/// <summary> /// Finds a point inside the polygon. /// </summary> public PointF GetInternalPoint() { int cvi = FindConvexVertex(); int prev = cvi > 0 ? cvi - 1 : _points.Count - 1; int next = (cvi + 1) % _points.Count; PointF v = _points[cvi]; PointF a = _points[prev]; PointF b = _points[next]; PointList pl = new PointList(); pl.Add(a); pl.Add(v); pl.Add(b); Polygon avb = new Polygon(pl); float minDist = float.MaxValue; PointF intPt = v; for (int i = 0; i < _points.Count; ++i) { if (i == cvi) continue; if (i == prev) continue; if (i == next) continue; PointF q = _points[i]; if (avb.Contains(q)) { float dist = (float)Math.Sqrt((q.X-v.X)*(q.X-v.X) + (q.Y-v.Y)*(q.Y-v.Y)); if (dist < minDist) { minDist = dist; intPt = q; } } } if (intPt == v) return new PointF((a.X + b.X) / 2, (a.Y + b.Y) / 2); else return new PointF((v.X + intPt.X)/ 2, (v.Y + intPt.Y) / 2); }
/// <summary> /// Creates single h-line at the specified vertical offset. /// </summary> private PointList BuildLine(float yOff) { PointF p11 = new PointF(_bounds.Left - 1, 0); PointF p12 = new PointF(_bounds.Right + 1, 0); PointF p21 = new PointF(_bounds.Left - 1, 0); PointF p22 = new PointF(_bounds.Right + 1, 0); p11.Y = p12.Y = yOff; yOff += _text.Height; if (yOff > _bounds.Bottom) return null; p21.Y = p22.Y = yOff; ArrayList merge = new ArrayList(); PointList result = new PointList(); PointList row1 = PolygonIntersect(p11, p12); PointList row2 = PolygonIntersect(p21, p22); int i; for (i = 0; i < row1.Count; i++) merge.Add(new DirPt(row1[i], i % 2 == 1 ? 2 : 0)); for (i = 0; i < row2.Count; i++) merge.Add(new DirPt(row2[i], i % 2 == 1 ? 3 : 1)); merge.Sort(); PointF pt = PointF.Empty; int inter = -1; // 0 - for first line, 2 for second line, 4 - for both for (i = 0; i < merge.Count; i++) { DirPt temp = merge[i] as DirPt; if (temp.Direction == 2 || temp.Direction == 3) // out { if (inter != 4) { if (inter == 0 && temp.Direction == 2) inter = -1; else if (inter == 2 && temp.Direction == 3) inter = -1; continue; } pt.Y = yOff - _text.Height; temp.Point = new PointF(temp.Point.X, yOff); // Make points relative to the upper-left point of the polygon pt.X -= _bounds.Left; pt.Y -= _bounds.Top; temp.Point = new PointF( temp.Point.X - _bounds.Left, temp.Point.Y - _bounds.Top); result.Add(pt); result.Add(temp.Point); if (temp.Direction == 2) inter = 2; else inter = 0; } else { pt = temp.Point; if (temp.Direction == 0) { if (inter == -1) inter = 0; else if (inter == 2) inter = 4; } else { if (inter == -1) inter = 2; else if (inter == 0) inter = 4; } } } // Check if the center point of each // rectangle lies within the polygon for (i = 0; i < result.Count; ) { PointF pt1 = result[i]; PointF pt2 = result[i + 1]; PointF ptc = PointF.Empty; ptc.X = (pt1.X + pt2.X) / 2 + _bounds.Left; ptc.Y = (pt1.Y + pt2.Y) / 2 + _bounds.Top; if (!_polygon.Contains(ptc)) { result.RemoveAt(i); result.RemoveAt(i); } else { i += 2; } } return result; }
/// <summary> /// Calculates the intersections between the /// polygon and the line defined by the given points. /// The result is a list containing all points of intersection. /// </summary> public PointList IntersectLine(PointF a, PointF b) { PointList result = new PointList(); PointF point; for (int i = 0; i < _points.Count - 1; i++) { point = new Line(_points[i], _points[i + 1]). IntersectLine(a, b); if (!float.IsPositiveInfinity(point.X)) result.Add(point); } return result; }