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details Data Accessors VIGRA

Classes

class  BilinearInterpolatingAccessor< ACCESSOR, VALUETYPE >
 Bilinear interpolation at non-integer positions. More...
class  FFTWRealAccessor
class  MultiImageAccessor2< Iter1, Acc1, Iter2, Acc2 >
 Access two images simultaneously. More...
class  RGBAccessor< RGBVALUE >
class  SequenceAccessor< SEQUENCE >
 Accessor for items that are STL compatible sequences. More...
class  StandardAccessor< VALUETYPE >
 Encapsulate access to the values an iterator points to. More...
class  StandardConstAccessor< VALUETYPE >
 Encapsulate read access to the values an iterator points to. More...
class  StandardConstValueAccessor< VALUETYPE >
 Encapsulate access to the values an iterator points to. More...
class  StandardValueAccessor< VALUETYPE >
 Encapsulate access to the values an iterator points to. More...
class  VectorAccessor< VECTOR >
 Accessor for items that are STL compatible vectors. More...
class  VectorComponentAccessor< VECTORTYPE >
 Accessor for one component of a vector. More...
class  VectorComponentValueAccessor< VECTORTYPE >
 Accessor for one component of a vector. More...
class  VectorElementAccessor< ACCESSOR >
 Accessor for one component of a vector. More...

Modules

 Accessors for FFTWComplex
 Accessors for RGBValue


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 (ullrich.koethe@iwr.uni-heidelberg.de)
Heidelberg Collaboratory for Image Processing, University of Heidelberg, Germany

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VIGRA 1.6.0 (5 Nov 2009)