get_scroll_direction

Extracts the scroll direction from an event.

If this is not of type gdk_scroll, the contents of direction are undefined.

If you wish to handle both discrete and smooth scrolling, you should check the return value of this function, or of get_scroll_deltas; for instance:

  GdkScrollDirection direction;
  double vscroll_factor = 0.0;
  double x_scroll, y_scroll;

  if (gdk_event_get_scroll_direction (event, &direction))
    {
      // Handle discrete scrolling with a known constant delta;
      const double delta = 12.0;

      switch (direction)
        {
        case GDK_SCROLL_UP:
          vscroll_factor = -delta;
          break;
        case GDK_SCROLL_DOWN:
          vscroll_factor = delta;
          break;
        default:
          // no scrolling
          break;
        }
    }
  else if (gdk_event_get_scroll_deltas (event, &x_scroll, &y_scroll))
    {
      // Handle smooth scrolling directly
      vscroll_factor = y_scroll;
    }

Parameters:

this	a Event
direction	location to store the scroll direction

Returns:

true if the event delivered a scroll direction and false otherwise