void CalculateMiter(IVertexDest vc,
VertexDistance v0,
VertexDistance v1,
VertexDistance v2,
double dx1, double dy1,
double dx2, double dy2,
ELineJoin 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 (PictorMath.CalculateIntersection(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 = PictorMath.CalculateDistance(v1.x, v1.y, xi, yi);
if (di <= lim)
{
// Inside the miter limit
//---------------------
AddVertex(vc, 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 ((PictorMath.CrossProduct(v0.x, v0.y, v1.x, v1.y, x2, y2) < 0.0) ==
(PictorMath.CrossProduct(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(vc, v1.x + dx1, v1.y - dy1);
miter_limit_exceeded = false;
}
}
if (miter_limit_exceeded)
{
// Miter limit exceeded
//------------------------
switch (lj)
{
case ELineJoin.miter_join_revert:
// For the compatibility with SVG, PDF, etc,
// we use a simple bevel join instead of
// "smart" bevel
//-------------------
AddVertex(vc, v1.x + dx1, v1.y - dy1);
AddVertex(vc, v1.x + dx2, v1.y - dy2);
break;
case ELineJoin.miter_join_round:
CalculateArc(vc, 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(vc, v1.x + dx1 + dy1 * mlimit,
v1.y - dy1 + dx1 * mlimit);
AddVertex(vc, 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(vc, x1 + (xi - x1) * di,
y1 + (yi - y1) * di);
AddVertex(vc, x2 + (xi - x2) * di,
y2 + (yi - y2) * di);
}
break;
}
}
}
public double CalculateWeight(double x)
{
return((x == 0.0) ? Math.PI / 4.0 : PictorMath.Bessel(Math.PI * x, 1) / (2.0 * x));
}
public void CalculateJoin(IVertexDest vc, 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;
vc.RemoveAll();
double cp = PictorMath.CrossProduct(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(vc, v1.x + dx1, v1.y - dy1);
AddVertex(vc, v1.x + dx2, v1.y - dy2);
break;
case EInnerJoin.inner_miter:
CalculateMiter(vc,
v0, v1, v2, dx1, dy1, dx2, dy2,
ELineJoin.miter_join_revert,
limit, 0);
break;
case EInnerJoin.inner_jag:
case EInnerJoin.inner_round:
cp = (dx1 - dx2) * (dx1 - dx2) + (dy1 - dy2) * (dy1 - dy2);
if (cp < len1 * len1 && cp < len2 * len2)
{
CalculateMiter(vc,
v0, v1, v2, dx1, dy1, dx2, dy2,
ELineJoin.miter_join_revert,
limit, 0);
}
else
{
if (m_inner_join == EInnerJoin.inner_jag)
{
AddVertex(vc, v1.x + dx1, v1.y - dy1);
AddVertex(vc, v1.x, v1.y);
AddVertex(vc, v1.x + dx2, v1.y - dy2);
}
else
{
AddVertex(vc, v1.x + dx1, v1.y - dy1);
AddVertex(vc, v1.x, v1.y);
CalculateArc(vc, v1.x, v1.y, dx2, -dy2, dx1, -dy1);
AddVertex(vc, v1.x, v1.y);
AddVertex(vc, 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 == ELineJoin.round_join || m_line_join == ELineJoin.bevel_join)
{
// 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 (PictorMath.CalculateIntersection(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(vc, dx, dy);
}
else
{
AddVertex(vc, v1.x + dx1, v1.y - dy1);
}
return;
}
}
switch (m_line_join)
{
case ELineJoin.miter_join:
case ELineJoin.miter_join_revert:
case ELineJoin.miter_join_round:
CalculateMiter(vc,
v0, v1, v2, dx1, dy1, dx2, dy2,
m_line_join,
m_miter_limit,
dbevel);
break;
case ELineJoin.round_join:
CalculateArc(vc, v1.x, v1.y, dx1, -dy1, dx2, -dy2);
break;
default: // Bevel join
AddVertex(vc, v1.x + dx1, v1.y - dy1);
AddVertex(vc, v1.x + dx2, v1.y - dy2);
break;
}
}
}
