public void CreateCap(VertexStore output, VertexDistance v0, VertexDistance v1, double len)
{
output.Clear();
double dx1 = (v1.y - v0.y) / len;
double dy1 = (v1.x - v0.x) / len;
double dx2 = 0;
double dy2 = 0;
dx1 *= m_width;
dy1 *= m_width;
if (m_line_cap != LineCap.Round)
{
if (m_line_cap == LineCap.Square)
{
dx2 = dy1 * m_width_sign;
dy2 = dx1 * m_width_sign;
}
AddVertex(output, v0.x - dx1 - dx2, v0.y + dy1 - dy2);
AddVertex(output, v0.x + dx1 - dx2, v0.y - dy1 - dy2);
}
else
{
double da = Math.Acos(m_width_abs / (m_width_abs + 0.125 / m_approx_scale)) * 2;
double a1;
int i;
int n = (int)(Math.PI / da);
da = Math.PI / (n + 1);
AddVertex(output, v0.x - dx1, v0.y + dy1);
if (m_width_sign > 0)
{
a1 = Math.Atan2(dy1, -dx1);
a1 += da;
for (i = 0; i < n; i++)
{
AddVertex(output, v0.x + Math.Cos(a1) * m_width,
v0.y + Math.Sin(a1) * m_width);
a1 += da;
}
}
else
{
a1 = Math.Atan2(-dy1, dx1);
a1 -= da;
for (i = 0; i < n; i++)
{
AddVertex(output, v0.x + Math.Cos(a1) * m_width,
v0.y + Math.Sin(a1) * m_width);
a1 -= da;
}
}
AddVertex(output, v0.x + dx1, v0.y - dy1);
}
}
//-------------------------------------------------------calc_polygon_area
public static double CalculatePolygonArea(VertexDistanceList st)
{
int i;
double sum = 0.0;
double x = st[0].x;
double y = st[0].y;
double xs = x;
double ys = y;
int j = st.Count;
for (i = 1; i < j; i++)
{
VertexDistance v = st[i];
sum += x * v.y - y * v.x;
x = v.x;
y = v.y;
}
return((sum + x * ys - y * xs) * 0.5);
}
public static void ShortenPath(VertexDistanceList vertexDistanceList, double s, bool closed)
{
if (s > 0.0 && vertexDistanceList.Count > 1)
{
double d;
int n = (int)(vertexDistanceList.Count - 2);
while (n != 0)
{
d = vertexDistanceList[n].dist;
if (d > s)
{
break;
}
vertexDistanceList.RemoveLast();
s -= d;
--n;
}
if (vertexDistanceList.Count < 2)
{
vertexDistanceList.Clear();
}
else
{
n = (int)vertexDistanceList.Count - 1;
VertexDistance prev = vertexDistanceList[n - 1];
VertexDistance last = vertexDistanceList[n];
d = (prev.dist - s) / prev.dist;
double x = prev.x + (last.x - prev.x) * d;
double y = prev.y + (last.y - prev.y) * d;
last.x = x;
last.y = y;
if (!prev.IsEqual(last))
{
vertexDistanceList.RemoveLast();
}
vertexDistanceList.Close(closed);
}
}
}
void CreateMiter(VertexStore output,
VertexDistance v0,
VertexDistance v1,
VertexDistance v2,
double dx1, double dy1,
double dx2, double dy2,
LineJoin lj,
double mlimit,
double dbevel)
{
double xi = v1.x;
double yi = v1.y;
double di = 1;
double lim = m_width_abs * mlimit;
bool miter_limit_exceeded = true; // Assume the worst
bool intersection_failed = true; // Assume the worst
if (AggMath.CalcIntersect(v0.x + dx1, v0.y - dy1,
v1.x + dx1, v1.y - dy1,
v1.x + dx2, v1.y - dy2,
v2.x + dx2, v2.y - dy2,
out xi, out yi))
{
// Calculation of the intersection succeeded
//---------------------
di = AggMath.calc_distance(v1.x, v1.y, xi, yi);
if (di <= lim)
{
// Inside the miter limit
//---------------------
AddVertex(output, xi, yi);
miter_limit_exceeded = false;
}
intersection_failed = false;
}
else
{
// Calculation of the intersection failed, most probably
// the three points lie one straight line.
// First check if v0 and v2 lie on the opposite sides of vector:
// (v1.x, v1.y) -> (v1.x+dx1, v1.y-dy1), that is, the perpendicular
// to the line determined by vertices v0 and v1.
// This condition determines whether the next line segments continues
// the previous one or goes back.
