protected override void UpdateConnectorOffset()
{
if (this.IsVisible && this.RenderSize.Width > 0 && this.PlacementTarget?.IsVisible == true)
{
if (!this.IsLoaded)
{
this.Dispatcher.Invoke(this.UpdateConnectorOffset, DispatcherPriority.Loaded);
return;
}
var selfRect = new Rect(new Point(0, 0).ToScreen(this), this.RenderSize).ToScreen(this);
var ellipse = new Ellipse(selfRect);
var targetRect = new Rect(new Point(0, 0).ToScreen(this.PlacementTarget), this.PlacementTarget.RenderSize).ToScreen(this);
var tp = this.PlacementOptions?.GetPointOnTarget(selfRect, targetRect);
if (tp == null || ellipse.Contains(tp.Value))
{
this.InvalidateProperty(ConnectorOffsetProperty);
return;
}
if (ellipse.Contains(tp.Value))
{
this.SetCurrentValue(ConnectorOffsetProperty, new Vector(0, 0));
return;
}
var mp = ellipse.CenterPoint;
var ip = new Ray(mp, mp.VectorTo(tp.Value)).FirstIntersectionWith(ellipse);
Debug.Assert(ip != null, "Did not find an intersection, bug in the library");
if (ip == null)
{
// failing silently in release
this.InvalidateProperty(ConnectorOffsetProperty);
}
else
{
var v = tp.Value - ip.Value;
// ReSharper disable once CompareOfFloatsByEqualityOperator
if (this.PlacementOptions != null && v.Length > 0 && this.PlacementOptions.Offset != 0)
{
v = v - this.PlacementOptions.Offset * v.Normalized();
}
this.SetCurrentValue(ConnectorOffsetProperty, v);
}
}
else
{
this.InvalidateProperty(ConnectorOffsetProperty);
}
}
private static Point FindTangentPoint(Ray toCenter, Ellipse ellipse)
{
var toEllipseCenter = toCenter.PerpendicularLineTo(ellipse.CenterPoint);
Debug.Assert(toEllipseCenter != null, "Ray should not go through ellipse center here");
if (toEllipseCenter == null)
{
// this should never happen but failing silently
// the balloons should not throw much returning random point.
return ellipse.CenterPoint;
}
return ellipse.PointOnCircumference(toEllipseCenter.Value.Direction.Negated());
}
internal static Point Find(Ray ray, double angle, double strokeThickness, Ellipse ellipse)
{
return Find(ray.Rotate(angle), strokeThickness, ellipse);
}
private static Point Find(Ray ray, double strokeThickness, Ellipse ellipse)
{
var ip = ray.FirstIntersectionWith(ellipse);
if (ip != null)
{
return ip.Value + strokeThickness * ray.Direction;
}
return FindTangentPoint(ray, ellipse);
}
// http://www.mare.ee/indrek/misc/2d.pdf
internal Point? FirstIntersectionWith(Ellipse ellipse)
{
if (Math.Abs(ellipse.CenterPoint.X) < Constants.Tolerance && Math.Abs(ellipse.CenterPoint.Y) < Constants.Tolerance)
{
return FirstIntersectionWithEllipseCenteredAtOrigin(this.Point, this.Direction, ellipse.RadiusX, ellipse.RadiusY);
}
var offset = new Point(0, 0).VectorTo(ellipse.CenterPoint);
var ip = FirstIntersectionWithEllipseCenteredAtOrigin(this.Point - offset, this.Direction, ellipse.RadiusX, ellipse.RadiusY);
return ip + offset;
}
