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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: Defines BindingExpressionBase object,
// base class for BindingExpression, PriorityBindingExpression,
// and MultiBindingExpression.
//
// See spec at Data Binding.mht
//
// build with this symbol defined to catch errors about not using
// BindingExpression.GetReference correctly
//#define USE_ITEM_REFERENCE
using System;
using System.Collections.Generic; // List<T>
using System.Collections.ObjectModel; // Collection<T>
using System.ComponentModel; // TypeConverter
using System.Diagnostics; // StackTrace
using System.Globalization; // CultureInfo
using System.Threading; // Thread
using System.Windows; // FrameworkElement
using System.Windows.Controls; // Validation
using System.Windows.Markup; // XmlLanguage
using System.Windows.Threading; // Dispatcher
using MS.Internal; // Invariant.Assert
using MS.Internal.Controls; // ValidationErrorCollection
using MS.Internal.Data; // DataBindEngine
using MS.Internal.KnownBoxes; // BooleanBoxes
using MS.Internal.Utility; // TraceLog
namespace System.Windows.Data
{
/// <summary>
/// Base class for Binding Expressions.
/// </summary>
public abstract class BindingExpressionBase : Expression, IWeakEventListener
{
// Flags indicating run-time properties of a BindingExpression
[Flags]
internal enum BindingFlags : uint
{
// names used by Binding
OneWay = PrivateFlags.iSourceToTarget,
TwoWay = PrivateFlags.iSourceToTarget | PrivateFlags.iTargetToSource,
OneWayToSource = PrivateFlags.iTargetToSource,
OneTime = 0,
PropDefault = PrivateFlags.iPropDefault,
NotifyOnTargetUpdated = PrivateFlags.iNotifyOnTargetUpdated,
NotifyOnSourceUpdated = PrivateFlags.iNotifyOnSourceUpdated,
NotifyOnValidationError = PrivateFlags.iNotifyOnValidationError,
UpdateOnPropertyChanged = 0,
UpdateOnLostFocus = PrivateFlags.iUpdateOnLostFocus,
UpdateExplicitly = PrivateFlags.iUpdateExplicitly,
UpdateDefault = PrivateFlags.iUpdateDefault,
PathGeneratedInternally = PrivateFlags.iPathGeneratedInternally,
ValidatesOnExceptions = PrivateFlags.iValidatesOnExceptions,
ValidatesOnDataErrors = PrivateFlags.iValidatesOnDataErrors,
ValidatesOnNotifyDataErrors = PrivateFlags.iValidatesOnNotifyDataErrors,
Default = PropDefault | UpdateDefault,
/// <summary> Error value, returned by FlagsFrom to indicate faulty input</summary>
IllegalInput = PrivateFlags.iIllegalInput,
PropagationMask = OneWay | TwoWay | OneWayToSource | OneTime | PropDefault,
UpdateMask = UpdateOnPropertyChanged | UpdateOnLostFocus | UpdateExplicitly | UpdateDefault,
}
[Flags]
private enum PrivateFlags : uint
{
// internal use
iSourceToTarget = 0x00000001,
iTargetToSource = 0x00000002,
iPropDefault = 0x00000004,
iNotifyOnTargetUpdated = 0x00000008,
iDefaultValueConverter = 0x00000010,
iInTransfer = 0x00000020,
iInUpdate = 0x00000040,
iTransferPending = 0x00000080,
iNeedDataTransfer = 0x00000100,
iTransferDeferred = 0x00000200, // used by MultiBindingExpression
iUpdateOnLostFocus = 0x00000400,
iUpdateExplicitly = 0x00000800,
iUpdateDefault = iUpdateExplicitly | iUpdateOnLostFocus,
iNeedsUpdate = 0x00001000,
iPathGeneratedInternally = 0x00002000,
iUsingMentor = 0x00004000,
iResolveNamesInTemplate = 0x00008000,
iDetaching = 0x00010000,
iNeedsCollectionView = 0x00020000,
iInPriorityBindingExpression= 0x00040000,
iInMultiBindingExpression = 0x00080000,
iUsingFallbackValue = 0x00100000,
iNotifyOnValidationError = 0x00200000,
iAttaching = 0x00400000,
iNotifyOnSourceUpdated = 0x00800000,
iValidatesOnExceptions = 0x01000000,
iValidatesOnDataErrors = 0x02000000,
iIllegalInput = 0x04000000,
iNeedsValidation = 0x08000000,
iTargetWantsXTNotification = 0x10000000,
iValidatesOnNotifyDataErrors= 0x20000000,
iDataErrorsChangedPending = 0x40000000,
iDeferUpdateForComposition = 0x80000000,
iPropagationMask = iSourceToTarget | iTargetToSource | iPropDefault,
iUpdateMask = iUpdateOnLostFocus | iUpdateExplicitly,
iAdoptionMask = iSourceToTarget | iTargetToSource | iNeedsUpdate | iNeedsValidation,
}
//------------------------------------------------------
//
// Constructors
//
//------------------------------------------------------
static BindingExpressionBase()
{
Debug.Assert((int)Feature.LastFeatureId <= 32, "UncommonValueTable supports only 32 Ids");
}
/// <summary> Constructor </summary>
internal BindingExpressionBase(BindingBase binding, BindingExpressionBase parent) : base(ExpressionMode.SupportsUnboundSources)
{
ArgumentNullException.ThrowIfNull(binding);
_binding = binding;
SetValue(Feature.ParentBindingExpressionBase, parent, null);
_flags = (PrivateFlags)binding.Flags;
if (parent != null)
{
ResolveNamesInTemplate = parent.ResolveNamesInTemplate;
Type type = parent.GetType();
if (type == typeof(MultiBindingExpression))
ChangeFlag(PrivateFlags.iInMultiBindingExpression, true);
else if (type == typeof(PriorityBindingExpression))
ChangeFlag(PrivateFlags.iInPriorityBindingExpression, true);
}
// initialize tracing information
PresentationTraceLevel traceLevel = PresentationTraceSources.GetTraceLevel(binding);
if (traceLevel > 0)
{
// copy TraceLevel from parent BindingBase - it can be changed later
PresentationTraceSources.SetTraceLevel(this, traceLevel);
}
if (TraceData.IsExtendedTraceEnabled(this, TraceDataLevel.CreateExpression))
{
if (parent == null)
{
TraceData.TraceAndNotify(TraceEventType.Warning,
TraceData.CreatedExpression(
TraceData.Identify(this),
TraceData.Identify(binding)),
this);
}
else
{
TraceData.TraceAndNotifyWithNoParameters(TraceEventType.Warning,
TraceData.CreatedExpressionInParent(
TraceData.Identify(this),
TraceData.Identify(binding),
TraceData.Identify(parent)),
this);
}
}
if (LookupValidationRule(typeof(ExceptionValidationRule)) != null)
{
ChangeFlag(PrivateFlags.iValidatesOnExceptions, true);
}
if (LookupValidationRule(typeof(DataErrorValidationRule)) != null)
{
ChangeFlag(PrivateFlags.iValidatesOnDataErrors, true);
}
}
//------------------------------------------------------
//
// Public Properties
//
//------------------------------------------------------
/// <summary> The element to which this BindingExpression is attached </summary>
public DependencyObject Target { get { return TargetElement; } }
/// <summary> The property to which this BindingExpression is attached </summary>
public DependencyProperty TargetProperty { get { return _targetProperty; } }
/// <summary> Binding from which this BindingExpression was created </summary>
public BindingBase ParentBindingBase { get { return _binding; } }
/// <summary> The BindingGroup to which this BindingExpression belongs (or null) </summary>
public BindingGroup BindingGroup
{
get
{
BindingExpressionBase root = RootBindingExpression;
WeakReference<BindingGroup> wr = (WeakReference<BindingGroup>)root.GetValue(Feature.BindingGroup, null);
if (wr == null)
return null;
else
{
BindingGroup bg;
return (wr.TryGetTarget(out bg)) ? bg : null;
}
}
}
/// <summary>Status of the BindingExpression</summary>
public BindingStatus Status { get { return (BindingStatus)_status; } }
internal BindingStatusInternal StatusInternal { get { return _status; } }
/// <summary>
/// The ValidationError that caused this
/// BindingExpression to be invalid.
/// </summary>
public virtual ValidationError ValidationError
{
get { return BaseValidationError; }
}
internal ValidationError BaseValidationError
{
get { return (ValidationError)GetValue(Feature.ValidationError, null); }
}
internal List<ValidationError> NotifyDataErrors
{
get { return (List<ValidationError>)GetValue(Feature.NotifyDataErrors, null); }
}
/// <summary>
/// HasError returns true if any of the ValidationRules
/// in the ParentBinding failed its validation rule.
/// </summary>
public virtual bool HasError
{
get { return HasValidationError; }
}
/// <summary>
/// HasValidationError returns true if any of the ValidationRules
/// in the ParentBinding failed its validation rule.
/// </summary>
public virtual bool HasValidationError
{
get
{
return HasValue(Feature.ValidationError) || HasValue(Feature.NotifyDataErrors);
}
}
/// <summary>
/// IsDirty returns true if the target property has a new value that
/// has not yet been written to the source property. (This applies
/// only to bindings that are TwoWay or OneWayToSource.)
/// </summary>
public bool IsDirty
{
get { return NeedsUpdate; }
}
/// <summary>
/// ValidationErrors returns the validation errors currently
/// arising from this binding, or null if there are no errors.
/// </summary>
public virtual ReadOnlyCollection<ValidationError> ValidationErrors
{
get
{
if (HasError)
{
List<ValidationError> list;
if (!HasValue(Feature.ValidationError))
{
list = NotifyDataErrors;
}
else
{
if (NotifyDataErrors == null)
{
list = new List<ValidationError>();
}
else
{
list = new List<ValidationError>(NotifyDataErrors);
}
list.Insert(0, BaseValidationError);
}
return new ReadOnlyCollection<ValidationError>(list);
}
else
return null;
}
}
//------------------------------------------------------
//
// Public Methods
//
//------------------------------------------------------
/// <summary> Force a data transfer from source to target </summary>
public virtual void UpdateTarget()
{
}
/// <summary> Send the current value back to the source </summary>
/// <remarks> Does nothing when binding's Mode is not TwoWay or OneWayToSource </remarks>
public virtual void UpdateSource()
{
}
/// <summary>
/// Run UI-side validation rules on the proposed value held by this
/// binding expression, but do not write the proposed value back to
/// the source, or run source-side validation rules.
/// </summary>
/// <returns>
/// True, if the validation rules all pass, or if there is no proposed
/// value to check. False, otherwise.
