Start.X - End.X) / 2.0 + cosPhi * (Start.Y - End.Y) / 2.0;
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double root;
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double numerator = RadiusX * RadiusX * RadiusY * RadiusY - RadiusX * RadiusX * y1dash * y1dash - RadiusY * RadiusY * x1dash * x1dash;
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float rx = RadiusX;
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float ry = RadiusY;
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if (numerator < 0.0)
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{
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float s = (float)Math.Sqrt(1.0 - numerator / (RadiusX * RadiusX * RadiusY * RadiusY));
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rx *= s;
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ry *= s;
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root = 0.0;
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}
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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));
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double cxdash = root * rx * y1dash / ry;
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double cydash = -root * ry * x1dash / rx;
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double cx = cosPhi * cxdash - sinPhi * cydash + (Start.X + End.X) / 2.0;
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double cy = sinPhi * cxdash + cosPhi * cydash + (Start.Y + End.Y) / 2.0;
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double theta1 = CalculateVectorAngle(1.0, 0.0, (x1dash - cxdash) / rx, (y1dash - cydash) / ry);
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double dtheta = CalculateVectorAngle((x1dash - cxdash) / rx, (y1dash - cydash) / ry, (-x1dash - cxdash) / rx, (-y1dash - cydash) / ry);
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if (Sweep == SvgArcSweep.Negative && dtheta > 0)
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{
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dtheta -= 2.0 * Math.PI;
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}
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else if (Sweep == SvgArcSweep.Positive && dtheta < 0)
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{
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dtheta += 2.0 * Math.PI;
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}
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int segments = (int)Math.Ceiling((double)Math.Abs(dtheta / (Math.PI / 2.0)));
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double delta = dtheta / segments;
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double t = 8.0 / 3.0 * Math.Sin(delta / 4.0) * Math.Sin(delta / 4.0) / Math.Sin(delta / 2.0);
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double startX = Start.X;
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double startY = Start.Y;
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for (int i = 0; i < segments; ++i)
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{
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double cosTheta1 = Math.Cos(theta1);
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double sinTheta1 = Math.Sin(theta1);
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double theta2 = theta1 + delta;
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double cosTheta2 = Math.Cos(theta2);
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double sinTheta2 = Math.Sin(theta2);
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double endpointX = cosPhi * rx * cosTheta2 - sinPhi * ry * sinTheta2 + cx;
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double endpointY = sinPhi * rx * cosTheta2 + cosPhi * ry * sinTheta2 + cy;
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double dx1 = t * (-cosPhi * rx * sinTheta1 - sinPhi * ry * cosTheta1);
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double dy1 = t * (-sinPhi * rx * sinTheta1 + cosPhi * ry * cosTheta1);
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double dxe = t * (cosPhi * rx * sinTheta2 + sinPhi * ry * cosTheta2);
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double dye = t * (sinPhi * rx * sinTheta2 - cosPhi * ry * cosTheta2);
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graphicsPath.AddBezier((float)startX, (float)startY, (float)(startX + dx1), (float)(startY + dy1),
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(float)(endpointX + dxe), (float)(endpointY + dye), (float)endpointX, (float)endpointY);
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theta1 = theta2;
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startX = (float)endpointX;
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startY = (float)endpointY;
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}
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}
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public override string ToString()
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{
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var arcFlag = Size == SvgArcSize.Large ? "1" : "0";
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var sweepFlag = Sweep == SvgArcSweep.Positive ? "1" : "0";
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return "A" + RadiusX.ToString() + " " + RadiusY.ToString() + " " + Angle.ToString() + " " + arcFlag + " " + sweepFlag + " " + End.ToSvgString();
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}
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}
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[Flags]
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public enum SvgArcSweep
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{
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Negative = 0,
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Positive = 1
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}
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[Flags]
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public enum SvgArcSize
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{
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Small = 0,
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Large = 1
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}
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}
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