//----------------
double x2 = v1.x + dx1;
double y2 = v1.y - dy1;
if ((AggMath.Cross(v0.x, v0.y, v1.x, v1.y, x2, y2) < 0.0) ==
(AggMath.Cross(v1.x, v1.y, v2.x, v2.y, x2, y2) < 0.0))
{
// This case means that the next segment continues
// the previous one (straight line)
//-----------------
AddVertex(output, v1.x + dx1, v1.y - dy1);
miter_limit_exceeded = false;
}
}
if (miter_limit_exceeded)
{
// Miter limit exceeded
//------------------------
switch (lj)
{
case LineJoin.MiterRevert:
// For the compatibility with SVG, PDF, etc,
// we use a simple bevel join instead of
// "smart" bevel
//-------------------
AddVertex(output, v1.x + dx1, v1.y - dy1);
AddVertex(output, v1.x + dx2, v1.y - dy2);
break;
case LineJoin.MiterRound:
CreateArc(output, v1.x, v1.y, dx1, -dy1, dx2, -dy2);
break;
default:
// If no miter-revert, calculate new dx1, dy1, dx2, dy2
//----------------
if (intersection_failed)
{
mlimit *= m_width_sign;
AddVertex(output, v1.x + dx1 + dy1 * mlimit,
v1.y - dy1 + dx1 * mlimit);
AddVertex(output, v1.x + dx2 - dy2 * mlimit,
v1.y - dy2 - dx2 * mlimit);
}
else
{
double x1 = v1.x + dx1;
double y1 = v1.y - dy1;
double x2 = v1.x + dx2;
double y2 = v1.y - dy2;
di = (lim - dbevel) / (di - dbevel);
AddVertex(output, x1 + (xi - x1) * di,
y1 + (yi - y1) * di);
AddVertex(output, x2 + (xi - x2) * di,
y2 + (yi - y2) * di);
}
break;
}
}
}
public void CreateJoin(VertexStore output,
VertexDistance v0,
VertexDistance v1,
VertexDistance v2,
double len1,
double len2)
{
double dx1 = m_width * (v1.y - v0.y) / len1;
double dy1 = m_width * (v1.x - v0.x) / len1;
double dx2 = m_width * (v2.y - v1.y) / len2;
double dy2 = m_width * (v2.x - v1.x) / len2;
output.Clear();
double cp = AggMath.Cross(v0.x, v0.y, v1.x, v1.y, v2.x, v2.y);
if (cp != 0 && (cp > 0) == (m_width > 0))
{
// Inner join
//---------------
double limit = ((len1 < len2) ? len1 : len2) / m_width_abs;
if (limit < m_inner_miter_limit)
{
limit = m_inner_miter_limit;
}
switch (m_inner_join)
{
default: // inner_bevel
AddVertex(output, v1.x + dx1, v1.y - dy1);
AddVertex(output, v1.x + dx2, v1.y - dy2);
break;
case InnerJoin.Miter:
CreateMiter(output,
v0, v1, v2, dx1, dy1, dx2, dy2,
LineJoin.MiterRevert,
limit, 0);
break;
case InnerJoin.Jag:
case InnerJoin.Round:
cp = (dx1 - dx2) * (dx1 - dx2) + (dy1 - dy2) * (dy1 - dy2);
if (cp < len1 * len1 && cp < len2 * len2)
{
CreateMiter(output,
v0, v1, v2, dx1, dy1, dx2, dy2,
LineJoin.MiterRevert,
limit, 0);
}
else
{
if (m_inner_join == InnerJoin.Jag)
{
AddVertex(output, v1.x + dx1, v1.y - dy1);
AddVertex(output, v1.x, v1.y);
AddVertex(output, v1.x + dx2, v1.y - dy2);
}
else
{
AddVertex(output, v1.x + dx1, v1.y - dy1);
AddVertex(output, v1.x, v1.y);
CreateArc(output, v1.x, v1.y, dx2, -dy2, dx1, -dy1);
AddVertex(output, v1.x, v1.y);
AddVertex(output, v1.x + dx2, v1.y - dy2);
}
}
break;
}
}
else
{
// Outer join
//---------------
// Calculate the distance between v1 and
// the central point of the bevel line segment
//---------------
double dx = (dx1 + dx2) / 2;
double dy = (dy1 + dy2) / 2;
double dbevel = Math.Sqrt(dx * dx + dy * dy);
if (m_line_join == LineJoin.Round || m_line_join == LineJoin.Bevel)
{
// This is an optimization that reduces the number of points
// in cases of almost collinear segments. If there's no
// visible difference between bevel and miter joins we'd rather
// use miter join because it adds only one point instead of two.
//
// Here we calculate the middle point between the bevel points
// and then, the distance between v1 and this middle point.
// At outer joins this distance always less than stroke width,
// because it's actually the height of an isosceles triangle of
// v1 and its two bevel points. If the difference between this
// width and this value is small (no visible bevel) we can
// add just one point.
//
// The constant in the expression makes the result approximately
// the same as in round joins and caps. You can safely comment
// out this entire "if".
//-------------------
if (m_approx_scale * (m_width_abs - dbevel) < m_width_eps)
{
if (AggMath.CalcIntersect(v0.x + dx1, v0.y - dy1,
v1.x + dx1, v1.y - dy1,
v1.x + dx2, v1.y - dy2,
v2.x + dx2, v2.y - dy2,
out dx, out dy))
{
AddVertex(output, dx, dy);
}
else
{
AddVertex(output, v1.x + dx1, v1.y - dy1);
}
return;
}
}
switch (m_line_join)
{
case LineJoin.Miter:
case LineJoin.MiterRevert:
case LineJoin.MiterRound:
CreateMiter(output,
v0, v1, v2, dx1, dy1, dx2, dy2,
m_line_join,
m_miter_limit,
dbevel);
break;
case LineJoin.Round:
CreateArc(output, v1.x, v1.y, dx1, -dy1, dx2, -dy2);
break;
default: // Bevel join
AddVertex(output, v1.x + dx1, v1.y - dy1);
AddVertex(output, v1.x + dx2, v1.y - dy2);
break;
}
}
}
