/// <summary>
/// 删除子图元
/// </summary>
/// <param name="glyph">删除的图元</param>
protected virtual void Remove(Glyph glyph)
{
}
/// <summary>
/// 在index处插入一个子图元
/// </summary>
/// <param name="glyph">要插入的子图元</param>
/// <param name="index">插入子图元的位置</param>
protected virtual void Insert(Glyph glyph, int index)
{
}