/// <summary>
/// This is an helper function to overcome the restriction on WPF framework to have
/// hetrogenious hierarchy ItemsControl. The problem is an ItemsControl in it's
/// internal logic fetches Item related properties from it's parent if that is an ItemsControl.
/// That approach can only be successful only in homogenous hierarchy of controls from first layer
/// as in case of TreeViewItem.
///
/// In Ribbon control it is not true at various places and most common example could RibbonGalleryCategory.
/// RibbonGalleryCategory's parent is RibbonGallery which is an ItemsControl and hence the above explained
/// fetch happens. But the property specified on RibbonGallery are applicable to RibbonGalleryCategory only.
/// Now, RibbonGalleryCategory's Item are not RibbonGalleryCategory but RibbonGalleryItem and hence a conflict.
///
/// This function gets called from PrepareContainerOverride after the base.PrepareContainerOverride is being called
/// and if the properties being fetched from the parent (changed) it sets them back to original values passed as arguments.
/// </summary>
/// <param name="itemsControl"> current ItemsControl</param>
/// <param name="itemTemplate"></param>
/// <param name="itemTemplateSelector"></param>
/// <param name="itemStringFormat"></param>
/// <param name="itemContainerStyle"></param>
/// <param name="itemContainerStyleSelector"></param>
/// <param name="alternationCount"></param>
/// <param name="itemBindingGroup"></param>
public static void IgnoreDPInheritedFromParentItemsControl(
ItemsControl itemsControl,
ItemsControl parentItemsControl,
ValueAndValueSource itemTemplate,
ValueAndValueSource itemTemplateSelector,
ValueAndValueSource itemStringFormat,
ValueAndValueSource itemContainerStyle,
ValueAndValueSource itemContainerStyleSelector,
ValueAndValueSource alternationCount,
ValueAndValueSource itemBindingGroup,
ValueAndValueSource headerTemplate,
ValueAndValueSource headerTemplateSelector,
ValueAndValueSource headerStringFormat)
{
// HeaderedItemsControl needs special consideration as some of the properties needs to be kept as is
// if HierarichalDataTemplate is used. The reason is internal method PrepareHeirarchy() in HeaderedItemsControl
// fetches appropriate values from the template and updates the one assigned using parentItemsControl and
// those values should be kept for master-detail scenarios to be working correctly.
HeaderedItemsControl hic = itemsControl as HeaderedItemsControl;
HierarchicalDataTemplate hTemplate = hic != null ? hic.HeaderTemplate as HierarchicalDataTemplate : null;
if (itemsControl.ItemTemplate == parentItemsControl.ItemTemplate)
{
if (hTemplate == null || (hTemplate.ItemTemplate == null && string.IsNullOrEmpty(hTemplate.ItemStringFormat) && hTemplate.ItemTemplateSelector == null))
{
RestoreValue(itemsControl, ItemsControl.ItemTemplateProperty, itemTemplate);
}
}
if (itemsControl.ItemTemplateSelector == parentItemsControl.ItemTemplateSelector)
{
if (hTemplate == null || (string.IsNullOrEmpty(hTemplate.ItemStringFormat) && hTemplate.ItemTemplateSelector == null))
{
RestoreValue(itemsControl, ItemsControl.ItemTemplateSelectorProperty, itemTemplateSelector);
}
}
if (itemsControl.ItemStringFormat == parentItemsControl.ItemStringFormat)
{
if (hTemplate == null || string.IsNullOrEmpty(hTemplate.ItemStringFormat))
{
RestoreValue(itemsControl, ItemsControl.ItemStringFormatProperty, itemStringFormat);
}
}
if (itemsControl.ItemContainerStyle == parentItemsControl.ItemContainerStyle)
{
if (hTemplate == null || (hTemplate.ItemContainerStyleSelector == null && hTemplate.ItemContainerStyle == null))
{
RestoreValue(itemsControl, ItemsControl.ItemContainerStyleProperty, itemContainerStyle);
}
}
if (itemsControl.ItemContainerStyleSelector == parentItemsControl.ItemContainerStyleSelector)
{
if (hTemplate == null || hTemplate.ItemContainerStyleSelector == null)
{
RestoreValue(itemsControl, ItemsControl.ItemContainerStyleSelectorProperty, itemContainerStyleSelector);
}
}
if (itemsControl.AlternationCount == parentItemsControl.AlternationCount)
{
// Potential issue if 0 is set intentionally, but one can argue if it is explicitly defined on
// ItemsControl itself then use that one.
if (hTemplate == null || hTemplate.AlternationCount == 0)
{
RestoreValue(itemsControl, ItemsControl.AlternationCountProperty, alternationCount);
}
}
if (itemsControl.ItemBindingGroup == parentItemsControl.ItemBindingGroup)
{
if (hTemplate == null || hTemplate.ItemBindingGroup == null)
{
RestoreValue(itemsControl, ItemsControl.ItemBindingGroupProperty, itemBindingGroup);
}
}
if (hic != null)
{
if (headerTemplate != null && hic.HeaderTemplate == parentItemsControl.ItemTemplate && hTemplate == null)
{
RestoreValue(hic, HeaderedItemsControl.HeaderTemplateProperty, headerTemplate);
}
if (headerTemplateSelector != null && hic.HeaderTemplateSelector == parentItemsControl.ItemTemplateSelector && hTemplate == null)
{
RestoreValue(hic, HeaderedItemsControl.HeaderTemplateSelectorProperty, headerTemplateSelector);
}
if (headerStringFormat != null && hic.HeaderStringFormat == parentItemsControl.ItemStringFormat && hTemplate == null)
{
RestoreValue(hic, HeaderedItemsControl.HeaderStringFormatProperty, headerStringFormat);
}
}
}
private static void RestoreValue(DependencyObject d, DependencyProperty property, ValueAndValueSource v)
{
Debug.Assert(d != null);
Debug.Assert(property != null);
Debug.Assert(v != null);
if (v.ValueSource == BaseValueSource.Local)
{
d.SetValue(property, v.Value);
}
else
{
d.ClearValue(property);
d.CoerceValue(property);
}
}
