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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
//
//
// Description:
// This data-structure is used
// 1. As the data that is passed around by the DescendentsWalker
// during an AncestorChanged tree-walk.
//
//
using MS.Internal;
using MS.Utility;
namespace System.Windows
{
/// <summary>
/// This is the data that is passed through the DescendentsWalker
/// during an AncestorChange tree-walk.
/// </summary>
internal struct TreeChangeInfo
{
#region Properties
public TreeChangeInfo(DependencyObject root, DependencyObject parent, bool isAddOperation)
{
_rootOfChange = root;
_isAddOperation = isAddOperation;
_topmostCollapsedParentNode = null;
_rootInheritableValues = null;
_inheritablePropertiesStack = null;
_valueIndexer = 0;
// Create the InheritableProperties cache for the parent
// and push it to start the stack ... we don't need to
// pop this when we're done because we'll be throing the
// stack away at that point.
InheritablePropertiesStack.Push(CreateParentInheritableProperties(root, parent, isAddOperation));
}
//
// This method
// 1. Is called from AncestorChange InvalidateTree.
// 2. It is used to create the InheritableProperties on the given node.
// 3. It also accumulates oldValues for the inheritable properties that are about to be invalidated
//
internal FrugalObjectList<DependencyProperty> CreateParentInheritableProperties(
DependencyObject d,
DependencyObject parent,
bool isAddOperation)
{
Debug.Assert(d != null, "Must have non-null current node");
if (parent == null)
{
return new FrugalObjectList<DependencyProperty>(0);
}
DependencyObjectType treeObjDOT = d.DependencyObjectType;
// See if we have a cached value.
EffectiveValueEntry[] parentEffectiveValues = null;
uint parentEffectiveValuesCount = 0;
uint inheritablePropertiesCount = 0;
// If inheritable properties aren't cached on you then use the effective
// values cache on the parent to discover those inherited properties that
// may need to be invalidated on the children nodes.
if (!parent.IsSelfInheritanceParent)
{
DependencyObject inheritanceParent = parent.InheritanceParent;
if (inheritanceParent != null)
{
parentEffectiveValues = inheritanceParent.EffectiveValues;
parentEffectiveValuesCount = inheritanceParent.EffectiveValuesCount;
inheritablePropertiesCount = inheritanceParent.InheritableEffectiveValuesCount;
}
}
else
{
parentEffectiveValues = parent.EffectiveValues;
parentEffectiveValuesCount = parent.EffectiveValuesCount;
inheritablePropertiesCount = parent.InheritableEffectiveValuesCount;
}
FrugalObjectList<DependencyProperty> inheritableProperties = new FrugalObjectList<DependencyProperty>((int) inheritablePropertiesCount);
if (inheritablePropertiesCount == 0)
{
return inheritableProperties;
}
_rootInheritableValues = new InheritablePropertyChangeInfo[(int) inheritablePropertiesCount];
int inheritableIndex = 0;
FrameworkObject foParent = new FrameworkObject(parent);
for (uint i=0; i<parentEffectiveValuesCount; i++)
{
// Add all the inheritable properties from the effectiveValues
// cache to the TreeStateCache on the parent
EffectiveValueEntry entry = parentEffectiveValues[i];
DependencyProperty dp = DependencyProperty.RegisteredPropertyList.List[entry.PropertyIndex];
// There are UncommonFields also stored in the EffectiveValues cache. We need to exclude those.
if ((dp != null) && dp.IsPotentiallyInherited)
{
PropertyMetadata metadata = dp.GetMetadata(parent.DependencyObjectType);
if (metadata != null && metadata.IsInherited)
{
Debug.Assert(!inheritableProperties.Contains(dp), "EffectiveValues cache must not contains duplicate entries for the same DP");
FrameworkPropertyMetadata fMetadata = (FrameworkPropertyMetadata)metadata;
// Children do not need to inherit properties across a tree boundary
// unless the property is set to override this behavior.
