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/************************************************************************/
/* */
/* Copyright 1998-2002 by Ullrich Koethe */
/* Cognitive Systems Group, University of Hamburg, Germany */
/* */
/* This file is part of the VIGRA computer vision library. */
/* ( Version 1.4.0, Dec 21 2005 ) */
/* The VIGRA Website is */
/* http://kogs-www.informatik.uni-hamburg.de/~koethe/vigra/ */
/* Please direct questions, bug reports, and contributions to */
/* koethe@informatik.uni-hamburg.de or */
/* vigra@kogs1.informatik.uni-hamburg.de */
/* */
/* Permission is hereby granted, free of charge, to any person */
/* obtaining a copy of this software and associated documentation */
/* files (the "Software"), to deal in the Software without */
/* restriction, including without limitation the rights to use, */
/* copy, modify, merge, publish, distribute, sublicense, and/or */
/* sell copies of the Software, and to permit persons to whom the */
/* Software is furnished to do so, subject to the following */
/* conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the */
/* Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES */
/* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND */
/* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT */
/* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, */
/* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING */
/* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR */
/* OTHER DEALINGS IN THE SOFTWARE. */
/* */
/************************************************************************/
#ifndef VIGRA_ITERATORTRAITS_HXX
#define VIGRA_ITERATORTRAITS_HXX
#include <vigra/accessor.hxx>
#include <vigra/imageiteratoradapter.hxx>
namespace vigra {
/** \addtogroup ImageIterators
*/
//@{
/** \brief Export associated information for each image iterator.
The IteratorTraits class contains the following fields:
\code
template <class T>
struct IteratorTraits
{
typedef T Iterator;
typedef Iterator iterator;
typedef typename iterator::iterator_category iterator_category;
typedef typename iterator::value_type value_type;
typedef typename iterator::reference reference;
typedef typename iterator::index_reference index_reference;
typedef typename iterator::pointer pointer;
typedef typename iterator::difference_type difference_type;
typedef typename iterator::row_iterator row_iterator;
typedef typename iterator::column_iterator column_iterator;
typedef StandardAccessor<value_type> DefaultAccessor;
typedef StandardAccessor<value_type> default_accessor;
typedef VigraTrueType/VigraFalseType hasConstantStrides;
};
\endcode
By (partially) specializing this template for an iterator class
the defaults given above can be changed as appropriate. For example, iterators
for rgb images are associated with <TT>RGBAccessor<value_type></TT>
instead of <TT>StandardAccessor<value_type></TT>. To get the accessor
associated with a given iterator, use code like this:
\code
template <class Iterator>
void foo(Iterator i)
{
typedef typename IteratorTraits<Iterator>::DefaultAccessor Accessor;
Accessor a;
...
}
\endcode
This technique is, for example, used by the
\ref IteratorBasedArgumentObjectFactories. The possibility to retrieve the default accessor by means of a traits
class is especially important since this information is not
contained in the iterator directly.
The member <tt>hasConstantStrides</tt> is useful for certain
optimizations: it helps to decide whether we can replace iterator
operations such as <tt>iter++</tt> ot <tt>iter =+ n</tt> with
corresponding pointer operations (which may be faster), where
the pointer is obtained as the address of iterator's pointee
(the object the iterator currently refers to).
This flag would be tt>VigraFalseType</tt> for a
<tt>std::list&lt;int&gt;::iterator</tt>, but is <tt>VigraTrueType</tt>
for most VIGRA iterators.
<b>\#include</b> "<a href="iteratortraits_8hxx-source.html">vigra/iteratortraits.hxx</a>"
Namespace: vigra
*/
template <class T>
struct IteratorTraits
{
typedef T Iterator;
typedef Iterator iterator;
typedef typename iterator::iterator_category iterator_category;
typedef typename iterator::value_type value_type;
typedef typename iterator::reference reference;
typedef typename iterator::index_reference index_reference;
typedef typename iterator::pointer pointer;
typedef typename iterator::difference_type difference_type;
typedef typename iterator::row_iterator row_iterator;
typedef typename iterator::column_iterator column_iterator;
typedef typename
AccessorTraits<value_type>::default_accessor DefaultAccessor;
typedef DefaultAccessor default_accessor;
// default: disable the constant strides optimization
typedef VigraFalseType hasConstantStrides;
};
template <class T>
struct IteratorTraitsBase
{
typedef T Iterator;
typedef Iterator iterator;
typedef typename iterator::iterator_category iterator_category;
typedef typename iterator::value_type value_type;
typedef typename iterator::reference reference;
typedef typename iterator::index_reference index_reference;
typedef typename iterator::pointer pointer;
typedef typename iterator::difference_type difference_type;
typedef typename iterator::row_iterator row_iterator;
typedef typename iterator::column_iterator column_iterator;
};
/***********************************************************/
/** \page ArgumentObjectFactories Argument Object Factories
Factory functions to create argument objects which simplify long argument lists.
