graph_display/graph_display.cpp

This example gives a minimalistic approach of importing a graph and displaying it with Tulip OpenGL rendering engine In this example, we are making a standalone program that will load a graph file passed as argument to the program and display it into a new window.

The code contains a step-by-step explanation of the process, please refer to classes documentation for more information about their usage.

#include <tulip/PluginLoaderTxt.h>
#include <tulip/PluginLibraryLoader.h>
#include <tulip/GlMainWidget.h>
#include <tulip/MouseInteractors.h>
#include <tulip/TlpQtTools.h>
#include <tulip/LayoutProperty.h>
#include <tulip/SizeProperty.h>
#include <tulip/StringProperty.h>
#include <tulip/DoubleProperty.h>
#include <tulip/IntegerProperty.h>
#include <tulip/TulipViewSettings.h>
#include <tulip/GlGraphComposite.h>
#include <tulip/GlGraphRenderingParameters.h>

#include <QApplication>
#include <QString>

#include <iostream>

using namespace tlp;
using namespace std;

void addChildren(Graph *graph, node root, int depth, int degree) {
  if (depth > 0) {
    for (int i = 0; i < degree; ++i) {
      node child = graph->addNode();
      graph->addEdge(root, child);
      addChildren(graph, child, depth - 1, degree);
    }
  }
}

Graph *createCompleteTree(int depth, int degree) {
  Graph *graph = newGraph();
  node root = graph->addNode();
  addChildren(graph, root, depth, degree);
  return graph;
}

// That function sets some visual properties on a complete tree whose depth equals 5
void setTreeVisualProperties(Graph *tree) {

  // First compute a layout, we use the Bubble Tree algorithm
  LayoutProperty *viewLayout = tree->getProperty<LayoutProperty>("viewLayout");
  std::string errMsg;
  tree->applyPropertyAlgorithm("Bubble Tree", viewLayout, errMsg);

  // Then apply Auto Sizing on the nodes
  SizeProperty *viewSize = tree->getProperty<SizeProperty>("viewSize");
  tree->applyPropertyAlgorithm("Auto Sizing", viewSize, errMsg);

  // Labels the node with their id
  StringProperty *viewLabel = tree->getProperty<StringProperty>("viewLabel");
  for (auto n : tree->nodes()) {
    viewLabel->setNodeValue(n, QStringToTlpString(QString::number(n.id)));
  }

  // Add a border to the nodes, keep the default color who is black
  DoubleProperty *viewBorderWidth = tree->getProperty<DoubleProperty>("viewBorderWidth");
  viewBorderWidth->setAllNodeValue(1);

  // Build some maps to set shapes and colors according to the dag level of a node
  std::vector<int> glyphsMap;
  glyphsMap.push_back(tlp::NodeShape::Square);
  glyphsMap.push_back(tlp::NodeShape::Circle);
  glyphsMap.push_back(tlp::NodeShape::RoundedBox);
  glyphsMap.push_back(tlp::NodeShape::Hexagon);
  glyphsMap.push_back(tlp::NodeShape::Star);
  glyphsMap.push_back(tlp::NodeShape::Ring);

  std::vector<Color> colorsMap;
  colorsMap.push_back(Color::Red);
  colorsMap.push_back(Color::Azure);
  colorsMap.push_back(Color::Lemon);
  colorsMap.push_back(Color::SpringGreen);
  colorsMap.push_back(Color::Apricot);
  colorsMap.push_back(Color::Magenta);

  // Compute the Dag Level metric, the value of each node will correspond
  // to their layer id in the tree
  DoubleProperty dagLevel(tree);
  tree->applyPropertyAlgorithm("Dag Level", &dagLevel, errMsg);

  // Sets different shapes and colors for each layer of the tree
  IntegerProperty *viewShape = tree->getProperty<IntegerProperty>("viewShape");
  ColorProperty *viewColor = tree->getProperty<ColorProperty>("viewColor");
  for (auto n : tree->nodes()) {
    viewShape->setNodeValue(n, glyphsMap[int(dagLevel.getNodeValue(n))]);
    viewColor->setNodeValue(n, colorsMap[int(dagLevel.getNodeValue(n))]);
  }
}

// That function sets some rendering parameters on the graph to visualize
void setGraphRenderingParameters(GlGraphComposite *glGraphComposite) {
  GlGraphRenderingParameters *renderingParameters =
      glGraphComposite->getRenderingParametersPointer();
  // Activate the display of edge extremities (arrows by default)
  renderingParameters->setViewArrow(true);
  // No color interpolation for the edges
  renderingParameters->setEdgeColorInterpolate(false);
  // Size interpolation for the edges
  renderingParameters->setEdgeSizeInterpolate(true);
  // Scale labels to node sizes
  renderingParameters->setLabelScaled(true);
}

int main(int argc, char **argv) {

  // A QApplication must always be declared at the beginning of the main function if you intend to
  // use the tulip-gui library
  // This must be done before calling tlp::initTulipSoftware()
  QApplication app(argc, argv);

  // Initialize the library and load all plugins
  tlp::initTulipSoftware();

  Graph *g = nullptr;
  if (QApplication::arguments().size() == 2) {
    // Load the file passed as first argument into a graph.
    // This method will select the default Tulip algorithm plugin (TLP)
    QString filename = QApplication::arguments()[1];
    if (!((filename.endsWith(".tlp")) || (filename.endsWith(".tlp.gz")))) {
      cout << "File " << QStringToTlpString(filename)
           << " not compatible. Use a tlp file or a tlp.gz file" << endl;
      exit(EXIT_FAILURE);
    }
    g = tlp::loadGraph(QStringToTlpString(filename));
  } else {
    // If no arguments were given to the command, create a complete tree of depth 5
    // and degree 2 for demo purpose
    g = createCompleteTree(5, 2);
    // Set some visual properties in order to visualize the tree
    setTreeVisualProperties(g);
  }

  // Creates the main widget that will display our graph
  GlMainWidget *mainWidget = new GlMainWidget(nullptr);

  // Adds a layer to the scene
  GlLayer *mainLayer = mainWidget->getScene()->createLayer("Main");

  // Adds the graph to this layer
  mainLayer->addGraph(g, "graph");

  // Sets some rendering parameters on the graph to visualize
  setGraphRenderingParameters(mainWidget->getScene()->getGlGraphComposite());

  // Display the widget
  mainWidget->show();

  // Flush event loop in order to let paint events pass through in order for the scene to be
  // initialized.
  QApplication::processEvents();

  // Center the camera and draw the graph
  mainWidget->centerScene();
  mainWidget->draw();

  // Adds Zoom and pan navigation to the widget
  mainWidget->installEventFilter(new MouseNKeysNavigator);
  return app.exec();
}