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| ImageIteratorBase [Image Iterators] |

Base class for 2D random access iterators. More...

`#include <vigra/imageiterator.hxx>`

Inheritance diagram for ImageIteratorBase:

List of all members.

## Public Types

typedef ColumnIteratorSelector::res | column_iterator
typedef Diff2D | difference_type
typedef REFERENCE | index_reference
typedef image_traverser_tag | iterator_category
typedef detail::DirectionSelector < StridedOrUnstrided > ::template type< pointer > | MoveX
typedef detail::DirectionSelector < StridedArrayTag >::template type< int > | MoveY
typedef PIXELTYPE | PixelType
typedef POINTER | pointer
typedef REFERENCE | reference
typedef RowIteratorSelector::res | row_iterator
typedef PIXELTYPE | value_type

## Public Member Functions

Comparison of Iterators
bool | operator!= (ImageIteratorBase const &rhs) const
difference_type | operator- (ImageIteratorBase const &rhs) const
bool | operator== (ImageIteratorBase const &rhs) const
Access the Pixels
index_reference | operator() (int dx, int dy) const
reference | operator* () const
pointer | operator-> () const
pointer | operator[] (int dy) const
index_reference | operator[] (Diff2D const &d) const
Random navigation
IMAGEITERATOR | operator+ (difference_type const &s) const
IMAGEITERATOR & | operator+= (difference_type const &s)
IMAGEITERATOR | operator- (difference_type const &s) const
IMAGEITERATOR & | operator-= (difference_type const &s)

## Public Attributes

Specify coordinate to operate on
MoveX | x
MoveY | y

## Protected Member Functions

| ImageIteratorBase ()
| ImageIteratorBase (ImageIteratorBase const &rhs)
| ImageIteratorBase (pointer base, int xstride, int ystride)
| ImageIteratorBase (pointer base, int ystride)
ImageIteratorBase & | operator= (ImageIteratorBase const &rhs)

## Detailed Description

### template<class IMAGEITERATOR, class PIXELTYPE, class REFERENCE, class POINTER, class StridedOrUnstrided = UnstridedArrayTag>
class vigra::ImageIteratorBase< IMAGEITERATOR, PIXELTYPE, REFERENCE, POINTER, StridedOrUnstrided >

Base class for 2D random access iterators.

This class contains the navigational part of the iterator. It is usually not constructed directly, but via some derived class such as ImageIterator or StridedImageIterator.

#include <vigra/imageiterator.hxx>

Namespace: vigra

The usage examples assume that you constructed two iterators like this:

        vigra::ImageIterator<SomePixelType> iterator(base, width);
        vigra::ImageIterator<SomePixelType> iterator1(base, width);

See the paper: U. Koethe: Reusable Algorithms in Image Processing for a discussion of the concepts behind ImageIterators.

## Member Typedef Documentation

typedef ColumnIteratorSelector::res column_iterator

The associated column iterator.

typedef Diff2D difference_type

the iterator's difference type (argument type of `iter[diff]`)

Reimplemented in ImageIterator, ConstImageIterator, StridedImageIterator, and ConstStridedImageIterator.

typedef REFERENCE index_reference

the iterator's index reference type (return type of `iter[diff]`)

typedef image_traverser_tag iterator_category

the iterator tag (image traverser)

typedef detail::DirectionSelector<StridedOrUnstrided>::template type<pointer> MoveX

Let operations act in X direction

typedef detail::DirectionSelector<StridedArrayTag>::template type<int> MoveY

Let operations act in Y direction

typedef PIXELTYPE PixelType

deprecated, use `value_type` instead.

typedef POINTER pointer

the iterator's pointer type (return type of `iter.operator->()`)

Reimplemented in ImageIterator, ConstImageIterator, StridedImageIterator, and ConstStridedImageIterator.

typedef REFERENCE reference

the iterator's reference type (return type of `*iter`)

typedef RowIteratorSelector::res row_iterator

The associated row iterator.

typedef PIXELTYPE value_type

The underlying image's pixel type.

