/// <summary>
/// When overridden in a derived class, is invoked whenever application code or internal
/// processes call <see cref="FrameworkElement.ApplyTemplate"/>.
/// </summary>
public override void OnApplyTemplate()
{
// Clean up.
_sectorPath = null;
_sectorGeometry = null;
_leaderLinePath = null;
_leaderLineGeometry = null;
_innerLabel = null;
_outerLabel = null;
// Apply template.
base.OnApplyTemplate();
// Get template parts and prepare path geometries.
_sectorPath = GetTemplateChild("PART_Sector") as Path ?? new Path();
_leaderLinePath = GetTemplateChild("PART_LeaderLine") as Path ?? new Path();
_innerLabel = GetTemplateChild("PART_InnerLabel") as ContentControl ?? new ContentControl();
_outerLabel = GetTemplateChild("PART_OuterLabel") as ContentControl ?? new ContentControl();
_sectorGeometry = _sectorPath.SetPathGeometry();
_leaderLineGeometry = _leaderLinePath.SetPathGeometry();
Invalidate();
}
