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QwtDiMap Class Reference

Map a double interval into an integer interval. More...

#include <qwt_dimap.h>

Inheritance diagram for QwtDiMap::

List of all members.

Public Methods
	QwtDiMap ()
	QwtDiMap (int i1, int i2, double d1, double d2, bool lg=FALSE)
	~QwtDiMap ()
bool	contains (double x) const
bool	contains (int x) const
void	setIntRange (int i1, int i2)
void	setDblRange (double d1, double d2, bool lg=FALSE)
int	transform (double x) const
double	invTransform (int i) const
int	limTransform (double x) const
double	xTransform (double x) const
double	d1 () const
double	d2 () const
int	i1 () const
int	i2 () const
bool	logarithmic () const
Public Attributes
QT_STATIC_CONST double	LogMin = 1.0e-150
QT_STATIC_CONST double	LogMax = 1.0e150

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Detailed Description

Map a double interval into an integer interval.

The QwtDiMap class maps an interval of type double into an interval of type int. It consists of two intervals D = [d1, d2] (double) and I = [i1, i2] (int), which are specified with the QwtDiMap::setDblRange and QwtDiMap::setIntRange members. The point d1 is mapped to the point i1, and d2 is mapped to i2. Any point inside or outside D can be mapped to a point inside or outside I using QwtDiMap::transform or QwtDiMap::limTransform or vice versa using QwtPlot::invTransform. D can be scaled linearly or logarithmically, as specified with QwtDiMap::setDblRange.

Usage

#include <qwt_dimap.h>

QwtDiMap map;
int ival;
double dval;

map.setDblRange(0.0, 3.1415);   // Assign an interval of type double with
        // linear mapping
map.setIntRange(0,100);         // Assign an integer interval

ival = map.transform(1.0);      // obtain integer value corresponding to 1.0
dval = map.invTransform(77);    // obtain double value corresponding to 77

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Constructor & Destructor Documentation

QwtDiMap::QwtDiMap (    )

Constructor. The double and integer intervals are both set to [0,1].

QwtDiMap::QwtDiMap (  int    i1, int    i2, double    d1, double    d2, bool    logarithmic = FALSE )

Constructor. Constructs a QwtDiMap instance with initial integer and double intervals Parameters: i1  first border of integer interval i2  second border of integer interval d1  first border of double interval d2  second border of double interval \bool logarithmic logarithmic mapping, TRUE or FALSE.

QwtDiMap::~QwtDiMap (    )

Destructor.

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Member Function Documentation

bool QwtDiMap::contains (  int    x )  const

\eturn TRUE if a value x lies inside or at the border of the map's integer range Parameters: x  value

bool QwtDiMap::contains (  double    x )  const

Returns: TRUE if a value x lies inside or at the border of the map's double range. Parameters: x  value

double QwtDiMap::d1 (    )  const

Returns: the first border of the double interval

double QwtDiMap::d2 (    )  const

Returns: the second border of the double interval

int QwtDiMap::i1 (    )  const

Returns: the second border of the integer interval

int QwtDiMap::i2 (    )  const

Returns: the second border of the integer interval

double QwtDiMap::invTransform (  int    y )  const

Transform an integer value into a double value. Parameters: integer  value to be transformed Returns: linear mapping: d1 + (d2 - d1) / (i2 - i1) * (y - i1) logarithmic mapping: d1 + (d2 - d1) / log(i2 / i1) * log(y / i1)

int QwtDiMap::limTransform (  double    x )  const

Transform and limit. The function is similar to QwtDiMap::transform, but limits the input value to the nearest border of the map's double interval if it lies outside that interval. Parameters: x  value to be transformed Returns: transformed value

bool QwtDiMap::logarithmic (    )  const

Returns: TRUE if the double interval is scaled logarithmically

void QwtDiMap::setDblRange (  double    d1, double    d2, bool    lg = FALSE )

Specify the borders of the double interval. Parameters: d1  first border d2  second border lg  logarithmic (TRUE) or linear (FALSE) scaling

void QwtDiMap::setIntRange (  int    i1, int    i2 )

Specify the borders of the integer interval. Parameters: i1  first border i2  second border

int QwtDiMap::transform (  double    x )  const

Transform a point in double interval into an point in the integer interval. Parameters: x  value Returns: linear mapping: rint(i1 + (i2 - i1) / (d2 - d1) * (x - d1)) logarithmic mapping: rint(i1 + (i2 - i1) / log(d2 / d1) * log(x / d1)) Warning: The specified point is allowed to lie outside the intervals. If you want to limit the returned value, use QwtDiMap::limTransform.

double QwtDiMap::xTransform (  double    x )  const

Exact transformation. This function is similar to QwtDiMap::transform, but makes the integer interval appear to be double. Parameters: x  value to be transformed Returns: linear mapping: i1 + (i2 - i1) / (d2 - d1) * (x - d1) logarithmic mapping: i1 + (i2 - i1) / log(d2 / d1) * log(x / d1)

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