## Constructor & Destructor Documentation

ImageIteratorBase | ( | pointer | base,
|  | int | ystride |
| ) |  |  | `[protected]`

Construct from raw memory with a vertical stride of `ystride`. `ystride` must equal the physical image width (row length), even if the iterator will only be used for a sub image. This constructor must only be called for unstrided iterators (`StridedOrUnstrided == UnstridedArrayTag`)

ImageIteratorBase | ( | pointer | base,
|  | int | xstride,
|  | int | ystride |
| ) |  |  | `[protected]`

Construct from raw memory with a horizontal stride of `xstride` and a vertical stride of `ystride`. This constructor may be used for iterators that shall skip pixels. Thus, it must only be called for strided iterators (`StridedOrUnstrided == StridedArrayTag`)

ImageIteratorBase | ( | ImageIteratorBase< IMAGEITERATOR, PIXELTYPE, REFERENCE, POINTER, StridedOrUnstrided > const & | rhs | ) | `[protected]`

Copy constructor

ImageIteratorBase | ( |  | ) | `[protected]`

Default constructor

## Member Function Documentation

bool operator!= | ( | ImageIteratorBase< IMAGEITERATOR, PIXELTYPE, REFERENCE, POINTER, StridedOrUnstrided > const & | rhs | ) | const

usage: `iterator != iterator1`

index_reference operator() | ( | int | dx,
|  | int | dy |
| ) |  |  | const

Access pixel at offset (dx, dy) from current location.
usage: `SomePixelType value = iterator(dx, dy)`

reference operator* | ( |  | ) | const

Access current pixel.
usage: `SomePixelType value = *iterator`

IMAGEITERATOR operator+ | ( | difference_type const & | s | ) | const

Add a distance

IMAGEITERATOR& operator+= | ( | difference_type const & | s | ) |

Add offset via Diff2D

IMAGEITERATOR operator- | ( | difference_type const & | s | ) | const

Subtract a distance

difference_type operator- | ( | ImageIteratorBase< IMAGEITERATOR, PIXELTYPE, REFERENCE, POINTER, StridedOrUnstrided > const & | rhs | ) | const

usage: `Diff2D dist = iterator - iterator1`

IMAGEITERATOR& operator-= | ( | difference_type const & | s | ) |

Subtract offset via Diff2D

pointer operator-> | ( |  | ) | const

Call member of current pixel.
usage: `iterator->pixelMemberFunction()`

ImageIteratorBase& operator= | ( | ImageIteratorBase< IMAGEITERATOR, PIXELTYPE, REFERENCE, POINTER, StridedOrUnstrided > const & | rhs | ) | `[protected]`

Copy assignment

bool operator== | ( | ImageIteratorBase< IMAGEITERATOR, PIXELTYPE, REFERENCE, POINTER, StridedOrUnstrided > const & | rhs | ) | const

usage: `iterator == iterator1`

pointer operator[] | ( | int | dy | ) | const

Read pixel with offset [dy][dx] from current pixel. Note that the 'x' index is the trailing index.
usage: `SomePixelType value = iterator[dy][dx]`

index_reference operator[] | ( | Diff2D const & | d | ) | const

Access pixel at offset from current location.
usage: `SomePixelType value = iterator[Diff2D(1,1)]`

## Member Data Documentation

MoveX x

Refer to iterator's x coordinate. Usage examples:

                ++iterator.x;        // move one step to the right
                --iterator.x;        // move one step to the left
                iterator.x += dx;    // move dx steps to the right
                iterator.x -= dx;    // move dx steps to the left
                bool notAtEndOfRow = iterator.x < lowerRight.x;   // compare x coordinates of two iterators
                int width = lowerRight.x - upperLeft.x;           // calculate difference of x coordinates
                                                                  // between two iterators

MoveY y

Refer to iterator's y coordinate. Usage examples:

                ++iterator.y;        // move one step down
                --iterator.y;        // move one step up
                iterator.y += dy;    // move dy steps down
                iterator.y -= dy;    // move dy steps up
                bool notAtEndOfColumn = iterator.y < lowerRight.y; // compare y coordinates of two iterators
                int height = lowerRight.y - upperLeft.y;           // calculate difference of y coordinates
                                                                   // between two iterators

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

- vigra/imageiterator.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)