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.

Code

Screenshot.cxx

#include <vtkVersion.h>

#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 <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 >= 1
  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 2.8)

PROJECT(Screenshot)

find_package(VTK REQUIRED)
include(${VTK_USE_FILE})

add_executable(Screenshot MACOSX_BUNDLE Screenshot.cxx )

target_link_libraries(Screenshot ${VTK_LIBRARIES})

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.