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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.
using MS.Utility;
using MS.Internal;
using MS.Internal.KnownBoxes;
namespace System.Windows
{
/// <summary>
/// Container for the route to be followed
/// by a RoutedEvent when raised
/// </summary>
/// <remarks>
/// EventRoute constitues <para/>
/// a non-null <see cref="RoutedEvent"/>
/// and <para/>
/// an ordered list of (target object, handler list)
/// pairs <para/>
/// <para/>
///
/// It facilitates adding new entries to this list
/// and also allows for the handlers in the list
/// to be invoked
/// </remarks>
public sealed class EventRoute
{
#region Construction
/// <summary>
/// Constructor for <see cref="EventRoute"/> given
/// the associated <see cref="RoutedEvent"/>
/// </summary>
/// <param name="routedEvent">
/// Non-null <see cref="RoutedEvent"/> to be associated with
/// this <see cref="EventRoute"/>
/// </param>
public EventRoute(RoutedEvent routedEvent)
{
ArgumentNullException.ThrowIfNull(routedEvent);
_routedEvent = routedEvent;
// Changed the initialization size to 16
// to achieve performance gain based
// on standard app behavior
_routeItemList = new FrugalStructList<RouteItem>(16);
_sourceItemList = new FrugalStructList<SourceItem>(16);
}
#endregion Construction
#region External API
/// <summary>
/// Adds this handler for the
/// specified target to the route
/// </summary>
/// <remarks>
/// NOTE: It is not an error to add a
/// handler for a particular target instance
/// twice (handler will simply be called twice).
/// </remarks>
/// <param name="target">
/// Target object whose handler is to be
/// added to the route
/// </param>
/// <param name="handler">
/// Handler to be added to the route
/// </param>
/// <param name="handledEventsToo">
/// Flag indicating whether or not the listener wants to
/// hear about events that have already been handled
/// </param>
public void Add(object target, Delegate handler, bool handledEventsToo)
{
ArgumentNullException.ThrowIfNull(target);
ArgumentNullException.ThrowIfNull(handler);
RouteItem routeItem = new RouteItem(target, new RoutedEventHandlerInfo(handler, handledEventsToo));
_routeItemList.Add(routeItem);
}
/// <summary>
/// Invokes all the handlers that have been
/// added to the route
/// </summary>
/// <remarks>
/// NOTE: If the <see cref="RoutingStrategy"/>
/// of the associated <see cref="RoutedEvent"/>
/// is <see cref="RoutingStrategy.Bubble"/>
/// the last handlers added are the
/// last ones invoked <para/>
/// However if the <see cref="RoutingStrategy"/>
/// of the associated <see cref="RoutedEvent"/>
/// is <see cref="RoutingStrategy.Tunnel"/>,
/// the last handlers added are the
/// first ones invoked
/// </remarks>
/// <param name="source">
/// <see cref="RoutedEventArgs.Source"/>
/// that raised the RoutedEvent
/// </param>
/// <param name="args">
/// <see cref="RoutedEventArgs"/> that carry
/// all the details specific to this RoutedEvent
/// </param>
internal void InvokeHandlers(object source, RoutedEventArgs args)
{
InvokeHandlersImpl(source, args, false);
}
internal void ReInvokeHandlers(object source, RoutedEventArgs args)
{
InvokeHandlersImpl(source, args, true);
}
private void InvokeHandlersImpl(object source, RoutedEventArgs args, bool reRaised)
{
ArgumentNullException.ThrowIfNull(source);
ArgumentNullException.ThrowIfNull(args);
if (args.Source == null)
{
throw new ArgumentException(SR.SourceNotSet);
}
if (args.RoutedEvent != _routedEvent)
{
throw new ArgumentException(SR.Mismatched_RoutedEvent);
}
// Check RoutingStrategy to know the order of invocation
if (args.RoutedEvent.RoutingStrategy == RoutingStrategy.Bubble ||
args.RoutedEvent.RoutingStrategy == RoutingStrategy.Direct)
{
int endSourceChangeIndex = 0;
// If the RoutingStrategy of the associated is
// Bubble the handlers for the last target
// added are the last ones invoked
// Invoke class listeners
for (int i=0; i<_routeItemList.Count; i++)
{
// Query for new source only if we are
// past the range of the previous source change
if (i >= endSourceChangeIndex)
{
// Get the source at this point in the bubble route and also
// the index at which this source change seizes to apply
object newSource = GetBubbleSource(i, out endSourceChangeIndex);
// Set appropriate source
// The first call to setsource seems redundant
// but is necessary because the source could have
// been modified during BuildRoute call and hence
// may need to be reset to the original source.
