Method WindowLevel

Interaction/Style/vtkInteractorStyleImage.cxx:446–513

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

//------------------------------------------------------------------------------
void vtkInteractorStyleImage::WindowLevel()
{
  vtkRenderWindowInteractor* rwi = this->Interactor;

  this->WindowLevelCurrentPosition[0] = rwi->GetEventPosition()[0];
  this->WindowLevelCurrentPosition[1] = rwi->GetEventPosition()[1];

  if (this->HandleObservers && this->HasObserver(vtkCommand::WindowLevelEvent))
  {
    this->InvokeEvent(vtkCommand::WindowLevelEvent, this);
  }
  else if (this->CurrentImageProperty)
  {
    const int* size = this->CurrentRenderer->GetSize();

    double window = this->WindowLevelInitial[0];
    double level = this->WindowLevelInitial[1];

    // Compute normalized delta

    double dx =
      (this->WindowLevelCurrentPosition[0] - this->WindowLevelStartPosition[0]) * 4.0 / size[0];
    double dy =
      (this->WindowLevelStartPosition[1] - this->WindowLevelCurrentPosition[1]) * 4.0 / size[1];

    // Scale by current values

    if (fabs(window) > 0.01)
    {
      dx = dx * window;
    }
    else
    {
      dx = dx * (window < 0 ? -0.01 : 0.01);
    }
    if (fabs(level) > 0.01)
    {
      dy = dy * level;
    }
    else
    {
      dy = dy * (level < 0 ? -0.01 : 0.01);
    }

    // Abs so that direction does not flip

    if (window < 0.0)
    {
      dx = -1 * dx;
    }
    if (level < 0.0)
    {
      dy = -1 * dy;
    }

    // Compute new window level

    double newWindow = dx + window;