<DL>
<DT>
<IMG BORDER=0 ALT="-" SRC="documents/bullet.gif">
\ref ImageBasedArgumentObjectFactories
<DD>
<DT>
<IMG BORDER=0 ALT="-" SRC="documents/bullet.gif">
\ref MultiArrayBasedArgumentObjectFactories
<DD>
<DT>
<IMG BORDER=0 ALT="-" SRC="documents/bullet.gif">
\ref IteratorBasedArgumentObjectFactories
<DD>
</DL>
Long argument lists provide for greater flexibility of functions,
but they are also tedious and error prone, when we don't need
the flexibility. Thus, we define argument objects which
automatically provide reasonable defaults for those arguments that we
didn't specify explicitly.
The argument objects are created via a number of factory functions.
Since these functions have descriptive names, they also serve
to improve readability: the name of each factory tells te purpose of its
argument object.
Consider the following example. Without argument objects we had to
write something like this (cf. \ref copyImageIf()):
\code
vigra::BImage img1, img2, img3;
// fill img1 and img2 ...
vigra::copyImageIf(img1.upperLeft(), img1.lowerRight(), img1.accessor(),
img2.upperLeft(), img2.accessor(),
img3.upperLeft(), img3.accessor());
\endcode
Using the argument object factories, this becomes much shorter and
more readable:
\code
vigra::copyImageIf(srcImageRange(img1),
maskImage(img2),
destImage(img3));
\endcode
The names of the factories clearly tell which image is source, mask,
and destination. In addition, the suffix <TT>Range</TT> must be used
for those argument objects that need to specify the lower right
corner of the region of interest. Typically, this is only the first
source argument, but sometimes the first destiniation argument must
also contain a range.
The factory functions come in two flavours: Iterator based and
image based factories. Above we have seen the image based variant.
The iterator based variant would look like this:
\code
vigra::copyImageIf(srcIterRange(img1.upperLeft(), img1.lowerRight()),
maskIter(img2.upperLeft()),
destIter(img3.upperLeft()));
\endcode
These factory functions contain the word <TT>Iter</TT> instead of the word
<TT>Image</TT>, They would normally be used if we couldn't access the
images (for example, within a function which got passed iterators)
or if we didn't want to operate on the entire image. The default
accessor is obtained via \ref vigra::IteratorTraits.
All factory functions also allow to specify accessors explicitly. This
is useful if we can't use the default accessor. This variant looks
like this:
\code
vigra::copyImageIf(srcImageRange(img1),
maskImage(img2, MaskPredicateAccessor()),
destImage(img3));
\endcode
or
\code
vigra::copyImageIf(srcIterRange(img1.upperLeft(), img1.lowerRight()),
maskIter(img2.upperLeft(), MaskPredicateAccessor()),
destIter(img3.upperLeft()));
\endcode
All versions can be mixed freely within one explession.
Technically, the argument objects are simply defined as
pairs and triples of iterators and accessor so that all algorithms
should declare a call interface version based on pairs and triples
(see for example \ref copyImageIf()).
\section ImageBasedArgumentObjectFactories Image Based Argument Object Factories
<b>Include:</b> automatically included with the image classes<br>
Namespace: vigra
These factories can be used to create argument objects when we
are given instances or subclasses of \ref vigra::BasicImage (see
\ref StandardImageTypes for instances defined per default).