// Note: we skip this logic if reRaised is set, which is done when we're trying
// to convert MouseDown/Up into a MouseLeft/RightButtonDown/Up
if(!reRaised)
{
if (newSource == null)
args.Source=source;
else
args.Source=newSource;
}
}
// Invoke listeners
var traceRoutedEventIsEnabled = TraceRoutedEvent.IsEnabled;
if ( traceRoutedEventIsEnabled )
{
_traceArguments ??= new object[3];
_traceArguments[0] = _routeItemList[i].Target;
_traceArguments[1] = args;
_traceArguments[2] = BooleanBoxes.Box(args.Handled);
TraceRoutedEvent.Trace(
TraceEventType.Start,
TraceRoutedEvent.InvokeHandlers,
_traceArguments);
}
_routeItemList[i].InvokeHandler(args);
if( traceRoutedEventIsEnabled )
{
_traceArguments[2] = BooleanBoxes.Box(args.Handled);
TraceRoutedEvent.Trace(
TraceEventType.Stop,
TraceRoutedEvent.InvokeHandlers,
_traceArguments);
}
}
}
else
{
int startSourceChangeIndex = _routeItemList.Count;
int endTargetIndex =_routeItemList.Count-1;
int startTargetIndex;
// If the RoutingStrategy of the associated is
// Tunnel the handlers for the last target
// added are the first ones invoked
while (endTargetIndex >= 0)
{
// For tunnel events we need to invoke handlers for the last target first.
// However the handlers for that individual target must be fired in the right order.
// Eg. Class Handlers must be fired before Instance Handlers.
object currTarget = _routeItemList[endTargetIndex].Target;
for (startTargetIndex=endTargetIndex; startTargetIndex>=0; startTargetIndex--)
{
if (_routeItemList[startTargetIndex].Target != currTarget)
{
break;
}
}
for (int i=startTargetIndex+1; i<=endTargetIndex; i++)
{
// Query for new source only if we are
// past the range of the previous source change
if (i < startSourceChangeIndex)
{
// Get the source at this point in the tunnel route and also
// the index at which this source change seizes to apply
object newSource = GetTunnelSource(i, out startSourceChangeIndex);
// Set appropriate source
// The first call to setsource seems redundant
// but is necessary because the source could have
// been modified during BuildRoute call and hence
// may need to be reset to the original source.
if (newSource == null)
args.Source=source;
else
args.Source=newSource;
}
var traceRoutedEventIsEnabled = TraceRoutedEvent.IsEnabled;
if ( traceRoutedEventIsEnabled )
{
_traceArguments ??= new object[3];
_traceArguments[0] = _routeItemList[i].Target;
_traceArguments[1] = args;
_traceArguments[2] = BooleanBoxes.Box(args.Handled);
TraceRoutedEvent.Trace(
TraceEventType.Start,
TraceRoutedEvent.InvokeHandlers,
_traceArguments);
}
// Invoke listeners
_routeItemList[i].InvokeHandler(args);
if (traceRoutedEventIsEnabled)
{
_traceArguments[2] = BooleanBoxes.Box(args.Handled);
TraceRoutedEvent.Trace(
TraceEventType.Stop,
TraceRoutedEvent.InvokeHandlers,
_traceArguments);
}
}
endTargetIndex = startTargetIndex;
}
}
}
/// <summary>
/// Pushes the given node at the top of the stack of branches.
/// </summary>
/// <remarks>
/// If a node in the tree has different visual and logical,
/// FrameworkElement will store the node on this stack of
/// branches. If the route ever returns to the same logical
/// tree, the event source will be restored.
/// <para/>
/// NOTE: This method needs to be public because it is used
/// by FrameworkElement.
/// </remarks>
/// <param name="node">
/// The node where the visual parent is different from the logical
/// parent.
/// </param>
/// <param name="source">
/// The source that is currently being used, and which should be
/// restored when this branch is popped off the stack.
/// </param>
[System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Advanced)]
public void PushBranchNode(object node, object source)
{
BranchNode branchNode = new BranchNode();
branchNode.Node = node;
branchNode.Source = source;
(_branchNodeStack ??= new Stack<BranchNode>(1)).Push(branchNode);
}
/// <summary>
/// Pops the given node from the top of the stack of branches.
/// </summary>
/// <remarks>
/// If a node in the tree has different visual and logical,
/// FrameworkElement will store the node on this stack of
/// branches. If the route ever returns to the same logical
/// tree, the event source will be restored.
/// <para/>
/// NOTE: This method needs to be public because it is used
/// by FrameworkElement.
/// </remarks>
/// <returns>
/// The node where the visual parent was different from the
/// logical parent.
/// </returns>
[System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Advanced)]
public object PopBranchNode()
{
if (_branchNodeStack is { Count: > 0 } stack)
{
return stack.Pop().Node;
}
return null;
}
/// <summary>
/// Peeks the given node from the top of the stack of branches.
/// </summary>
/// <remarks>
/// If a node in the tree has different visual and logical,
/// FrameworkElement will store the node on this stack of
/// branches. If the route ever returns to the same logical
/// tree, the event source will be restored.
/// <para/>
/// NOTE: This method needs to be public because it is used
/// by FrameworkElement.