/// </returns>
/// <remarks>
/// "UI-side" validation rules are those whose validation step is
/// RawProposedValue or ConvertedProposedValue. Previous validation
/// errors for these rules are cleared, and new errors discovered for
/// these rules are added to the Validation.Errors collections. The
/// Validation.HasError property, validation adorner feedback, and
/// validation error events are updated appropriately.
/// </remarks>
public bool ValidateWithoutUpdate()
{
if (!NeedsValidation)
return true;
Collection<ProposedValue> values;
return ValidateAndConvertProposedValue(out values);
}
#region Expression overrides
/// <summary>
/// Notification that the Expression has been set as a property's value
/// </summary>
/// <remarks>
/// Subclasses should not override OnAttach(), but must override Attach()
/// </remarks>
/// <param name="d">DependencyObject being set</param>
/// <param name="dp">Property being set</param>
internal sealed override void OnAttach(DependencyObject d, DependencyProperty dp)
{
ArgumentNullException.ThrowIfNull(d);
ArgumentNullException.ThrowIfNull(dp);
Attach(d, dp);
}
/// <summary>
/// Notification that the Expression has been removed as a property's value
/// </summary>
/// <remarks>
/// Subclasses should not override OnDetach(), but must override DetachOverride()
/// </remarks>
/// <param name="d">DependencyObject being cleared</param>
/// <param name="dp">Property being cleared</param>
internal sealed override void OnDetach(DependencyObject d, DependencyProperty dp)
{
Detach();
}
/// <summary>
/// Called to evaluate the Expression value
/// </summary>
/// <param name="d">DependencyObject being queried</param>
/// <param name="dp">Property being queried</param>
/// <returns>Computed value. Unset if unavailable.</returns>
internal override object GetValue(DependencyObject d, DependencyProperty dp)
{
return Value;
}
/// <summary>
/// Allows Expression to store set values
/// </summary>
/// <param name="d">DependencyObject being set</param>
/// <param name="dp">Property being set</param>
/// <param name="value">Value being set</param>
/// <returns>true if Expression handled storing of the value</returns>
internal override bool SetValue(DependencyObject d, DependencyProperty dp, object value)
{
if (IsReflective)
{
Value = value;
return true;
}
else
{
// if the binding doesn't push values back to the source, allow
// SetValue to overwrite the binding with a local value
return false;
}
}
/// <summary>
/// Notification that a Dependent that this Expression established has
/// been invalidated as a result of a Source invalidation
/// </summary>
/// <param name="d">DependencyObject that was invalidated</param>
/// <param name="args">Changed event args for the property that was invalidated</param>
internal override void OnPropertyInvalidation(DependencyObject d, DependencyPropertyChangedEventArgs args)
{
// It's possible to receive this notification after we've unsubscribed to it.
// This can happen if the sender raises the notification to a list of
// clients and one of the earlier clients causes a later client to
// unsubscribe. The sender uses a copy of the list, so the later client
// will still get the notification.
// If this happens, simply ignore the notification.
if (IsDetached)
return;
IsTransferPending = true;
// if the notification arrived on the right Dispatcher, handle it now.
if (Dispatcher.Thread == Thread.CurrentThread)
{
HandlePropertyInvalidation(d, args);
}
else // Otherwise, marshal it to the right Dispatcher.
{
Engine.Marshal(
new DispatcherOperationCallback(HandlePropertyInvalidationOperation),
new object[]{d, args});
}
}
/// <summary>
/// List of sources of the Expression
/// </summary>
/// <returns>Sources list</returns>
internal override DependencySource[] GetSources()
{
int j, k;
int n = (_sources != null) ? _sources.Length : 0;
if (n == 0)
return null;
DependencySource[] result = new DependencySource[n];
// convert the weak references into strong ones
for (j=0, k=0; k<n; ++k)
{
DependencyObject d = _sources[k].DependencyObject;
if (d != null)
{
result[j++] = new DependencySource(d, _sources[k].DependencyProperty);
}
}
// if any of the references died, return a shortened list
if (j < n)
{
DependencySource[] temp = result;
result = new DependencySource[j];
Array.Copy(temp, 0, result, 0, j);
}
return result;
}
// We need this Clone method to copy a binding during Freezable.Copy. We shouldn't be taking
// the target object/dp parameters here, but Binding.ProvideValue requires it. (Binding
// could probably be re-factored so that we don't need this).
internal override Expression Copy( DependencyObject targetObject, DependencyProperty targetDP )
{
return ParentBindingBase.CreateBindingExpression(targetObject, targetDP);
}
#endregion Expression overrides
/// <summary>
/// Handle events from the centralized event table
/// </summary>
bool IWeakEventListener.ReceiveWeakEvent(Type managerType, object sender, EventArgs e)
{
return ReceiveWeakEvent(managerType, sender, e);
}
#region BindingExpressions with no target DP
//------------------------------------------------------
//
// API for BindingExpressions with no target DP (task 20769)
// This is internal for now, until we review whether we wish to
// make it public
//
//------------------------------------------------------
/// <summary> Create an untargeted BindingExpression </summary>
internal static BindingExpressionBase CreateUntargetedBindingExpression(DependencyObject d, BindingBase binding)
{
return binding.CreateBindingExpression(d, NoTargetProperty);
}
/// <summary> Attach the BindingExpression to its target element </summary>
/// <remarks>
/// This method must be called once during the initialization.
/// </remarks>
/// <param name="d">The target element </param>
internal void Attach(DependencyObject d)
{
Attach(d, NoTargetProperty);
}
/// <summary> This event is raised when the BindingExpression's value changes </summary>
internal event EventHandler<BindingValueChangedEventArgs> ValueChanged;
/* The following APIs are also needed for untargeted bindings, but they already exist
for other reasons.
/// <summary> The current value of the BindingExpression </summary>
internal object Value { get; set; }
/// <summary> Activate the BindingExpression, using the given item as its root item. </summary>
internal void Activate(object item) {}
/// <summary> Deactivate the BindingExpression. </summary>
internal void Deactivate() {}
/// <summary> Detach the BindingExpression from its target element </summary>
/// <remarks>
/// This method must be called once when the BindingExpression is no longer needed.
/// </remarks>
internal void Detach() {}
*/
#endregion BindingExpressions with no target DP
//------------------------------------------------------
//
// Protected Properties
//
//------------------------------------------------------
/// <summary> True if this binding expression is attaching </summary>
internal bool IsAttaching
{
get { return TestFlag(PrivateFlags.iAttaching); }
set { ChangeFlag(PrivateFlags.iAttaching, value); }
}
/// <summary> True if this binding expression is detaching </summary>
internal bool IsDetaching
{
get { return TestFlag(PrivateFlags.iDetaching); }
set { ChangeFlag(PrivateFlags.iDetaching, value); }
}
/// <summary> True if this binding expression is detached </summary>
internal bool IsDetached
{
get { return (_status == BindingStatusInternal.Detached); }
}
private bool IsAttached
{
get { return (_status != BindingStatusInternal.Unattached &&
_status != BindingStatusInternal.Detached &&
!IsDetaching); }
}
/// <summary> True if this binding expression updates the target </summary>
internal bool IsDynamic
{
get
{
return ( TestFlag(PrivateFlags.iSourceToTarget)
&& (!IsInMultiBindingExpression || ParentMultiBindingExpression.IsDynamic));
}
}
/// <summary> True if this binding expression updates the source </summary>
internal bool IsReflective
{
get
{
return ( TestFlag(PrivateFlags.iTargetToSource)
&& (!IsInMultiBindingExpression || ParentMultiBindingExpression.IsReflective));
}
set { ChangeFlag(PrivateFlags.iTargetToSource, value); }
}
/// <summary> True if this binding expression uses a default ValueConverter </summary>
internal bool UseDefaultValueConverter
{
get { return TestFlag(PrivateFlags.iDefaultValueConverter); }
set { ChangeFlag(PrivateFlags.iDefaultValueConverter, value); }
}
/// <summary> True if this binding expression is OneWayToSource </summary>
internal bool IsOneWayToSource
{
get { return (_flags & PrivateFlags.iPropagationMask) == PrivateFlags.iTargetToSource; }
}
/// <summary> True if this binding expression updates on PropertyChanged </summary>
internal bool IsUpdateOnPropertyChanged
{
get { return (_flags & PrivateFlags.iUpdateMask) == 0; }
}
/// <summary> True if this binding expression updates on LostFocus </summary>
internal bool IsUpdateOnLostFocus
{
get { return TestFlag(PrivateFlags.iUpdateOnLostFocus); }
}
/// <summary> True if this binding expression has a pending target update </summary>
internal bool IsTransferPending
{
get { return TestFlag(PrivateFlags.iTransferPending); }
set { ChangeFlag(PrivateFlags.iTransferPending, value); }
}
/// <summary> True if this binding expression is deferring a target update </summary>
internal bool TransferIsDeferred
{
get { return TestFlag(PrivateFlags.iTransferDeferred); }
set { ChangeFlag(PrivateFlags.iTransferDeferred, value); }
}
/// <summary> True if this binding expression is updating the target </summary>
internal bool IsInTransfer
{
get { return TestFlag(PrivateFlags.iInTransfer); }
set { ChangeFlag(PrivateFlags.iInTransfer, value); }
}
/// <summary> True if this binding expression is updating the source </summary>
internal bool IsInUpdate
{
get { return TestFlag(PrivateFlags.iInUpdate); }
set { ChangeFlag(PrivateFlags.iInUpdate, value); }
}
/// <summary> True if this binding expression is using the fallback value </summary>
internal bool UsingFallbackValue
{
get { return TestFlag(PrivateFlags.iUsingFallbackValue); }
set { ChangeFlag(PrivateFlags.iUsingFallbackValue, value); }
}
/// <summary> True if this binding expression uses the mentor of the target element </summary>
internal bool UsingMentor
{
get { return TestFlag(PrivateFlags.iUsingMentor); }
set { ChangeFlag(PrivateFlags.iUsingMentor, value); }
}
/// <summary> True if this binding expression should resolve ElementName within the template of the target element </summary>
internal bool ResolveNamesInTemplate
{
get { return TestFlag(PrivateFlags.iResolveNamesInTemplate); }
set { ChangeFlag(PrivateFlags.iResolveNamesInTemplate, value); }
}
/// <summary> True if this binding expression has a pending target update </summary>
internal bool NeedsDataTransfer
{
get { return TestFlag(PrivateFlags.iNeedDataTransfer); }
set { ChangeFlag(PrivateFlags.iNeedDataTransfer, value); }
}
/// <summary> True if this binding expression has a pending source update </summary>
