Function reproject_bbox

ThirdParty/libproj/vtklibproj/src/4D_api.cpp:984–1041

/

/*****************************************************************************/
static void reproject_bbox(PJ* pjGeogToCrs,
                          double west_lon, double south_lat,
                          double east_lon, double north_lat,
                          double& minx,
                          double& miny,
                          double& maxx,
                          double& maxy) {
/*****************************************************************************/

    minx = -std::numeric_limits<double>::max();
    miny = -std::numeric_limits<double>::max();
    maxx = std::numeric_limits<double>::max();
    maxy = std::numeric_limits<double>::max();

    if( !(west_lon == -180.0 && east_lon == 180.0 &&
          south_lat == -90.0 && north_lat == 90.0) )
    {
        minx = -minx;
        miny = -miny;
        maxx = -maxx;
        maxy = -maxy;

        constexpr int N_STEPS = 20;
        constexpr int N_STEPS_P1 = N_STEPS+1;
        constexpr int XY_SIZE = N_STEPS_P1 * 4;
        std::vector<double> x(XY_SIZE);
        std::vector<double> y(XY_SIZE);
        const double step_lon = (east_lon - west_lon) / N_STEPS;
        const double step_lat = (north_lat - south_lat) / N_STEPS;
        for( int j = 0; j <= N_STEPS; j++ )
        {
            x[j] = west_lon + j * step_lon;
            y[j] = south_lat;
            x[N_STEPS_P1+j] = x[j];
            y[N_STEPS_P1+j] = north_lat;
            x[N_STEPS_P1*2+j] = west_lon;
            y[N_STEPS_P1*2+j] = south_lat + j * step_lat;
            x[N_STEPS_P1*3+j] = east_lon;
            y[N_STEPS_P1*3+j] = y[N_STEPS_P1*2+j];
        }
        proj_trans_generic (
            pjGeogToCrs, PJ_FWD,
                &x[0], sizeof(double), XY_SIZE,
                &y[0], sizeof(double), XY_SIZE,
                nullptr, 0, 0,
                nullptr, 0, 0);
        for( int j = 0; j < XY_SIZE; j++ )
        {
            if( x[j] != HUGE_VAL && y[j] != HUGE_VAL )
            {
                minx = std::min(minx, x[j]);
                miny = std::min(miny, y[j]);
                maxx = std::max(maxx, x[j]);
                maxy = std::max(maxy, y[j]);
            }
        }
    }
}