Difference between revisions of "VTK/Examples/Cxx/Qt/ImageDataToQImage"

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(minor tweaks to the code; whitespace; documentation)
(use actual number of scalar components, instead of hardcoding 3; use smart pointer instead of raw pointer; adjust brace indentation)
Line 29: Line 29:
  
 
   for ( int y = 0; y < height; y++ )
 
   for ( int y = 0; y < height; y++ )
 +
  {
 +
    for ( int x = 0; x < width; x++ )
 
     {
 
     {
    for ( int x = 0; x < width; x++ )
 
      {
 
 
       unsigned char *pixel =
 
       unsigned char *pixel =
 
         static_cast<unsigned char *>( image->GetScalarPointer( x, y, 0 ) );
 
         static_cast<unsigned char *>( image->GetScalarPointer( x, y, 0 ) );
Line 37: Line 37:
 
       pixel[1] = 255;
 
       pixel[1] = 255;
 
       pixel[2] = 0;
 
       pixel[2] = 0;
      }
 
 
     }
 
     }
 +
  }
  
 
   return image;
 
   return image;
 
}
 
}
  
QImage vtkImageDataToQImage( vtkImageData* imageData )
+
QImage vtkImageDataToQImage( vtkSmartPointer<vtkImageData> imageData )
 
{
 
{
 
   if ( !imageData ) { return QImage(); }
 
   if ( !imageData ) { return QImage(); }
Line 58: Line 58:
 
   // Loop over the vtkImageData contents.
 
   // Loop over the vtkImageData contents.
 
   for ( int row = 0; row < height; row++ )
 
   for ( int row = 0; row < height; row++ )
 +
  {
 +
    for ( int col = 0; col < width; col++ )
 
     {
 
     {
    for ( int col = 0; col < width; col++ )
 
      {
 
 
       // Swap the vtkImageData RGB values with an equivalent QColor
 
       // Swap the vtkImageData RGB values with an equivalent QColor
 
       *( rgbPtr++ ) = QColor( colorsPtr[0], colorsPtr[1], colorsPtr[2] ).rgb();
 
       *( rgbPtr++ ) = QColor( colorsPtr[0], colorsPtr[1], colorsPtr[2] ).rgb();
       colorsPtr += 3;
+
       colorsPtr += imageData->GetNumberOfScalarComponents();
      }
+
    }
  
 
     rgbPtr -= width * 2;
 
     rgbPtr -= width * 2;
    }
+
  }
  
 
   return image;
 
   return image;

Revision as of 14:50, 29 November 2016

This example shows how a vtkImageData can be converted into a QImage.

See also the QImageToImageSource example.

ImageDataToQImage.cxx

#include <vtkImageData.h>
#include <vtkSmartPointer.h>

#include <QImage>
#include <QApplication>

// Create a green 50x50 imageData for demonstration purposes
vtkSmartPointer<vtkImageData> createDemoImageData()
{
  vtkSmartPointer<vtkImageData> image = vtkSmartPointer<vtkImageData>::New();
  image->SetDimensions( 50, 50, 1 );
#if VTK_MAJOR_VERSION <= 5
  #pragma message( VTK_MAJOR_VERSION )
  image->SetNumberOfScalarComponents( 3 );
  image->SetScalarTypeToUnsignedChar();
  image->AllocateScalars();
#else
  image->AllocateScalars( VTK_UNSIGNED_CHAR, 3 );
#endif

  int width = image->GetDimensions()[0];
  int height = image->GetDimensions()[1];

  for ( int y = 0; y < height; y++ )
  {
    for ( int x = 0; x < width; x++ )
    {
      unsigned char *pixel =
        static_cast<unsigned char *>( image->GetScalarPointer( x, y, 0 ) );
      pixel[0] = 0;
      pixel[1] = 255;
      pixel[2] = 0;
    }
  }

  return image;
}

QImage vtkImageDataToQImage( vtkSmartPointer<vtkImageData> imageData )
{
  if ( !imageData ) { return QImage(); }

