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QwtDiMap Class Reference

Inheritance diagram for QwtDiMap:

QwtScaleDraw QwtDialScaleDraw List of all members.

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


Public Member Functions

 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


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
logarithmic logarithmic mapping, TRUE or FALSE.

QwtDiMap::~QwtDiMap  ) 
 

Destructor.


Member Function Documentation

bool QwtDiMap::contains int  x  )  const
 

Returns:
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:
y 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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