public override Entity2D Copy()
{
var cir =
new CircleArc2D(
Center,
Radius,
StartAngle,
EndAngle);
cir.LayerName = LayerName;
return(cir);
}
public CircleArc2D(Point2D pt1, Point2D pt2, Point2D pt3, bool isWholeCircle)
{
if (isWholeCircle)
{
var xy1 = Math.Pow(pt1.X, 2) + Math.Pow(pt1.Y, 2);
var xy2 = xy1 - Math.Pow(pt3.X, 2) - Math.Pow(pt3.Y, 2);
var xy3 = xy1 - Math.Pow(pt2.X, 2) - Math.Pow(pt2.Y, 2);
xy1 = (pt1.X - pt2.X) * (pt1.Y - pt3.Y) - (pt1.X - pt3.X) * (pt1.Y - pt2.Y);
if (GeoUtils.Equals(xy1, 0))
{
throw new Exception("无法创建圆!");
}
Center =
new Point2D(
(xy3 * (pt1.Y - pt3.Y) - xy2 * (pt1.Y - pt2.Y)) / (2 * xy1),
(xy2 * (pt1.X - pt2.X) - xy3 * (pt1.X - pt3.X)) / (2 * xy1));
Radius = (pt1 - Center).Length;
if (GeoUtils.Equals(Radius, 0))
{
throw new Exception("半径为零!");
}
StartAngle = Angle.Zero;
EndAngle = Angle.Degree360;
}
else
{
CircleArc2D cir = new CircleArc2D(pt1, pt2, pt3, true);
Center = cir.Center;
Radius = cir.Radius;
IsClockWise =
Vector2D.IsClockWise(
pt1 - cir.Center,
pt2 - cir.Center,
pt3 - cir.Center);
}
}
public override IEnumerable <int> Draw(Graphics g, Pen pen, GraphicsPath path)
{
GraphicsPath fill = new GraphicsPath();
for (int i = 0; i < SegmentCount; i++)
{
var curve = GetSegmentAt(i);
var ver = Vertexs[i];
if (ver.StartWidth == 0 && ver.EndWidth == 0)
{
curve.DrawTo(g, path);
}
else
{
var w1 = ver.StartWidth / 2;
var w2 = ver.EndWidth / 2;
var cpath = new GraphicsPath();
if (curve is LineSegment2D)
{
var line = curve as LineSegment2D;
var vec = line.EndPoint - line.StartPoint;
vec = vec.UnitVector.RotateBy(Angle.Degree90);
var pts =
new PointF[]
{
line.StartPoint + vec * w1,
line.EndPoint + vec * w2,
line.EndPoint - vec * w2,
line.StartPoint - vec * w1
};
cpath.AddLines(pts);
cpath.CloseFigure();
}
else
{
var arc = curve as CircleArc2D;
var vec1 = new Vector2D(w1, arc.StartAngle);
var pt = arc.GetPointAtParam(arc.EndParam / 2);
var vec2 = (pt - arc.Center).UnitVector * (w1 + w2) / 2;
var vec3 = new Vector2D(w2, arc.EndAngle);
var pts =
new Point2D[]
{
arc.StartPoint + vec1,
pt + vec2,
arc.EndPoint + vec3,
arc.EndPoint - vec3,
pt - vec2,
arc.StartPoint - vec1
};
var arc1 = new CircleArc2D(pts[0], pts[1], pts[2]);
var line1 = new LineSegment2D(pts[2], pts[3]);
var arc2 = new CircleArc2D(pts[3], pts[4], pts[5]);
var line2 = new LineSegment2D(pts[5], pts[0]);
arc1.DrawTo(g, cpath);
line1.DrawTo(g, cpath);
arc2.DrawTo(g, cpath);
line2.DrawTo(g, cpath);
}
fill.AddPath(cpath, false);
path.AddPath(cpath, false);
path.StartFigure();
}
}
yield return(0);
g.FillPath(pen.Brush, fill);
yield break;
}