void ReturnListener()
{
listener.Changed -= HandleValueChanged;
freeListeners.Add(listener);
listener = null;
}
void Attach()
{
Detach();
if (target != null && binding != null)
{
listener = GetListener();
listener.Attach(target, binding);
}
}
void Attach()
{
Detach();
if (target != null && binding != null)
{
listener = GetListener();
listener.Attach(target, binding);
}
}
DependencyPropertyListener GetListener()
{
DependencyPropertyListener listener;
if (freeListeners.Count != 0)
{
listener = freeListeners[freeListeners.Count - 1];
freeListeners.RemoveAt(freeListeners.Count - 1);
return(listener);
}
listener = new DependencyPropertyListener();
listener.Changed += HandleValueChanged;
return(listener);
}
DependencyPropertyListener GetListener()
{
DependencyPropertyListener listener;
if (freeListeners.Count != 0)
{
listener = freeListeners[freeListeners.Count - 1];
freeListeners.RemoveAt(freeListeners.Count - 1);
return listener;
}
listener = new DependencyPropertyListener();
listener.Changed += HandleValueChanged;
return listener;
}
static void element_Loaded(object sender, RoutedEventArgs e)
{
FrameworkElement element = (FrameworkElement)sender;
element.Loaded -= element_Loaded;
ScrollViewer scrollViewer = FindChildOfType <ScrollViewer>(element);
if (scrollViewer == null)
{
throw new InvalidOperationException("ScrollViewer not found.");
}
var listener = new DependencyPropertyListener();
listener.Changed
+= delegate
{
bool atBottom = scrollViewer.VerticalOffset
>= scrollViewer.ScrollableHeight;
if (atBottom)
{
var atEnd = GetAtEndCommand(element);
if (atEnd != null)
{
atEnd.Execute(null);
}
}
};
Binding binding = new Binding("VerticalOffset")
{
Source = scrollViewer
};
listener.Attach(scrollViewer, binding);
}
void ReturnListener()
{
listener.Changed -= HandleValueChanged;
freeListeners.Add(listener);
listener = null;
}