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| VectorComponentValueAccessor [Data Accessors] |

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

`#include <vigra/accessor.hxx>`

List of all members.

## Public Types
typedef VECTORTYPE::value_type | value_type
## Public Member Functions
template<class ITERATOR, class DIFFERENCE>
value_type | operator() (ITERATOR const &i, DIFFERENCE const &diff) const
template<class ITERATOR>
value_type | operator() (ITERATOR const &i) const
template<class V, class ITERATOR, class DIFFERENCE>
void | set (V value, ITERATOR const &i, DIFFERENCE const &diff) const
template<class V, class ITERATOR>
void | set (V value, ITERATOR const &i) const
void | setIndex (int i)
| VectorComponentValueAccessor (int index)

## Detailed Description

### template<class VECTORTYPE>
class vigra::VectorComponentValueAccessor< VECTORTYPE >

Accessor for one component of a vector.

This accessor allows to select a single component (a single 'band') of a vector valued pixel type. The pixel type must support `operator[]`. The index of the component to be selected is passed in the constructor. The accessor returns its items by value. If you want to pass/return items by reference, use VectorComponentAccessor. If a floating point number is assigned by means of an accessor with integral value_type, the value is rounded and clipped as appropriate.

Usage:

        vigra::BRGBImage image(w,h);

        // init red channel with 255
        initImage(destImageRange(image,
                                 VectorComponentValueAccessor<vigra::BRGBImage::value_type>(0)),
                  255);

#include <vigra/accessor.hxx>
Namespace: vigra

## Member Typedef Documentation

typedef VECTORTYPE::value_type value_type

the value_type

## Constructor & Destructor Documentation

VectorComponentValueAccessor | ( | int | index | ) |

determine the component to be accessed

## Member Function Documentation

value_type operator() | ( | ITERATOR const & | i,
|  | DIFFERENCE const & | diff |
| ) |  |  | const

Read the data item at an offset (can be 1D or 2D or higher order difference). The type `ITERATOR::index_reference::value_type` is automatically converted to `value_type`. In case of a conversion floating point -> intergral this includes rounding and clipping.

value_type operator() | ( | ITERATOR const & | i | ) | const

Read the current data item. The type `ITERATOR::index_reference::value_type` is automatically converted to `value_type`. In case of a conversion floating point -> intergral this includes rounding and clipping.

template<class V, class ITERATOR, class DIFFERENCE>
void set | ( | V | value,
|  | ITERATOR const & | i,
|  | DIFFERENCE const & | diff |
| ) |  |  | const

Write the data item at an offset (can be 1D or 2D or higher order difference).. The type `V` of the passed in `value` is automatically converted to `value_type`. In case of a conversion floating point -> intergral this includes rounding and clipping.

template<class V, class ITERATOR>
void set | ( | V | value,
|  | ITERATOR const & | i |
| ) |  |  | const

Write the current data item. The type `V` of the passed in `value` is automatically converted to `value_type`. In case of a conversion floating point -> intergral this includes rounding and clipping.

void setIndex | ( | int | i | ) |

Reset the index to the given number.

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

- vigra/accessor.hxx

© Ullrich Köthe (ullrich.koethe@iwr.uni-heidelberg.de) Heidelberg Collaboratory for Image Processing, University of Heidelberg, Germany | html generated using doxygen and Python VIGRA 1.6.0 (13 Aug 2008)