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add a few more centroid algorithms for testing

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This commit is contained in:
Dane Springmeyer 2011-05-03 21:38:02 +00:00
parent 107f38a4dd
commit 2f77de0bf9
1 changed files with 50 additions and 1 deletions
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51
include/mapnik/geometry.hpp
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@ -179,6 +179,9 @@ public:
}
}
/* center of gravity centroid
- best visually but does not work with multipolygons
*/
void label_position(double *x, double *y) const
{
if (type_ == LineString || type_ == MultiLineString)
@ -232,7 +235,48 @@ public:
*x=x0;
*y=y0;
}
/* center of bounding box centroid */
void label_position2(double *x, double *y) const
{
box2d<double> box = envelope();
*x = box.center().x;
*y = box.center().y;
}
/* summarized distance centroid */
void label_position3(double *x, double *y) const
{
if (type_ == LineString || type_ == MultiLineString)
{
middle_point(x,y);
return;
}
unsigned i = 0;
double l = 0.0;
double tl = 0.0;
double cx = 0.0;
double cy = 0.0;
double x0 = 0.0;
double y0 = 0.0;
double x1 = 0.0;
double y1 = 0.0;
unsigned size = cont_.size();
for (i = 0; i < size-1; i++)
{
cont_.get_vertex(i,&x0,&y0);
cont_.get_vertex(i+1,&x1,&y1);
l = distance(x0,y0,x1,y1);
cx += l * (x1 + x0)/2;
cy += l * (y1 + y0)/2;
tl += l;
}
*x = cx / tl;
*y = cy / tl;
}
void middle_point(double *x, double *y) const
{
// calculate mid point on path
@ -310,6 +354,11 @@ public:
return cont_.get_vertex(itr_++,x,y);
}
unsigned get_vertex(unsigned pos, double* x, double* y) const
{
return cont_.get_vertex(pos, x, y);
}
void rewind(unsigned ) const
{
itr_=0;