/// <summary>
/// Offset the source polyline to specified side(s).
/// </summary>
/// <param name="source">The polyline to be offseted.</param>
/// <param name="offsetDist">The offset distance.</param>
/// <param name="side">The offset side(s).</param>
/// <returns>A polyline sequence resulting from the offset of the source polyline.</returns>
public static IEnumerable <Polyline> Offset(this Polyline source, double offsetDist, OffsetSide side)
{
side = OffsetSide.Out;
offsetDist = Math.Abs(offsetDist);
using (var plines = new DisposableSet <Polyline>())
{
var offsetRight = source.GetOffsetCurves(offsetDist).Cast <Polyline>();
plines.AddRange(offsetRight);
var offsetLeft = source.GetOffsetCurves(-offsetDist).Cast <Polyline>();
plines.AddRange(offsetLeft);
var areaRight = offsetRight.Select(pline => pline.Area).Sum();
var areaLeft = offsetLeft.Select(pline => pline.Area).Sum();
switch (side)
{
case OffsetSide.In:
return(plines.RemoveRange(
areaRight < areaLeft ? offsetRight : offsetLeft));
case OffsetSide.Out:
return(plines.RemoveRange(
areaRight < areaLeft ? offsetLeft : offsetRight));
case OffsetSide.Left:
return(plines.RemoveRange(offsetLeft));
case OffsetSide.Right:
return(plines.RemoveRange(offsetRight));
case OffsetSide.Both:
plines.Clear();
return(offsetRight.Concat(offsetLeft));
default:
return(null);
}
}
}
public static IEnumerable <Polyline> Offset([NotNull] this Polyline source, double offsetDist, OffsetSide side)
{
offsetDist = Math.Abs(offsetDist);
var offsetRight = source.GetOffsetCurves(offsetDist).Cast <Polyline>().ToList();
var areaRight = offsetRight.Select(pline => pline.Area).Sum();
var offsetLeft = source.GetOffsetCurves(-offsetDist).Cast <Polyline>().ToList();
var areaLeft = offsetLeft.Select(pline => pline.Area).Sum();
switch (side)
{
case OffsetSide.In:
if (areaRight < areaLeft)
{
offsetLeft.Dispose();
return(offsetRight);
}
else
{
offsetRight.Dispose();
return(offsetLeft);
}
case OffsetSide.Out:
if (areaRight < areaLeft)
{
offsetRight.Dispose();
return(offsetLeft);
}
else
{
offsetLeft.Dispose();
return(offsetRight);
}
case OffsetSide.Left:
offsetRight.Dispose();
return(offsetLeft);
case OffsetSide.Right:
offsetLeft.Dispose();
return(offsetRight);
case OffsetSide.Both:
return(offsetRight.Concat(offsetLeft));
default:
return(null);
}
}
/// <summary>
/// Offset the source polyline to specified side(s).
/// </summary>
/// <param name="source">The polyline to be offseted.</param>
/// <param name="offsetDist">The offset distance.</param>
/// <param name="side">The offset side(s).</param>
/// <returns>A polyline sequence resulting from the offset of the source polyline.</returns>
public static IEnumerable<Polyline> Offset(this Polyline source, double offsetDist, OffsetSide side)
{
offsetDist = Math.Abs(offsetDist);
IEnumerable<Polyline> offsetRight = source.GetOffsetCurves(offsetDist).Cast<Polyline>();
double areaRight = offsetRight.Select(pline => pline.Area).Sum();
IEnumerable<Polyline> offsetLeft = source.GetOffsetCurves(-offsetDist).Cast<Polyline>();
double areaLeft = offsetLeft.Select(pline => pline.Area).Sum();
switch (side)
{
case OffsetSide.In:
if (areaRight < areaLeft)
{
offsetLeft.Dispose();
return offsetRight;
}
else
{
offsetRight.Dispose();
return offsetLeft;
}
case OffsetSide.Out:
if (areaRight < areaLeft)
{
offsetRight.Dispose();
return offsetLeft;
}
else
{
offsetLeft.Dispose();
return offsetRight;
}
case OffsetSide.Left:
offsetRight.Dispose();
return offsetLeft;
case OffsetSide.Right:
offsetLeft.Dispose();
return offsetRight;
case OffsetSide.Both:
return offsetRight.Concat(offsetLeft);
default:
return null;
}
}