  /// \todo retrieve just the UpdateExtent
  int width = imageData->GetDimensions()[0];
  int height = imageData->GetDimensions()[1];
  QImage image( width, height, QImage::Format_RGB32 );
  QRgb *rgbPtr =
    reinterpret_cast<QRgb *>( image.bits() ) + width * ( height - 1 );
  unsigned char *colorsPtr =
    reinterpret_cast<unsigned char *>( imageData->GetScalarPointer() );

  // Loop over the vtkImageData contents.
  for ( int row = 0; row < height; row++ )
  {
    for ( int col = 0; col < width; col++ )
    {
      // Swap the vtkImageData RGB values with an equivalent QColor
      *( rgbPtr++ ) = QColor( colorsPtr[0], colorsPtr[1], colorsPtr[2] ).rgb();
      colorsPtr += imageData->GetNumberOfScalarComponents();
    }

    rgbPtr -= width * 2;
  }

  return image;
}

int main( int argc, char *argv[] )
{
  QApplication app( argc, argv );

  QImage qimage = vtkImageDataToQImage( createDemoImageData() );
  qimage.save( "qimage.png" );

  return EXIT_SUCCESS;
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8)
 
if(POLICY CMP0020)
  cmake_policy(SET CMP0020 NEW)
endif()

PROJECT(ImageDataToQImage)

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

if(${VTK_VERSION} VERSION_GREATER "6" AND VTK_QT_VERSION VERSION_GREATER "4")
  # Instruct CMake to run moc automatically when needed.
  set(CMAKE_AUTOMOC ON)
  find_package(Qt5Widgets REQUIRED QUIET)
else()
  find_package(Qt4 REQUIRED)
  include(${QT_USE_FILE})
endif()

include_directories(${CMAKE_CURRENT_SOURCE_DIR} ${CMAKE_CURRENT_BINARY_DIR})

file(GLOB UI_FILES *.ui)
file(GLOB QT_WRAP *.h)
file(GLOB CXX_FILES *.cxx)

if(${VTK_VERSION} VERSION_GREATER "6" AND VTK_QT_VERSION VERSION_GREATER "4")
  qt5_wrap_ui(UISrcs ${UI_FILES} )
  # CMAKE_AUTOMOC in ON so the MOC headers will be automatically wrapped.
  add_executable(ImageDataToQImage MACOSX_BUNDLE
    ${CXX_FILES} ${UISrcs} ${QT_WRAP})
  qt5_use_modules(ImageDataToQImage Core Gui)
  target_link_libraries(ImageDataToQImage ${VTK_LIBRARIES})
else()
  QT4_WRAP_UI(UISrcs ${UI_FILES})
  QT4_WRAP_CPP(MOCSrcs ${QT_WRAP})
  add_executable(ImageDataToQImage MACOSX_BUNDLE ${CXX_FILES} ${UISrcs} ${MOCSrcs})

  if(VTK_LIBRARIES)
    if(${VTK_VERSION} VERSION_LESS "6")
      target_link_libraries(ImageDataToQImage ${VTK_LIBRARIES} QVTK)
    else()
      target_link_libraries(ImageDataToQImage ${VTK_LIBRARIES})
    endif()
  else()
    target_link_libraries(ImageDataToQImage vtkHybrid QVTK vtkViews ${QT_LIBRARIES})
  endif()
endif()

Download and Build ImageDataToQImage

Click here to download ImageDataToQImage. and its CMakeLists.txt file.

Once the tarball ImageDataToQImage.tar has been downloaded and extracted,

cd ImageDataToQImage/build

This example requires Qt and VTK.

  • If VTK and Qt are 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 ..
  • If Qt is not found on your system, you will need to tell CMake where to find qmake:
cmake -DQT_QMAKE_EXECUTABLE:FILEPATH=/usr/something/qmake  ..

Build the project:

make

and run it:

./ImageDataToQImage

WINDOWS USERS PLEASE NOTE: Be sure to add the VTK bin directory to your path. This will resolve the VTK dll's at run time. You may also need to add a Qt related path.