Diagram

Description¶

This example show how to create a custom vtkChartXY by providing a subclass of vtkContextItem.

Also, the example uses vtkColorSeries to specify the colors of the diagram's boxes. The vtkColorSeries scheme can be specified on the command line. If an unknown scheme is used, a list of valid schemes is provided.

Code¶

Diagram.cxx

#include <vtkRenderer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkSmartPointer.h>
#include <vtkObjectFactory.h>
#include <vtkContext2D.h>
#include <vtkContextItem.h>
#include <vtkContextActor.h>
#include <vtkContextScene.h>
#include <vtkPen.h>
#include <vtkBrush.h>
#include <vtkTextProperty.h>
#include <vtkOpenGLContextDevice2D.h>
#include <vtkStdString.h>
#include <vtkColorSeries.h>
#include <vtkNamedColors.h>

//----------------------------------------------------------------------------
class APIDiagram : public vtkContextItem
{
public:
  static APIDiagram *New();
  vtkTypeMacro(APIDiagram, vtkContextItem);
  APIDiagram()
  {
    this->ColorSeries = vtkSmartPointer<vtkColorSeries>::New();
    this->ColorSchemeName = "Brewer Diverging Spectral (7)";
    this->ColorSeries->SetColorSchemeByName(this->ColorSchemeName);
  }
  // Paint event for the chart, called whenever the chart needs to be drawn
  virtual bool Paint(vtkContext2D *painter);
  void SetColorSchemeName (std::string seriesName)
  {
    this->ColorSeries->SetColorSchemeByName(seriesName);
    if (this->ColorSeries->GetColorScheme() > vtkColorSeries::BREWER_QUALITATIVE_SET3)
    {
      this->PrintColorSchemes();
    }
  }
  void PrintColorSchemes(ostream& os = std::cout)
  {
    int saveId = this->ColorSeries->GetColorScheme();
    for (unsigned int i = 0; i < vtkColorSeries::BREWER_QUALITATIVE_SET3; ++i)
    {
      this->ColorSeries->SetColorScheme(i);
      os << this->ColorSeries->GetColorSchemeName() << std::endl;
    }
    this->ColorSeries->SetColorScheme(saveId);
  }
protected:
  vtkSmartPointer<vtkColorSeries> ColorSeries;
  std::string ColorSchemeName;
};

//----------------------------------------------------------------------------
int main( int argc, char *argv[] )
{
  std::string colorSchemeName = "Brewer Diverging Brown-Blue-Green (7)";
  if (argc > 1)
  {
    colorSchemeName = std::string(argv[1]);
  }

  // Set up a 2D chart actor, APIDiagram object andn add them to the renderer
  vtkNew<APIDiagram>  diagram;
  diagram->SetColorSchemeName(colorSchemeName);

  vtkNew<vtkContextActor>  actor;
  actor->GetScene()->AddItem(diagram);

  vtkNew<vtkNamedColors> colors;
  vtkNew<vtkRenderer>  renderer;
  renderer->SetBackground(colors->GetColor3d("Tan").GetData());

  vtkNew<vtkRenderWindow>  renderWindow;
  renderWindow->SetSize(800, 600);
  renderWindow->AddRenderer(renderer);
  renderer->AddActor(actor);

  vtkNew<vtkRenderWindowInteractor>  interactor;
  interactor->SetRenderWindow(renderWindow);
  renderWindow->SetMultiSamples(0);
  renderWindow->Render();

  interactor->Start();

  return EXIT_SUCCESS;
}

// Make our new derived class to draw a diagram
vtkStandardNewMacro(APIDiagram);
// This function draws our API diagram
bool APIDiagram::Paint(vtkContext2D *painter)
{
  // Drawing a hard wired diagram 800x600 as a demonstration of the 2D API
  painter->GetTextProp()->SetVerticalJustificationToCentered();
  painter->GetTextProp()->SetJustificationToCentered();
  painter->GetTextProp()->SetColor(0.0, 0.0, 0.0);
  painter->GetTextProp()->SetFontSize(24);
  painter->GetPen()->SetColor(0, 0, 0);

  unsigned int c = 0;
  painter->GetBrush()->SetColor((this->ColorSeries->GetColorRepeating(c)).GetData());
  c++;

  painter->DrawRect(100, 50, 200, 100);
  painter->DrawString(200, 100, "OpenGL");

  painter->GetBrush()->SetColor((this->ColorSeries->GetColorRepeating(c)).GetData());
  c++;
  painter->DrawRect(300, 50, 200, 100);
  painter->DrawString(400, 100, "Others?");

  painter->GetBrush()->SetColor((this->ColorSeries->GetColorRepeating(c)).GetData());
  c++;
  painter->DrawRect(500, 50, 200, 100);
  painter->DrawString(600, 100, "Others?");

  painter->GetBrush()->SetColor((this->ColorSeries->GetColorRepeating(c)).GetData());
  c++;
  painter->DrawRect(100, 150, 600, 100);
  painter->DrawString(400, 200, "2D API");

  painter->GetBrush()->SetColor((this->ColorSeries->GetColorRepeating(c)).GetData());
  c++;
  painter->DrawRect(100, 250, 600, 200);
  painter->DrawString(400, 400, "Canvas API");

  painter->GetBrush()->SetColor((this->ColorSeries->GetColorRepeating(c)).GetData());
  c++;
  painter->DrawRect(100, 250, 300, 100);
  painter->DrawString(250, 300, "Point Mark");

  painter->GetBrush()->SetColor((this->ColorSeries->GetColorRepeating(c)).GetData());
  painter->DrawRect(100, 450, 600, 100);
  painter->DrawString(400, 500, "Canvas View");

return true;
}

CMakeLists.txt¶

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(Diagram)

find_package(VTK COMPONENTS 
  vtkCommonColor
  vtkCommonCore
  vtkInteractionStyle
  vtkRenderingContext2D
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
  message("Skipping Diagram: ${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(Diagram MACOSX_BUNDLE Diagram.cxx )
  target_link_libraries(Diagram PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(Diagram MACOSX_BUNDLE Diagram.cxx )
  target_link_libraries(Diagram PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS Diagram
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build Diagram¶

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

cd Diagram/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:

./Diagram

WINDOWS USERS

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