Screenshot

VTKExamples/Cxx/Utilities/Screenshot

Description

This example shows how to save the window to a file (png in this case). You can combine this with the KeypressEvents example to make a useful functionality.

Other Languages

See (Python), (Java)

Question

If you have a simple question about this example contact us at VTKExamplesProject If your question is more complex and may require extended discussion, please use the VTK Discourse Forum

Code

Screenshot.cxx

#include <vtkPolyDataMapper.h>
#include <vtkActor.h>
#include <vtkSmartPointer.h>
#include <vtkRenderWindow.h>
#include <vtkRenderer.h>
#include <vtkRenderWindowInteractor.h>
#include <vtkPolyData.h>
#include <vtkSphereSource.h>
#include <vtkWindowToImageFilter.h>
#include <vtkVersion.h>
#include <vtkPNGWriter.h>

int main(int, char *[])
{
  vtkSmartPointer<vtkSphereSource> sphereSource = 
    vtkSmartPointer<vtkSphereSource>::New();
  sphereSource->SetCenter(0.0, 0.0, 0.0);
  sphereSource->SetRadius(5.0);
  sphereSource->Update();

  // Visualize
  vtkSmartPointer<vtkPolyDataMapper> mapper = 
    vtkSmartPointer<vtkPolyDataMapper>::New();
  mapper->SetInputConnection(sphereSource->GetOutputPort());

  vtkSmartPointer<vtkActor> actor = 
    vtkSmartPointer<vtkActor>::New();
  actor->SetMapper(mapper);

  vtkSmartPointer<vtkRenderer> renderer = 
    vtkSmartPointer<vtkRenderer>::New();
  vtkSmartPointer<vtkRenderWindow> renderWindow = 
    vtkSmartPointer<vtkRenderWindow>::New();
  renderWindow->AddRenderer(renderer);
  renderWindow->SetAlphaBitPlanes(1); //enable usage of alpha channel

  vtkSmartPointer<vtkRenderWindowInteractor> renderWindowInteractor = 
    vtkSmartPointer<vtkRenderWindowInteractor>::New();
  renderWindowInteractor->SetRenderWindow(renderWindow);

  renderer->AddActor(actor);
  renderer->SetBackground(1,1,1); // Background color white

  renderWindow->Render();

  // Screenshot  
  vtkSmartPointer<vtkWindowToImageFilter> windowToImageFilter = 
    vtkSmartPointer<vtkWindowToImageFilter>::New();
  windowToImageFilter->SetInput(renderWindow);
#if VTK_MAJOR_VERSION >= 8 || VTK_MAJOR_VERSION == 8 && VTK_MINOR_VERSION >= 90
  windowToImageFilter->SetScale(2); // image quality
#else
  windowToImageFilter->SetMagnification(2); //image quality
#endif
  windowToImageFilter->SetInputBufferTypeToRGBA(); //also record the alpha (transparency) channel
  windowToImageFilter->ReadFrontBufferOff(); // read from the back buffer
  windowToImageFilter->Update();

  vtkSmartPointer<vtkPNGWriter> writer = 
    vtkSmartPointer<vtkPNGWriter>::New();
  writer->SetFileName("screenshot2.png");
  writer->SetInputConnection(windowToImageFilter->GetOutputPort());
  writer->Write();

  renderWindow->Render();  
  renderer->ResetCamera();
  renderWindow->Render();
  renderWindowInteractor->Start();

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.3 FATAL_ERROR)

project(Screenshot)

find_package(VTK COMPONENTS 
  vtkCommonCore
  vtkCommonDataModel
  vtkFiltersSources
  vtkIOImage
  vtkInteractionStyle
  vtkRenderingContextOpenGL2
  vtkRenderingCore
  vtkRenderingFreeType
  vtkRenderingGL2PSOpenGL2
  vtkRenderingOpenGL2 QUIET)
if (NOT VTK_FOUND)
  message("Skipping Screenshot: ${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(Screenshot MACOSX_BUNDLE Screenshot.cxx )
  target_link_libraries(Screenshot PRIVATE ${VTK_LIBRARIES})
else ()
  # include all components
  add_executable(Screenshot MACOSX_BUNDLE Screenshot.cxx )
  target_link_libraries(Screenshot PRIVATE ${VTK_LIBRARIES})
  # vtk_module_autoinit is needed
  vtk_module_autoinit(
    TARGETS Screenshot
    MODULES ${VTK_LIBRARIES}
    )
endif ()

Download and Build Screenshot

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

cd Screenshot/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:

./Screenshot

WINDOWS USERS

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