internal bool NeedsUpdate
{
get { return TestFlag(PrivateFlags.iNeedsUpdate); }
set
{
ChangeFlag(PrivateFlags.iNeedsUpdate, value);
if (value)
{
NeedsValidation = true;
}
}
}
/// <summary> True if this binding expression needs validation </summary>
internal bool NeedsValidation
{
get { return TestFlag(PrivateFlags.iNeedsValidation) || HasValue(Feature.ValidationError); }
set { ChangeFlag(PrivateFlags.iNeedsValidation, value); }
}
/// <summary> True if this binding expression should raise the TargetUpdated event </summary>
internal bool NotifyOnTargetUpdated
{
get { return TestFlag(PrivateFlags.iNotifyOnTargetUpdated); }
set { ChangeFlag(PrivateFlags.iNotifyOnTargetUpdated, value); }
}
/// <summary> True if this binding expression should raise the SourceUpdated event </summary>
internal bool NotifyOnSourceUpdated
{
get { return TestFlag(PrivateFlags.iNotifyOnSourceUpdated); }
set { ChangeFlag(PrivateFlags.iNotifyOnSourceUpdated, value); }
}
/// <summary> True if this binding expression should raise the ValidationError event </summary>
internal bool NotifyOnValidationError
{
get { return TestFlag(PrivateFlags.iNotifyOnValidationError); }
set { ChangeFlag(PrivateFlags.iNotifyOnValidationError, value); }
}
/// <summary> True if this binding expression belongs to a PriorityBinding </summary>
internal bool IsInPriorityBindingExpression
{
get { return TestFlag(PrivateFlags.iInPriorityBindingExpression); }
}
/// <summary> True if this binding expression belongs to a MultiBinding </summary>
internal bool IsInMultiBindingExpression
{
get { return TestFlag(PrivateFlags.iInMultiBindingExpression); }
}
/// <summary> True if this binding expression belongs to a PriorityBinding or MultiBinding </summary>
internal bool IsInBindingExpressionCollection
{
get { return TestFlag(PrivateFlags.iInPriorityBindingExpression | PrivateFlags.iInMultiBindingExpression); }
}
/// <summary> True if this binding expression validates on exceptions </summary>
internal bool ValidatesOnExceptions
{
get { return TestFlag(PrivateFlags.iValidatesOnExceptions); }
}
/// <summary> True if this binding expression validates on data errors </summary>
internal bool ValidatesOnDataErrors
{
get { return TestFlag(PrivateFlags.iValidatesOnDataErrors); }
}
/// <summary> True if the target wants to hear about cross-thread property changes immediately </summary>
internal bool TargetWantsCrossThreadNotifications
{
get { return TestFlag(PrivateFlags.iTargetWantsXTNotification); }
set { ChangeFlag(PrivateFlags.iTargetWantsXTNotification, value); }
}
/// <summary> True if this binding expression has a pending DataErrorsChanged notification </summary>
internal bool IsDataErrorsChangedPending
{
get { return TestFlag(PrivateFlags.iDataErrorsChangedPending); }
set { ChangeFlag(PrivateFlags.iDataErrorsChangedPending, value); }
}
/// <summary> True if this binding expression is waiting for an IME composition to complete before updating its source </summary>
internal bool IsUpdateDeferredForComposition
{
get { return TestFlag(PrivateFlags.iDeferUpdateForComposition); }
set { ChangeFlag(PrivateFlags.iDeferUpdateForComposition, value); }
}
/// <summary> True if this binding expression validates on notify data errors </summary>
internal bool ValidatesOnNotifyDataErrors
{
get { return TestFlag(PrivateFlags.iValidatesOnNotifyDataErrors); }
}
/// <summary> The parent MultiBindingExpression (if any) </summary>
internal MultiBindingExpression ParentMultiBindingExpression
{
get { return GetValue(Feature.ParentBindingExpressionBase, null) as MultiBindingExpression; }
}
/// <summary> The parent PriorityBindingExpression (if any) </summary>
internal PriorityBindingExpression ParentPriorityBindingExpression
{
get { return GetValue(Feature.ParentBindingExpressionBase, null) as PriorityBindingExpression; }
}
/// <summary> The parent PriorityBindingExpression or MultiBindingExpression (if any) </summary>
internal BindingExpressionBase ParentBindingExpressionBase
{
get { return (BindingExpressionBase)GetValue(Feature.ParentBindingExpressionBase, null); }
}
/// <summary> The FallbackValue (from the parent Binding), possibly converted
/// to a type suitable for the target property.</summary>
internal object FallbackValue
{
// perf note: we recompute the value every time it's needed. This is
// a good decision if we seldom need the value. Alternatively we could
// cache it. Wait until we know what the perf impact really is.
get { return ConvertFallbackValue(ParentBindingBase.FallbackValue, TargetProperty, this); }
}
/// <summary> The default value of the target property </summary>
internal object DefaultValue
{
// perf note: we recompute the value every time it's needed. This is
// a good decision if we seldom need the value. Alternatively we could
// cache it. Wait until we know what the perf impact really is.
get
{
DependencyObject target = TargetElement;
if (target != null)
{
return TargetProperty.GetDefaultValue(target.DependencyObjectType);
}
return DependencyProperty.UnsetValue;
}
}
/// <summary> The effective string format, taking into account the target
/// property, parent bindings, convenience syntax, etc. </summary>
internal string EffectiveStringFormat
{
get { return (string)GetValue(Feature.EffectiveStringFormat, null); }
}
/// <summary> The effective TargetNullValue, taking into account the target
/// property, parent bindings, etc. </summary>
internal object EffectiveTargetNullValue
{
get { return GetValue(Feature.EffectiveTargetNullValue, DependencyProperty.UnsetValue); }
}
/// <summary> return the root of the tree of {Multi/Priority}BindingExpressions</summary>
internal BindingExpressionBase RootBindingExpression
{
get
{
BindingExpressionBase child = this;
BindingExpressionBase parent = this.ParentBindingExpressionBase;
while (parent != null)
{
child = parent;
parent = child.ParentBindingExpressionBase;
}
return child;
}
}
internal virtual bool IsParentBindingUpdateTriggerDefault
{
get { return false; }
}
internal bool UsesLanguage
{
get { return (ParentBindingBase.ConverterCultureInternal == null); }
}
internal bool IsEligibleForCommit
{
get
{
if (IsDetaching)
return false;
switch (StatusInternal)
{
case BindingStatusInternal.Unattached:
case BindingStatusInternal.Inactive:
case BindingStatusInternal.Detached:
case BindingStatusInternal.PathError:
return false;
default:
return true;
}
}
}
//------------------------------------------------------
//
// Protected Methods
//
//------------------------------------------------------
/// <summary>
/// Attach the binding expression to the given target object and property.
/// Derived classes should call base.AttachOverride before doing their work,
/// and should continue only if it returns true.
/// </summary>
internal virtual bool AttachOverride(DependencyObject target, DependencyProperty dp)
{
_targetElement = new WeakReference(target);
_targetProperty = dp;
// get the engine
DataBindEngine engine = DataBindEngine.CurrentDataBindEngine;
if (engine == null || engine.IsShutDown)
{
return false; // don't even think about doing any work if the DBE is shut down
// we do this after setting TargetElement and TargetProperty so that
// an app that (rather futilely) creates a binding after shutdown
// will at least see the default value. This avoids the assert in
// EffectiveValueEntry.SetExpressionValue.
}
_engine = engine;
DetermineEffectiveStringFormat();
DetermineEffectiveTargetNullValue();
DetermineEffectiveUpdateBehavior();
DetermineEffectiveValidatesOnNotifyDataErrors();
// root bindings on TextBox.Text need to listen for IME composition events
if (dp == System.Windows.Controls.TextBox.TextProperty && IsReflective && !IsInBindingExpressionCollection)
{
System.Windows.Controls.Primitives.TextBoxBase tbb = target as System.Windows.Controls.Primitives.TextBoxBase;
if (tbb != null)
{
tbb.PreviewTextInput += OnPreviewTextInput;
}
}
if (TraceData.IsExtendedTraceEnabled(this, TraceDataLevel.Attach))
{
TraceData.TraceAndNotifyWithNoParameters(TraceEventType.Warning,
TraceData.AttachExpression(
TraceData.Identify(this),
target.GetType().FullName, dp.Name, AvTrace.GetHashCodeHelper(target)),
this);
}
return true;
}
/// <summary>
/// Detach the binding expression from its target object and property.
/// Derived classes should call base.DetachOverride after doing their work.
/// </summary>
internal virtual void DetachOverride()
{
UpdateValidationError(null);
UpdateNotifyDataErrorValidationErrors(null);
// root bindings on TextBox.Text need to stop listening for IME composition events
if (TargetProperty == System.Windows.Controls.TextBox.TextProperty && IsReflective && !IsInBindingExpressionCollection)
{
System.Windows.Controls.Primitives.TextBoxBase tbb = TargetElement as System.Windows.Controls.Primitives.TextBoxBase;
if (tbb != null)
{
tbb.PreviewTextInput -= OnPreviewTextInput;
}
}
_engine = null;
_targetElement = null;
_targetProperty = null;
SetStatus(BindingStatusInternal.Detached);
if (TraceData.IsExtendedTraceEnabled(this, TraceDataLevel.Attach))
{
TraceData.TraceAndNotifyWithNoParameters(TraceEventType.Warning,
TraceData.DetachExpression(
TraceData.Identify(this)),
this);
}
}
/// <summary>
/// Invalidate the given child expression.
/// </summary>
internal abstract void InvalidateChild(BindingExpressionBase bindingExpression);
/// <summary>
/// Change the dependency sources for the given child expression.
/// </summary>
internal abstract void ChangeSourcesForChild(BindingExpressionBase bindingExpression, WeakDependencySource[] newSources);
/// <summary>
/// Replace the given child expression with a new one.
/// </summary>
internal abstract void ReplaceChild(BindingExpressionBase bindingExpression);
internal abstract void HandlePropertyInvalidation(DependencyObject d, DependencyPropertyChangedEventArgs args);
private object HandlePropertyInvalidationOperation(object o)
{
// This is the case where the source of the Binding belonged to a different Dispatcher
// than the target. For this scenario the source marshals off the invalidation information
// onto the target's Dispatcher queue. This is where we unpack the marshalled information
// to fire the invalidation on the target object.
object[] args = (object[])o;
HandlePropertyInvalidation((DependencyObject)args[0], (DependencyPropertyChangedEventArgs)args[1]);
return null;
}
// handle joining or leaving a binding group
internal void OnBindingGroupChanged(bool joining)
{
if (joining)
{
// joining a binding group:
// update Explicitly, unless declared otherwise
if (IsParentBindingUpdateTriggerDefault)
{
if (IsUpdateOnLostFocus)
{
LostFocusEventManager.RemoveHandler(TargetElement, OnLostFocus);
}
SetUpdateSourceTrigger(UpdateSourceTrigger.Explicit);
}
}
else
{
// leaving a binding group:
// restore update trigger
if (IsParentBindingUpdateTriggerDefault)
{
// do this asynchronously, to avoid event-leapfrogging.
