A transformation between coordinate systems. More...

Inheritance diagram for QwtTransform:

Public Member Functions
	QwtTransform ()
	Constructor.

virtual	~QwtTransform ()
	Destructor.

virtual double	bounded (double value) const
	Modify value to be a valid value for the transformation.

virtual double	transform (double value) const =0
	Transformation function.

virtual double	invTransform (double value) const =0
	Inverse transformation function.

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 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 ) );

Constructor & Destructor Documentation

QwtTransform::QwtTransform ( )

Constructor.

Default constructor.

double QwtTransform::bounded ( double value ) const

virtual

Modify value to be a valid value for the transformation.

Bounded function - returns value unmodified.

Parameters

value Value to be bounded

Reimplemented in QwtLogTransform.

virtual QwtTransform * QwtTransform::copy ( ) const

pure virtual

Virtualized copy operation.

virtual double QwtTransform::invTransform ( double value ) const

pure virtual

Inverse transformation function.

virtual double QwtTransform::transform ( double value ) const

pure virtual

Transformation function.

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