protected override void StartListeningCore(WeakReference <object> reference)
{
if (_nameScope.TryGetTarget(out var scope))
{
_subscription = NameScopeLocator.Track(scope, _name).Subscribe(ValueChanged);
}
else
{
_subscription = null;
}
}
protected ExpressionObserver CreateElementObserver(
IStyledElement target,
string elementName,
ExpressionNode node)
{
_ = target ?? throw new ArgumentNullException(nameof(target));
if (NameScope is null || !NameScope.TryGetTarget(out var scope) || scope is null)
{
throw new InvalidOperationException("Name scope is null or was already collected");
}
var result = new ExpressionObserver(
NameScopeLocator.Track(scope, elementName),
node,
null);
return(result);
}
protected ExpressionObserver CreateElementObserver(
IStyledElement target,
string elementName,
ExpressionNode node)
{
Contract.Requires <ArgumentNullException>(target != null);
NameScope.TryGetTarget(out var scope);
if (scope == null)
{
throw new InvalidOperationException("Name scope is null or was already collected");
}
var result = new ExpressionObserver(
NameScopeLocator.Track(scope, elementName),
node,
null);
return(result);
}