C++ GeoDataCoordinates::geoCoordinates方法代码示例

bool ViewportParams::resolves ( const GeoDataCoordinates &coord1, 
                                const GeoDataCoordinates &coord2 ) const
{
    qreal lon1, lat1;
    coord1.geoCoordinates( lon1, lat1 );

    qreal lon2, lat2;
    coord2.geoCoordinates( lon2, lat2 );

    // We take the manhattan length as an approximation for the distance
    return ( fabs( lon2 - lon1 ) + fabs( lat2 - lat1 ) < angularResolution() );
}

bool EquirectProjection::screenCoordinates( const GeoDataCoordinates &geopoint, 
                                            const ViewportParams *viewport,
                                            qreal &x, qreal &y, bool &globeHidesPoint ) const
{
    globeHidesPoint = false;

    // Convenience variables
    int  radius = viewport->radius();
    int  width  = viewport->width();
    int  height = viewport->height();

    qreal  lon;
    qreal  lat;
    qreal  rad2Pixel = 2.0 * viewport->radius() / M_PI;

    const qreal centerLon = viewport->centerLongitude();
    const qreal centerLat = viewport->centerLatitude();

    geopoint.geoCoordinates( lon, lat );

    // Let (x, y) be the position on the screen of the geopoint.
    x = ((qreal)(viewport->width())  / 2.0 + rad2Pixel * (lon - centerLon));
    y = ((qreal)(viewport->height()) / 2.0 - rad2Pixel * (lat - centerLat));

    // Return true if the calculated point is inside the screen area,
    // otherwise return false.
    return ( ( 0 <= y && y < height )
             && ( ( 0 <= x && x < width )
                  || ( 0 <= x - 4 * radius && x - 4 * radius < width )
                  || ( 0 <= x + 4 * radius && x + 4 * radius < width ) ) );
}

bool EquirectProjection::screenCoordinates( const GeoDataCoordinates &geopoint,
                                            const ViewportParams *viewport,
                                            qreal *x, qreal &y,
                                            int &pointRepeatNum,
                                            const QSizeF& size,
                                            bool &globeHidesPoint ) const
{
    pointRepeatNum = 0;
    // On flat projections the observer's view onto the point won't be
    // obscured by the target planet itself.
    globeHidesPoint = false;

    // Convenience variables
    int  radius = viewport->radius();
    qreal  width  = (qreal)(viewport->width());
    qreal  height = (qreal)(viewport->height());

    qreal  lon;
    qreal  lat;
    qreal  rad2Pixel = 2.0 * radius / M_PI;

    const qreal centerLon = viewport->centerLongitude();
    const qreal centerLat = viewport->centerLatitude();

    geopoint.geoCoordinates( lon, lat );

    // Let (itX, y) be the first guess for one possible position on screen.
    qreal itX = ( width  / 2.0 + rad2Pixel * ( lon - centerLon ) );
    y = ( height / 2.0 - rad2Pixel * ( lat - centerLat ) );

    // Make sure that the requested point is within the visible y range:
    if ( 0 <= y + size.height() / 2.0 && y < height + size.height() / 2.0 ) {
        // First we deal with the case where the repetition doesn't happen
        if ( !repeatX() ) {
            *x = itX;
            if ( 0 < itX + size.width() / 2.0  && itX < width + size.width() / 2.0 ) {
                return true;
            }
            else {
                // the requested point is out of the visible x range:
                return false;
            }
        }
        // For the repetition case the same geopoint gets displayed on 
        // the map many times.across the longitude.

        int xRepeatDistance = 4 * radius;

        // Finding the leftmost positive x value
        if ( itX + size.width() > xRepeatDistance ) {
            const int repeatNum = (int)( ( itX + size.width() ) / xRepeatDistance );
            itX = itX - repeatNum * xRepeatDistance;
        }
        if ( itX + size.width() / 2.0 < 0 ) {
            itX += xRepeatDistance;
        }
        // The requested point is out of the visible x range:
        if ( itX > width + size.width() / 2.0 ) {
            return false;
        }

        // Now iterate through all visible x screen coordinates for the point 
        // from left to right.
        int itNum = 0;
        while ( itX - size.width() / 2.0 < width ) {
            *x = itX;
            ++x;
            ++itNum;
            itX += xRepeatDistance;
        }

        pointRepeatNum = itNum;

        return true;
    }

    // The requested point is out of the visible y range.
    return false;
}