These factory functions access <TT>img.upperLeft()</TT>,
<TT>img.lowerRight()</TT>, and <TT>img.accessor()</TT> to obtain the iterators
and accessor for the given image (unless the accessor is
given explicitly). The following factory functions are provided:
<table>
<tr><td>
\htmlonly
<th bgcolor="#f0e0c0" colspan=2 align=left>
\endhtmlonly
<TT>\ref vigra::BasicImage "vigra::BasicImage<SomeType>" img;</TT>
\htmlonly
</th>
\endhtmlonly
</td></tr>
<tr><td>
<TT>srcImageRange(img)</TT>
</td><td>
create argument object containing upper left, lower right, and
default accessor of source image
</td></tr>
<tr><td>
<TT>srcImageRange(img, SomeAccessor())</TT>
</td><td>
create argument object containing upper left, lower right
of source image, and given accessor
</td></tr>
<tr><td>
<TT>srcImage(img)</TT>
</td><td>
create argument object containing upper left, and
default accessor of source image
</td></tr>
<tr><td>
<TT>srcImage(img, SomeAccessor())</TT>
</td><td>
create argument object containing upper left
of source image, and given accessor
</td></tr>
<tr><td>
<TT>maskImage(img)</TT>
</td><td>
create argument object containing upper left, and
default accessor of mask image
</td></tr>
<tr><td>
<TT>maskImage(img, SomeAccessor())</TT>
</td><td>
create argument object containing upper left
of mask image, and given accessor
</td></tr>
<tr><td>
<TT>destImageRange(img)</TT>
</td><td>
create argument object containing upper left, lower right, and
default accessor of destination image
</td></tr>
<tr><td>
<TT>destImageRange(img, SomeAccessor())</TT>
</td><td>
create argument object containing upper left, lower right
of destination image, and given accessor
</td></tr>
<tr><td>
<TT>destImage(img)</TT>
</td><td>
create argument object containing upper left, and
default accessor of destination image
</td></tr>
<tr><td>
<TT>destImage(img, SomeAccessor())</TT>
</td><td>
create argument object containing upper left
of destination image, and given accessor
</td></tr>
</table>
\section MultiArrayBasedArgumentObjectFactories MultiArrayView Based Argument Object Factories
<b>Include:</b> automatically included with
"<a href="multi__array_8hxx-source.html">vigra/multi_array.hxx</a>"<br>
Namespace: vigra
These factories can be used to create argument objects when we
are given instances or subclasses of \ref vigra::MultiArrayView.
These factory functions access <TT>array.traverser_begin()</TT>,
<TT>array.traverser_end()</TT> to obtain the iterators. If no accessor is
given, they use the <tt>AccessorTraits<T></tt> to determine the default
accessor associated with the array's value type <tt>T</tt>.
The following factory functions are provided:
<table>
<tr><td>
\htmlonly
<th bgcolor="#f0e0c0" colspan=2 align=left>
\endhtmlonly
<TT>\ref vigra::MultiArrayView "vigra::MultiArrayView<N, SomeType>" array;</TT>
\htmlonly
</th>
\endhtmlonly
</td></tr>
<tr><td>
<TT>srcMultiArrayRange(img)</TT>
</td><td>
create argument object containing a \ref vigra::MultiIterator
marking the begin of the array, a shape object giving the desired
shape of the array (possibly a subarray) and the default const accessor for
<tt>SomeType</tt>
</td></tr>
<tr><td>
<TT>srcMultiArrayRange(img, SomeAccessor())</TT>
</td><td>
create argument object containing a \ref vigra::MultiIterator
marking the begin of the array, a shape object giving the desired
shape of the array (possibly a subarray) and the given accessor
</td></tr>
<tr><td>
<TT>srcMultiArray(img)</TT>
</td><td>
create argument object containing a \ref vigra::MultiIterator
marking the begin of the array, and the default const accessor for
<tt>SomeType</tt>
</td></tr>
<tr><td>
<TT>srcMultiArray(img, SomeAccessor())</TT>
</td><td>
create argument object containing a \ref vigra::MultiIterator
marking the begin of the array and the given accessor
</td></tr>
<tr><td>
<TT>destMultiArrayRange(img)</TT>
</td><td>
create argument object containing a \ref vigra::MultiIterator
marking the begin of the array, a shape object giving the desired
shape of the array (possibly a subarray) and the default accessor for
<tt>SomeType</tt>
</td></tr>
<tr><td>
<TT>destMultiArrayRange(img, SomeAccessor())</TT>
</td><td>
create argument object containing a \ref vigra::MultiIterator's
marking the begin of the array, a shape object giving the desired
shape of the array (possibly a subarray) and the given accessor
</td></tr>
<tr><td>
<TT>destMultiArray(img)</TT>
</td><td>
create argument object containing a \ref vigra::MultiIterator
marking the begin of the array and the default accessor for
<tt>SomeType</tt>
</td></tr>
<tr><td>
<TT>destMultiArray(img, SomeAccessor())</TT>
</td><td>
create argument object containing a \ref vigra::MultiIterator's
marking the begin of the array and the given accessor
</td></tr>
</table>
\section IteratorBasedArgumentObjectFactories Iterator Based Argument Object Factories
<b>\#include</b> "<a href="iteratortraits_8hxx-source.html">vigra/iteratortraits.hxx</a>"
Namespace: vigra
These factories can be used to create argument objects when we
are given \ref ImageIterators.