/// </remarks>
/// <returns>
/// The node where the visual parent was different from the
/// logical parent.
/// </returns>
[System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Advanced)]
public object PeekBranchNode()
{
if (_branchNodeStack is { Count: > 0 } stack)
{
return stack.Peek().Node;
}
return null;
}
/// <summary>
/// Peeks the given source from the top of the stack of branches.
/// </summary>
/// <remarks>
/// If a node in the tree has different visual and logical,
/// FrameworkElement will store the node on this stack of
/// branches. If the route ever returns to the same logical
/// tree, the event source will be restored.
/// <para/>
/// NOTE: This method needs to be public because it is used
/// by FrameworkElement.
/// </remarks>
/// <returns>
/// The source that was stored along with the node where the
/// visual parent was different from the logical parent.
/// </returns>
[System.ComponentModel.EditorBrowsable(System.ComponentModel.EditorBrowsableState.Advanced)]
public object PeekBranchSource()
{
if (_branchNodeStack is { Count: > 0 } stack)
{
return stack.Peek().Source;
}
return null;
}
#endregion External API
#region Operations
// Return associated RoutedEvent
internal RoutedEvent RoutedEvent
{
get {return _routedEvent;}
set { _routedEvent = value; }
}
// A BranchNode indicates a point in the tree where the logical and
// visual structure might diverge. When building a route, we store
// this branch node for every logical link we find. Along with the
// node where the possible divergence occurred, we store the source
// that the event should use. This is so that the source of an
// event will always be in the logical tree of the element handling
// the event.
private struct BranchNode
{
public object Node;
public object Source;
}
// Add the given source to the source item list
// indicating what the source will be this point
// onwards in the route
internal void AddSource(object source)
{
int startIndex = _routeItemList.Count;
_sourceItemList.Add(new SourceItem(startIndex, source));
}
// Determine what the RoutedEventArgs.Source should be, at this
// point in the bubble. Also the endIndex output parameter tells
// you the exact index of the handlersList at which this source
// change ceases to apply
private object GetBubbleSource(int index, out int endIndex)
{
// If the Source never changes during the route execution,
// then we're done (just return null).
if (_sourceItemList.Count == 0)
{
endIndex = _routeItemList.Count;
return null;
}
// Similarly, if we're not to the point of the route of the first Source
// change, simply return null.
if (index < _sourceItemList[0].StartIndex)
{
endIndex = _sourceItemList[0].StartIndex;
return null;
}
// See if we should be using one of the intermediate
// sources
for (int i=0; i<_sourceItemList.Count -1; i++)
{
if (index >= _sourceItemList[i].StartIndex &&
index < _sourceItemList[i+1].StartIndex)
{
endIndex = _sourceItemList[i+1].StartIndex;
return _sourceItemList[i].Source;
}
}
// If we get here, we're on the last one,
// so return that.
endIndex = _routeItemList.Count;
return _sourceItemList[_sourceItemList.Count -1].Source;
}
// Determine what the RoutedEventArgs.Source should be, at this
// point in the tunnel. Also the startIndex output parameter tells
// you the exact index of the handlersList at which this source
// change starts to apply
private object GetTunnelSource(int index, out int startIndex)
{
// If the Source never changes during the route execution,
// then we're done (just return null).
if (_sourceItemList.Count == 0)
{
startIndex = 0;
return null;
}
// Similarly, if we're past the point of the route of the first Source
// change, simply return null.
if (index < _sourceItemList[0].StartIndex)
{
startIndex = 0;
return null;
}
// See if we should be using one of the intermediate
// sources
for (int i=0; i<_sourceItemList.Count -1; i++)
{
if (index >= _sourceItemList[i].StartIndex &&
index < _sourceItemList[i+1].StartIndex)
{
startIndex = _sourceItemList[i].StartIndex;
return _sourceItemList[i].Source;
}
}
// If we get here, we're on the last one, so return that.
startIndex = _sourceItemList[_sourceItemList.Count -1].StartIndex;
return _sourceItemList[_sourceItemList.Count -1].Source;
}
/// <summary>
/// Cleanup all the references within the data
/// </summary>
internal void Clear()
{
_routedEvent = null;
_routeItemList.Clear();
if (_branchNodeStack != null)
{
_branchNodeStack.Clear();
}
_sourceItemList.Clear();
}
#endregion Operations
#region Data
private RoutedEvent _routedEvent;
// Stores the routed event handlers to be
// invoked for the associated RoutedEvent
private FrugalStructList<RouteItem> _routeItemList;
// Stores the branching nodes in the route
// that need to be backtracked while
// augmenting the route
private Stack<BranchNode> _branchNodeStack;
// Stores Source Items for separated trees
private FrugalStructList<SourceItem> _sourceItemList;
// Stores arguments that are passed to TraceRoutedEvent.Trace (to reduce allocations)
private object[] _traceArguments;
#endregion Data
}
}
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