if (!TreeWalkHelper.SkipNow(foParent.InheritanceBehavior) || fMetadata.OverridesInheritanceBehavior)
{
inheritableProperties.Add(dp);
EffectiveValueEntry oldEntry;
EffectiveValueEntry newEntry;
oldEntry = d.GetValueEntry(
d.LookupEntry(dp.GlobalIndex),
dp,
dp.GetMetadata(treeObjDOT),
RequestFlags.DeferredReferences);
if (isAddOperation)
{
// set up the new value
newEntry = entry;
if ((newEntry.BaseValueSourceInternal != BaseValueSourceInternal.Default) || newEntry.HasModifiers)
{
newEntry = newEntry.GetFlattenedEntry(RequestFlags.FullyResolved);
newEntry.BaseValueSourceInternal = BaseValueSourceInternal.Inherited;
}
}
else
{
newEntry = new EffectiveValueEntry();
}
_rootInheritableValues[inheritableIndex++] =
new InheritablePropertyChangeInfo(d, dp, oldEntry, newEntry);
if (inheritablePropertiesCount == inheritableIndex)
{
// no more inheritable properties, bail early
break;
}
}
}
}
}
return inheritableProperties;
}
// This is called by TreeWalker.InvalidateTreeDependentProperties before looping through
// all of the items in the InheritablesPropertiesStack
internal void ResetInheritableValueIndexer()
{
_valueIndexer = 0;
}
// This is called by TreeWalker.InvalidateTreeDependentProperty.
// _valueIndexer is an optimization because we know (a) that the last DP list pushed on the
// InheritablePropertiesStack is a subset of the first DP list pushed on this stack;
// (b) the first DP list pushed on the stack has the same # (and order) of entries as the
// RootInheritableValues list; and (c) the last DP list pushed on the stack will have its
// DPs in the same order as those DPs appear in the first DP list pushed on the stack. This
// allows us to simply increment _valueIndexer until we find a match; and on subsequent
// calls to GetRootInheritableValue just continue our incrementing from where we left off
// the last time.
internal InheritablePropertyChangeInfo GetRootInheritableValue(DependencyProperty dp)
{
InheritablePropertyChangeInfo info;
do
{
info = _rootInheritableValues[_valueIndexer++];
}
while (info.Property != dp);
return info;
}
/// <summary>
/// This is a stack that is used during an AncestorChange operation.
/// I holds the InheritableProperties cache on the parent nodes in
/// the tree in the order of traversal. The top of the stack holds
/// the cache for the immediate parent node.
/// </summary>
internal Stack<FrugalObjectList<DependencyProperty>> InheritablePropertiesStack
{
get
{
if (_inheritablePropertiesStack == null)
{
_inheritablePropertiesStack = new Stack<FrugalObjectList<DependencyProperty>>(1);
}
return _inheritablePropertiesStack;
}
}
/// <summary>
/// When we enter a Visibility=Collapsed subtree, we remember that node
/// using this property. As we process the children of this collapsed
/// node, we see this property as non-null and know we're collapsed.
/// As we exit the subtree, this reference is nulled out which means
/// we don't know whether we're in a collapsed tree and the optimizations
/// based on Visibility=Collapsed are not valid and should not be used.
/// </summary>
internal object TopmostCollapsedParentNode
{
get { return _topmostCollapsedParentNode; }
set { _topmostCollapsedParentNode = value; }
}
// Indicates if this is a add child tree operation
internal bool IsAddOperation
{
get { return _isAddOperation; }
}
// This is the element at the root of the sub-tree that had a parent change.
internal DependencyObject Root
{
get { return _rootOfChange; }
}
#endregion Properties
#region Data
private Stack<FrugalObjectList<DependencyProperty>> _inheritablePropertiesStack;
private object _topmostCollapsedParentNode;
private bool _isAddOperation;
private DependencyObject _rootOfChange;
private InheritablePropertyChangeInfo[] _rootInheritableValues;
private int _valueIndexer;
#endregion Data
}
}
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