bool middle_point(PathType & path, double & x, double & y)
{
double x0 = 0;
double y0 = 0;
double x1 = 0;
double y1 = 0;
double mid_length = 0.5 * path_length(path);
path.rewind(0);
unsigned command = path.vertex(&x0,&y0);
if (command == SEG_END) return false;
double dist = 0.0;
while (SEG_END != (command = path.vertex(&x1, &y1)))
{
double seg_length = distance(x0, y0, x1, y1);
if ( dist + seg_length >= mid_length)
{
double r = (mid_length - dist)/seg_length;
x = x0 + (x1 - x0) * r;
y = y0 + (y1 - y0) * r;
break;
}
dist += seg_length;
x0 = x1;
y0 = y1;
}
return true;
}
bool hit_test(PathType & path, double x, double y, double tol)
{
bool inside=false;
double x0 = 0;
double y0 = 0;
double x1 = 0;
double y1 = 0;
path.rewind(0);
unsigned command = path.vertex(&x0, &y0);
if (command == SEG_END) return false;
unsigned count = 0;
while (SEG_END != (command = path.vertex(&x1, &y1)))
{
++count;
if (command == SEG_MOVETO)
{
x0 = x1;
y0 = y1;
continue;
}
if ((((y1 <= y) && (y < y0)) ||
((y0 <= y) && (y < y1))) &&
(x < (x0 - x1) * (y - y1)/ (y0 - y1) + x1))
inside=!inside;
x0 = x1;
y0 = y1;
}
if (count == 0) // one vertex
{
return distance(x, y, x0, y0) <= std::fabs(tol);
}
return inside;
}
bool hit_test(PathType & path, double x, double y, double tol)
{
bool inside=false;
double x0 = 0;
double y0 = 0;
double x1 = 0;
double y1 = 0;
path.rewind(0);
unsigned command = path.vertex(&x0, &y0);
if (command == SEG_END)
{
return false;
}
unsigned count = 0;
mapnik::geometry_type::types geom_type = static_cast<mapnik::geometry_type::types>(path.type());
while (SEG_END != (command = path.vertex(&x1, &y1)))
{
if (command == SEG_CLOSE)
{
continue;
}
++count;
if (command == SEG_MOVETO)
{
x0 = x1;
y0 = y1;
continue;
}
switch(geom_type)
{
case mapnik::geometry_type::types::Polygon:
{
if ((((y1 <= y) && (y < y0)) ||
((y0 <= y) && (y < y1))) &&
(x < (x0 - x1) * (y - y1)/ (y0 - y1) + x1))
inside=!inside;
break;
}
case mapnik::geometry_type::types::LineString:
{
double distance = point_to_segment_distance(x,y,x0,y0,x1,y1);
if (distance < tol)
return true;
break;
}
default:
break;
}
x0 = x1;
y0 = y1;
}
// TODO - handle multi-point?
if (count == 0) // one vertex
{
return distance(x, y, x0, y0) <= tol;
}
return inside;
}
bool centroid(PathType & path, double & x, double & y)
{
double x0 = 0.0;
double y0 = 0.0;
double x1 = 0.0;
double y1 = 0.0;
double start_x;
double start_y;
path.rewind(0);
unsigned command = path.vertex(&x0, &y0);
if (command == SEG_END) return false;
start_x = x0;
start_y = y0;
double atmp = 0.0;
double xtmp = 0.0;
double ytmp = 0.0;
unsigned count = 1;
while (SEG_END != (command = path.vertex(&x1, &y1)))
{
if (command == SEG_CLOSE) continue;
double dx0 = x0 - start_x;
double dy0 = y0 - start_y;
double dx1 = x1 - start_x;
double dy1 = y1 - start_y;
double ai = dx0 * dy1 - dx1 * dy0;
atmp += ai;
xtmp += (dx1 + dx0) * ai;
ytmp += (dy1 + dy0) * ai;
x0 = x1;
y0 = y1;
++count;
}
if (count <= 2) {
x = (start_x + x0) * 0.5;
y = (start_y + y0) * 0.5;
return true;
}
if (atmp != 0)
{
x = (xtmp/(3*atmp)) + start_x;
y = (ytmp/(3*atmp)) + start_y;
}
else
{
x = x0;
y = y0;
}
return true;
}
double path_length(PathType & path)
{
double x0 = 0;
double y0 = 0;
double x1 = 0;
double y1 = 0;
path.rewind(0);
unsigned command = path.vertex(&x0,&y0);
if (command == SEG_END) return 0;
double length = 0;
while (SEG_END != (command = path.vertex(&x1, &y1)))
{
length += distance(x0,y0,x1,y1);
x0 = x1;
y0 = y1;
}
return length;
}
