Basic Shapefile to Shape2d

PolygonShapes.cpp

/*
 *  PolygonShapes.cpp
 *  HereToThere
 *
 *  Created by David Wicks on 2/23/11.
 *  Copyright 2011 David Wicks. All rights reserved.
 *
 */

#include "PolygonShapes.h"
#include "cinder/Filesystem.h"
#include "cinder/app/App.h"

using namespace std;
using namespace cinder;

namespace sansumbrella
{
    namespace 
    {
		
		
        void readPolygonShapefile( SHPHandle shp, DBFHandle dbf, int numEntities, Shape2d* shape, float mapWidth, float mapHeight )
        {
            for( int i = 0; i < numEntities; ++i )
            {
                SHPObject* obj = SHPReadObject( shp, i );
                
                for( int partNumber = 0; partNumber < obj->nParts; partNumber++ )
                {			
                    int start = obj->nParts > 1 ? obj->panPartStart[partNumber] : 0;
                    int end = obj->nParts > 1 ? obj->panPartStart[ partNumber + 1 ] : obj->nVertices;
                    
                    if( partNumber == obj->nParts-1 )
                    {
                        end = obj->nVertices;
                    }
                    
                    Vec2f pt = geo::projectLatLon( obj->padfY[start], obj->padfX[start], mapWidth, mapHeight );
                    shape->moveTo( pt );
                    
                    for( int v = start+1; v < end; ++v )
                    {
                        pt = geo::projectLatLon( obj->padfY[v], obj->padfX[v], mapWidth, mapHeight );
                        shape->lineTo( pt );
                    }
                    shape->close();
                }
                SHPDestroyObject( obj );
            }
        }
        
        void readPolylineShapefile( SHPHandle shp, DBFHandle dbf, int numEntities, Shape2d* shape, float mapWidth, float mapHeight )
        {
            for( int i = 0; i < numEntities; ++i )
            {
                SHPObject* obj = SHPReadObject( shp, i );
                
                for( int partNumber = 0; partNumber < obj->nParts; partNumber++ )
                {			
                    int start = obj->nParts > 1 ? obj->panPartStart[partNumber] : 0;
                    int end = obj->nParts > 1 ? obj->panPartStart[ partNumber + 1 ] : obj->nVertices;
                    
                    if( partNumber == obj->nParts-1 )
                    {
                        end = obj->nVertices;
                    }
                    
                    Vec2f pt = geo::projectLatLon( obj->padfY[start], obj->padfX[start], mapWidth, mapHeight );
                    shape->moveTo( pt );
                    
                    for( int v = start+1; v < end; ++v )
                    {
                        pt = geo::projectLatLon( obj->padfY[v], obj->padfX[v], mapWidth, mapHeight );
                        shape->lineTo( pt );
                    }
                }
                SHPDestroyObject( obj );
            }
        }
        
        void readPointShapefile( SHPHandle shp, DBFHandle dbf, int numEntities, Shape2d* shape, float mapWidth, float mapHeight )
        {
            
        }
    }   // end anonymous namespace
    
	Shape2d geo::readShapefile( const string& shpLoc, const string& dbfLoc, float mapWidth, float mapHeight )
	{
		Shape2d shape;
		
		if( !fs::exists( fs::path( shpLoc ) ) || !fs::exists( fs::path( dbfLoc ) ) )
		{	// return empty shape if the shapefile doesn't exist
			return shape;
		}
		
		SHPHandle shp = SHPOpen( shpLoc.c_str(), "rb" );
		DBFHandle dbf = DBFOpen( dbfLoc.c_str(), "rb" );
		
		int numEntities;
		int shapeType;
		double minBound[4];
		double maxBound[4];
		
		SHPGetInfo(shp, &numEntities, &shapeType, &minBound[0], &maxBound[0] );
        
        switch ( shapeType ) {
            case 1: //point
                readPointShapefile( shp, dbf, numEntities, &shape, mapWidth, mapHeight );
                break;
            case 3: //polyline
                readPolylineShapefile( shp, dbf, numEntities, &shape, mapWidth, mapHeight );
                break;
            case 5: //polygon
                readPolygonShapefile( shp, dbf, numEntities, &shape, mapWidth, mapHeight );
                break;
            default:
                break;
        }
		
		app::console() << "Reading shapefile: " << numEntities << ", " << shapeType << endl;
		
		SHPClose( shp );
		DBFClose( dbf );
		
		return shape;
	}
	
	inline ci::Vec2f geo::projectLatLon( float x, float y, float mapWidth, float mapHeight )
	{
		return Vec2f( x, y ) * 1.0f;
	}
}

PolygonShapes.h

/*
 *  PolygonShapes.h
 *  HereToThere
 *
 *  Created by David Wicks on 2/23/11.
 *  Copyright 2011 David Wicks. All rights reserved.
 *
 */

#pragma once

#include "cinder/Shape2d.h"
#include "shapefil.h"

namespace sansumbrella
{
	namespace geo
	{
		//! factory method for creating shapes from shapefiles
        //! supports polygon and polyline shapefiles
		ci::Shape2d readShapefile(  const std::string& shpLoc, const std::string& dbfLoc,
                                    float mapWidth, float mapHeight  );
		
		inline ci::Vec2f projectLatLon( float x, float y, float mapWidth, float mapHeight );
	}
}

Utilizes the ShapeLib C library:
http://shapelib.maptools.org/