GPXSee/src/map/osm.cpp

#include "common/wgs84.h"
#include "osm.h"


#define EPSILON       1e-6

QPointF osm::ll2m(const Coordinates &c)
{
	return QPointF(c.lon(), rad2deg(log(tan(M_PI_4 + deg2rad(c.lat())/2.0))));
}

Coordinates osm::m2ll(const QPointF &p)
{
	return Coordinates(p.x(), rad2deg(2.0 * atan(exp(deg2rad(p.y()))) - M_PI_2));
}

QPoint osm::mercator2tile(const QPointF &m, int zoom)
{
	return QPoint((int)(floor((m.x() + 180.0) / 360.0 * (1<<zoom))),
	  (int)(floor((1.0 - (m.y() / 180.0)) / 2.0 * (1<<zoom))));
}

qreal osm::zoom2scale(int zoom, int tileSize)
{
	return (360.0/(qreal)((1<<zoom) * tileSize));
}

int osm::scale2zoom(qreal scale, int tileSize)
{
	return (int)(log2(360.0/(scale * (qreal)tileSize)) + EPSILON);
}

qreal osm::resolution(const QPointF &p, int zoom, int tileSize)
{
	qreal scale = zoom2scale(zoom, tileSize);

	return (WGS84_RADIUS * 2.0 * M_PI * scale / 360.0
	  * cos(2.0 * atan(exp(deg2rad(-p.y() * scale))) - M_PI/2));
}