public static PlacementValidity GetPlacementValidity(ITimelineItem item, IEnumerable <ITimelineItem> otherItems)
{
if (item.duration <= 0.0)
{
return(PlacementValidity.Valid); //items without any duration can always be placed
}
var sortedItems = otherItems.Where(i => i.duration > 0.0).OrderBy(c => c.start);
var candidates = new List <ITimelineItem>();
foreach (var sortedItem in sortedItems)
{
if ((DiscreteTime)sortedItem.start >= (DiscreteTime)item.end)
{
// No need to process further
break;
}
if ((DiscreteTime)sortedItem.end <= (DiscreteTime)item.start)
{
// Skip
continue;
}
candidates.Add(sortedItem);
}
var discreteStart = (DiscreteTime)item.start;
var discreteEnd = (DiscreteTime)item.end;
// Note: Order of tests matters
for (int i = 0, n = candidates.Count; i < n; i++)
{
var candidate = candidates[i];
var blendItem = item as IBlendable;
if (blendItem != null && blendItem.supportsBlending)
{
if (EditModeUtils.Contains(candidate.start, candidate.end, item))
{
return(PlacementValidity.InvalidIsWithin);
}
if (i < n - 1)
{
var nextCandidate = candidates[i + 1];
var discreteNextCandidateStart = (DiscreteTime)nextCandidate.start;
var discreteCandidateEnd = (DiscreteTime)candidate.end;
if (discreteCandidateEnd > discreteNextCandidateStart)
{
if (discreteStart >= discreteNextCandidateStart)
{
// Note: In case the placement is fully within a blend,
// InvalidStartsInBlend MUST have priority
return(PlacementValidity.InvalidStartsInBlend);
}
if (discreteEnd > discreteNextCandidateStart && discreteEnd <= discreteCandidateEnd)
{
return(PlacementValidity.InvalidEndsInBlend);
}
if (discreteStart < discreteNextCandidateStart && discreteEnd > discreteCandidateEnd)
{
return(PlacementValidity.InvalidContainsBlend);
}
}
}
if (EditModeUtils.Contains(item.start, item.end, candidate))
{
return(PlacementValidity.InvalidContains);
}
}
else
{
if (EditModeUtils.Overlaps(item, candidate.start, candidate.end) ||
EditModeUtils.Overlaps(candidate, item.start, item.end))
{
return(PlacementValidity.InvalidOverlapWithNonBlendableClip);
}
}
}
return(PlacementValidity.Valid);
}