//
// Property Invalidation of Inheritable Properties
//
// At the context level, we need to keep track of all inheritable property invalidations currently
// in action. The reason that there can be multiple invalidations going on at the same time is because
// an invalidation of one property can cause an invalidation of a different property. The result is that
// the first invalidation *pauses* while the second invalidation is delivered to the tree.
//
// We keep track of these invalidations to be able to optimize a recursion of the same property
// invalidation from an element to that element's children. FrameworkElement.InvalidateTree will
// check the stack of walkers here and, if it finds a match, will conclude that a new DescendentsWalker
// need not be spun up. And there was much rejoicing.
//
public void AddWalker(object data, DescendentsWalkerBase walker)
{
// push a new walker on the top of the stack
WalkerEntry walkerEntry = new WalkerEntry();
walkerEntry.Data = data;
walkerEntry.Walker = walker;
_currentWalkers.Add(walkerEntry);
}
//
// Property Invalidation of Inheritable Properties
//
// At the context level, we need to keep track of all inheritable property invalidations currently
// in action. The reason that there can be multiple invalidations going on at the same time is because
// an invalidation of one property can cause an invalidation of a different property. The result is that
// the first invalidation *pauses* while the second invalidation is delivered to the tree.
//
// We keep track of these invalidations to be able to optimize a recursion of the same property
// invalidation from an element to that element's children. FrameworkElement.InvalidateTree will
// check the stack of walkers here and, if it finds a match, will conclude that a new DescendentsWalker
// need not be spun up. And there was much rejoicing.
//
public void AddWalker(object data, DescendentsWalkerBase walker)
{
// push a new walker on the top of the stack
WalkerEntry walkerEntry = new WalkerEntry();
walkerEntry.Data = data;
walkerEntry.Walker = walker;
_currentWalkers.Add(walkerEntry);
}
public void RemoveWalker(object data, DescendentsWalkerBase walker)
{
// pop the walker off the top of the stack
int last = _currentWalkers.Count - 1;
#if DEBUG
WalkerEntry walkerEntry = _currentWalkers[last];
Debug.Assert((walkerEntry.Data == data) && (walkerEntry.Walker == walker),
"Inheritance DescendentsWalker tracker removal failed");
#endif
_currentWalkers.RemoveAt(last);
}
public bool WasNodeVisited(DependencyObject d, object data)
{
// check to see if the given property on the given object is going to be visited by the
// DescendentsWalker on the top of the stack
if (_currentWalkers.Count > 0)
{
int last = _currentWalkers.Count - 1;
WalkerEntry walkerEntry = _currentWalkers[last];
if (walkerEntry.Data == data)
{
return(walkerEntry.Walker.WasVisited(d));
}
}
return(false);
}
