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Timer

vtk-examples/Cxx/Utilities/Timer

Description

This example demonstrates how to use a timer with an interactor. It outputs a count every specified interval.

Question

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

Code

Timer.cxx

#include <vtkCallbackCommand.h>
#include <vtkCommand.h>
#include <vtkNew.h>
#include <vtkRenderWindow.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkRenderer.h>

#include <iostream>
#include <string>

class vtkTimerCallback : public vtkCallbackCommand
{
public:
  vtkTimerCallback() = default;

  static vtkTimerCallback* New()
  {
    vtkTimerCallback* cb = new vtkTimerCallback;
    cb->TimerCount = 0;
    return cb;
  }

  virtual void Execute(vtkObject* caller, unsigned long eventId,
                       void* vtkNotUsed(callData))
  {
    if (vtkCommand::TimerEvent == eventId)
    {
      ++this->TimerCount;
    }
    std::cout << this->TimerCount << std::endl;
    if (this->TimerCount >= this->maxCount)
    {
      auto iren = dynamic_cast<vtkRenderWindowInteractor*>(caller);
      if (this->timerId > -1)
      {
        iren->DestroyTimer(this->timerId);
      }
    }
  }

private:
  int TimerCount = 0;

public:
  int maxCount = 0;
  int timerId = -1;
};

int main(int, char*[])
{
  // Setup renderer, render window, and interactor.
  vtkNew<vtkRenderer> renderer;
  vtkNew<vtkRenderWindow> renderWindow;
  renderWindow->AddRenderer(renderer);
  renderWindow->SetWindowName("Timer");

  vtkNew<vtkRenderWindowInteractor> interactor;
  interactor->SetRenderWindow(renderWindow);

  // Initialize must be called prior to creating timer events.
  renderWindow->Render();
  interactor->Initialize();

  // Sign up to receive TimerEvent.
  vtkNew<vtkTimerCallback> cb;
  interactor->AddObserver(vtkCommand::TimerEvent, cb);

  int timerId = interactor->CreateRepeatingTimer(100);
  std::cout << "timerId: " << timerId << std::endl;
  // Destroy the timer when maxCount is reached.
  cb->maxCount = 10;
  cb->timerId = timerId;

  // Note: nothing is displayed in the render window.
  // Start the interaction and timer.
  interactor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.12 FATAL_ERROR)

project(Timer)

find_package(VTK COMPONENTS 
  CommonCore
  InteractionStyle
  RenderingContextOpenGL2
  RenderingCore
  RenderingFreeType
  RenderingGL2PSOpenGL2
  RenderingOpenGL2
)

if (NOT VTK_FOUND)
  message(FATAL_ERROR "Timer: Unable to find the VTK build folder.")
endif()

# Prevent a "command line is too long" failure in Windows.
set(CMAKE_NINJA_FORCE_RESPONSE_FILE "ON" CACHE BOOL "Force Ninja to use response files.")
add_executable(Timer MACOSX_BUNDLE Timer.cxx )
  target_link_libraries(Timer PRIVATE ${VTK_LIBRARIES}
)
# vtk_module_autoinit is needed
vtk_module_autoinit(
  TARGETS Timer
  MODULES ${VTK_LIBRARIES}
)

Download and Build Timer

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

cd Timer/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:

./Timer

WINDOWS USERS

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