// In the template-swapping scenario (common in DataGrid) it's
// common to leave a binding group because you've lost focus.
// We don't want that focus-loss to cause an update.
Dispatcher.BeginInvoke(
DispatcherPriority.Loaded,
new DispatcherOperationCallback(RestoreUpdateTriggerOperation),
null);
}
}
}
object RestoreUpdateTriggerOperation(object arg)
{
DependencyObject target = TargetElement;
if (!IsDetached && target != null)
{
FrameworkPropertyMetadata fwMetaData = TargetProperty.GetMetadata(target.DependencyObjectType) as FrameworkPropertyMetadata;
UpdateSourceTrigger ust = GetDefaultUpdateSourceTrigger(fwMetaData);
SetUpdateSourceTrigger(ust);
if (IsUpdateOnLostFocus)
{
LostFocusEventManager.AddHandler(target, OnLostFocus);
}
}
return null;
}
// register the leaf bindings with the binding group
internal abstract void UpdateBindingGroup(BindingGroup bg);
// transfer a value from target to source
internal bool UpdateValue()
{
ValidationError oldValidationError = BaseValidationError;
if (StatusInternal == BindingStatusInternal.UpdateSourceError)
SetStatus(BindingStatusInternal.Active);
object value = GetRawProposedValue();
if (!Validate(value, ValidationStep.RawProposedValue))
return false;
value = ConvertProposedValue(value);
if (!Validate(value, ValidationStep.ConvertedProposedValue))
return false;
value = UpdateSource(value);
if (!Validate(value, ValidationStep.UpdatedValue))
return false;
value = CommitSource(value);
if (!Validate(value, ValidationStep.CommittedValue))
return false;
if (BaseValidationError == oldValidationError)
{
// the binding is now valid - remove the old error
UpdateValidationError(null);
}
EndSourceUpdate();
NotifyCommitManager();
return !HasValue(Feature.ValidationError);
}
/// <summary>
/// Get the raw proposed value
/// <summary>
internal virtual object GetRawProposedValue()
{
object value = Value;
// TargetNullValue is the UI representation of a "null" value. Use null internally.
if (ItemsControl.EqualsEx(value, EffectiveTargetNullValue))
{
value = null;
}
return value;
}
/// <summary>
/// Get the converted proposed value
/// <summary>
internal abstract object ConvertProposedValue(object rawValue);
/// <summary>
/// Get the converted proposed value and inform the binding group
/// <summary>
internal abstract bool ObtainConvertedProposedValue(BindingGroup bindingGroup);
/// <summary>
/// Update the source value
/// <summary>
internal abstract object UpdateSource(object convertedValue);
/// <summary>
/// Update the source value and inform the binding group
/// <summary>
internal abstract bool UpdateSource(BindingGroup bindingGroup);
/// <summary>
/// Commit the source value
/// <summary>
internal virtual object CommitSource(object value)
{
return value;
}
/// <summary>
/// Store the value in the binding group
/// </summary>
internal abstract void StoreValueInBindingGroup(object value, BindingGroup bindingGroup);
/// <summary>
/// Run validation rules for the given step
/// <summary>
internal virtual bool Validate(object value, ValidationStep validationStep)
{
if (value == Binding.DoNothing)
return true;
if (value == DependencyProperty.UnsetValue)
{
SetStatus(BindingStatusInternal.UpdateSourceError);
return false;
}
// get old errors from this step - we're about to reevaluate those rules.
ValidationError oldValidationError = GetValidationErrors(validationStep);
// ignore an error from the implicit DataError rule - this is checked
// separately (in BindingExpression.Validate).
if (oldValidationError != null &&
oldValidationError.RuleInError == DataErrorValidationRule.Instance)
{
oldValidationError = null;
}
Collection<ValidationRule> validationRules = ParentBindingBase.ValidationRulesInternal;
if (validationRules != null)
{
CultureInfo culture = GetCulture();
foreach (ValidationRule validationRule in validationRules)
{
if (validationRule.ValidationStep == validationStep)
{
ValidationResult validationResult = validationRule.Validate(value, culture, this);
if (!validationResult.IsValid)
{
if (TraceData.IsExtendedTraceEnabled(this, TraceDataLevel.Update))
{
TraceData.TraceAndNotifyWithNoParameters(TraceEventType.Warning,
TraceData.ValidationRuleFailed(
TraceData.Identify(this),
TraceData.Identify(validationRule)),
this);
}
UpdateValidationError( new ValidationError(validationRule, this, validationResult.ErrorContent, null));
return false; // kenlai: REVIEW: does not clear iNeedsUpdate flag
}
}
}
}
// this step is now valid - clear the old error (if any)
if (oldValidationError != null && oldValidationError == GetValidationErrors(validationStep))
{
UpdateValidationError(null);
}
return true;
}
/// <summary>
/// Run validation rules for the given step, and inform the binding group
/// <summary>
internal abstract bool CheckValidationRules(BindingGroup bindingGroup, ValidationStep validationStep);
/// <summary>
/// Get the proposed value(s) that would be written to the source(s), applying
/// conversion and checking UI-side validation rules.
/// </summary>
/// <returns>
/// if binding is not dirty: return true, (values = null)
/// if conversion and validation succeed: return true
/// if conversion or validation fails: return false
/// In the last two cases, values is set to a list of ProposedValue records
/// describing the proposed values. Each entry hold a BindingExpression
/// and a value - the value is UnsetValue if the conversion or validation
/// failed.
/// </returns>
internal abstract bool ValidateAndConvertProposedValue(out Collection<ProposedValue> values);
internal class ProposedValue
{
internal ProposedValue(BindingExpression bindingExpression, object rawValue, object convertedValue)
{
_bindingExpression = bindingExpression;
_rawValue = rawValue;
_convertedValue = convertedValue;
}
internal BindingExpression BindingExpression { get { return _bindingExpression; } }
internal object RawValue { get { return _rawValue; } }
internal object ConvertedValue { get { return _convertedValue; } }
BindingExpression _bindingExpression;
object _rawValue;
object _convertedValue;
}
/// <summary>
/// Compute the culture, either from the parent Binding, or from the target element.
/// </summary>
internal CultureInfo GetCulture()
{
// lazy initialization, to let the target element acquire all its properties
if (_culture == DefaultValueObject)
{
// explicit culture set in Binding
_culture = ParentBindingBase.ConverterCultureInternal;
// if that doesn't work, use target element's xml:lang property
if (_culture == null)
{
DependencyObject target = TargetElement;
if (target != null)
{
if (IsInTransfer && (TargetProperty == FrameworkElement.LanguageProperty))
{
// A binding for the Language property needs the value
// of the Language property. This circularity is not
// supported (bug 1274874).
if (TraceData.IsEnabled)
{
TraceData.TraceAndNotify(TraceEventType.Critical, TraceData.RequiresExplicitCulture, this,
traceParameters: new object[] { TargetProperty.Name, this });
}
throw new InvalidOperationException(SR.Format(SR.RequiresExplicitCulture, TargetProperty.Name));
}
// cache CultureInfo since requerying an inheritable property on every Transfer/Update can be quite expensive
// CultureInfo DP rarely changes once a XAML document is loaded.
// To be 100% correct, changes to the CultureInfo attached DP should be tracked
// and cause a re-evaluation of this binding.
_culture = ((XmlLanguage) target.GetValue(FrameworkElement.LanguageProperty)).GetSpecificCulture();
}
}
}
return (CultureInfo)_culture;
}
/// <summary> Culture has changed. Re-fetch the value with the new culture. </summary>
internal void InvalidateCulture()
{
_culture = DefaultValueObject;
}
/// <summary> Begin a source update </summary>
internal void BeginSourceUpdate()
{
ChangeFlag(PrivateFlags.iInUpdate, true);
}
/// <summary> End a source update </summary>
internal void EndSourceUpdate()
{
if (IsInUpdate && IsDynamic && StatusInternal == BindingStatusInternal.Active)
{
// After a successful source update, always re-transfer the source value.
// This picks up changes that the source item may make in the setter,
// and applies the converter (if any) to the value. This fixes
// the so-called "$10 bug".
// When the target is a TextBox with a composition in effect,
// do this asynchronously, to avoid confusing the composition's Undo stack
System.Windows.Controls.Primitives.TextBoxBase tbb = Target as System.Windows.Controls.Primitives.TextBoxBase;
MS.Internal.Documents.UndoManager undoManager = (tbb == null) ? null :
tbb.TextContainer.UndoManager;
if (undoManager != null &&
undoManager.OpenedUnit != null &&
undoManager.OpenedUnit.GetType() != typeof(System.Windows.Documents.TextParentUndoUnit))
{
if (!HasValue(Feature.UpdateTargetOperation))
{
DispatcherOperation op = Dispatcher.BeginInvoke(DispatcherPriority.Send,
new DispatcherOperationCallback(UpdateTargetCallback),
null);
SetValue(Feature.UpdateTargetOperation, op);
}
}
else
{
UpdateTarget();
}
}
ChangeFlag(PrivateFlags.iInUpdate | PrivateFlags.iNeedsUpdate, false);
}
object UpdateTargetCallback(object unused)
{
ClearValue(Feature.UpdateTargetOperation);
IsInUpdate = true; // pretend to be in an update - as when this callback was posted
UpdateTarget();
IsInUpdate = false;
return null;
}
// Consider the markup <Element A="x" B="{Binding...}"/>, and suppose
// that setting A (to x) causes the element to assign a new value y for B.
// (Lots of examples of this: e.g. setting Selector.SelectedIndex causes
// Selector to assign a new value to Selector.SelectedItem.) The end
// result depends on what order the assignments are done. If A=x happens
// first, it assigns y to B but that is later overwritten by the
// data-bound value z; if B happens first, the binding is installed and
// produces the value z, then the assignment A=x sends the value y through
// the binding (if it's two-way) to the data source. In other words, you
// end up with z in the first case, but y in the second, and only the
// second case changes the data source.
//
// The order of assignment (during initialization) is out of the user's
// control, especially when the element is part of a template instance.
// It can depend on the order in which static constructors are called,
// which can vary depending on which elements appear first in the markup.
