protected virtual Binding CreateBinding(BindingTarget bindingTarget, MyBindingInfo bInfo, Type sourceType,
PropertyPath newPath, bool isPropBagBased)
{
Binding result;
if (isPropBagBased)
{
IValueConverter converter = GetConverter(bindingTarget, bInfo, sourceType,
newPath.Path, isPropBagBased, out object converterParameter);
result = new Binding
{
Path = newPath,
Converter = converter,
ConverterParameter = converterParameter,
};
ApplyStandardBindingParams(bInfo, ref result);
}
else
{
result = CreateDefaultBinding(bindingTarget, bInfo, sourceType, newPath);
}
return(result);
}
//private string GetXmlnsPrefix(IXamlSchemaContextProvider schemaProvider, Type type)
//{
// string ourName = type.Name;
// XamlSchemaContext context = schemaProvider.SchemaContext;
// IEnumerable<string> namespaces = context.GetAllXamlNamespaces();
// foreach(string ns in namespaces)
// {
// ICollection<XamlType> xamlTypes = context.GetAllXamlTypes(ns);
// foreach(XamlType xt in xamlTypes)
// {
// if(xt.IsMarkupExtension)
// {
// if(xt.Name == ourName)
// {
// return ns;
// }
// }
// }
// }
// return null;
//}
#endregion
public Binding GetBinding(BindingTarget bindingTarget)
{
MyBindingInfo bindingInfo = GatherBindingInfo(Path, Mode);
MyBindingEngine mb = new MyBindingEngine(bindingInfo, SourceType, _bindingTarget, UseMultiBinding);
return(mb.ProvideTheBindingDirectly());
}
protected bool InitPathListeners(BindingTarget bindingTarget, MyBindingInfo bInfo, Type sourceType, OSCollection pathListeners)
{
DataSourceChangedEventArgs dsChangedEventArgs = new DataSourceChangedEventArgs(
DataSourceChangeTypeEnum.Initializing, dataWasChanged: true);
return(RefreshPathListeners(bindingTarget, bInfo, sourceType, pathListeners,
dsChangedEventArgs, pathListeners[ROOT_INDEX]));
}
public MyBindingEngineBase(BindingTarget bindingTarget, MyBindingInfo bindingInfo, Type sourceType,
bool useMultiBinding = true, string binderInstanceName = DEFAULT_BINDER_NAME)
{
BindingInfo = bindingInfo;
SourceType = sourceType ?? throw new ArgumentNullException(nameof(sourceType));
BindingTarget = bindingTarget ?? throw new ArgumentNullException(nameof(bindingTarget));
UseMultiBinding = useMultiBinding;
BinderName = binderInstanceName;
_dataSourceChangeListeners = null;
}
protected Binding CreateTheBinding(BindingTarget bindingTarget, MyBindingInfo bInfo, Type sourceType,
OSCollection pathListeners, out bool isCustom)
{
System.Diagnostics.Debug.Assert(sourceType != null, "The SourceType should never be null here.");
// One node: 1 parent, 0 intervening objects, the terminal path element is "." -- The binding binds to the source data itself.
// Two nodes: 1 parent, 0 intervening objects, 1 terminal path element.
// Three nodes: 1 parent, 1 intervening object, 1 terminal path element.
// Four nodes: 1 parent, 2 intervening objects, 1 terminal path element.
// The next to last node, must have data, in order to avoid binding warnings.
ObservableSource lastParent = pathListeners[pathListeners.Count - 2];
string strNewPath = pathListeners.GetNewPath(justForDiag: false);
ObservableSourceStatusEnum lastParentStatus = lastParent.Status;
System.Diagnostics.Debug.WriteLine($"Path = {bInfo.PropertyPath.Path}, NewPath = {strNewPath}, " +
$"Terminal Node Status = {lastParentStatus}.");
if (lastParentStatus.IsReadyOrWatching())
{
// Check to see if DataContext holds source property.
// When a DataContext is set via a binding, in some cases,
// bindings that rely on that DataContext may get set
// before the binding that provides the correct DataContext is set.
