A transformation between coordinate systems 更多...

类 QwtTransform 继承关系图:

Public 成员函数
	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

详细描述

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 ) );

构造及析构函数说明

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

参数

value Value to be bounded

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

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