private ExpressionObserver CreateFindAncestorObserver(
IStyledElement target,
RelativeSource relativeSource,
string path,
bool enableDataValidation)
{
Contract.Requires <ArgumentNullException>(target != null);
IObservable <object> controlLocator;
switch (relativeSource.Tree)
{
case TreeType.Logical:
controlLocator = ControlLocator.Track(
(ILogical)target,
relativeSource.AncestorLevel - 1,
relativeSource.AncestorType);
break;
case TreeType.Visual:
controlLocator = VisualLocator.Track(
(IVisual)target,
relativeSource.AncestorLevel - 1,
relativeSource.AncestorType);
break;
default:
throw new InvalidOperationException("Invalid tree to traverse.");
}
return(new ExpressionObserver(
controlLocator,
path,
enableDataValidation));
}
protected ExpressionObserver CreateFindAncestorObserver(
IStyledElement target,
RelativeSource relativeSource,
ExpressionNode node)
{
_ = target ?? throw new ArgumentNullException(nameof(target));
IObservable <object?> controlLocator;
switch (relativeSource.Tree)
{
case TreeType.Logical:
controlLocator = ControlLocator.Track(
(ILogical)target,
relativeSource.AncestorLevel - 1,
relativeSource.AncestorType);
break;
case TreeType.Visual:
controlLocator = VisualLocator.Track(
(IVisual)target,
relativeSource.AncestorLevel - 1,
relativeSource.AncestorType);
break;
default:
throw new InvalidOperationException("Invalid tree to traverse.");
}
return(new ExpressionObserver(
controlLocator,
node,
null));
}
protected override void StartListeningCore(WeakReference <object> reference)
{
if (reference.TryGetTarget(out object target) && target is IVisual visual)
{
_subscription = VisualLocator.Track(visual, _level, _ancestorType).Subscribe(ValueChanged);
}
