private bool VerifyEqual(object knownValue, Type knownType, object itemValue, DynamicValueConverter converter)
{
object tempValue = knownValue;
if (knownType != null && itemValue != null)
{
Type itemType = itemValue.GetType();
// determine if selectedValue is comparable to itemValue, convert if necessary
// using a DefaultValueConverter
if (!knownType.IsAssignableFrom(itemType))
{
tempValue = converter.Convert(knownValue, itemType);
if (tempValue == DependencyProperty.UnsetValue)
{
// can't convert, keep original value for the following object comparison
tempValue = knownValue;
}
}
}
return Object.Equals(tempValue, itemValue);
}
private object FindItemWithValue(object value)
{
if (!HasItems)
return DependencyProperty.UnsetValue;
// use a representative item to determine which kind of binding to use (XML vs. CLR)
BindingExpression bindingExpr = PrepareItemValueBinding(Items.GetRepresentativeItem());
if (bindingExpr == null)
return DependencyProperty.UnsetValue; // no suitable item found
// optimize for case where there is no SelectedValuePath (meaning
// that the value of the item is the item itself, or the InnerText
// of the item)
if (string.IsNullOrEmpty(SelectedValuePath))
{
// when there's no SelectedValuePath, the binding's Path
// is either empty (CLR) or "/InnerText" (XML)
string path = bindingExpr.ParentBinding.Path.Path;
Debug.Assert(String.IsNullOrEmpty(path) || path == "/InnerText");
if (string.IsNullOrEmpty(path))
{
// CLR - item is its own selected value
if (Items.Contains(value))
return value;
else
return DependencyProperty.UnsetValue;
}
else
{
// XML - use the InnerText as the selected value
return FindXmlNodeWithInnerText(value);
}
}
Type selectedType = (value != null) ? value.GetType() : null;
object selectedValue = value;
DynamicValueConverter converter = new DynamicValueConverter(false);
foreach (object current in Items)
{
bindingExpr.Activate(current);
object itemValue = bindingExpr.Value;
if (VerifyEqual(value, selectedType, itemValue, converter))
{
bindingExpr.Deactivate();
return current;
}
}
bindingExpr.Deactivate();
return DependencyProperty.UnsetValue;
}