shp_polygon_t Struct Reference

Polygon. More...

#include <shp-polygon.h>

Public Member Functions
size_t	shp_polygon_points (const shp_polygon_t *polygon, size_t part_num, size_t *start, size_t *end)
	Get the points that form a part.
void	shp_polygon_point (const shp_polygon_t *polygon, size_t point_num, shp_point_t *point)
	Get a Point.

Data Fields
double	x_min
	X minimum value.
double	x_max
	X maximum value.
double	y_min
	Y minimum value.
double	y_max
	Y maximum value.
size_t	num_parts
	Number of parts.
size_t	num_points
	Total number of points.

Detailed Description

A polygon consists of one or more parts. A part is a connected sequence of four or more points that form a closed, non-self-intersecting loop. See the "ESRI Shapefile Technical Description" [2] for more information.

Member Function Documentation

shp_polygon_points()

size_t shp_polygon_points	(	const shp_polygon_t *	polygon,
		size_t	part_num,
		size_t *	start,
		size_t *	end
	)

Gets the indices for the points specified by part_num.

Parameters

	polygon	a polygon.
	part_num	a zero-based part number.
[out]	start	the range start.
[out]	end	the range end (exclusive).

Returns

the number of points in the part. At least 4 if the part is valid.

See also

shp_polygon_point

shp_polygon_point()

void shp_polygon_point	(	const shp_polygon_t *	polygon,
		size_t	point_num,
		shp_point_t *	point
	)

Gets a Point that belongs to the edges of a Polygon.

Example

// Iterate over all parts and points
size_t part_num, i, n;
shp_point_t point;
 
for (part_num = 0; part_num < polygon->num_parts; ++part_num) {
  shp_polygon_points(polygon, part_num, &i, &n);
  while (i < n) {
    shp_polygon_point(polygon, i, &point);
    ++i;
  }
}

Parameters

	polygon	a polygon.
	point_num	a zero-based point number.
[out]	point	a shp_point_t structure.

See also

shp_polygon_points

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The documentation for this struct was generated from the following file:

• shp-polygon.h