Basic usage of shapelib

shapelib_example.cpp

//By Tim Sheerman-Chase, released under CC0
//Compile: g++ shapelib_example.cpp -lshp -o shapelib_example

#include <iostream>
#include <vector>
#include <string>
#include "shapefil.h"
using namespace std;

int main(int argc, const char **argv)
{
	string fina = "map.shp";
	SHPHandle h = SHPOpen(fina.c_str(), "rb");

	if(h==nullptr)
	{
		cout << "Failed to open shp" << endl;
		return -1;
	}

	int nEntities=0, nShapeType=0;

	SHPGetInfo(h, &nEntities, &nShapeType, nullptr, nullptr);

	cout << nEntities << endl;
	for(int i=0; i<nEntities; i++)
	{
		SHPObject *obj = SHPReadObject(h, i);
		if(obj == nullptr) continue;

		int &shpType = obj->nSHPType; //Shape Type (SHPT_* - see list above)
		int &shapeId = obj->nShapeId; //Shape Number (-1 is unknown/unassigned)

		int &parts = obj->nParts; //# of Parts (0 implies single part with no info)
		int *panPartStart = obj->panPartStart;  //Start Vertex of part
		int *panPartType = obj->panPartType;   //Part Type (SHPP_RING if not SHPT_MULTIPATCH)
		int &vertices = obj->nVertices; //Vertex list 

		double &xMin = obj->dfXMin; //Bounds in X, Y, Z and M dimensions
		double &yMin = obj->dfYMin;
		double &zMin = obj->dfZMin;

		double &xMax = obj->dfXMax;
		double &yMax = obj->dfYMax;
		double &zMax = obj->dfZMax;
		cout << SHPTypeName(shpType) << "," << xMin << "," << xMax << "," << yMin << "," << yMax << endl;
		cout << i << "," << vertices << "," << parts << endl;

		std::vector<int> partStart, partType;
		for(int k=0; k<parts; k++)
		{
			partStart.push_back(panPartStart[k]);
			partType.push_back(panPartType[k]);
			//cout << panPartStart[k] << "," << SHPPartTypeName(panPartType[k]) << endl;
		}

		int part = -1;
		for(int j=0; j<vertices; j++)
		{
			if((part+1) < partStart.size() and partStart[part+1] == j)
				part ++;
			int pt = -1;
			if(part >= 0)
				pt = partType[part];
			//cout << part << "," << obj->padfX[j] << "," << obj->padfY[j] << "," << obj->padfZ[j] << endl;
			//cout << SHPPartTypeName(pt) << endl;
		}

		SHPDestroyObject(obj);
	}

	SHPClose(h);

	return 0;
}