int ViewportParams::polarity() const
{
// For mercator this just gives the extreme latitudes
// instead of the actual poles but it works fine as well:
GeoDataCoordinates northPole( 0.0, +currentProjection()->maxLat() );
GeoDataCoordinates southPole( 0.0, -currentProjection()->maxLat() );
bool globeHidesN, globeHidesS;
qreal x;
qreal yN, yS;
currentProjection()->screenCoordinates( northPole, this,
x, yN, globeHidesN );
currentProjection()->screenCoordinates( southPole, this,
x, yS, globeHidesS );
int polarity = 0;
// case of the flat map:
if ( !globeHidesN && !globeHidesS ) {
if ( yN < yS ) {
polarity = +1;
}
if ( yS < yN ) {
polarity = -1;
}
}
else {
if ( !globeHidesN && yN < height() / 2 ) {
polarity = +1;
}
if ( !globeHidesN && yN > height() / 2 ) {
polarity = -1;
}
if ( !globeHidesS && yS > height() / 2 ) {
polarity = +1;
}
if ( !globeHidesS && yS < height() / 2 ) {
polarity = -1;
}
}
return polarity;
}
/**
This method calculates the bearing from this locality to the
supplied locality.
@param[in] aTargetLocality is the supplied target locality.
@param[out] aBearing upon successful completion, this is set to the bearing
from this locality to aTargetLocality, in degrees counting clockwise
relative to true north.
@param[out] aDelta upon successful completion, this is set to an estimate of the
accuracy of the calculation, in degrees relative to aBearing.
@return a Symbian OS error code.
@return KErrArgument if any of iLatitude, iLongitude,
aTargetLocality.iLatitude or aTargetLocality.iLongitude are set to NaN.
@return KErrArgument if any of iHorizontalAccuracy
or aTargetLocality.iHorizontalAccuracy are set to NaN.
@return KErrPositionIncalculable if the error circle (horizontal accuracy)
of this locality includes a pole.
@return KErrPositionIncalculable if the two localities has overlapping
error circles.
@return KErrPositionIncalculable if the error circle of this locality
overlaps with the error circle of aTargetLocality when projected antipodal.
*/
EXPORT_C TInt TLocality::BearingTo(const TLocality& aTargetLocality,
TReal32& aBearing,
TReal32& aDelta) const
{
if (Math::IsNaN(iLatitude) ||
Math::IsNaN(iLongitude) ||
Math::IsNaN(iHorizontalAccuracy) ||
Math::IsNaN(aTargetLocality.iLatitude) ||
Math::IsNaN(aTargetLocality.iLongitude) ||
Math::IsNaN(aTargetLocality.iHorizontalAccuracy))
{
return KErrArgument;
}
// Validate that this locality does not include the North Pole
TCoordinate northPole(90, 0);
TReal64 distance;
RETURN_IF_ERROR(Distance64(*this, northPole, distance));
if (distance <= iHorizontalAccuracy)
{
return KErrPositionIncalculable;
}
// Validate that this locality does not include the South Pole
TCoordinate southPole(-90, 0);
RETURN_IF_ERROR(Distance64(*this, southPole, distance));
if (distance <= iHorizontalAccuracy)
{
return KErrPositionIncalculable;
}
// Validate that this locality does not overlap with the target locality
// when target is projected antipodal.
TCoordinate antipodalTarget(-aTargetLocality.iLatitude,
aTargetLocality.iLongitude + 180);
RETURN_IF_ERROR(Distance64(*this, antipodalTarget, distance));
TReal64 accuracySum = iHorizontalAccuracy +
aTargetLocality.iHorizontalAccuracy;
if (distance <= accuracySum)
{
return KErrPositionIncalculable;
}
// Validate that this locality does not overlap with the target locality.
RETURN_IF_ERROR(Distance64(*this, aTargetLocality, distance));
if (distance <= accuracySum)
{
return KErrPositionIncalculable;
}
// Calculate the bearing
RETURN_IF_ERROR(BearingTo(aTargetLocality, aBearing));
// Calculate the bearing delta
TReal64 gammaInRad;
TReal64 sinGamma = accuracySum / distance;
RETURN_IF_ERROR(Math::ASin(gammaInRad, sinGamma));
aDelta = TReal32(gammaInRad * KRadToDeg);
return KErrNone;
}
