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SelectedVerticesAndEdgesObserver

vtk-examples/Cxx/Graphs/SelectedVerticesAndEdgesObserver


Description

  • Thanks to Eric Monson

Question

If you have a question about this example, please use the VTK Discourse Forum

Code

SelectedVerticesAndEdgesObserver.cxx

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

namespace {

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

int main(int, char*[])
{
  vtkNew<vtkNamedColors> colors;

  vtkNew<vtkMutableUndirectedGraph> g;

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

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

  vtkNew<vtkCallbackCommand> selectionCallback;
  selectionCallback->SetCallback(SelectionCallbackFunction);

  vtkNew<vtkGraphLayoutView> view;
  view->AddRepresentationFromInput(g);
  view->SetLayoutStrategy("Simple 2D");
  view->GetRepresentation()->GetAnnotationLink()->AddObserver(
      "AnnotationChangedEvent", selectionCallback);

  view->GetRenderer()->SetBackground(colors->GetColor3d("Navy").GetData());
  view->GetRenderer()->SetBackground2(
      colors->GetColor3d("MidnightBlue").GetData());
  view->GetRenderWindow()->SetWindowName("SelectedVerticesAndEdges");
  view->ResetCamera();
  view->Render();

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

  return EXIT_SUCCESS;
}

namespace {

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 =
      dynamic_cast<vtkIdTypeArray*>(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 =
      dynamic_cast<vtkIdTypeArray*>(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;
}

} // namespace

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(SelectedVerticesAndEdgesObserver)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkCommonDataModel
  vtkFiltersGeneral
  vtkIOLegacy
  vtkInfovisLayout
  vtkInteractionStyle
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2
  vtkViewsInfovis
  QUIET
)

if (NOT VTK_FOUND)
  message("Skipping SelectedVerticesAndEdgesObserver: ${VTK_NOT_FOUND_MESSAGE}")
  return ()
endif()
message (STATUS "VTK_VERSION: ${VTK_VERSION}")
if (VTK_VERSION VERSION_LESS "8.90.0")
  # old system
  include(${VTK_USE_FILE})
  add_executable(SelectedVerticesAndEdgesObserver MACOSX_BUNDLE SelectedVerticesAndEdgesObserver.cxx )
  target_link_libraries(SelectedVerticesAndEdgesObserver PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(SelectedVerticesAndEdgesObserver MACOSX_BUNDLE SelectedVerticesAndEdgesObserver.cxx )
  target_link_libraries(SelectedVerticesAndEdgesObserver PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS SelectedVerticesAndEdgesObserver
    MODULES ${VTK_LIBRARIES}
    )
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

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