// To mitigate this mysterious behavior, the following code attempts to
// detect the situation and make it appear as if the binding always
// happened first.
internal bool ShouldUpdateWithCurrentValue(DependencyObject target, out object currentValue)
{
if (IsReflective)
{
// the bad situation only arises during initialization. After that,
// the order of property assignments is determined by the app's
// normal control flow. Unfortunately, we can only detect
// initialization for framework elements; fortunately, this covers
// all the known cases of the bad situation
FrameworkObject fo = new FrameworkObject(target);
if (!fo.IsInitialized)
{
// if the target property (B) already has a changed value (y),
// we're in the bad situation and should propagate y back to
// the data source
DependencyProperty dp = TargetProperty;
EntryIndex entryIndex = target.LookupEntry(dp.GlobalIndex);
if (entryIndex.Found)
{
EffectiveValueEntry entry = target.GetValueEntry(entryIndex, dp, null, RequestFlags.RawEntry);
if (entry.IsCoercedWithCurrentValue)
{
currentValue = entry.GetFlattenedEntry(RequestFlags.FullyResolved).Value;
if (entry.IsDeferredReference)
{
DeferredReference deferredReference = (DeferredReference)currentValue;
currentValue = deferredReference.GetValue(entry.BaseValueSourceInternal);
}
return true;
}
}
}
}
currentValue = null;
return false;
}
/// <summary> change the value to the new value, and notify listeners </summary>
internal void ChangeValue(object newValue, bool notify)
{
object oldValue = (_value != DefaultValueObject) ? _value : DependencyProperty.UnsetValue;
_value = newValue;
if (notify && ValueChanged != null)
{
ValueChanged(this, new BindingValueChangedEventArgs(oldValue, newValue));
}
}
// after a successful transfer, mark the binding clean
internal void Clean()
{
if (NeedsUpdate)
{
NeedsUpdate = false;
}
if (!IsInUpdate)
{
NeedsValidation = false;
NotifyCommitManager();
}
}
/// <summary> the target value has changed - the source needs to be updated </summary>
internal void Dirty()
{
if (ShouldReactToDirty())
{
NeedsUpdate = true;
if (!HasValue(Feature.Timer))
{
ProcessDirty();
}
else
{
// restart the timer
DispatcherTimer timer = (DispatcherTimer)GetValue(Feature.Timer, null);
timer.Stop();
timer.Start();
}
NotifyCommitManager();
}
}
private bool ShouldReactToDirty()
{
if (IsInTransfer || !IsAttached) // don't react if the binding isn't attached
{
return false;
}
return ShouldReactToDirtyOverride();
}
internal virtual bool ShouldReactToDirtyOverride()
{
return true;
}
private void ProcessDirty()
{
if (IsUpdateOnPropertyChanged)
{
// cancel a pending UpdateTarget, so that it doesn't negate
// the effect of this change to the target value
DispatcherOperation op = (DispatcherOperation)GetValue(Feature.UpdateTargetOperation, null);
if (op != null)
{
ClearValue(Feature.UpdateTargetOperation);
op.Abort();
}
if (Helper.IsComposing(Target, TargetProperty))
{
// wait for the IME composition to complete
IsUpdateDeferredForComposition = true;
}
else
{
// no composition, so update now
Update();
}
}
}
void OnTimerTick(object sender, EventArgs e)
{
ProcessDirty();
}
void OnPreviewTextInput(object sender, System.Windows.Input.TextCompositionEventArgs e)
{
// if the IME composition we're waiting for completes, update the source.
if (IsUpdateDeferredForComposition && e.TextComposition.Source == TargetElement && e.TextComposition.Stage == System.Windows.Input.TextCompositionStage.Done)
{
IsUpdateDeferredForComposition = false;
Dirty();
}
}
// invalidate the target property
internal void Invalidate(bool isASubPropertyChange)
{
// don't invalidate during Attach. The property engine does it
// already, and it would interfere with the on-demand activation
// of style-defined BindingExpressions.
if (IsAttaching)
return;
DependencyObject target = TargetElement;
if (target != null)
{
if (IsInBindingExpressionCollection)
ParentBindingExpressionBase.InvalidateChild(this);
else
{
if (TargetProperty != NoTargetProperty)
{
// recompute expression
if (!isASubPropertyChange)
{
target.InvalidateProperty(TargetProperty);
}
else
{
target.NotifySubPropertyChange(TargetProperty);
}
}
}
}
}
/// <summary> use the Fallback or Default value, called when a real value is not available </summary>
internal object UseFallbackValue()
{
object value = FallbackValue;
// if there's a problem with the fallback, use Default instead
if (value == DefaultValueObject)
{
value = DependencyProperty.UnsetValue;
}
// OneWayToSource bindings should initialize to the Fallback/Default
// value without error
if (value == DependencyProperty.UnsetValue && IsOneWayToSource)
{
value = DefaultValue;
}
if (value != DependencyProperty.UnsetValue)
{
UsingFallbackValue = true;
}
else
{
// if fallback isn't available, use Default (except when in a binding collection)
if (StatusInternal == BindingStatusInternal.Active)
SetStatus(BindingStatusInternal.UpdateTargetError);
if (!IsInBindingExpressionCollection)
{
value = DefaultValue;
if (TraceData.IsEnabled)
{
TraceData.TraceAndNotify(TraceEventType.Information, TraceData.NoValueToTransfer, this);
}
}
}
return value;
}
// determine if the given value is "null" (in a general sense)
internal static bool IsNullValue(object value)
{
if (value == null)
return true;
if (Convert.IsDBNull(value))
return true;
if (SystemDataHelper.IsSqlNull(value))
return true;
return false;
}
// determine a "null" value appropriate for the given type
internal object NullValueForType(Type type)
{
if (type == null)
return null;
if (SystemDataHelper.IsSqlNullableType(type))
return SystemDataHelper.NullValueForSqlNullableType(type);
if (!type.IsValueType)
return null;
if (type.IsGenericType && type.GetGenericTypeDefinition() == typeof(Nullable<>))
return null;
return DependencyProperty.UnsetValue;
}
internal ValidationRule LookupValidationRule(Type type)
{
ValidationRule result = ParentBindingBase.GetValidationRule(type);
if (result == null && HasValue(Feature.ParentBindingExpressionBase))
{
result = ParentBindingExpressionBase.LookupValidationRule(type);
}
return result;
}
// discover the binding group (if any) that this binding should join,
// and join it. More precisely, cause the root binding to join.
internal void JoinBindingGroup(bool isReflective, DependencyObject contextElement)
{
BindingGroup bindingGroup = RootBindingExpression.FindBindingGroup(isReflective, contextElement);
if (bindingGroup != null)
{
JoinBindingGroup(bindingGroup, /*explicit*/false);
}
}
// remove the binding from its group
internal void LeaveBindingGroup()
{
BindingExpressionBase root = RootBindingExpression;
BindingGroup bg = root.BindingGroup;
if (bg != null)
{
bg.BindingExpressions.Remove(root);
root.ClearValue(Feature.BindingGroup);
}
}
// reevaluate which binding group this binding should join, and perform
// the change if required
internal void RejoinBindingGroup(bool isReflective, DependencyObject contextElement)
{
BindingExpressionBase root = RootBindingExpression;
BindingGroup oldBindingGroup = root.BindingGroup;
// discover the binding group, as if this were the first time
BindingGroup newBindingGroup;
WeakReference<BindingGroup> oldBindingGroupWR = (WeakReference<BindingGroup>)root.GetValue(Feature.BindingGroup, null);
root.SetValue(Feature.BindingGroup, null, oldBindingGroupWR); // not ClearValue, as we'll reset it soon
try
{
newBindingGroup = root.FindBindingGroup(isReflective, contextElement);
}
finally
{
root.SetValue(Feature.BindingGroup, oldBindingGroupWR, null);
}
// if it's different from the current binding group, move
if (oldBindingGroup != newBindingGroup)
{
root.LeaveBindingGroup();
if (newBindingGroup != null)
{
JoinBindingGroup(newBindingGroup, /*explicit*/false);
}
}
}
// discover the binding group (if any) that this root binding should join.
internal BindingGroup FindBindingGroup(bool isReflective, DependencyObject contextElement)
{
Debug.Assert(RootBindingExpression == this, "Only call this with a root binding");
// if we've already joined (or failed to join) a group, just return the result
if ((WeakReference<BindingGroup>)GetValue(Feature.BindingGroup, null) != null)
{
return BindingGroup;
}
BindingGroup bg;
string groupName = ParentBindingBase.BindingGroupName;
// a null group name means "don't join any group".
if (groupName == null)
{
MarkAsNonGrouped();
return null;
}
// an empty group name means join by DataContext
if (String.IsNullOrEmpty(groupName))
{
// check further preconditions:
if (!isReflective || // must have target-to-source data flow
contextElement == null) // must use data context
{
// later child bindings might pass this test, so don't mark
// this root binding as non-grouped yet
return null;
}
// only the innermost binding group is eligible
bg = (BindingGroup)contextElement.GetValue(FrameworkElement.BindingGroupProperty);
if (bg == null)
{
MarkAsNonGrouped();
return null;
}
// the context element must share data context with the group
DependencyProperty dataContextDP = FrameworkElement.DataContextProperty;
DependencyObject groupContextElement = bg.InheritanceContext;
if (groupContextElement == null ||
!ItemsControl.EqualsEx( contextElement.GetValue(dataContextDP),
groupContextElement.GetValue(dataContextDP)))
{
MarkAsNonGrouped();
return null;
}
// if the binding survives the gauntlet, return the group
return bg;
}
// a non-empty group name means join by name
else
{
// walk up the tree, looking for a matching binding group
DependencyProperty bindingGroupDP = FrameworkElement.BindingGroupProperty;
FrameworkObject fo = new FrameworkObject(Helper.FindMentor(TargetElement));
while (fo.DO != null)
{
BindingGroup bgCandidate = (BindingGroup)fo.DO.GetValue(bindingGroupDP);
if (bgCandidate == null)
{
MarkAsNonGrouped();
return null;
}
if (bgCandidate.Name == groupName)
{
if (bgCandidate.SharesProposedValues && TraceData.IsEnabled)
{
TraceData.TraceAndNotifyWithNoParameters(TraceEventType.Warning,
TraceData.SharesProposedValuesRequriesImplicitBindingGroup(
TraceData.Identify(this),
groupName,
TraceData.Identify(bgCandidate)),
this);
}
// return the matching group
return bgCandidate;
}
fo = fo.FrameworkParent;
}
// no match - report an error
if (TraceData.IsEnabled)
{
TraceData.TraceAndNotify(TraceEventType.Error,
TraceData.BindingGroupNameMatchFailed(groupName),
this);
}
MarkAsNonGrouped();
return null;
}
}
// add a binding to the given binding group
internal void JoinBindingGroup(BindingGroup bg, bool explicitJoin)
{
BindingExpressionBase root = null; // set to non-null by the next loop
for ( BindingExpressionBase bindingExpr = this;
bindingExpr != null;
bindingExpr = bindingExpr.ParentBindingExpressionBase)
{
root = bindingExpr;
// bindings in a group update Explicitly, unless declared otherwise
bindingExpr.OnBindingGroupChanged(/*joining*/true);
bg.AddToValueTable(bindingExpr);
}
// add the root binding to the group
if (!root.HasValue(Feature.BindingGroup))
{
// use WeakReference because the BindingGroup contains a strong reference
// to the visual tree (via InheritanceContext)
root.SetValue(Feature.BindingGroup, new WeakReference<BindingGroup>(bg));
// when the group is implicitly discovered, always add the root binding to the group's collection.