These factory functions use \ref vigra::IteratorTraits to
get the default accessor for the given iterator unless the
accessor is given explicitly. The following factory functions
are provided:
<table>
<tr><td>
\htmlonly
<th bgcolor="#f0e0c0" colspan=2 align=left>
\endhtmlonly
<TT>\ref vigra::BasicImage::Iterator "vigra::BasicImage<SomeType>::Iterator" i1, i2;</TT>
\htmlonly
</th>
\endhtmlonly
</td></tr>
<tr><td>
<TT>srcIterRange(i1, i2)</TT>
</td><td>
create argument object containing the given iterators and
corresponding default accessor (for source image)
</td></tr>
<tr><td>
<TT>srcIterRange(i1, i2, SomeAccessor())</TT>
</td><td>
create argument object containing given iterators and
accessor (for source image)
</td></tr>
<tr><td>
<TT>srcIter(i1)</TT>
</td><td>
create argument object containing the given iterator and
corresponding default accessor (for source image)
</td></tr>
<tr><td>
<TT>srcIter(i1, SomeAccessor())</TT>
</td><td>
create argument object containing given iterator and
accessor (for source image)
</td></tr>
<tr><td>
<TT>maskIter(i1)</TT>
</td><td>
create argument object containing the given iterator and
corresponding default accessor (for mask image)
</td></tr>
<tr><td>
<TT>maskIter(i1, SomeAccessor())</TT>
</td><td>
create argument object containing given iterator and
accessor (for mask image)
</td></tr>
<tr><td>
<TT>destIterRange(i1, i2)</TT>
</td><td>
create argument object containing the given iterators and
corresponding default accessor (for destination image)
</td></tr>
<tr><td>
<TT>destIterRange(i1, i2, SomeAccessor())</TT>
</td><td>
create argument object containing given iterators and
accessor (for destination image)
</td></tr>
<tr><td>
<TT>destIter(i1)</TT>
</td><td>
create argument object containing the given iterator and
corresponding default accessor (for destination image)
</td></tr>
<tr><td>
<TT>destIter(i1, SomeAccessor())</TT>
</td><td>
create argument object containing given iterator and
accessor (for destination image)
</td></tr>
</table>
*/
template <class Iterator, class Accessor>
inline triple<Iterator, Iterator, Accessor>
srcIterRange(Iterator const & upperleft, Iterator const & lowerright, Accessor a)
{
return triple<Iterator, Iterator, Accessor>(upperleft, lowerright, a);
}
template <class Iterator, class Accessor>
inline pair<Iterator, Accessor>
srcIter(Iterator const & upperleft, Accessor a)
{
return pair<Iterator, Accessor>(upperleft, a);
}
template <class Iterator, class Accessor>
inline pair<Iterator, Accessor>
maskIter(Iterator const & upperleft, Accessor a)
{
return pair<Iterator, Accessor>(upperleft, a);
}
template <class Iterator, class Accessor>
inline pair<Iterator, Accessor>
destIter(Iterator const & upperleft, Accessor a)
{
return pair<Iterator, Accessor>(upperleft, a);
}
template <class Iterator, class Accessor>
inline triple<Iterator, Iterator, Accessor>
destIterRange(Iterator const & upperleft, Iterator const & lowerright, Accessor a)
{
return triple<Iterator, Iterator, Accessor>(upperleft, lowerright, a);
}
template <class Iterator>
inline pair<Iterator, typename IteratorTraits<Iterator>::DefaultAccessor>
srcIter(Iterator const & upperleft)
{
return pair<Iterator, typename IteratorTraits<Iterator>::DefaultAccessor>(
upperleft,
typename IteratorTraits<Iterator>::DefaultAccessor());
}
template <class Iterator>
inline triple<Iterator, Iterator, typename IteratorTraits<Iterator>::DefaultAccessor>
srcIterRange(Iterator const & upperleft, Iterator const & lowerright)
{
return triple<Iterator, Iterator,
typename IteratorTraits<Iterator>::DefaultAccessor>(
upperleft, lowerright,
typename IteratorTraits<Iterator>::DefaultAccessor());
}
template <class Iterator>
inline pair<Iterator, typename IteratorTraits<Iterator>::DefaultAccessor>
maskIter(Iterator const & upperleft)
{
return pair<Iterator, typename IteratorTraits<Iterator>::DefaultAccessor>(
upperleft,
typename IteratorTraits<Iterator>::DefaultAccessor());
}
template <class Iterator>
inline pair<Iterator, typename IteratorTraits<Iterator>::DefaultAccessor>
destIter(Iterator const & upperleft)
{
return pair<Iterator, typename IteratorTraits<Iterator>::DefaultAccessor>(
upperleft,
typename IteratorTraits<Iterator>::DefaultAccessor());
}
template <class Iterator>
inline triple<Iterator, Iterator, typename IteratorTraits<Iterator>::DefaultAccessor>
destIterRange(Iterator const & upperleft, Iterator const & lowerright)
{
return triple<Iterator, Iterator,
typename IteratorTraits<Iterator>::DefaultAccessor>(
upperleft, lowerright,
typename IteratorTraits<Iterator>::DefaultAccessor());
}
//@}
} // namespace vigra
#endif // VIGRA_ITERATORTRAITS_HXX