/// <summary>
/// Returns a collection of properties for our object. We first rely on base
/// CLR properties and then we attempt to match these with dependency properties.
/// </summary>
public PropertyDescriptorCollection GetProperties(Attribute[] attributes)
{
// Because attached properties can come and go at any time,
// the set of properties we have here always needs to be rebuilt.
// We have two code paths here based on filtered attributes. An attribute
// filter is just a notificaiton of a filter, it doesn't actually perform
// the filter. Because the default PropertyFilterAttribute is PropertyFilter.All,
// it acts as a nice "don't care" in later filtering stages that TypeDescriptor
// may apply. That means that regardless of the filter value, we don't have
// to fiddle with adding the attribute to the property descriptor.
PropertyFilterOptions filter = PropertyFilterOptions.Valid | PropertyFilterOptions.SetValues;
if (attributes != null)
{
foreach (Attribute attr in attributes)
{
PropertyFilterAttribute filterAttr = attr as PropertyFilterAttribute;
if (filterAttr != null)
{
filter = filterAttr.Filter;
break;
}
}
}
if (filter == PropertyFilterOptions.None)
{
return(PropertyDescriptorCollection.Empty);
}
// First, get the set of all known registered properties in the
// app domain. GetRegisteredProperties caches its results and
// will automatically re-fetch if new properties have been
// registered
DependencyProperty[] registeredProperties = GetRegisteredProperties();
Type instanceType = _instance.GetType();
// Next, walk through them and see which ones can be attached to this
// object. If our filter is specifically SetValues, we can
// greatly shortcut the entire process by using the local value
// enumerator.
List <PropertyDescriptor> filteredProps;
if (filter == PropertyFilterOptions.SetValues)
{
LocalValueEnumerator localEnum = _instance.GetLocalValueEnumerator();
filteredProps = new List <PropertyDescriptor>(localEnum.Count);
while (localEnum.MoveNext())
{
DependencyProperty dp = localEnum.Current.Property;
DependencyPropertyKind kind = DependencyObjectProvider.GetDependencyPropertyKind(dp, instanceType);
// For locally set values, we just want to exclude direct and internal properties.
if (!kind.IsDirect && !kind.IsInternal)
{
DependencyObjectPropertyDescriptor dpProp = DependencyObjectProvider.GetAttachedPropertyDescriptor(dp, instanceType);
filteredProps.Add(dpProp);
}
}
}
else
{
filteredProps = new List <PropertyDescriptor>(registeredProperties.Length);
foreach (DependencyProperty dp in registeredProperties)
{
bool addProp = false;
DependencyPropertyKind kind = DependencyObjectProvider.GetDependencyPropertyKind(dp, instanceType);
if (kind.IsAttached)
{
// Check bit combinations that would yield true in
// any case. For non-attached properties, they're all valid, so if
// the valid bit is set, we're done.
PropertyFilterOptions anySet = PropertyFilterOptions.SetValues | PropertyFilterOptions.UnsetValues;
PropertyFilterOptions anyValid = PropertyFilterOptions.Valid | PropertyFilterOptions.Invalid;
if ((filter & anySet) == anySet || (filter & anyValid) == anyValid)
{
addProp = true;
}
if (!addProp && (filter & anyValid) != 0)
{
bool canAttach = CanAttachProperty(dp, _instance);
addProp = canAttach ^ ((filter & anyValid) == PropertyFilterOptions.Invalid);
}
if (!addProp && (filter & anySet) != 0)
{
bool shouldSerialize = _instance.ContainsValue(dp);
addProp = shouldSerialize ^ ((filter & anySet) == PropertyFilterOptions.UnsetValues);
}
}
else if ((filter & PropertyFilterOptions.SetValues) != 0 && _instance.ContainsValue(dp) && !kind.IsDirect && !kind.IsInternal)
{
// The property is not attached. However, it isn't an internal DP and the user
// has requested set values. See if the property is set on the object and include
// it if it is.
addProp = true;
}
if (addProp)
{
DependencyObjectPropertyDescriptor dpProp = DependencyObjectProvider.GetAttachedPropertyDescriptor(dp, instanceType);
filteredProps.Add(dpProp);
}
}
}
PropertyDescriptorCollection properties;
properties = new PropertyDescriptorCollection(filteredProps.ToArray(), true);
return(properties);
}
//------------------------------------------------------
//
// Private Methods
//
//------------------------------------------------------
#region Private Methods
/// <summary>
/// This method determines if the given property can be attached
/// to the given instance.
/// </summary>
private bool CanAttachProperty(DependencyProperty dp, DependencyObject instance)
{
AttachInfo info = DependencyObjectProvider.GetAttachInfo(dp);
return(info.CanAttach(instance));
}