ITK
4.1.0
Insight Segmentation and Registration Toolkit
|
/*========================================================================= * * Copyright Insight Software Consortium * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0.txt * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * *=========================================================================*/ // Software Guide : BeginLatex // // The \doxygen{PointSet} class uses an internal container to manage the storage of // \doxygen{Point}s. It is more efficient, in general, to manage points by using the // access methods provided directly on the points container. The following // example illustrates how to interact with the point container and how to use // point iterators. // // Software Guide : EndLatex #include "itkPointSet.h" int main(int, char *[]) { typedef itk::PointSet< unsigned short, 3 > PointSetType; // Software Guide : BeginLatex // // The type is defined by the \emph{traits} of the PointSet // class. The following line conveniently takes the PointsContainer type // from the PointSet traits and declare it in the global namespace. // // \index{itk::PointSet!PointsContainer} // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet typedef PointSetType::PointsContainer PointsContainer; // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // The actual type of the PointsContainer depends on what style of // PointSet is being used. The dynamic PointSet use the // \doxygen{MapContainer} while the static PointSet uses the // \doxygen{VectorContainer}. The vector and map containers are basically // ITK wrappers around the \href{http://www.sgi.com/tech/stl/}{STL} // classes \href{http://www.sgi.com/tech/stl/Map.html}{\code{std::map}} // and \href{http://www.sgi.com/tech/stl/Vector.html}{\code{std::vector}}. // By default, the PointSet uses a static style, hence the default // type of point container is an VectorContainer. Both the map // and vector container are templated over the type of the elements they // contain. In this case they are templated over PointType. // Containers are reference counted object. They are then created with the // \code{New()} method and assigned to a \doxygen{SmartPointer} after // creation. The following line creates a point container compatible with // the type of the PointSet from which the trait has been taken. // // \index{PointsContainer!New()} // \index{PointsContainer!Pointer} // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet PointsContainer::Pointer points = PointsContainer::New(); // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // Points can now be defined using the \code{PointType} trait from the // PointSet. // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet typedef PointSetType::PointType PointType; PointType p0; PointType p1; p0[0] = -1.0; p0[1] = 0.0; p0[2] = 0.0; // Point 0 = {-1,0,0 } p1[0] = 1.0; p1[1] = 0.0; p1[2] = 0.0; // Point 1 = { 1,0,0 } // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // The created points can be inserted in the PointsContainer using the // generic method \code{InsertElement()} which requires an identifier to // be provided for each point. // // \index{PointsContainer!InsertElement()} // \index{PointsContainer!InsertElement()} // \index{itk::VectorContainer!InsertElement()} // \index{itk::MapContainer!InsertElement()} // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet unsigned int pointId = 0; points->InsertElement( pointId++ , p0 ); points->InsertElement( pointId++ , p1 ); // Software Guide : EndCodeSnippet PointSetType::Pointer pointSet = PointSetType::New(); // Software Guide : BeginLatex // // Finally the PointsContainer can be assigned to the PointSet. This will // substitute any previously existing PointsContainer on the PointSet. The // assignment is done using the \code{SetPoints()} method. // // \index{itk::PointSet!SetPoints()} // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet pointSet->SetPoints( points ); // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // The PointsContainer object can be obtained from the PointSet using the // \code{GetPoints()} method. This method returns a pointer // to the actual container owned by the PointSet which is then assigned to // a SmartPointer. // // \index{itk::PointSet!GetPoints()} // \index{PointsContainer!Pointer} // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet PointsContainer::Pointer points2 = pointSet->GetPoints(); // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // The most efficient way to sequentially visit the points is to use the // iterators provided by PointsContainer. The \code{Iterator} type belongs // to the traits of the PointsContainer classes. It behaves pretty much like // the STL iterators.\footnote{If you dig deep enough into the code, you // will discover that these iterators are actually ITK wrappers around STL // iterators.} The Points iterator is not a reference counted class, so it // is created directly from the traits without using SmartPointers. // // \index{PointsContainer!Iterator} // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet typedef PointsContainer::Iterator PointsIterator; // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // The subsequent use of the iterator follows what you may expect from a STL // iterator. The iterator to the first point is obtained from the container // with the \code{Begin()} method and assigned to another iterator. // // \index{PointsContainer!Begin()} // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet PointsIterator pointIterator = points->Begin(); // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // The \code{++} operator on the iterator can be used to advance from one // point to the next. The actual value of the Point to which the iterator is // pointing can be obtained with the \code{Value()} method. The loop for // walking through all the points can be controlled by comparing the current // iterator with the iterator returned by the \code{End()} method of the // PointsContainer. The following lines illustrate the typical loop for // walking through the points. // // \index{PointsContainer!End()} // \index{PointsContainer!Iterator} // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet PointsIterator end = points->End(); while( pointIterator != end ) { PointType p = pointIterator.Value(); // access the point std::cout << p << std::endl; // print the point ++pointIterator; // advance to next point } // Software Guide : EndCodeSnippet // Software Guide : BeginLatex // // Note that as in STL, the iterator returned by the \code{End()} method is // not a valid iterator. This is called a past-end iterator in order to // indicate that it is the value resulting from advancing one step after // visiting the last element in the container. // // The number of elements stored in a container can be queried with the // \code{Size()} method. In the case of the PointSet, the following two // lines of code are equivalent, both of them returning the number of points // in the PointSet. // // \index{itk::PointSet!GetNumberOfPoints()} // \index{itk::PointSet!GetPoints()} // \index{PointsContainer!Size()} // // Software Guide : EndLatex // Software Guide : BeginCodeSnippet std::cout << pointSet->GetNumberOfPoints() << std::endl; std::cout << pointSet->GetPoints()->Size() << std::endl; // Software Guide : EndCodeSnippet return 0; }