/// <summary>
/// Returns distance between the top edge of the rectangle and another rectangle.
/// </summary>
/// <param name="first">First rectangle.</param>
/// <param name="second">Second rectangle.</param>
/// <returns>Minimal distance.</returns>
private double DistanceBetweenTopEdgeAndRectangle(Rect first, Rect second)
{
double snap;
double distance = double.NaN;
if (first.OverlapsHorizontally(second, Accuracy))
{
snap = second.Y;
if (first.Y.IsNear(snap, SnapinDistance))
{
distance = MathExtensions.AbsMin(snap - first.Y, distance);
}
snap = second.Y + second.Height + SnapinMargin;
if (first.Y.IsNear(snap, SnapinDistance))
{
distance = MathExtensions.AbsMin(snap - first.Y, distance);
}
}
return distance;
}