/// <summary>
/// Gets the sort index of an element.
/// </summary>
/// <param name="element"> The element. </param>
/// <param name="indexInContainer"> The index of the element in its container or null if the index is not available. </param>
/// <returns>
/// The sort index of the element.
/// <see cref="int.MaxValue" /> is returned if the element does not provide a sort index in any way.
/// </returns>
/// <remarks>
/// <para>
/// The sort index of an element is retrieved using <see cref="IRegionElement.SortIndex" /> (high priority),
/// <see cref="RegionElementSortHintAttribute" /> (medium priority), and the index of the element in the container
/// (if available, low priority).
/// </para>
/// </remarks>
protected virtual int GetSortIndex(object element, int?indexInContainer)
{
if (element is IRegionElement)
{
IRegionElement regionElement = (IRegionElement)element;
if (regionElement.SortIndex.HasValue)
{
return(regionElement.SortIndex.Value);
}
}
object[] attributes = element.GetType()
.GetCustomAttributes(typeof(RegionElementSortHintAttribute), true);
if (attributes.Length != 0)
{
return(((RegionElementSortHintAttribute)attributes[0]).Index);
}
if (indexInContainer.HasValue)
{
return(indexInContainer.Value);
}
return(int.MaxValue);
}
/// <summary>
/// Navigates the specified element to its new container.
/// </summary>
/// <param name="container"> The new container. </param>
/// <param name="element"> The new element. </param>
protected virtual void NavigatedTo(object container, object element)
{
if (element is IRegionElement)
{
IRegionElement regionElement = (IRegionElement)element;
regionElement.NavigatedTo();
}
}
/// <summary>
/// Checks whether the specified element can be navigated to its new container.
/// </summary>
/// <param name="container"> The new container. </param>
/// <param name="element"> The new element. </param>
/// <returns>
/// true if the navigation is allowed, false otherwise.
/// </returns>
protected virtual bool CanNavigateTo(object container, object element)
{
if (element is IRegionElement)
{
IRegionElement regionElement = (IRegionElement)element;
return(regionElement.CanNavigateTo());
}
return(true);
}
/// <inheritdoc />
public virtual void Deactivate(object container, object element)
{
if (container == null)
{
throw new ArgumentNullException(nameof(container));
}
if (element == null)
{
throw new ArgumentNullException(nameof(element));
}
if (element is IRegionElement)
{
IRegionElement regionElement = (IRegionElement)element;
regionElement.Deactivated();
}
}
