SelectGraphVertices

VTKExamples/Java/Graphs/SelectGraphVertices


Question

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Code

SelectGraphVertices.java

import vtk.vtkAnnotationLink;
import vtk.vtkDataRepresentation;
import vtk.vtkGraphLayoutView;
import vtk.vtkIdTypeArray;
import vtk.vtkNativeLibrary;
import vtk.vtkRandomGraphSource;
import vtk.vtkSelection;
import vtk.vtkSelectionNode;

/*
 * Java language example to select edges and vertices from a generated Graph.
 */
public class SelectGraphVertices {

  static SelectGraphVertices me;

  /*
   * The following static calls will load the respective
   * vtkJava interface libraries on first reference to this
   * class.
   */
  // Loading Native Libraries.
  // Now it works in eclipse without any issues.
  static {
    if (!vtkNativeLibrary.LoadAllNativeLibraries()) {
      for (vtkNativeLibrary lib : vtkNativeLibrary.values()) {
        if (!lib.IsLoaded()) {
          System.out.println(lib.GetLibraryName() + " not loaded");
        }
      }
    }
    vtkNativeLibrary.DisableOutputWindow(null);
  }

  /**
   * All Java programs require a host class. in addition,
   * these two instance variables provide access to the
   * callback data used in this example.
   */
  vtkGraphLayoutView view;
  vtkAnnotationLink link;

  /*
   * primary test driver, creates an instance of this class
   * and then runs the example function.
   */
  public static void main(String[] args) {

    me = new SelectGraphVertices();
    me.doit();
  }

  /*
   * doit creates local objects and instantiates instance variables
   */
  public void doit() {
    vtkRandomGraphSource source = new vtkRandomGraphSource();
    source.Update();

    view = new vtkGraphLayoutView();
    view.AddRepresentationFromInputConnection(source.GetOutputPort());
    /*
     * This was described as vtkRenderedGraphRepresentation in the python example,
     * but the java type returns it as vtkDataRepresentation.
     */
    vtkDataRepresentation rep = view.GetRepresentation(0);

    /*
     * The vtkDataRepresentation should already have a vtkAnnotationLink,
     * so we just want to grab it and add an observer with our callback function attached
     * Note that Java callbacks use the this "pointer" to anchor vtk objects used by the callback
     * to establish references to required vtkobjects.
     */
    link = rep.GetAnnotationLink();
    link.AddObserver("AnnotationChangedEvent", this, "selectionCallback");

    view.GetRenderWindow().SetSize(600, 600);
    view.ResetCamera();
    view.Render();
    view.GetInteractor().Start();

  }

  /*
   * The Java callback signature has no parameters. This complicates some
   * vtk processes by eliminating the eventid and user data normally available
   * to C++ logic.
   */
  public void selectionCallback() {
    // In C++ there is some extra data passed to the callback, but in Python
    // the callback data is lost...

    // There can be two selection nodes, but which one is vertices and which is edges
    // does not seem to be guaranteed...
    System.out.println("in selection callback");

    vtkSelection sel = link.GetCurrentSelection();
    vtkSelectionNode node0 = sel.GetNode(0);
    int node0_field_type = node0.GetFieldType();

    vtkIdTypeArray sel_list0 = (vtkIdTypeArray) (link.GetCurrentSelection().GetNode(0).GetSelectionList());

    vtkSelectionNode node1 = sel.GetNode(1);
    int node1_field_type = node1.GetFieldType();

    vtkIdTypeArray sel_list1 = (vtkIdTypeArray) (link.GetCurrentSelection().GetNode(1).GetSelectionList());

    if (sel_list0.GetNumberOfTuples() > 0) {
      printFieldType(node0_field_type);
      for (int ii = 0; ii < sel_list0.GetNumberOfTuples(); ii++) {
        System.out.print("\t" + sel_list0.GetValue(ii));
      }
      System.out.println(" - on list 0.");
    }
    if (sel_list1.GetNumberOfTuples() > 0) {
      printFieldType(node1_field_type);
      for (int ii = 0; ii < sel_list1.GetNumberOfTuples(); ii++) {
        System.out.print("\t" + sel_list1.GetValue(ii));
      }
      System.out.println(" - on list 1.");
    }
    System.out.println("- - -");

  }

  public void printFieldType(int field_type) {
    if (field_type == 3)
      System.out.print("Vertices Selected:");
    else if (field_type == 4)
      System.out.print("Edges Selected:");
    else
      System.out.print("Unknown type:");
  }

}