AlgorithmSource

VTKExamples/Cxx/Developers/AlgorithmSource

Description

This example demonstrates how to create a source that returns a custom class. To test that it is working, the class vtkTest1 simply stores a double named 'Value' that is instantiated to the value of 4.5. Example.cxx instantiates a vtkTestSource which produces a vtkTest1.

Code

AlgorithmSource.cxx

#include <vtkSmartPointer.h>

#include "vtkTestAlgorithmSource.h"
#include "vtkTest1.h"

int main(int, char *[])
{
  vtkTestAlgorithmSource* source = vtkTestAlgorithmSource::New();
  source->Update();

  vtkTest1* test = source->GetOutput();
  std::cout << test->GetValue() << std::endl;

  return EXIT_SUCCESS;
}

vtkTest1.h

#ifndef __vtkTest1_h
#define __vtkTest1_h

#include <vtkDataObject.h>

class vtkTest1 : public vtkDataObject
{
  public:
    static vtkTest1* New();
    vtkTypeMacro(vtkTest1,vtkDataObject);
    void PrintSelf( ostream& os, vtkIndent indent );

    vtkGetMacro(Value, double);

  protected:
    vtkTest1();
    ~vtkTest1();

  private:
    vtkTest1( const vtkTest1& ); // Not implemented.
    void operator = ( const vtkTest1& ); // Not implemented.

    double Value;
};

#endif 

vtkTestAlgorithmSource.h

#ifndef __vtkTestAlgorithmSource_h
#define __vtkTestAlgorithmSource_h

#include <vtkAlgorithm.h>

class vtkDataSet;
class vtkTest1;

class vtkTestAlgorithmSource : public vtkAlgorithm
{
public:
  static vtkTestAlgorithmSource *New();
  vtkTypeMacro(vtkTestAlgorithmSource,vtkAlgorithm);
  void PrintSelf(ostream& os, vtkIndent indent);

  // Description:
  // Get the output data object for a port on this algorithm.
  vtkTest1* GetOutput();
  vtkTest1* GetOutput(int);
  virtual void SetOutput(vtkDataObject* d);

  // Description:
  // see vtkAlgorithm for details
  virtual int ProcessRequest(vtkInformation*,
                             vtkInformationVector**,
                             vtkInformationVector*);

protected:
  vtkTestAlgorithmSource();
  ~vtkTestAlgorithmSource();

  // Description:
  // This is called by the superclass.
  // This is the method you should override.
  virtual int RequestDataObject(
    vtkInformation* request,
    vtkInformationVector** inputVector,
    vtkInformationVector* outputVector );

  // convenience method
  virtual int RequestInformation(
    vtkInformation* request,
    vtkInformationVector** inputVector,
    vtkInformationVector* outputVector );

  // Description:
  // This is called by the superclass.
  // This is the method you should override.
  virtual int RequestData(
    vtkInformation* request,
    vtkInformationVector** inputVector,
    vtkInformationVector* outputVector );

  // Description:
  // This is called by the superclass.
  // This is the method you should override.
  virtual int RequestUpdateExtent(
    vtkInformation*,
    vtkInformationVector**,
    vtkInformationVector* );

  virtual int FillOutputPortInformation( int port, vtkInformation* info );

private:
  vtkTestAlgorithmSource( const vtkTestAlgorithmSource& ); // Not implemented.
  void operator = ( const vtkTestAlgorithmSource& );  // Not implemented.
};

#endif

vtkTest1.cxx

#include "vtkTest1.h"

#include <vtkObjectFactory.h>

vtkStandardNewMacro(vtkTest1);

vtkTest1::vtkTest1()
{
  this->Value = 4.5;
}

vtkTest1::~vtkTest1()
{

}

void vtkTest1::PrintSelf( ostream& os, vtkIndent indent )
{
  this->Superclass::PrintSelf( os, indent );
}

vtkTestAlgorithmSource.cxx

#include "vtkTestAlgorithmSource.h"
#include "vtkTest1.h"

#include <vtkCommand.h>
#include <vtkInformation.h>
#include <vtkInformationVector.h>
#include <vtkObjectFactory.h>
#include <vtkStreamingDemandDrivenPipeline.h>

vtkStandardNewMacro(vtkTestAlgorithmSource);

//----------------------------------------------------------------------------
vtkTestAlgorithmSource::vtkTestAlgorithmSource()
{
  this->SetNumberOfInputPorts( 0 );
  this->SetNumberOfOutputPorts( 1 );
}

//----------------------------------------------------------------------------
vtkTestAlgorithmSource::~vtkTestAlgorithmSource()
{
}

//----------------------------------------------------------------------------
void vtkTestAlgorithmSource::PrintSelf(ostream& os, vtkIndent indent)
{
  this->Superclass::PrintSelf(os, indent);
}

//----------------------------------------------------------------------------
vtkTest1* vtkTestAlgorithmSource::GetOutput()
{
  return this->GetOutput(0);
}

