int spins;

        // The MouseWheel event can contain multiple "spins" of the wheel so we need to adjust accordingly
        spins = Math.Abs(e.Delta / SystemInformation.MouseWheelScrollDelta);

        // TODO: Really should update the source method to handle multiple increments rather than calling it multiple times
        for (int i = 0; i < spins; i++)
        {
          this.ProcessMouseZoom(e.Delta > 0, e.Location);
        }

    private const int MouseWheelScrollDeltaRemainderResetDelay = 250;
    private int _mouseWheelScrollDeltaRemainder;
    private int _mouseWheelScrollDeltaUpdateTime;

    protected override void OnMouseWheel(MouseEventArgs e)
    {
      base.OnMouseWheel(e);

      if (this.AllowZoom && this.SizeMode == ImageBoxSizeMode.Normal)
      {
        // A remainder is kept so can support mice that use a  delta value that isn't SystemInformation.MouseWheelScrollDelta
        // for the mouse wheel.
        //
        // The remainder will also be reset to 0 after a time delay to prevent it affecting future scrolling where user stops
        // scrolling and then comes back and starts scrolling again. In that case we want the remainder to start at 0 again.
        //
        // To detect the switching of scroll direction will simply just check the sign of delta and delta remainder.
        // Then can reset the remainder to 0 because do not want the scrolling in different direction to affect the current direction.
        int delta = e.Delta + this._mouseWheelScrollDeltaRemainder;

        if (Environment.TickCount - this._mouseWheelScrollDeltaUpdateTime > MouseWheelScrollDeltaRemainderResetDelay ||
            (delta < 0) != (this._mouseWheelScrollDeltaRemainder < 0))
        {
          this._mouseWheelScrollDeltaRemainder = 0;
        }

        this._mouseWheelScrollDeltaRemainder = delta % SystemInformation.MouseWheelScrollDelta;
        this._mouseWheelScrollDeltaUpdateTime = Environment.TickCount;

        int spins;

        // The MouseWheel event can contain multiple "spins" of the wheel so we need to adjust accordingly
        spins = Math.Abs(delta / SystemInformation.MouseWheelScrollDelta);

        // TODO: Really should update the source method to handle multiple increments rather than calling it multiple times
        for (int i = 0; i < spins; i++)
        {
          this.ProcessMouseZoom(e.Delta > 0, e.Location);
        }
      }
    }