/// <summary>
/// Indicates whether a navigation would be valid if it were to be performed.
/// </summary>
/// <param name="command">The navigation command to test.</param>
/// <param name="activity">The destination activity, if this is a choice navigation.</param>
/// <returns>True if the navigation would be valid, false otherwise.</returns>
/// <remarks>
/// <para>
/// This makes a partial copy of the activity tree for processing and attempts to
/// perform a navigation on that copy. This may result in poor performance if this
/// is called many times, but the alternative is to duplicate most of the sequencing
/// code with lots of special cases for changes of state that should have happened but
/// could not because of the temporary nature of this request. This makes it a
/// maintenance nightmare, for something that should only rarely be called anyway
/// except in the case of <Mth>LoadTableOfContents</Mth>.
/// </para>
/// <para>
/// The case of <Mth>LoadTableOfContents</Mth> is tough, but steps are taken within
/// that method to reduce the number of calls to this method to a bare minimum.
/// </para>
/// </remarks>
protected bool IsNavigationValid(NavigationCommand command, Activity activity)
{
SeqNav seqNav;
try
{
NavigatorData clone = CloneForNavigationTest();
Activity destination;
if (activity != null)
{
destination = clone.Activities[activity.ActivityId];
}
else
{
destination = null;
}
if (m_packageFormat == PackageFormat.V1p3)
{
seqNav = new Scorm2004SeqNav(clone);
}
else
{
seqNav = new Scorm12SeqNav(clone);
}
seqNav.OverallSequencingProcess(command, destination);
}
catch (SequencingException)
{
// if there was a sequencing exception,
// this is a failure condition.
return(false);
}
return(true);
}
/// <summary>
/// Produces an incomplete clone sufficient for testing sequencing and navigation.
/// </summary>
/// <returns>A new object with enough data cloned to be viable for sequencing and navigation.</returns>
public virtual NavigatorData CloneForNavigationTest()
{
NavigatorData clone = new NavigatorData();
clone.RootActivity = m_activityTree.Root.CloneForNavigationTest();
clone.Activities.Add(clone.RootActivity.ActivityId, clone.RootActivity);
if (CurrentActivity == RootActivity)
{
clone.CurrentActivity = clone.RootActivity;
}
if (SuspendedActivity == RootActivity)
{
clone.SuspendedActivity = clone.RootActivity;
}
CloneChildren(clone, clone.RootActivity, m_activityTree.Root);
clone.SortActivityTree();
return(clone);
}
/// <summary>
/// Recursively clones children of the specified activity and inserts them into the clone tree.
/// </summary>
/// <param name="navigator">The cloned navigator data object.</param>
/// <param name="cloneParent">The cloned parent to add the children to.</param>
/// <param name="originalParent">The original parent to clone the children from.</param>
protected void CloneChildren(NavigatorData navigator, Activity cloneParent, Activity originalParent)
{
foreach (Activity child in originalParent.Children)
{
Activity clone = child.CloneForNavigationTest();
cloneParent.AddChild(clone);
clone.Parent = cloneParent;
if (CurrentActivity == child)
{
navigator.CurrentActivity = clone;
}
if (SuspendedActivity == child)
{
navigator.SuspendedActivity = clone;
}
navigator.Activities.Add(clone.ActivityId, clone);
CloneChildren(navigator, clone, child);
}
}
/// <summary>
/// Initializes the class that performs sequencing/navigation using SCORM 2004 sequencing/navigation rules.
/// </summary>
/// <param name="navigator">The <Typ>Navigator</Typ> performing the sequencing operation.</param>
public Scorm2004SeqNav(NavigatorData navigator) : base(navigator)
{
}
/// <summary>
/// Initializes the class that performs sequencing/navigation.
/// </summary>
/// <param name="navigator">The <Typ>Navigator</Typ> performing the sequencing operation.</param>
public SeqNav(NavigatorData navigator)
{
m_navigator = navigator;
}
/// <summary>
/// Initializes the class that performs sequencing/navigation using SCORM 1.2004 sequencing/navigation rules.
/// </summary>
/// <param name="navigator">The <Typ>Navigator</Typ> performing the sequencing operation.</param>
public Scorm12SeqNav(NavigatorData navigator) : base(navigator)
{
}
/// <summary>
/// Produces an incomplete clone sufficient for testing sequencing and navigation.
/// </summary>
/// <returns>A new object with enough data cloned to be viable for sequencing and navigation.</returns>
public virtual NavigatorData CloneForNavigationTest()
{
NavigatorData clone = new NavigatorData();
clone.RootActivity = m_activityTree.Root.CloneForNavigationTest();
clone.Activities.Add(clone.RootActivity.ActivityId, clone.RootActivity);
if(CurrentActivity == RootActivity)
{
clone.CurrentActivity = clone.RootActivity;
}
if(SuspendedActivity == RootActivity)
{
clone.SuspendedActivity = clone.RootActivity;
}
CloneChildren(clone, clone.RootActivity, m_activityTree.Root);
clone.SortActivityTree();
return clone;
}
/// <summary>
/// Recursively clones children of the specified activity and inserts them into the clone tree.
/// </summary>
/// <param name="navigator">The cloned navigator data object.</param>
/// <param name="cloneParent">The cloned parent to add the children to.</param>
/// <param name="originalParent">The original parent to clone the children from.</param>
protected void CloneChildren(NavigatorData navigator, Activity cloneParent, Activity originalParent)
{
foreach(Activity child in originalParent.Children)
{
Activity clone = child.CloneForNavigationTest();
cloneParent.AddChild(clone);
clone.Parent = cloneParent;
if(CurrentActivity == child)
{
navigator.CurrentActivity = clone;
}
if(SuspendedActivity == child)
{
navigator.SuspendedActivity = clone;
}
navigator.Activities.Add(clone.ActivityId, clone);
CloneChildren(navigator, clone, child);
}
}