//----------------------------------------------------------------------------
vtkTest1* vtkTestAlgorithmSource::GetOutput(int port)
{
  return vtkTest1::SafeDownCast(this->GetOutputDataObject(port));
}

//----------------------------------------------------------------------------
void vtkTestAlgorithmSource::SetOutput(vtkDataObject* d)
{
  this->GetExecutive()->SetOutputData(0, d);
}


//----------------------------------------------------------------------------
int vtkTestAlgorithmSource::ProcessRequest(vtkInformation* request,
                                     vtkInformationVector** inputVector,
                                     vtkInformationVector* outputVector)
{
  // Create an output object of the correct type.
  if(request->Has(vtkDemandDrivenPipeline::REQUEST_DATA_OBJECT()))
  {
    return this->RequestDataObject(request, inputVector, outputVector);
  }
  // generate the data
  if(request->Has(vtkDemandDrivenPipeline::REQUEST_DATA()))
  {
    return this->RequestData(request, inputVector, outputVector);
  }

  if(request->Has(vtkStreamingDemandDrivenPipeline::REQUEST_UPDATE_EXTENT()))
  {
    return this->RequestUpdateExtent(request, inputVector, outputVector);
  }

  // execute information
  if(request->Has(vtkDemandDrivenPipeline::REQUEST_INFORMATION()))
  {
    return this->RequestInformation(request, inputVector, outputVector);
  }

  return this->Superclass::ProcessRequest(request, inputVector, outputVector);
}

//----------------------------------------------------------------------------
int vtkTestAlgorithmSource::FillOutputPortInformation(
    int vtkNotUsed(port), vtkInformation* info)
{
  // now add our info
  info->Set(vtkDataObject::DATA_TYPE_NAME(), "vtkTest1");
  return 1;
}


//----------------------------------------------------------------------------
int vtkTestAlgorithmSource::RequestDataObject(
                                        vtkInformation* vtkNotUsed(request),
    vtkInformationVector** vtkNotUsed(inputVector),
                                      vtkInformationVector* outputVector )
{
  for ( int i = 0; i < this->GetNumberOfOutputPorts(); ++i )
  {
    vtkInformation* outInfo = outputVector->GetInformationObject( i );
    vtkTest1* output = vtkTest1::SafeDownCast(
                                            outInfo->Get( vtkDataObject::DATA_OBJECT() ) );
    if ( ! output )
    {
      output = vtkTest1::New();
      outInfo->Set( vtkDataObject::DATA_OBJECT(), output );
      output->FastDelete();
      this->GetOutputPortInformation( i )->Set(
                                      vtkDataObject::DATA_EXTENT_TYPE(), output->GetExtentType() );
    }
  }
  return 1;
}

//----------------------------------------------------------------------------
int vtkTestAlgorithmSource::RequestInformation(
                                         vtkInformation* vtkNotUsed(request),
    vtkInformationVector** vtkNotUsed(inputVector),
                                      vtkInformationVector* vtkNotUsed(outputVector))
{
  // do nothing let subclasses handle it
  return 1;
}

//----------------------------------------------------------------------------
int vtkTestAlgorithmSource::RequestUpdateExtent(
                                          vtkInformation* vtkNotUsed(request),
    vtkInformationVector** inputVector,
    vtkInformationVector* vtkNotUsed(outputVector))
{
  int numInputPorts = this->GetNumberOfInputPorts();
  for (int i=0; i<numInputPorts; i++)
  {
    int numInputConnections = this->GetNumberOfInputConnections(i);
    for (int j=0; j<numInputConnections; j++)
    {
      vtkInformation* inputInfo = inputVector[i]->GetInformationObject(j);
      inputInfo->Set(vtkStreamingDemandDrivenPipeline::EXACT_EXTENT(), 1);
    }
  }
  return 1;
}

//----------------------------------------------------------------------------
// This is the superclasses style of Execute method.  Convert it into
// an imaging style Execute method.
int vtkTestAlgorithmSource::RequestData(
                                  vtkInformation* vtkNotUsed(request),
    vtkInformationVector** vtkNotUsed( inputVector ),
                                       vtkInformationVector* vtkNotUsed(outputVector) )
{
  // do nothing let subclasses handle it
  return 1;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(AlgorithmSource)

find_package(VTK REQUIRED)
include(${VTK_USE_FILE})

add_executable(AlgorithmSource MACOSX_BUNDLE AlgorithmSource.cxx  vtkTest1.cxx vtkTestAlgorithmSource.cxx)

target_link_libraries(AlgorithmSource ${VTK_LIBRARIES})

Download and Build AlgorithmSource

Click here to download AlgorithmSource and its CMakeLists.txt file. Once the tarball AlgorithmSource.tar has been downloaded and extracted,

cd AlgorithmSource/build 

If VTK is installed:

cmake ..

If VTK is not installed but compiled on your system, you will need to specify the path to your VTK build:

cmake -DVTK_DIR:PATH=/home/me/vtk_build ..

Build the project:

make

and run it:

./AlgorithmSource

WINDOWS USERS

Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time.