QwtScaleTransformation Class Reference

A transformation between coordinate systems. More...

#include <qwt_scale_map.h>

Public Types
enum	Type { Linear, Log10, Other }
	Transformation type. More...

Public Member Functions
	QwtScaleTransformation (Type type)
	Constructor for a linear transformation.
virtual	~QwtScaleTransformation ()
	Destructor.
virtual double	xForm (double s, double s1, double s2, double p1, double p2) const
	Transform a value from the coordinate system of a scale into the coordinate system of the paint device. More...
virtual double	invXForm (double p, double p1, double p2, double s1, double s2) const
	Transform a value from the coordinate system of the paint device into the coordinate system of a scale. More...
Type	type () const
virtual QwtScaleTransformation *	copy () const
	Create a clone of the transformation.

Detailed Description

A transformation between coordinate systems.

QwtScaleTransformation offers transformations from the coordinate system of a scale into the linear coordinate system of a paint device and vice versa.

Member Enumeration Documentation

enum QwtScaleTransformation::Type

Transformation type.

Enumerator
Linear	Transformation between 2 linear scales.
Log10	Transformation between a linear and a logarithmic ( base 10 ) scale.
Other	Any other type of transformation.

Member Function Documentation

double QwtScaleTransformation::invXForm ( double  p, double  p1, double  p2, double  s1, double  s2  ) const

virtual

Transform a value from the coordinate system of the paint device into the coordinate system of a scale.

Parameters

p	Value related to the coordinate system of the paint device
p1	First border of the coordinate system of the paint device
p2	Second border of the coordinate system of the paint device
s1	First border of the coordinate system of the scale
s2	Second border of the coordinate system of the scale

Returns

linear mapping:

s1 + ( s2 - s1 ) / ( p2 - p1 ) * ( p - p1 );

log10 mapping:

exp((p - p1) / (p2 - p1) * log(s2 / s1)) * s1;

QwtScaleTransformation::Type QwtScaleTransformation::type ( ) const

inline

Returns

Transformation type

double QwtScaleTransformation::xForm ( double  s, double  s1, double  s2, double  p1, double  p2  ) const

virtual

Transform a value from the coordinate system of a scale into the coordinate system of the paint device.

Parameters

s	Value related to the coordinate system of the scale
s1	First border of the coordinate system of the scale
s2	Second border of the coordinate system of the scale
p1	First border of the coordinate system of the paint device
p2	Second border of the coordinate system of the paint device

Returns

linear mapping:

p1 + (p2 - p1) / (s2 - s1) * (s - s1);

log10 mapping:

p1 + (p2 - p1) / log(s2 / s1) * log(s / s1);

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The documentation for this class was generated from the following files:

• QWT/qwt_scale_map.h
• QWT/qwt_scale_map.cpp