ObservableSource root = pathListeners[ROOT_INDEX];
if (root.SourceKind == SourceKindEnum.FrameworkElement || root.SourceKind == SourceKindEnum.FrameworkContentElement)
{
string firstChildPathElement = pathListeners[ROOT_INDEX + 1].PathElement;
if (!root.DoesChildExist(firstChildPathElement))
{
System.Diagnostics.Debug.WriteLine($"No Binding is being created. Data is present, but doesn't contain source property: {firstChildPathElement}.");
isCustom = false;
return(null);
}
}
// TODO: What about the original PropertyPath parameters?
PropertyPath newPath = new PropertyPath(strNewPath);
isCustom = lastParent.IsPropBagBased; // .IsPropBagBasedAndNoCustomTypeDescriptors;
return(CreateBinding(bindingTarget, bInfo, sourceType, newPath, isCustom));
}
else
{
System.Diagnostics.Debug.Assert(pathListeners[0].IsListeningForNewDC, "There are no active listeners!");
System.Diagnostics.Debug.WriteLine("No Binding is being created, not enough data.");
isCustom = false;
return(null);
}
}
//protected virtual void SetDefaultConverter()
//{
// if (DefaultConverter == null)
// {
// if(DefaultConverterParameterBuilder != null)
// {
// throw new InvalidOperationException("The DefaultParameterBuilder has been given a value, but the DefaultConverter is unassigned.");
// }
// DefaultConverter = new Lazy<IValueConverter>(() => new PropValueConverter());
// DefaultConverterParameterBuilder = OurDefaultConverterParameterBuilder;
// }
//}
protected virtual IValueConverter GetConverter(BindingTarget bindingTarget, MyBindingInfo bInfo, Type sourceType,
string pathElement, bool isPropBagBased, out object converterParameter)
{
if (isPropBagBased)
{
if (bInfo.Converter != null)
{
// Use the one specified in the MarkUp
converterParameter = bInfo.ConverterParameterBuilder(bindingTarget, bInfo, sourceType, pathElement);
return(bInfo.Converter);
}
else
{
// Use the default for ItemsSource
if (bindingTarget.DependencyProperty.Name == "SelectedItem")
{
// If this is being used to supply a SelectedItem property.
converterParameter = null;
return(new SelectedItemConverter());
}
else
{
// Use the default converter provided by the caller or if no default provide our standard PropValueConverter.
converterParameter = DefaultConverterParameterBuilder(bindingTarget, bInfo, sourceType, pathElement);
return(DefaultConverter.Value);
}
}
}
else
{
// If no converter specified and the target is SelectedItem,
// use the SelectedItemConverter.
if (bInfo.Converter == null && bindingTarget.DependencyProperty?.Name == "SelectedItem")
{
converterParameter = null;
return(new SelectedItemConverter());
}
else
{
// TODO: Check this. I beleive that the Microsoft Binder supplies a default converter.
// If no converter specified in the markup, no converter will be used.
converterParameter = bInfo.ConverterParameterBuilder(bindingTarget, bInfo, sourceType, pathElement);
return(bInfo.Converter);
}
}
}
protected virtual Binding CreateDefaultBinding(BindingTarget bindingTarget, MyBindingInfo bInfo, Type sourceType,
PropertyPath newPath)
{
IValueConverter converter = GetConverter(bindingTarget, bInfo, sourceType,
newPath.Path, false, out object converterParameter);
Binding binding = new Binding
{
Path = newPath,
Converter = converter,
ConverterParameter = converterParameter
//ConverterCulture = bInfo.ConverterCulture,
};
ApplyStandardBindingParams(bInfo, ref binding);
return(binding);
}
public override object ProvideValue(IServiceProvider serviceProvider)
{
if (SourceType == null)
{
throw new InvalidOperationException("The SourceType must be specified.");
}
// Get the Target Object and Target Property
if (!SetOurEnv(serviceProvider, out _bindingTarget))
{
return(this);
}
MyBindingInfo bindingInfo = GatherBindingInfo(Path, Mode);
