QwtTransform - A transformation between coordinate systems.

NAME  SYNOPSIS  Public Member Functions  Detailed Description  Constructor & Destructor Documentation  QwtTransform::QwtTransform ()  QwtTransform::˜QwtTransform () [virtual]  Member Function Documentation  double QwtTransform::bounded (double value) const [virtual]  virtual QwtTransform * QwtTransform::copy () const [pure virtual]  virtual double QwtTransform::invTransform (double value) const [purevirtual]  virtual double QwtTransform::transform (double value) const [pure virtual]  Author 

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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:

	•		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.

Constructor & Destructor Documentation

QwtTransform::QwtTransform ()

Constructor.

Definition at line 20 of file qwt_transform.cpp.

QwtTransform::˜QwtTransform () [virtual]

Destructor.

Definition at line 25 of file qwt_transform.cpp.

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 QwtTransform * QwtTransform::copy () const [pure virtual]

Virtualized copy operation.

Implemented in QwtLogTransform, QwtNullTransform, and QwtPowerTransform.

virtual double QwtTransform::invTransform (double value) const [purevirtual]

Inverse transformation function

Parameters

value Value

Returns

Modified value

See also

transform()

Implemented in QwtLogTransform, QwtNullTransform, and QwtPowerTransform.

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

Transformation function

Parameters

value Value

Returns

Modified value

See also

invTransform()

Implemented in QwtLogTransform, QwtNullTransform, and QwtPowerTransform.

Author

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

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