#include <geos.h>
Public Types | |
enum | Type { FIXED, FLOATING, FLOATING_SINGLE } |
The types of Precision Model which GEOS supports. More... | |
Public Member Functions | |
PrecisionModel (void) | |
Creates a PrecisionModel with a default precision of FLOATING. | |
PrecisionModel (Type nModelType) | |
Creates a PrecisionModel specifying an explicit precision model type. | |
PrecisionModel (double newScale) | |
Creates a PrecisionModel with Fixed precision. | |
virtual | ~PrecisionModel (void) |
destructor | |
double | makePrecise (double val) const |
Rounds a numeric value to the PrecisionModel grid. | |
void | makePrecise (Coordinate *coord) const |
Rounds the given Coordinate to the PrecisionModel grid. | |
bool | isFloating () const |
Tests whether the precision model supports floating point. | |
int | getMaximumSignificantDigits () const |
Returns the maximum number of significant digits provided by this precision model. | |
Type | getType () const |
Gets the type of this PrecisionModel. | |
double | getScale () const |
Returns the multiplying factor used to obtain a precise coordinate. | |
int | compareTo (const PrecisionModel *other) const |
Compares this PrecisionModel object with the specified object for order. | |
Static Public Attributes | |
static const double | maximumPreciseValue |
The maximum precise value representable in a double. |
In other words, specifies the grid of allowable points for all Geometry
s.
The makePrecise method allows rounding a coordinate to a "precise" value; that is, one whose precision is known exactly.
Coordinates are assumed to be precise in geometries. That is, the coordinates are assumed to be rounded to the precision model given for the geometry. JTS input routines automatically round coordinates to the precision model before creating Geometries. All internal operations assume that coordinates are rounded to the precision model. Constructive methods (such as boolean operations) always round computed coordinates to the appropriate precision model.
Currently three types of precision model are supported:
Coordinates are represented internally as Java double-precision values. Since Java uses the IEEE-394 floating point standard, this provides 53 bits of precision. (Thus the maximum precisely representable integer is 9,007,199,254,740,992).
JTS methods currently do not handle inputs with different precision models.
The types of Precision Model which GEOS supports.
geos::PrecisionModel::PrecisionModel | ( | void | ) |
Creates a PrecisionModel with a default precision of FLOATING.
Creates a PrecisionModel
with a default precision of FLOATING.
geos::PrecisionModel::PrecisionModel | ( | Type | nModelType | ) |
Creates a PrecisionModel specifying an explicit precision model type.
If the model type is FIXED the scale factor will default to 1.
nModelType | the type of the precision model |
geos::PrecisionModel::PrecisionModel | ( | double | newScale | ) |
Creates a PrecisionModel with Fixed precision.
Fixed-precision coordinates are represented as precise internal coordinates which are rounded to the grid defined by the scale factor.
newScale | amount by which to multiply a coordinate after subtracting the offset, to obtain a precise coordinate |
double geos::PrecisionModel::makePrecise | ( | double | val | ) | const |
Rounds a numeric value to the PrecisionModel grid.
Rounds an numeric value to the PrecisionModel grid.
void geos::PrecisionModel::makePrecise | ( | Coordinate * | coord | ) | const |
Rounds the given Coordinate to the PrecisionModel grid.
Rounds given Coordinate to the PrecisionModel grid.
bool geos::PrecisionModel::isFloating | ( | ) | const |
Tests whether the precision model supports floating point.
true
if the precision model supports floating point int geos::PrecisionModel::getMaximumSignificantDigits | ( | ) | const |
Returns the maximum number of significant digits provided by this precision model.
Intended for use by routines which need to print out precise values.
PrecisionModel::Type geos::PrecisionModel::getType | ( | ) | const |
double geos::PrecisionModel::getScale | ( | ) | const |
Returns the multiplying factor used to obtain a precise coordinate.
Returns the multiplying factor used to obtain a precise coordinate. This method is private because PrecisionModel is intended to be an immutable (value) type.
int geos::PrecisionModel::compareTo | ( | const PrecisionModel * | other | ) | const |
Compares this PrecisionModel object with the specified object for order.
A PrecisionModel is greater than another if it provides greater precision. The comparison is based on the value returned by the getMaximumSignificantDigits method. This comparison is not strictly accurate when comparing floating precision models to fixed models; however, it is correct when both models are either floating or fixed.
other | the PrecisionModel with which this PrecisionModel is being compared |
const double geos::PrecisionModel::maximumPreciseValue [static] |
The maximum precise value representable in a double.
Since IEE754 double-precision numbers allow 53 bits of mantissa, the value is equal to 2^53 - 1. This provides almost 16 decimal digits of precision.