MyBindingEngine mb = new MyBindingEngine(bindingInfo, SourceType, _bindingTarget, UseMultiBinding);
return(mb.ProvideValue(serviceProvider));
}
private MyBindingInfo GatherBindingInfo(PropertyPath path, BindingMode mode)
{
MyBindingInfo result = new MyBindingInfo(path, mode)
{
ElementName = ElementName,
Source = Source,
RelativeSource = RelativeSource,
BindingGroupName = BindingGroupName,
BindsDirectlyToSource = BindsDirectlyToSource,
Converter = Converter,
ConverterCulture = ConverterCulture,
ConverterParameter = ConverterParameter,
FallBackValue = FallBackVallue,
IsAsync = IsAsync,
NotifyOnSourceUpdated = NotifyOnSourceUpdated,
NotifyOnTargetUpdated = NotifyOnTargetUpdated,
NotifyOnValidationError = NotifyOnValidationError,
StringFormat = StringFormat,
TargetNullValue = TargetNullValue,
UpdateSourceTrigger = UpdateSourceTrigger,
ValidatesOnDataErrors = ValidatesOnDataErrors,
ValidatesOnExceptions = ValidatesOnExceptions,
ValidatesOnNotifyDataErrors = ValidatesOnNotifyDataErrors,
UpdateSourceExceptionFilter = null,
ValidationRules = null,
Delay = Delay,
XPath = XPath
};
return(result);
}
protected virtual void ApplyStandardBindingParams(MyBindingInfo bInfo, ref Binding binding)
{
if (bInfo.ElementName != null)
{
binding.ElementName = bInfo.ElementName;
}
if (bInfo.RelativeSource != null)
{
binding.RelativeSource = bInfo.RelativeSource;
}
if (bInfo.Source != null)
{
binding.Source = bInfo.Source;
}
binding.BindingGroupName = bInfo.BindingGroupName;
binding.BindsDirectlyToSource = bInfo.BindsDirectlyToSource;
binding.Delay = bInfo.Delay;
binding.FallbackValue = bInfo.FallBackValue;
binding.NotifyOnSourceUpdated = bInfo.NotifyOnSourceUpdated;
binding.NotifyOnTargetUpdated = bInfo.NotifyOnTargetUpdated;
binding.NotifyOnValidationError = bInfo.NotifyOnValidationError;
binding.StringFormat = bInfo.StringFormat;
binding.TargetNullValue = bInfo.TargetNullValue;
binding.UpdateSourceExceptionFilter = bInfo.UpdateSourceExceptionFilter;
binding.UpdateSourceTrigger = bInfo.UpdateSourceTrigger;
binding.ValidatesOnDataErrors = bInfo.ValidatesOnDataErrors;
binding.ValidatesOnExceptions = bInfo.ValidatesOnExceptions;
binding.ValidatesOnNotifyDataErrors = bInfo.ValidatesOnNotifyDataErrors;
binding.XPath = bInfo.XPath;
}
private object GetConverterParameter(BindingTarget bindingTarget, MyBindingInfo bInfo, Type sourceType, string pathElement)
{
return bInfo.ConverterParameter;
}
protected OSCollection PreparePathListeners(BindingTarget bindingTarget, MyBindingInfo bInfo, Type sourceType)
{
string[] nodes = GetPathComponents(bInfo.PropertyPath, out int compCount);
return(new OSCollection(ROOT_PATH_ELEMENT, nodes, sourceType, BinderName));
}
protected virtual object OurDefaultConverterParameterBuilder(BindingTarget bindingTarget, MyBindingInfo bInfo, Type sourceType,
string pathElement)
{
return(new TwoTypes(sourceType, bindingTarget.PropertyType));
}
protected virtual bool SourceIsDependencyObject(MyBindingInfo bInfo) => (
bInfo.RelativeSource != null ||
bInfo.ElementName != null ||
bInfo.Source is DependencyObject ||
bInfo.Source is DataSourceProvider && bInfo.BindsDirectlyToSource
);
protected virtual MultiBindingExpression ProvideStandardMultiBindingExp(IServiceProvider serviceProvider,
BindingTarget bindingTarget, MyBindingInfo bInfo, Type sourceType)
{
// create wpf binding
MyMultiValueConverter mValueConverter = new MyMultiValueConverter(BindingInfo.Mode);
Binding binding = CreateDefaultBinding(bindingTarget, bInfo, sourceType, bInfo.PropertyPath);
// This also sets the binding.
MultiBindingExpression mExp = BuildMultiBindingExpression(serviceProvider, binding, isCustom: false);
return(mExp);
//// TODO: Should we SetTheBinding here? We need to test this.
