TPosition Class Reference

#include <lbsposition.h>

Link against: lbs.lib

class TPosition : public TLocality

Inherits from

TPosition
- TLocality
  - TCoordinate

Protected Attributes
TTime	iTime

Public Member Functions
	TPosition()
	TPosition(const TLocality &, TTime)
IMPORT_C void	SetCurrentTime()
IMPORT_C void	SetTime(TTime)
IMPORT_C TInt	Speed(const TPosition &, TReal32 &)
IMPORT_C TInt	Speed(const TPosition &, TReal32 &, TReal32 &)
IMPORT_C TTime	Time()

Inherited Attributes
	TCoordinate::iAltitude
	TCoordinate::iDatum
	TCoordinate::iLatitude
	TCoordinate::iLongitude
	TLocality::iHorizontalAccuracy
	TLocality::iVerticalAccuracy

Inherited Functions
	TCoordinate::Altitude()const
	TCoordinate::Datum()const
	TCoordinate::Latitude()const
	TCoordinate::Longitude()const
	TCoordinate::Move(TReal32,TReal32)
	TCoordinate::SetCoordinate(const TReal64 &,const TReal64 &)
	TCoordinate::SetCoordinate(const TReal64 &,const TReal64 &,TReal32)
	TCoordinate::SetDatum(TPositionDatumId)
	TCoordinate::TCoordinate()
	TCoordinate::TCoordinate(const TReal64 &,const TReal64 &)
	TCoordinate::TCoordinate(const TReal64 &,const TReal64 &,TReal32)
	TLocality::BearingTo(const TCoordinate &,TReal32 &)const
	TLocality::BearingTo(const TLocality &,TReal32 &,TReal32 &)const
	TLocality::Distance(const TCoordinate &,TReal32 &)const
	TLocality::Distance(const TLocality &,TReal32 &,TReal32 &)const
	TLocality::HorizontalAccuracy()const
	TLocality::SetAccuracy(TReal32,TReal32)
	TLocality::SetHorizontalAccuracy(TReal32)
	TLocality::SetVerticalAccuracy(TReal32)
	TLocality::TLocality()
	TLocality::TLocality(const TCoordinate &,TReal32)
	TLocality::TLocality(const TCoordinate &,TReal32,TReal32)
	TLocality::VerticalAccuracy()const

Detailed Description

This class is the standard data structure for retrieving location information. It adds a time dimension to the inherited TLocality information. This enables the speed to be calculated from two TPosition instances.

The time reflects the system time (that is, the mobile terminal) of when the location fix was obtained. It does not indicate the time as obtained from the position technology (for example network or satellite time).

The time is contained in a TTime data structure that provides microsecond resolution. However, it should be noted that system clocks only provide a resolution of milliseconds or indeed hundredths of a second.

Member Attribute Documentation

iTime

TTime

iTime

[protected]

This is the system time when the position related member data was obtained.

Constructor & Destructor Documentation

TPosition ( )

IMPORT_C

TPosition

(

)

Default constructor for TCoordinate. Sets the member data to default values (NaN for coordinates, 0 for time).

TPosition ( const TLocality &, TTime )

IMPORT_C	TPosition	(	const TLocality &	aLocality,
			TTime	aTime
		)

Constructor for TPosition. Allows the client to set a locality and an associated time.

Parameters
aLocality	specifies an initial value for the locality of the position.
aTime	specifies an initial value for the time of the position.

Member Function Documentation

SetCurrentTime ( )

IMPORT_C void

SetCurrentTime

(

)

Sets the time of this position data to the current universal time as indicated by the systems clock.

SetTime ( TTime )

IMPORT_C void

SetTime

(

TTime

aTime

)

Sets the time of this position data.

Parameters
aTime	is the new timing information.

Speed ( const TPosition &, TReal32 & )

IMPORT_C TInt	Speed	(	const TPosition &	aPosition,
			TReal32 &	aSpeed
		)	const

This method calculates the horizontal speed between the current position and the supplied instance aPosition. The speed is calculated based on the coordinates and time associated with each instance.

Parameters
aPosition	is another position to use in the calculation.
aSpeed	upon successful completion, this is set to the speed indicated by being at this position at its recorded time, and at aPosition at its recorded time. Always positive, in metres per second.

Return Value: a Symbian OS error code. KErrArgument if any of iLatitude, iLongitude, aPosition.iLatitude or aPosition.iLongitude are set to NaN. KErrArgument if either of iTime or aPosition.iTime are set to zero. KErrArgument if iTime and aPosition.iTime are the same.

Speed ( const TPosition &, TReal32 &, TReal32 & )

IMPORT_C TInt	Speed	(	const TPosition &	aPosition,
			TReal32 &	aSpeed,
			TReal32 &	aDelta
		)	const

This method calculates the horizontal speed between the current position and the supplied instance aPosition. The speed is calculated based on the coordinates and time associated with each instance. An estimate of the accuracy of the result is also provided.

Parameters
aPosition	is another position to use in the calculation.
aSpeed	upon successful completion, this is set to the speed indicated by being at this position at its recorded time, and at aPosition at its recorded time. Always positive, in metres per second.
aDelta	upon successful completion, this is set to an estimate of the accuracy of the calculation, in metres per second.

Return Value: a Symbian OS error code. KErrArgument if any of iLatitude, iLongitude, aPosition.iLatitude or aPosition.iLongitude are set to NaN. KErrArgument if any of iHorizontalAccuracy or aPosition.iHorizontalAccuracy are set to NaN. KErrArgument if either of iTime or aPosition.iTime are set to zero. KErrArgument if iTime and aPosition.iTime are the same.

Time ( )

IMPORT_C TTime

Time

(

)

const

Retrieves the time of this position data.

Return Value: the timing component of this position information.