QwtTransform(3)                Qwt User's Guide                QwtTransform(3)

NAME
       QwtTransform - A transformation between coordinate systems.


SYNOPSIS
       #include <qwt_transform.h>

       Inherited by QwtLogTransform, QwtNullTransform, and QwtPowerTransform.

   Public Member Functions
       QwtTransform ()
           Constructor.
       virtual ~QwtTransform ()
           Destructor.
       virtual double bounded (double value) const
       virtual double transform (double value) const =0
       virtual double invTransform (double value) const =0
       virtual QwtTransform * copy () const =0
           Virtualized copy operation.

Detailed Description
       A transformation between coordinate systems.

       QwtTransform manipulates values, when being mapped between the scale
       and the paint device coordinate system.

       A transformation consists of 2 methods:

       o transform

       o invTransform

       where one is is the inverse function of the other.

       When p1, p2 are the boundaries of the paint device coordinates and s1,
       s2 the boundaries of the scale, QwtScaleMap uses the following
       calculations:

       o p = p1 + ( p2 - p1 ) * ( T( s ) - T( s1 ) / ( T( s2 ) - T( s1 ) );

       o s = invT ( T( s1 ) + ( T( s2 ) - T( s1 ) ) * ( p - p1 ) / ( p2 - p1 )
         );

       Definition at line 35 of file qwt_transform.h.

Member Function Documentation
   double QwtTransform::bounded (double value) const [virtual]
       Modify value to be a valid value for the transformation. The default
       implementation does nothing.

       Parameters
           value Value to be bounded

       Returns
           value unmodified

       Reimplemented in QwtLogTransform.

       Definition at line 33 of file qwt_transform.cpp.

   virtual double QwtTransform::invTransform (double value) const [pure
       virtual]
       Inverse transformation function

       Parameters
           value Value

       Returns
           Modified value

       See also
           transform()

       Implemented in QwtPowerTransform, QwtLogTransform, and
       QwtNullTransform.

   virtual double QwtTransform::transform (double value) const [pure virtual]
       Transformation function

       Parameters
           value Value

       Returns
           Modified value

       See also
           invTransform()

       Implemented in QwtPowerTransform, QwtLogTransform, and
       QwtNullTransform.


Author
       Generated automatically by Doxygen for Qwt User's Guide from the source
       code.

Version 6.2.0                   Sun Jul 18 2021                QwtTransform(3)