//return WrapBindingInMultiValueConverter(serviceProvider, binding, binding.Mode);
}
protected virtual object ProvideStandardBindingExp(IServiceProvider serviceProvider,
BindingTarget bindingTarget, MyBindingInfo bInfo, Type sourceType)
{
Binding binding = CreateDefaultBinding(bindingTarget, bInfo, sourceType, bInfo.PropertyPath);
return(binding);
//BindingExpressionBase bExp = BuildBindingExpressionBase(serviceProvider, binding, isCustom: false);
//return bExp;
}
protected bool RefreshPathListeners(BindingTarget bindingTarget, MyBindingInfo bInfo, Type sourceType, OSCollection pathListeners,
DataSourceChangedEventArgs changeInfo, ObservableSource signalingOs)
{
// Assume that this operation will not require the binding to be updated,
// until proven otherwise.
bool bindingInfoChanged = false;
int nodeIndex = _dataSourceChangeListeners.IndexOf(signalingOs);
if (nodeIndex == -1)
{
throw new InvalidOperationException($"Could not get pointer to path element while processing " +
$"DataSourceChanged event for {BinderName} in PropBagControlsWPF.Binders.");
}
ObservableSource parentOs = pathListeners[nodeIndex];
ObservableSourceStatusEnum status;
// Initializing
// Attempt to get a reference to the Source Root (Object with DataContext property or DataSourceProvider.)
if (changeInfo.ChangeType == DataSourceChangeTypeEnum.Initializing)
{
System.Diagnostics.Debug.Assert(nodeIndex == ROOT_INDEX, $"The node index should refer to the ObservableSource for " +
$"the root when DataSourceChangeType = {nameof(DataSourceChangeTypeEnum.Initializing)}.");
string rootElementName = GetRootPathElementName(pathListeners);
ObservableSourceProvider osp = GetSourceRoot(bindingTarget, bInfo.Source, rootElementName, BinderName);
if (osp == null)
{
throw new InvalidOperationException($"{BinderName} could not locate a data source.");
}
status = pathListeners.ReplaceListener(ROOT_INDEX, ref osp, this.DataSourceHasChanged,
out parentOs);
if (parentOs?.IsListeningForNewDC != true)
{
throw new InvalidOperationException($"{BinderName} could not locate a data source.");
}
}
// DataContextUpdated
// Refresh the Source Root
else if (changeInfo.ChangeType == DataSourceChangeTypeEnum.DataContextUpdated)
{
System.Diagnostics.Debug.Assert(nodeIndex == ROOT_INDEX, $"The node index should refer to the ObservableSource for" +
$" the root when DataSourceChangeType = {nameof(DataSourceChangeTypeEnum.DataContextUpdated)}.");
status = parentOs.Status;
pathListeners.ResetListeners(ROOT_INDEX + 1, this.DataSourceHasChanged);
bindingInfoChanged = true;
}
// Handle Collection Change
else if (changeInfo.ChangeType == DataSourceChangeTypeEnum.CollectionChanged)
{
return(bindingInfoChanged);
}
// Handle Property Changed
else if (changeInfo.ChangeType == DataSourceChangeTypeEnum.PropertyChanged)
{
// The PropModel of the value of this node's child may have changed.
// Replace the child with a new SourceListner, if appropriate
// and then fall-through to normal processing, at signaled step + 2.
string changedPropName = changeInfo.PropertyName;
nodeIndex++;
ObservableSource child = pathListeners[nodeIndex];
bool matched =
changedPropName == child.NewPathElement ||
changedPropName == "Item[]" && child.NewPathElement.StartsWith("[");
if (!matched || !(nodeIndex < pathListeners.Count - 1))
{
// Action is not required if
// The updated property is not part of our path,
// or our child in the terminal node,
return(bindingInfoChanged);
}
// Replace the child, if
// 1. It was null and now is not, or
// 2. It is now null and was not null, or
// 3. It was PropBag-based and is now is not, or
// 4. It was a regular CLR object and is now PropBag-based, or
// 5. It is still PropBag-Based and the prop item corresponding
// to the grandchild node had a change in type.
if (!child.Status.IsReadyOrWatching())
{
string prevValueForNewPathElement = child.NewPathElement;
ObservableSourceProvider newChildProvider = parentOs.GetChild(child.PathElement);
if (newChildProvider?.Data == null)
{
// Still no data ??
