QwtDiMap(3)

NAME
QwtDiMap - Map a double interval into an integer interval.

SYNOPSIS

#include <qwt_dimap.h>

Inherited by QwtScaleDraw.

  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

  Static Public Attributes
const double LogMin = 1.0e-150
const double LogMax = 1.0e150

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

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.

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)

AUTHOR

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