/// <summary>
/// Adds a line that connects the arc midpoint to the label and positions the label appropriately.
/// Ideally, I would add the Polyline in the template and I would only change its points here. Unfortunately,
/// because of a WPF bug, the Polyline doesn't render in certain corner-case scenarios. As a workaround,
/// I create a new Polyline everytime the label is positioned, as can be seen in this method.
/// </summary>
private void PositionConnected()
{
try
{
this.RemovePolyline();
if (this.contentPart != null)
{
PointCollection newPoints = new PointCollection();
// First point
newPoints.Add(this.SnapPoint(this.arcMidpoint));
// Second point
Vector radialDirection = this.arcMidpoint - this.center;
radialDirection.Normalize();
Point secondPoint = this.arcMidpoint + (radialDirection*10);
newPoints.Add(this.SnapPoint(secondPoint));
// Third point
int sign = Math.Sign(radialDirection.X); // 1 if label is on the right side, -1 if it's on the left.
Point thirdPoint = secondPoint + new Vector(sign*20, 0);
newPoints.Add(this.SnapPoint(thirdPoint));
double contentX = (sign == 1) ? thirdPoint.X : thirdPoint.X - this.contentPart.DesiredSize.Width;
double contentY = thirdPoint.Y - 0.5*this.contentPart.DesiredSize.Height;
Canvas.SetTop(this.contentPart, contentY);
Canvas.SetLeft(this.contentPart, contentX);
Polyline polyline = new Polyline();
polyline.Points = newPoints;
polyline.SetBinding(Polyline.StrokeThicknessProperty, new Binding("LineStrokeThickness") {Source = this});
polyline.SetBinding(Polyline.StrokeProperty, new Binding("LineStroke") {Source = this});
polyline.StrokeLineJoin = PenLineJoin.Round;
this.canvasPart.Children.Add(polyline);
}
}
catch(Exception)
{ }
}
private void SetPolylineBindings(Polyline polyline)
{
polyline.SetBinding(Polyline.StrokeProperty, new Binding { Source = this, Path = new PropertyPath("Stroke") });
polyline.SetBinding(Polyline.StrokeThicknessProperty, new Binding { Source = this, Path = new PropertyPath("StrokeThickness") });
}