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details Data Accessors VIGRA


Modules

Accessors for FFTWComplex
Accessors for RGBValue

Classes

class  BilinearInterpolatingAccessor
 Bilinear interpolation at non-integer positions. More...

class  MultiImageAccessor2
 Access two images simultaneously. More...

class  SequenceAccessor
 Accessor for items that are STL compatible sequences. More...

class  StandardAccessor
 Encapsulate access to the values an iterator points to. More...

class  StandardConstAccessor
 Encapsulate read access to the values an iterator points to. More...

class  StandardConstValueAccessor
 Encapsulate access to the values an iterator points to. More...

class  StandardValueAccessor
 Encapsulate access to the values an iterator points to. More...

class  VectorAccessor
 Accessor for items that are STL compatible vectors. More...

class  VectorComponentAccessor
 Accessor for one component of a vector. More...

class  VectorComponentValueAccessor
 Accessor for one component of a vector. More...

class  VectorElementAccessor
 Accessor for one component of a vector. More...



Detailed Description


Basic templates to encapsulate access to the data of an iterator.

Data accessors are used to allow for flexible access to the data an iterator points to. When we access the data directly, we are bound to what operator *() returns, if this method exists at all. Encapsulating access in an accessor enables a better decoupling of data structures and algorithms. This paper contains a detailed description of the concept. Here is a brief list of the basic accessor requirements:

Operation Result Semantics
accessor(iter)convertible to
Iterator::value_type const &
read data at the current position of the iterator
accessor(iter, index)convertible to
Accessor::value_type const &
read data at offset index relative to iterator's current position (random-access iterator only)
accessor.set(value, iter)void write data value at the current position of the iterator (mutable iterator only)
accessor.set(value, iter, index)void write data value at offset index relative to iterator's current position (mutable random-access iterator only)
Accessor::value_type type of the data field the accessor refers to
iter is an iterator
index has the iterator's index type (Iterator::difference_type)
value is convertible to Accessor::value_type const &

The template AccessorTraits<T> can be used to find the default accessor associated with the type T, e.g.

    typedef typename AccessorTraits<typename Image::value_type>::default_accessor       Accessor;
    typedef typename AccessorTraits<typename Image::value_type>::default_const_accessor ConstAccessor;

© Ullrich Köthe (koethe@informatik.uni-hamburg.de)
Cognitive Systems Group, University of Hamburg, Germany

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VIGRA 1.5.0 (7 Dec 2006)