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

QwtTransform - A transformation between coordinate systems.

#include <qwt_transform.h>

Inherited by QwtLogTransform, QwtNullTransform, and QwtPowerTransform.


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.

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:

  • transform
  • 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:

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

Definition at line 35 of file qwt_transform.h.

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.

Inverse transformation function

Parameters

value Value

Returns

Modified value

See also

transform()

Implemented in QwtPowerTransform, QwtLogTransform, and QwtNullTransform.

Transformation function

Parameters

value Value

Returns

Modified value

See also

invTransform()

Implemented in QwtPowerTransform, QwtLogTransform, and QwtNullTransform.

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

Sun Jul 18 2021 Version 6.2.0