bool hit_test_first(PathType & path, double x, double y)
{
bool inside=false;
double x0 = 0;
double y0 = 0;
double x1 = 0;
double y1 = 0;
path.rewind(0);
unsigned command = path.vertex(&x0, &y0);
if (command == SEG_END)
{
return false;
}
unsigned count = 0;
while (SEG_END != (command = path.vertex(&x1, &y1)))
{
if (command == SEG_CLOSE)
{
break;
}
++count;
if (command == SEG_MOVETO)
{
x0 = x1;
y0 = y1;
continue;
}
if ((((y1 <= y) && (y < y0)) ||
((y0 <= y) && (y < y1))) &&
(x < (x0 - x1) * (y - y1)/ (y0 - y1) + x1))
inside=!inside;
x0 = x1;
y0 = y1;
}
return inside;
}
bool interior_position(PathType & path, double & x, double & y)
{
// start with the centroid
if (!label::centroid(path, x,y))
return false;
// if we are not a polygon, or the default is within the polygon we are done
if (hit_test(path,x,y,0.001))
return true;
// otherwise we find a horizontal line across the polygon and then return the
// center of the widest intersection between the polygon and the line.
std::vector<double> intersections; // only need to store the X as we know the y
double x0 = 0;
double y0 = 0;
path.rewind(0);
unsigned command = path.vertex(&x0, &y0);
double x1 = 0;
double y1 = 0;
while (SEG_END != (command = path.vertex(&x1, &y1)))
{
if (command != SEG_MOVETO)
{
// if the segments overlap
if (y0==y1)
{
if (y0==y)
{
double xi = (x0+x1)/2.0;
intersections.push_back(xi);
}
}
// if the path segment crosses the bisector
else if ((y0 <= y && y1 >= y) ||
(y0 >= y && y1 <= y))
{
// then calculate the intersection
double xi = x0;
if (x0 != x1)
{
double m = (y1-y0)/(x1-x0);
double c = y0 - m*x0;
xi = (y-c)/m;
}
intersections.push_back(xi);
}
}
x0 = x1;
y0 = y1;
}
// no intersections we just return the default
if (intersections.empty())
return true;
x0=intersections[0];
double max_width = 0;
for (unsigned ii = 1; ii < intersections.size(); ++ii)
{
double xi=intersections[ii];
double xc=(x0+xi)/2.0;
double width = std::fabs(xi-x0);
if (width > max_width && hit_test(path,xc,y,0))
{
x=xc;
max_width = width;
break;
}
}
return true;
}
bool interior_position(PathType & path, double & x, double & y)
{
// start with the centroid
if (!label::centroid(path, x,y))
return false;
// otherwise we find a horizontal line across the polygon and then return the
// center of the widest intersection between the polygon and the line.
std::vector<double> intersections; // only need to store the X as we know the y
double x0 = 0;
double y0 = 0;
path.rewind(0);
unsigned command = path.vertex(&x0, &y0);
double x1 = 0;
double y1 = 0;
while (SEG_END != (command = path.vertex(&x1, &y1)))
{
if (command == SEG_CLOSE)
continue;
if (command != SEG_MOVETO)
{
// if the segments overlap
if (y0==y1)
{
if (y0==y)
{
double xi = (x0+x1)/2.0;
intersections.push_back(xi);
}
}
// if the path segment crosses the bisector
else if ((y0 <= y && y1 >= y) ||
(y0 >= y && y1 <= y))
{
// then calculate the intersection
double xi = x0;
if (x0 != x1)
{
double m = (y1-y0)/(x1-x0);
double c = y0 - m*x0;
xi = (y-c)/m;
}
intersections.push_back(xi);
}
}
x0 = x1;
y0 = y1;
}
// no intersections we just return the default
if (intersections.empty())
return true;
std::sort(intersections.begin(), intersections.end());
double max_width = 0;
for (unsigned ii = 1; ii < intersections.size(); ii += 2)
{
double xlow = intersections[ii-1];
double xhigh = intersections[ii];
double width = xhigh - xlow;
if (width > max_width)
{
x = (xlow + xhigh) / 2.0;
max_width = width;
}
}
return true;
}