Method ComputeTexture

Charts/Core/vtkColorTransferFunctionItem.cxx:91–130

------------------------------------------------------------------------------

//------------------------------------------------------------------------------
void vtkColorTransferFunctionItem::ComputeTexture()
{
  double screenBounds[4];
  this->GetBounds(screenBounds);
  if (screenBounds[0] == screenBounds[1] || !this->ColorTransferFunction)
  {
    return;
  }
  if (this->Texture == nullptr)
  {
    this->Texture = vtkImageData::New();
  }

  double dataBounds[4];
  this->TransformScreenToData(screenBounds[0], screenBounds[2], dataBounds[0], dataBounds[2]);
  this->TransformScreenToData(screenBounds[1], screenBounds[3], dataBounds[1], dataBounds[3]);

  // Could depend of the screen resolution
  const int dimension = this->GetTextureWidth();
  double* values = new double[dimension];
  // Texture 1D
  this->Texture->SetExtent(0, dimension - 1, 0, 0, 0, 0);
  this->Texture->AllocateScalars(VTK_UNSIGNED_CHAR, 4);
  for (int i = 0; i < dimension; ++i)
  {
    values[i] = dataBounds[0] + i * (dataBounds[1] - dataBounds[0]) / (dimension - 1);
  }
  unsigned char* ptr = reinterpret_cast<unsigned char*>(this->Texture->GetScalarPointer(0, 0, 0));
  this->ColorTransferFunction->MapScalarsThroughTable2(
    values, ptr, VTK_DOUBLE, dimension, VTK_LUMINANCE, VTK_RGBA);
  if (this->Opacity != 1.0)
  {
    for (int i = 0; i < dimension; ++i)
    {
      ptr[3] = static_cast<unsigned char>(this->Opacity * ptr[3]);
      ptr += 4;
    }
  }
  delete[] values;
}

//------------------------------------------------------------------------------
bool vtkColorTransferFunctionItem::ConfigurePlotBar()