// When the binding is added explicitly - via BindingGroup.BindingExpressions.Add() -
// check first to see if it has already been added
bool addToGroup = explicitJoin ? !bg.BindingExpressions.Contains(root) : true;
if (addToGroup)
{
bg.BindingExpressions.Add(root);
}
// in the explicit case, register its items and values with the binding group
// (the implicit case does this when the bindings activate)
if (explicitJoin)
{
root.UpdateBindingGroup(bg);
if (bg.SharesProposedValues && TraceData.IsEnabled)
{
TraceData.TraceAndNotifyWithNoParameters(TraceEventType.Warning,
TraceData.SharesProposedValuesRequriesImplicitBindingGroup(
TraceData.Identify(root),
root.ParentBindingBase.BindingGroupName,
TraceData.Identify(bg)),
this);
}
}
}
else
{
if (root.BindingGroup != bg)
throw new InvalidOperationException(SR.BindingGroup_CannotChangeGroups);
}
}
// mark a binding as non-grouped, so that we avoid doing the discovery again
void MarkAsNonGrouped()
{
// Leaf bindings only get asked once, so there's no need to add a mark
if (!(this is BindingExpression))
{
SetValue(Feature.BindingGroup, NullBindingGroupReference);
}
}
// add to, or remove from, the CommitManager's set of dirty/invalid bindings
internal void NotifyCommitManager()
{
if (IsReflective && !IsDetached && !Engine.IsShutDown)
{
bool shouldStore = IsEligibleForCommit && (IsDirty || HasValidationError);
BindingExpressionBase root = RootBindingExpression;
BindingGroup bg = root.BindingGroup;
root.UpdateCommitState();
if (bg == null)
{
if (root != this && !shouldStore)
{
shouldStore = root.IsEligibleForCommit && (root.IsDirty || root.HasValidationError);
}
if (shouldStore)
{
Engine.CommitManager.AddBinding(root);
}
else
{
Engine.CommitManager.RemoveBinding(root);
}
}
else
{
if (!shouldStore)
{
shouldStore = (bg.Owner != null) && (bg.IsDirty || bg.HasValidationError);
}
if (shouldStore)
{
Engine.CommitManager.AddBindingGroup(bg);
}
else
{
Engine.CommitManager.RemoveBindingGroup(bg);
}
}
}
}
internal virtual void UpdateCommitState()
{
// for most bindings, the state is already current
}
// adopt the properties of another binding. Called by PriorityBindingExpression
// when its active binding changes. (Implemented here to get access to private flags.)
internal void AdoptProperties(BindingExpressionBase bb)
{
PrivateFlags newFlags = (bb != null) ? bb._flags : (PrivateFlags)0x0;
_flags = (_flags & ~PrivateFlags.iAdoptionMask) | (newFlags & PrivateFlags.iAdoptionMask);
}
/// <summary>
/// Handle events from the centralized event table
/// </summary>
internal virtual bool ReceiveWeakEvent(Type managerType, object sender, EventArgs e)
{
return false; // unrecognized event
}
internal virtual void OnLostFocus(object sender, RoutedEventArgs e)
{
}
// Return the object from which the given value was obtained, if possible
internal abstract object GetSourceItem(object newValue);
private bool TestFlag(PrivateFlags flag)
{
return (_flags & flag) != 0;
}
private void ChangeFlag(PrivateFlags flag, bool value)
{
if (value) _flags |= flag;
else _flags &= ~flag;
}
//------------------------------------------------------
//
// Internal Properties
//
//------------------------------------------------------
// A BindingExpression cannot hold a strong reference to the target element - this
// leads to memory leaks (bug 871139). The problem is that BindingExpression and its workers
// register for events from the data item, creating a reference from
// the data item to the BindingExpression. The data item typically has a long lifetime,
// so if the BindingExpression held a SR to the target, the target element would
// also stay alive forever.
// Instead, BindingExpression holds a WeakReference to the target. This means we
// have to check it before dereferencing (here), and cope when the
// reference fails (in callers to this property). Requests for the TargetElement
// are not trivial, so callers should request it once and cache the result
// in a local variable. They should not save it in a global or instance
// variable of course; that would defeat the purpose of the WR.
// This allows the target element to be GC'd when it's no longer in
// use by the tree or application. The next time the BindingExpression asks for
// its TargetElement, the WR will fail. At this point, the BindingExpression is no
// longer useful, so it can sever all connections to the outside world (i.e.
// stop listening for events). This allows the BindingExpression itself to be GC'd.
internal DependencyObject TargetElement
{
get
{
if (_targetElement != null)
{
DependencyObject result = _targetElement.Target as DependencyObject;
if (result != null)
return result;
// target has been GC'd, sever all connections
_targetElement = null; // prevents re-entry from Detach()
Detach();
}
return null;
}
}
internal WeakReference TargetElementReference
{
get { return _targetElement; }
}
internal DataBindEngine Engine
{
get { return _engine; }
}
internal Dispatcher Dispatcher
{
get { return (_engine != null) ? _engine.Dispatcher : null; }
}
internal object Value
{
get
{
if (_value == DefaultValueObject)
{
// don't notify listeners. This isn't a real value change.
ChangeValue(UseFallbackValue(), false /*notify*/);
}
return _value;
}
set
{
ChangeValue(value, true);
Dirty();
}
}
internal WeakDependencySource[] WeakSources
{
get { return _sources; }
}
// queried by MultiBindings. Only implemented today by BindingExpression.
// If we ever support nested MultiBindings, implement this in MultiBinding
// as well.
internal virtual bool IsDisconnected
{
get { return false; }
}
/// <summary>
/// NoTarget DependencyProperty, a placeholder used by BindingExpressions with no target property
/// </summary>
internal static readonly DependencyProperty NoTargetProperty =
DependencyProperty.RegisterAttached("NoTarget", typeof(object), typeof(BindingExpressionBase),
new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.None));
//------------------------------------------------------
//
// Internal Methods
//
//------------------------------------------------------
/// <summary>
/// Attach the binding expression to the given target object and property.
/// </summary>
internal void Attach(DependencyObject target, DependencyProperty dp)
{
// make sure we're on the right thread to access the target
if (target != null)
{
target.VerifyAccess();
}
IsAttaching = true;
AttachOverride(target, dp);
IsAttaching = false;
}
/// <summary>
/// Detach the binding expression from its target object and property.
/// </summary>
internal void Detach()
{
if (IsDetached || IsDetaching)
return;
IsDetaching = true;
// leave the binding group before doing anything else, so as to preserve
// a proposed value (if any).
LeaveBindingGroup();
// remove from CommitManager
NotifyCommitManager();
DetachOverride();
IsDetaching = false;
}
// disconnect from sources, and update the target property as cheaply as possible
internal virtual void Disconnect()
{
// determine the new value (if any) to expose
object newValue = DependencyProperty.UnsetValue; // usually none
DependencyProperty targetDP = TargetProperty;
if (targetDP == ContentControl.ContentProperty ||
targetDP == ContentPresenter.ContentProperty ||
targetDP == HeaderedItemsControl.HeaderProperty ||
targetDP == HeaderedContentControl.HeaderProperty)
{
// pass DisconnectedItem through content-like properties, so
// that their descendent bindings can disconnect
newValue = DisconnectedItem;
}
if (targetDP.PropertyType == typeof(System.Collections.IEnumerable))
{
// set IEnumerable properties (e.g. ItemsSource) to null, so that
// the control can disconnect from the individual items
newValue = null;
}
// notify the target property about the new value (cheaply)
if (newValue != DependencyProperty.UnsetValue)
{
ChangeValue(newValue, false);
Invalidate(false);
}
}
internal void SetStatus(BindingStatusInternal status)
{
if (IsDetached && status != _status)
{
throw new InvalidOperationException(SR.Format(SR.BindingExpressionStatusChanged, _status, status));
}
_status = status;
}
// convert a user-supplied fallback value to a usable equivalent
// returns: UnsetValue if user did not supply a fallback value
// value if fallback value is legal
// DefaultValueObject otherwise
internal static object ConvertFallbackValue(object value, DependencyProperty dp, object sender)
{
Exception e;
object result = ConvertValue(value, dp, out e);
if (result == DefaultValueObject)
{
if (TraceData.IsEnabled)
{
TraceData.TraceAndNotify(TraceEventType.Error,
TraceData.FallbackConversionFailed(
AvTrace.ToStringHelper(value),
AvTrace.TypeName(value),
dp.Name,
dp.PropertyType.Name),
sender as BindingExpressionBase, e);
}
}
return result;
}
// convert a user-supplied TargetNullValue to a usable equivalent
// returns: UnsetValue if user did not supply a fallback value
// value if fallback value is legal
// DefaultValueObject otherwise
internal static object ConvertTargetNullValue(object value, DependencyProperty dp, object sender)
{
Exception e;
object result = ConvertValue(value, dp, out e);
if (result == DefaultValueObject)
{
if (TraceData.IsEnabled)
{
TraceData.TraceAndNotify(TraceEventType.Error,
TraceData.TargetNullValueConversionFailed(
AvTrace.ToStringHelper(value),
AvTrace.TypeName(value),
dp.Name,
dp.PropertyType.Name),
sender as BindingExpressionBase, e);
}
}
return result;
}
static object ConvertValue(object value, DependencyProperty dp, out Exception e)
{
object result;
e = null;
if (value == DependencyProperty.UnsetValue || dp.IsValidValue(value))
{
result = value;
}
else
{
result = null; // placeholder to keep compiler happy
// if value isn't the right type, use a type converter to get a better value
bool success = false;
TypeConverter converter = DefaultValueConverter.GetConverter(dp.PropertyType);
if (converter != null && converter.CanConvertFrom(value.GetType()))
{
// PreSharp uses message numbers that the C# compiler doesn't know about.
// Disable the C# complaints, per the PreSharp documentation.
#pragma warning disable 1634, 1691
// PreSharp complains about catching NullReference (and other) exceptions.
// It doesn't recognize that IsCriticalException() handles these correctly.
#pragma warning disable 56500
try
{
result = converter.ConvertFrom(null, CultureInfo.InvariantCulture, value);
success = dp.IsValidValue(result);
}
// Catch all exceptions. If we can't convert the fallback value, it doesn't
// matter why not; we should always use the default value instead.
