public List <Region> GetClipped(Region clipToRegion, List <Region> excludeRegions = null)
{
var clippedIntervals = new List <Region>();
if (!clipToRegion.IsValid())
{
throw new ArgumentException(string.Format("Region {0} is not valid.", clipToRegion));
}
for (var i = _lastIndexCleared + 1; i < Intervals.Count; i++)
{
var interval = Intervals[i];
if (interval.StartPosition > clipToRegion.EndPosition)
{
break;
}
if (!clipToRegion.Overlaps(interval))
{
continue;
}
var clippedInterval = new Region(Math.Max(clipToRegion.StartPosition, interval.StartPosition),
Math.Min(clipToRegion.EndPosition, interval.EndPosition));
if (excludeRegions == null)
{
clippedIntervals.Add(clippedInterval);
}
else
{
clippedIntervals.AddRange(GetMinus(clippedInterval, excludeRegions));
}
}
return(clippedIntervals);
}
/// <summary>
/// Get intervals for a region, minus an overlaps with the exclude regions.
/// </summary>
/// <param name="keepRegion">Region to keep</param>
/// <param name="excludeRegions">List of regions to exclude from the final result. Assumes regions are sorted.</param>
/// <returns></returns>
public static List <Region> GetMinus(Region keepRegion, List <Region> excludeRegions)
{
var regions = new List <Region>();
if (keepRegion == null || !keepRegion.IsValid())
{
throw new ArgumentException(string.Format("Region {0} is not valid.", keepRegion));
}
if (excludeRegions == null)
{
regions.Add(keepRegion);
return(regions);
}
var remainingRegion = new Region(keepRegion.StartPosition, keepRegion.EndPosition);
foreach (var excludeRegion in excludeRegions)
{
if (excludeRegion == null || !excludeRegion.IsValid())
{
throw new ArgumentException(string.Format("Region {0} is not valid.", excludeRegion));
}
if (!remainingRegion.Overlaps(excludeRegion))
{
continue; // no overlap, keep checking other excluded regions
}
if (excludeRegion.FullyContains(remainingRegion))
{
remainingRegion = null; // done, fully excluded
break;
}
if (remainingRegion.FullyContains(excludeRegion))
{
// need to break up remaining region!
var leftRegion = new Region(remainingRegion.StartPosition, excludeRegion.StartPosition - 1, false);
var rightRegion = new Region(excludeRegion.EndPosition + 1, remainingRegion.EndPosition, false);
if (leftRegion.IsValid())
{
regions.Add(leftRegion);
}
if (!rightRegion.IsValid())
{
remainingRegion = null; // done, nothing left on right side
break;
}
remainingRegion = rightRegion; // pass right region on for more processing
}
else
{
remainingRegion = excludeRegion.ContainsPosition(remainingRegion.StartPosition)
? new Region(excludeRegion.EndPosition + 1, remainingRegion.EndPosition) // clip on left side
: new Region(remainingRegion.StartPosition, excludeRegion.StartPosition - 1);
}
}
if (remainingRegion != null)
{
regions.Add(remainingRegion);
}
return(regions);
}