Method ScrollUpDown

libraries/lib-viewport/Viewport.cpp:240–267

}

bool Viewport::ScrollUpDown(int delta)
{
   int oldPos = mpCallbacks ? mpCallbacks->GetVerticalThumbPosition() : 0;
   int pos = oldPos + delta;
   int max = mpCallbacks
      ? mpCallbacks->GetVerticalRange() - mpCallbacks->GetVerticalThumbSize()
      : 0;

   // Can be negative in case of only one track
   if (max < 0)
      max = 0;

   if (pos > max)
      pos = max;
   else if (pos < 0)
      pos = 0;

   if (pos != oldPos)
   {
      if (mpCallbacks)
         mpCallbacks->SetVerticalThumbPosition(pos);

      DoScroll();
      return true;
   }
   else
      return false;
}

void Viewport::UpdateScrollbarsForTracks()
{