VTK/Examples/Cxx/Graphs/SelectedVerticesAndEdgesObserver

• Thanks to Eric Monson

SelectedVerticesAndEdgesObserver.cxx

#include <vtkSmartPointer.h>
#include <vtkCallbackCommand.h>
#include <vtkAnnotationLink.h>
#include <vtkRenderedGraphRepresentation.h>
#include <vtkRenderer.h>
#include <vtkDoubleArray.h>
#include <vtkSelectionNode.h>
#include <vtkIdTypeArray.h>
#include <vtkSelection.h>
#include <vtkRenderWindow.h>
#include <vtkUnsignedCharArray.h>
#include <vtkObjectFactory.h>
#include <vtkGraphLayoutStrategy.h>
#include <vtkGraphLayoutView.h>
#include <vtkGraphWriter.h>
#include <vtkMutableUndirectedGraph.h>
#include <vtkRenderWindowInteractor.h>

void SelectionCallbackFunction(vtkObject* caller, long unsigned int eventId, void* clientData, void* callData);

int main(int, char *[])
{
  vtkSmartPointer<vtkMutableUndirectedGraph> g =
    vtkSmartPointer<vtkMutableUndirectedGraph>::New();

  vtkIdType v1 = g->AddVertex();
  vtkIdType v2 = g->AddVertex();

  g->AddEdge(v1, v2);
  g->AddEdge(v1, v2);

  vtkSmartPointer<vtkCallbackCommand> selectionCallback =
    vtkSmartPointer<vtkCallbackCommand>::New();
  selectionCallback->SetCallback (SelectionCallbackFunction);
  
  vtkSmartPointer<vtkGraphLayoutView> view =
    vtkSmartPointer<vtkGraphLayoutView>::New();
  view->AddRepresentationFromInput(g);
  view->SetLayoutStrategy("Simple 2D");
  view->GetRepresentation()->GetAnnotationLink()->AddObserver("AnnotationChangedEvent", selectionCallback);
  
  view->ResetCamera();
  view->Render();

  view->GetInteractor()->Start();

  return EXIT_SUCCESS;
}

void SelectionCallbackFunction(vtkObject* caller, long unsigned int eventId, void* clientData, void* callData)
{
  
  vtkAnnotationLink* annotationLink =
    static_cast<vtkAnnotationLink*>(caller);
    
  vtkSelection* selection = annotationLink->GetCurrentSelection();
  vtkSelectionNode* vertices;
  vtkSelectionNode* edges;
  if(selection->GetNode(0)->GetFieldType() == vtkSelectionNode::VERTEX)
    {
    vertices = selection->GetNode(0);
    }
  else if(selection->GetNode(0)->GetFieldType() == vtkSelectionNode::EDGE)
    {
    edges = selection->GetNode(0);
    }

  if(selection->GetNode(1)->GetFieldType() == vtkSelectionNode::VERTEX)
    {
    vertices = selection->GetNode(1);
    }
  else if(selection->GetNode(1)->GetFieldType() == vtkSelectionNode::EDGE)
    {
    edges = selection->GetNode(1);
    }

  vtkIdTypeArray* vertexList = vtkIdTypeArray::SafeDownCast(vertices->GetSelectionList());
  std::cout << "There are " << vertexList->GetNumberOfTuples() << " vertices selected." << std::endl;

  if(vertexList->GetNumberOfTuples() > 0)
    {
    std::cout << "Vertex Ids: ";
    }
  for(vtkIdType i = 0; i < vertexList->GetNumberOfTuples(); i++)
    {
    std::cout << vertexList->GetValue(i) << " ";
    }

  std::cout << std::endl;
  vtkIdTypeArray* edgeList = vtkIdTypeArray::SafeDownCast(edges->GetSelectionList());
  std::cout << "There are " << edgeList->GetNumberOfTuples() << " edges selected." << std::endl;
  if(edgeList->GetNumberOfTuples() > 0)
    {
    std::cout << "Edge Ids: ";
    }

  for(vtkIdType i = 0; i < edgeList->GetNumberOfTuples(); i++)
    {
    std::cout << edgeList->GetValue(i) << " ";
    }
  std::cout << std::endl;
 
}

Please try the new VTKExamples website.

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)

PROJECT(SelectedVerticesAndEdgesObserver)

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

add_executable(SelectedVerticesAndEdgesObserver MACOSX_BUNDLE SelectedVerticesAndEdgesObserver.cxx)

if(VTK_LIBRARIES)
  target_link_libraries(SelectedVerticesAndEdgesObserver ${VTK_LIBRARIES})
else()
  target_link_libraries(SelectedVerticesAndEdgesObserver vtkHybrid vtkWidgets)
endif()

Download and Build SelectedVerticesAndEdgesObserver

Click here to download SelectedVerticesAndEdgesObserver. and its CMakeLists.txt file.

Once the tarball SelectedVerticesAndEdgesObserver.tar has been downloaded and extracted,

cd SelectedVerticesAndEdgesObserver/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:

./SelectedVerticesAndEdgesObserver

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