private void SetupCollinearHandlesConstraint(int index, bool enforceConstraint)
{
PathFigureEditor pathFigureEditor = new PathFigureEditor(this.figure);
if (!pathFigureEditor.HasDownstreamBezierHandleNeighbor(index) || !pathFigureEditor.HasUpstreamBezierHandleNeighbor(index))
{
return;
}
Point point = pathFigureEditor.GetPoint(index);
Vector a = pathFigureEditor.GetPoint(index - 1) - point;
Vector b = pathFigureEditor.GetPoint(index + 1) - point;
if (!enforceConstraint || VectorUtilities.HaveOppositeDirections(a, b))
{
return;
}
double length1 = a.Length;
double length2 = b.Length;
if (length1 > length2)
{
a.Normalize();
b = -a * length2;
pathFigureEditor.SetPoint(index + 1, point + b);
}
else
{
b.Normalize();
Vector vector = -b * length1;
pathFigureEditor.SetPoint(index - 1, point - vector);
}
}