/// <summary>
/// Moves the <see cref="GuiItem"/> to a specified relative position.
/// If x is set the horizontal component of the anchor will have no effect.
/// If y is set the vertical component of the anchor will have no effect.
/// </summary>
/// <param name="anchor"> A valid relative position. </param>
/// <param name="x"> The horizontal component of the new position. </param>
/// <param name="y"> The vertical component of the new position. </param>
/// <exception cref="ArgumentException"> The anchor is invalid. </exception>
public void MoveRelative(Anchor anchor, float? x = null, float? y = null)
{
if (anchor.RequiresWork())
{
if (!x.HasValue)
{
if (anchor.ContainesValue(Anchor.MiddleWidth)) x = (device.Viewport.Width >> 1) - (Width >> 1);
if (anchor.ContainesValue(Anchor.Left)) x = 0;
if (anchor.ContainesValue(Anchor.Right)) x = device.Viewport.Width - Width;
if (!x.HasValue) x = Position.X;
}
if (!y.HasValue)
{
if (anchor.ContainesValue(Anchor.MiddelHeight)) y = (device.Viewport.Height >> 1) - (Height >> 1);
if (anchor.ContainesValue(Anchor.Top)) y = 0;
if (anchor.ContainesValue(Anchor.Bottom)) y = device.Viewport.Height - Height;
if (!y.HasValue) y = Position.Y;
}
if (x != Position.X || y != Position.Y) Position = new Vector2(x.Value, y.Value);
}
else if (!anchor.IsValid()) throw new ArgumentException("The anchor is invalid!");
}