// // 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); }