// (See bug 1853628 for an example of a converter that throws
// an exception not mentioned in the documentation for ConvertFrom.)
catch (Exception ex)
{
e = ex;
}
catch // non CLS compliant exception
{
}
#pragma warning restore 56500
#pragma warning restore 1634, 1691
}
if (!success)
{
// if can't convert it, don't use it
result = DefaultValueObject;
}
}
return result;
}
// Certain trace reports should be marked as 'error' unless the binding
// is prepared to handle it in some way (e.g. FallbackValue), in which
// case 'warning'.
internal TraceEventType TraceLevel
{
get
{
// FallbackValue is present
if (ParentBindingBase.FallbackValue != DependencyProperty.UnsetValue)
return TraceEventType.Warning;
// Binding is a member of MultiBinding or PriorityBinding
if (IsInBindingExpressionCollection)
return TraceEventType.Warning;
// all other cases - error
return TraceEventType.Error;
}
}
internal virtual void Activate()
{
}
internal virtual void Deactivate()
{
}
internal bool Update()
{
if (HasValue(Feature.Timer))
{
DispatcherTimer timer = (DispatcherTimer)GetValue(Feature.Timer, null);
timer.Stop();
}
return UpdateOverride();
}
internal virtual bool UpdateOverride()
{
return true;
}
internal void UpdateValidationError(ValidationError validationError, bool skipBindingGroup=false)
{
// the steps are carefully ordered to avoid going through a "no error"
// state while replacing one error with another
ValidationError oldValidationError = BaseValidationError;
SetValue(Feature.ValidationError, validationError, null);
if (validationError != null)
{
AddValidationError(validationError, skipBindingGroup);
}
if (oldValidationError != null)
{
RemoveValidationError(oldValidationError, skipBindingGroup);
}
}
internal void UpdateNotifyDataErrorValidationErrors(List<object> errors)
{
List<object> toAdd;
List<ValidationError> toRemove;
GetValidationDelta(NotifyDataErrors, errors, out toAdd, out toRemove);
// add the new errors, then remove the old ones - this avoid a transient
// "no error" state
if (toAdd != null && toAdd.Count > 0)
{
ValidationRule rule = NotifyDataErrorValidationRule.Instance;
List<ValidationError> notifyDataErrors = NotifyDataErrors;
if (notifyDataErrors == null)
{
notifyDataErrors = new List<ValidationError>();
SetValue(Feature.NotifyDataErrors, notifyDataErrors);
}
foreach (object o in toAdd)
{
ValidationError veAdd = new ValidationError(rule, this, o, null);
notifyDataErrors.Add(veAdd);
AddValidationError(veAdd);
}
}
if (toRemove != null && toRemove.Count > 0)
{
List<ValidationError> notifyDataErrors = NotifyDataErrors;
foreach (ValidationError veRemove in toRemove)
{
notifyDataErrors.Remove(veRemove);
RemoveValidationError(veRemove);
}
if (notifyDataErrors.Count == 0)
ClearValue(Feature.NotifyDataErrors);
}
}
internal static void GetValidationDelta(List<ValidationError> previousErrors, List<object> errors, out List<object> toAdd, out List<ValidationError> toRemove)
{
// determine the errors to add and the validation results to remove,
// taking duplicates into account
if (previousErrors == null || previousErrors.Count == 0)
{
toAdd = errors;
toRemove = null;
}
else if (errors == null || errors.Count == 0)
{
toAdd = null;
toRemove = new List<ValidationError>(previousErrors);
}
else
{
toAdd = new List<object>();
toRemove = new List<ValidationError>(previousErrors);
for (int i=errors.Count-1; i>=0; --i)
{
object errorContent = errors[i];
int j;
for (j=toRemove.Count-1; j>=0; --j)
{
if (ItemsControl.EqualsEx(toRemove[j].ErrorContent, errorContent))
{
// this error appears on both lists - remove it from toRemove
toRemove.RemoveAt(j);
break;
}
}
if (j<0)
{
// this error didn't appear on toRemove - add it to toAdd
toAdd.Add(errorContent);
}
}
}
}
internal void AddValidationError(ValidationError validationError, bool skipBindingGroup=false)
{
// add the error to the target element
Validation.AddValidationError(validationError, TargetElement, NotifyOnValidationError);
// add the error to the binding group's target element
if (!skipBindingGroup)
{
BindingGroup bindingGroup = BindingGroup;
if (bindingGroup != null)
{
bindingGroup.AddValidationError(validationError);
}
}
}
internal void RemoveValidationError(ValidationError validationError, bool skipBindingGroup=false)
{
// remove the error from the target element
Validation.RemoveValidationError(validationError, TargetElement, NotifyOnValidationError);
// remove the error from the binding group's target element
if (!skipBindingGroup)
{
BindingGroup bindingGroup = BindingGroup;
if (bindingGroup != null)
{
bindingGroup.RemoveValidationError(validationError);
}
}
}
// get all errors raised at the given step, in preparation for running
// the rules at that step
internal ValidationError GetValidationErrors(ValidationStep validationStep)
{
ValidationError validationError = BaseValidationError;
if (validationError == null || validationError.RuleInError.ValidationStep != validationStep)
return null;
return validationError;
}
internal void ChangeSources(WeakDependencySource[] newSources)
{
if (IsInBindingExpressionCollection)
ParentBindingExpressionBase.ChangeSourcesForChild(this, newSources);
else
ChangeSources(TargetElement, TargetProperty, newSources);
// store the sources with weak refs, so they don't cause memory leaks (bug 980041)
_sources = newSources;
}
/// <summary>
/// combine the sources of BindingExpressions, using new sources for
/// the BindingExpression at the given index
/// </summary>
/// <param name="index">-1 to indicate new sources</param>
/// <param name="bindingExpressions">collection of child binding expressions </param>
/// <param name="count">how many child expressions to include</param>
/// <param name="newSources">use null when no new sources</param>
/// <param name="commonSources">sources not tied to any of the binding expressions</param>
/// <returns></returns>
internal static WeakDependencySource[] CombineSources(int index,
Collection<BindingExpressionBase> bindingExpressions,
int count,
WeakDependencySource[] newSources,
WeakDependencySource[] commonSources = null)
{
if (index == count)
{
// Be sure to include newSources if they are being appended
count++;
}
var tempList = new List<WeakDependencySource>();
if (commonSources != null)
{
for (int i=0; i < commonSources.Length; ++i)
{
tempList.Add(commonSources[i]);
}
}
for (int i = 0; i < count; ++i)
{
BindingExpressionBase bindExpr = bindingExpressions[i];
WeakDependencySource[] sources = (i==index) ? newSources :
(bindExpr != null) ? bindExpr.WeakSources :
null;
int m = (sources == null) ? 0 : sources.Length;
for (int j = 0; j < m; ++j)
{
WeakDependencySource candidate = sources[j];
// don't add duplicate source
for (int k = 0; k < tempList.Count; ++k)
{
WeakDependencySource prior = tempList[k];
if (candidate.DependencyObject == prior.DependencyObject &&
candidate.DependencyProperty == prior.DependencyProperty)
{
candidate = null;
break;
}
}
if (candidate != null)
tempList.Add(candidate);
}
}
return tempList.Count > 0 ?
tempList.ToArray() :
null;
}
internal void ResolvePropertyDefaultSettings(BindingMode mode, UpdateSourceTrigger updateTrigger, FrameworkPropertyMetadata fwMetaData)
{
// resolve "property-default" dataflow
if (mode == BindingMode.Default)
{
BindingFlags f = BindingFlags.OneWay;
if (fwMetaData != null && fwMetaData.BindsTwoWayByDefault)
{
f = BindingFlags.TwoWay;
}
ChangeFlag(PrivateFlags.iPropagationMask, false);
ChangeFlag((PrivateFlags)f, true);
if (TraceData.IsExtendedTraceEnabled(this, TraceDataLevel.ResolveDefaults))
{
TraceData.TraceAndNotifyWithNoParameters(TraceEventType.Warning,
TraceData.ResolveDefaultMode(
TraceData.Identify(this),
(f == BindingFlags.OneWay) ? BindingMode.OneWay : BindingMode.TwoWay),
this);
}
}
Debug.Assert((_flags & PrivateFlags.iPropagationMask) != PrivateFlags.iPropDefault,
"BindingExpression should not have Default propagation");
// resolve "property-default" update trigger
if (updateTrigger == UpdateSourceTrigger.Default)
{
UpdateSourceTrigger ust = GetDefaultUpdateSourceTrigger(fwMetaData);
SetUpdateSourceTrigger(ust);
if (TraceData.IsExtendedTraceEnabled(this, TraceDataLevel.ResolveDefaults))
{
TraceData.TraceAndNotifyWithNoParameters(TraceEventType.Warning,
TraceData.ResolveDefaultUpdate(
TraceData.Identify(this),
ust),
this);
}
}
Invariant.Assert((_flags & PrivateFlags.iUpdateMask) != PrivateFlags.iUpdateDefault,
"BindingExpression should not have Default update trigger");
}
// return the effective update trigger, used when binding doesn't set one explicitly
internal UpdateSourceTrigger GetDefaultUpdateSourceTrigger(FrameworkPropertyMetadata fwMetaData)
{
UpdateSourceTrigger ust =
IsInMultiBindingExpression ? UpdateSourceTrigger.Explicit :
(fwMetaData != null) ? fwMetaData.DefaultUpdateSourceTrigger :
UpdateSourceTrigger.PropertyChanged;
return ust;
}
internal void SetUpdateSourceTrigger(UpdateSourceTrigger ust)
{
ChangeFlag(PrivateFlags.iUpdateMask, false);
ChangeFlag((PrivateFlags)BindingBase.FlagsFrom(ust), true);
}
internal Type GetEffectiveTargetType()
{
Type targetType = TargetProperty.PropertyType;
BindingExpressionBase be = this.ParentBindingExpressionBase;
while (be != null)
{
if (be is MultiBindingExpression)
{
// for descendants of a MultiBinding, the effective target
// type is Object.
