Method WindowLevel

Interaction/Widgets/vtkResliceCursorRepresentation.cxx:680–754

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//------------------------------------------------------------------------------
void vtkResliceCursorRepresentation::WindowLevel(double X, double Y)
{
  if (!this->Renderer)
  {
    return;
  }

  const int* size = this->Renderer->GetSize();
  double window = this->InitialWindow;
  double level = this->InitialLevel;

  // Compute normalized delta

  double dx = 2.0 * (X - this->StartEventPosition[0]) / size[0];
  double dy = 2.0 * (this->StartEventPosition[1] - Y) / 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;
  double newLevel = level - dy;

  if (fabs(newWindow) < 0.01)
  {
    newWindow = 0.01 * (newWindow < 0 ? -1 : 1);
  }
  if (fabs(newLevel) < 0.01)
  {
    newLevel = 0.01 * (newLevel < 0 ? -1 : 1);