QwtScaleTransformation Class Reference

Operations for linear or logarithmic (base 10) transformations. More...

#include <qwt_scale_map.h>

List of all members.

Public Types
enum	Type { Linear, Log10, Other }
Public Member Functions
	QwtScaleTransformation (Type type)
	Constructor for a linear transformation.
virtual	~QwtScaleTransformation ()
	Destructor.
virtual double	xForm (double x, double s1, double s2, double p1, double p2) const
	Transform a value between 2 linear intervals.
virtual double	invXForm (double x, double s1, double s2, double p1, double p2) const
	Transform a value from a linear to a logarithmic interval.
Type	type () const
virtual QwtScaleTransformation *	copy () const
	Create a clone of the transformation.

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Detailed Description

Operations for linear or logarithmic (base 10) transformations.

Definition at line 19 of file qwt_scale_map.h.

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Member Enumeration Documentation

enum QwtScaleTransformation::Type

Enumerator:

Linear
Log10
Other

Definition at line 22 of file qwt_scale_map.h.

    {
        Linear,
        Log10,

        Other
    };

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Constructor & Destructor Documentation

QwtScaleTransformation::QwtScaleTransformation

(

Type

type )

Constructor for a linear transformation.

Definition at line 16 of file qwt_scale_map.cpp.

References QwtScaleTransformation().

Referenced by QwtScaleTransformation().

                                                       :
    d_type(type)
{
}

QwtScaleTransformation::~QwtScaleTransformation

(

)

[virtual]

Destructor.

Definition at line 22 of file qwt_scale_map.cpp.

{
}

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Member Function Documentation

QwtScaleTransformation * QwtScaleTransformation::copy

(

)

const [virtual]

Create a clone of the transformation.

Definition at line 27 of file qwt_scale_map.cpp.

Referenced by QwtPlotScaleItem::draw(), QwtScaleMap::operator=(), and QwtScaleMap::QwtScaleMap().

{
    return new QwtScaleTransformation(d_type);
}

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

Transform a value from a linear to a logarithmic interval.

Parameters:

x	value related to the linear interval [p1, p2]
p1	first border of linear interval
p2	first border of linear interval
s1	first border of logarithmic interval
s2	first border of logarithmic interval

Returns:

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

Definition at line 72 of file qwt_scale_map.cpp.

References QuadProgPP::exp(), QuadProgPP::log(), and Log10.

Referenced by QwtScaleMap::invTransform().

{
    if ( d_type == Log10 )  
        return exp((p - p1) / (p2 - p1) * log(s2 / s1)) * s1;
    else
        return s1 + (s2 - s1) / (p2 - p1) * (p - p1);
}

Type QwtScaleTransformation::type

(

)

const [inline]

Returns:

Transformation type

Definition at line 39 of file qwt_scale_map.h.

Referenced by QwtScaleMap::setPaintInterval(), QwtScaleMap::setPaintXInterval(), QwtScaleWidget::setScaleDiv(), QwtScaleMap::setScaleInterval(), and QwtScaleMap::xTransform().

{ return d_type; }

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

Transform a value between 2 linear intervals.

Parameters:

x	value related to the interval [x1, x2]
x1	first border of source interval
x2	first border of source interval
y1	first border of target interval
y2	first border of target interval

Returns:

linear mapping:

y1 + (y2 - y1) / (x2 - x1) * (x - x1)

log10 mapping:

p1 + (p2 - p1) / log(s2 / s1) * log(x / s1)

Definition at line 49 of file qwt_scale_map.cpp.

References QuadProgPP::log(), and Log10.

Referenced by QwtScaleMap::xTransform().

{
    if ( d_type == Log10 )  
        return p1 + (p2 - p1) / log(s2 / s1) * log(s / s1);
    else 
        return p1 + (p2 - p1) / (s2 - s1) * (s - s1);
}

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

• qwt_scale_map.h
• qwt_scale_map.cpp