targetType = typeof(Object);
break;
}
be = be.ParentBindingExpressionBase;
}
return targetType;
}
internal void DetermineEffectiveStringFormat()
{
Type targetType = TargetProperty.PropertyType;
if (targetType != typeof(String))
{
// if the target type isn't String, we don't need a string format
return; // _effectiveStringFormat is already null
}
// determine the effective target type and the declared string format
// by looking up the tree of binding expressions
string stringFormat = ParentBindingBase.StringFormat;
BindingExpressionBase be = this.ParentBindingExpressionBase;
while (be != null)
{
if (be is MultiBindingExpression)
{
// MultiBindings should receive object values, not string
targetType = typeof(Object);
break;
}
else if (stringFormat == null && be is PriorityBindingExpression)
{
// use a PriorityBinding's string format, unless we already
// have a more specific one
stringFormat = be.ParentBindingBase.StringFormat;
}
be = be.ParentBindingExpressionBase;
}
// if we need a string format, cache it
if (targetType == typeof(String))
{
#if NotToday
// special case: when these conditions all apply
// a) target element belongs to a DataTemplate
// b) template was found by implicit (type-based) lookup
// c) container (ContentPresenter) has a string format
// d) binding has no effective string format
// then use the CP's string format. This enables scenarios like
// <DataTemplate DataType="{x:Type Customer}">
// <TextBlock Text="{Binding Path=AmountPayable}"
// </DataTemplate>
// <ContentControl Content="{StaticResource MyCustomer}" ContentStringFormat="C2"/>
// where you'd like to control the format at the point of use,
// rather than at the point of template declaration. This is
// especially useful when the template is declared in a global place
// like app resources or a theme file. In particular it makes the
// GroupStyle.HeaderStringFormat property work; the template for
// GroupItem is defined in the theme, but needs to pick up formatting
// from the app's markup.
if (stringFormat == null) // (d)
{
FrameworkObject fo = new FrameworkObject(Helper.FindMentor(TargetElement));
ContentPresenter cp = fo.TemplatedParent as ContentPresenter;
if (cp != null && // (a)
cp.ContentStringFormat != null) // (c)
{
DataTemplate dt = cp.TemplateInternal as DataTemplate;
if (dt != null && // (a)
dt.DataType != null) // (b)
{
stringFormat = cp.ContentStringFormat;
}
}
}
#endif
if (!String.IsNullOrEmpty(stringFormat))
{
SetValue(Feature.EffectiveStringFormat, Helper.GetEffectiveStringFormat(stringFormat), null);
}
}
}
internal void DetermineEffectiveTargetNullValue()
{
Type targetType = TargetProperty.PropertyType;
// determine the effective target type and the declared TargetNullValue
// by looking up the tree of binding expressions
object targetNullValue = ParentBindingBase.TargetNullValue;
BindingExpressionBase be = this.ParentBindingExpressionBase;
while (be != null)
{
if (be is MultiBindingExpression)
{
// MultiBindings should receive object values
targetType = typeof(Object);
break;
}
else if (targetNullValue == DependencyProperty.UnsetValue && be is PriorityBindingExpression)
{
// use a PriorityBinding's TargetNullValue, unless we already
// have a more specific one
targetNullValue = be.ParentBindingBase.TargetNullValue;
}
be = be.ParentBindingExpressionBase;
}
// if user declared a TargetNullValue, make sure it has the right type.
if (targetNullValue != DependencyProperty.UnsetValue)
{
targetNullValue = ConvertTargetNullValue(targetNullValue, TargetProperty, this);
if (targetNullValue == DefaultValueObject)
{
// if not, ignore it (having logged a trace message)
targetNullValue = DependencyProperty.UnsetValue;
}
}
// for back-compat, don't turn on TargetNullValue unless user explicitly
// asks for it. This means users have to add TargetNullValue to get
// pretty basic scenarios to work (e.g. binding a TextBox to a database
// string field that supports DBNull). It's painful, but can't be
// helped.
#if TargetNullValueBC //BreakingChange
// if no declared (or poorly declared) value, make one up
if (targetNullValue == DependencyProperty.UnsetValue)
{
targetNullValue = NullValueForType(targetType);
}
#endif
SetValue(Feature.EffectiveTargetNullValue, targetNullValue, DependencyProperty.UnsetValue);
}
void DetermineEffectiveUpdateBehavior()
{
// only need to honor update behavior when the binding does updates,
// and isn't governed by a multibinding (which drives the updates)
if (!IsReflective)
return;
for (BindingExpressionBase ancestor = ParentBindingExpressionBase;
ancestor != null; ancestor = ancestor.ParentBindingExpressionBase)
{
if (ancestor is MultiBindingExpression)
return;
}
// get the update behavior (delay, validation, preview) from the Binding
int delay = ParentBindingBase.Delay;
if (delay > 0 && (IsUpdateOnPropertyChanged))
{
DispatcherTimer timer = new DispatcherTimer();
SetValue(Feature.Timer, timer);
timer.Interval = TimeSpan.FromMilliseconds(delay);
timer.Tick += new EventHandler(OnTimerTick);
}
}
internal void DetermineEffectiveValidatesOnNotifyDataErrors()
{
bool result = ParentBindingBase.ValidatesOnNotifyDataErrorsInternal;
BindingExpressionBase beb = ParentBindingExpressionBase;
while (result && beb != null)
{
result = beb.ValidatesOnNotifyDataErrors;
beb = beb.ParentBindingExpressionBase;
}
ChangeFlag(PrivateFlags.iValidatesOnNotifyDataErrors, result);
}
// To prevent memory leaks, we store WeakReferences to certain objects
// in various places: _dataItem, _sources, worker fields. The logic
// for this is centralized in these two static methods. (See bug 940041)
internal static object CreateReference(object item)
{
// One source of leaks is the reference cycle formed when a BindingExpression's
// source item contains a reference chain to the target element:
// target -> BindingExpression -> source item -> target
//
// Making the second link into a WeakReference incurs some cost,
// so it should be avoided if we know the third link never exists.
// We definitely can't avoid this when the item is a DependencyObject,
// since it's reasonably common for the third link to occur (e.g.
// a ContextMenu contains a link to its Popup, which has a property
// bound back to the ContextMenu).
//
// For safety, we choose to use WeakRef all the time, unless the item is null.
// Exception (bug 1124954): Keep a strong reference to
// BindingListCollectionView - this keeps the underlying DataView
// alive, when nobody else will.
// Exception (bug 1970505): Don't allocate a WeakRef for the common
// case of the NullDataItem
if (item != null &&
!(item is BindingListCollectionView) &&
!(item == BindingExpression.NullDataItem) &&
!(item == DisconnectedItem))
{
item = new WeakReference(item);
}
#if USE_ITEM_REFERENCE
item = new ItemReference(item);
#endif
return item;
}
// like CreateReference, but use an existing WeakReference
internal static object CreateReference(WeakReference item)
{
object result = item;
#if USE_ITEM_REFERENCE
result = new ItemReference(item);
#endif
return result;
}
// like CreateReference, except re-target the old WeakReference (if any)
internal static object ReplaceReference(object oldReference, object item)
{
if (item != null &&
!(item is BindingListCollectionView) &&
!(item == BindingExpression.NullDataItem) &&
!(item == DisconnectedItem))
{
#if USE_ITEM_REFERENCE
// if this cast fails, it's because you have done a direct assignment of an
// item to some field instead of assigning the result of CreateReference.
oldReference = ((ItemReference)oldReference).Item;
#endif
WeakReference wr = oldReference as WeakReference;
if (wr != null)
{
wr.Target = item;
item = wr;
}
else
{
item = new WeakReference(item);
}
}
#if USE_ITEM_REFERENCE
item = new ItemReference(item);
#endif
return item;
}
internal static object GetReference(object reference)
{
if (reference == null)
return null;
#if USE_ITEM_REFERENCE
// if this cast fails, it's because you have done a direct assignment of an
// item to some field instead of assigning the result of CreateReference.
reference = ((ItemReference)reference).Item;
#endif
WeakReference wr = reference as WeakReference;
if (wr != null)
return wr.Target;
else
return reference;
}
internal static void InitializeTracing(BindingExpressionBase expr, DependencyObject d, DependencyProperty dp)
{
BindingBase parent = expr.ParentBindingBase;
}
//------------------------------------------------------
//
// Private Methods
//
//------------------------------------------------------
#if USE_ITEM_REFERENCE
private class ItemReference
{
internal ItemReference(object item)
{
_item = item;
}
internal object Item { get { return _item; } }
object _item;
}
#endif
// change WeakDependencySources to (strong) DependencySources, and notify
// the property engine about the new sources
void ChangeSources(DependencyObject target, DependencyProperty dp, WeakDependencySource[] newSources)
{
DependencySource[] sources;
if (newSources != null)
{
// convert weak reference to strong
sources = new DependencySource[newSources.Length];
int n = 0;
for (int i = 0; i < newSources.Length; ++i)
{
DependencyObject sourceDO = newSources[i].DependencyObject;
if (sourceDO != null)
{
// only include sources that are still alive
sources[n++] = new DependencySource(sourceDO, newSources[i].DependencyProperty);
}
}
// if any of the sources were no longer alive, trim the array
if (n < newSources.Length)
{
DependencySource[] temp;
if (n > 0)
{
temp = new DependencySource[n];
Array.Copy(sources, 0, temp, 0, n);
}
else
{
temp = null;
}
sources = temp;
}
}
else
{
sources = null;
}
// notify property engine
ChangeSources(target, dp, sources);
}
//------------------------------------------------------
//
// Private Fields
//
//------------------------------------------------------
BindingBase _binding;
WeakReference _targetElement;
DependencyProperty _targetProperty;
DataBindEngine _engine;
PrivateFlags _flags;
object _value = DefaultValueObject;
BindingStatusInternal _status;
WeakDependencySource[] _sources;
object _culture = DefaultValueObject;
/// <summary> Sentinel meaning "field has its default value" </summary>
internal static readonly object DefaultValueObject = new NamedObject("DefaultValue");
// sentinel value meaning "unhook from previous item's events, but do not
// change values (except for special cases)"
internal static readonly object DisconnectedItem = new NamedObject("DisconnectedItem");
// sentinel value meaning "no binding group"
static readonly WeakReference<BindingGroup> NullBindingGroupReference = new WeakReference<BindingGroup>(null);
#region Uncommon Values
internal enum Feature
{
// BindingExressionBase
ParentBindingExpressionBase,
ValidationError,
NotifyDataErrors,
EffectiveStringFormat,
EffectiveTargetNullValue,
BindingGroup,
Timer,
UpdateTargetOperation,
// BindingExpression
Converter,
SourceType,
DataProvider,
CollectionViewSource,
DynamicConverter,
DataErrorValue,
// MultiBindingExpression
// PriorityBindingExpression
// Sentinel, for error checking. Must be last.
LastFeatureId
}
internal bool HasValue(Feature id) { return _values.HasValue((int)id); }
internal object GetValue(Feature id, object defaultValue) { return _values.GetValue((int)id, defaultValue); }
internal void SetValue(Feature id, object value) { _values.SetValue((int)id, value); }
internal void SetValue(Feature id, object value, object defaultValue) { if (Object.Equals(value, defaultValue)) _values.ClearValue((int)id); else _values.SetValue((int)id, value); }
internal void ClearValue(Feature id) { _values.ClearValue((int)id); }
UncommonValueTable _values;
#endregion Uncommon Values
}
}
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