//-------------------------------------------------------------------
//
// Internal Methods
//
//-------------------------------------------------------------------
//
// ProcessTemplateBeforeSeal
//
// This is used in the case of templates defined with FEFs. For templates
// in Baml (the typical case), see the OnApply override.
//
// 1. Verify that
// a. root element is a Panel
// 2. Set IsItemsHost = true
//
internal override void ProcessTemplateBeforeSeal()
{
FrameworkElementFactory root;
if (HasContent)
{
// This is a Baml-style template
// Validate the root type (it must be a Panel)
TemplateContent templateHolder = Template as TemplateContent;
System.Xaml.XamlType panelType = templateHolder.SchemaContext.GetXamlType(typeof(Panel));
if (templateHolder.RootType == null || !templateHolder.RootType.CanAssignTo(panelType))
{
throw new InvalidOperationException(SR.Get(SRID.ItemsPanelNotAPanel, templateHolder.RootType));
}
}
else if ((root = this.VisualTree) != null)
{
// This is a FEF-style template
if (!typeof(Panel).IsAssignableFrom(root.Type))
{
throw new InvalidOperationException(SR.Get(SRID.ItemsPanelNotAPanel, root.Type));
}
root.SetValue(Panel.IsItemsHostProperty, true);
}
}
// workaround, pending bug 953483. The panel is
// being removed from the tree, so it should release
// its resources (chiefly - stop listening for generator's
// ItemsChanged event). Until there's a mechanism for
// this, just mark the panel as a non-ItemsHost, so
// that the next time it gets ItemsChanged it will
// stop listening. (See also bug 942265)
private void ClearPanel()
{
Panel oldPanel = (this.VisualChildrenCount > 0) ? this.GetVisualChild(0) as Panel : null;
Type type = null;
if (Template != null)
{
// Get the type of the template content's root
// Is this a FEF-based template?
if (Template.VisualTree != null)
{
type = Template.VisualTree.Type;
}
// Or, is it a (non-empty) Baml-based template?
else if (Template.HasXamlNodeContent)
{
System.Xaml.XamlType xType = (Template.Template as TemplateContent).RootType;
type = xType.UnderlyingType;
}
}
if (oldPanel != null && oldPanel.GetType() == type)
{
oldPanel.IsItemsHost = false;
}
}