System.Diagnostics.Debug.WriteLine("Child was null and is still null.");
//ResetPathListeners(pathListeners, nodeIndex);
pathListeners.ResetListeners(nodeIndex, this.DataSourceHasChanged);
bindingInfoChanged = true;
return(bindingInfoChanged);
}
//ObservableSourceStatusEnum newCStatus =
// ReplaceListener(pathListeners, nodeIndex, ref newChildProvider,
// this.DataSourceHasChanged, out ObservableSource newChild);
ObservableSourceStatusEnum newCStatus = pathListeners.ReplaceListener(nodeIndex, ref newChildProvider,
this.DataSourceHasChanged, out ObservableSource newChild);
if (newChild != null)
{
string newPathElement = GetNewPathElement(newChild.PathElement, newChild.Type, parentOs.IsPropBagBased);
newChild.NewPathElement = newPathElement;
bindingInfoChanged = (newPathElement != prevValueForNewPathElement);
}
}
// If the child was updated, begin processing our grand children.
parentOs = pathListeners[nodeIndex];
status = parentOs?.Status ?? ObservableSourceStatusEnum.NoType;
}
else
{
throw new ApplicationException($"The DataSourceChangedType: {changeInfo.ChangeType} is not recognized.");
}
// Now, starting at step: stepNo + 1, replace or refresh each listener.
int nPtr = nodeIndex + 1;
for (; nPtr < pathListeners.Count - 1 && status.IsReadyOrWatching(); nPtr++)
{
// This is an itermediate step and the path has at least two components.
parentOs.BeginListeningToSource();
if (nPtr > 1)
{
// Make sure we are listening to events that this ObservableSource may raise.
// We know that we are subscribed to the root.
parentOs.Subscribe(this.DataSourceHasChanged);
}
string pathElement = pathListeners[nPtr].PathElement;
string prevValueForNewPathElement = pathListeners[nPtr].NewPathElement;
ObservableSourceProvider osp = parentOs.GetChild(pathElement);
//status = ReplaceListener(pathListeners, nPtr, ref osp, this.DataSourceHasChanged,
// out ObservableSource os);
status = pathListeners.ReplaceListener(nPtr, ref osp, this.DataSourceHasChanged,
out ObservableSource os);
if (os != null)
{
string newPathElement = GetNewPathElement(pathElement, os.Type, parentOs.IsPropBagBased);
os.NewPathElement = newPathElement;
bindingInfoChanged = (newPathElement != prevValueForNewPathElement);
}
// Note: if os is null, status will be "NoType", i.e. not ready.
if (status == ObservableSourceStatusEnum.Ready)
{
System.Diagnostics.Debug.WriteLine($"Listener for {pathElement} is ready.");
}
else
{
System.Diagnostics.Debug.WriteLine($"Listener for {pathElement} is not ready.");
}
parentOs = os;
//status = os.Status; -- Not needed, ReplaceListener sets this variable.
}
if (nPtr == pathListeners.Count - 1)
{
// Process terminal node.
ObservableSource lastNode = pathListeners[nPtr];
if (status.IsReadyOrWatching())
{
string newPathElement = GetNewPathElement(lastNode.PathElement, lastNode.Type, parentOs.IsPropBagBased);
if (lastNode.NewPathElement != newPathElement)
{
lastNode.NewPathElement = newPathElement;
bindingInfoChanged = true;
}
if (!status.IsWatching())
{
parentOs.BeginListeningToSource();
}
}
}
else
{
// Don't have all of the data present required to create a binding.
System.Diagnostics.Debug.WriteLine($"RefreshPathListeners claims that no binding should be created for path = {bInfo.PropertyPath.Path}.");
//ResetPathListeners(pathListeners, nPtr);
pathListeners.ResetListeners(nPtr, this.DataSourceHasChanged);
}
return(bindingInfoChanged);
}
public MyBindingEngine(MyBindingInfo bindingInfo, Type sourceType, BindingTarget bindingTarget, bool useMultiBinding = true, string binderInstanceName = "pbb:Binder")
: base(bindingTarget, bindingInfo, sourceType, useMultiBinding, binderInstanceName)
{
}