| private StartAt ( GeneratorPosition position, GeneratorDirection direction, bool allowStartAtRealizedItem ) : IDisposable | ||
| position | GeneratorPosition | |
| direction | GeneratorDirection | |
| allowStartAtRealizedItem | bool | |
| Результат | IDisposable | |
void AddItemsToPresenter(GeneratorPosition position, int count)
{
if (_presenter == null || _presenter._elementRoot == null || _presenter._elementRoot is VirtualizingPanel)
{
return;
}
Panel panel = _presenter._elementRoot;
int newIndex = ItemContainerGenerator.IndexFromGeneratorPosition(position);
using (var p = ItemContainerGenerator.StartAt(position, GeneratorDirection.Forward, true))
for (int i = 0; i < count; i++)
{
var item = Items [newIndex + i];
DependencyObject container = null;
bool fresh;
container = ItemContainerGenerator.GenerateNext(out fresh);
ContentControl c = container as ContentControl;
if (c != null)
{
c.ContentSetsParent = false;
}
FrameworkElement f = container as FrameworkElement;
if (f != null && !(item is FrameworkElement))
{
f.DataContext = item;
}
panel.Children.Insert(newIndex + i, (UIElement)container);
ItemContainerGenerator.PrepareItemContainer(container);
}
}
void UpdateDisplayedItem(object selectedItem)
{
object content;
// Can't do anything with no content presenter
if (_contentPresenter == null)
{
return;
}
// Return the currently displayed object (which is a UIElement)
// to its original container.
if (DisplayedItem != null)
{
content = _contentPresenter.Content;
DisplayedItem.Content = content;
DisplayedItem = null;
}
_contentPresenter.Content = null;
if (selectedItem == null)
{
_contentPresenter.Content = NothingSelectedFallback;
_contentPresenter.ContentTemplate = null;
SelectionBoxItem = null;
SelectionBoxItemTemplate = null;
return;
}
// If the currently selected item is a ComboBoxItem (not ListBoxItem!), we
// display its Content instead of the CBI itself.
content = selectedItem;
if (content is ComboBoxItem)
{
content = ((ComboBoxItem)content).Content;
}
// Only allow DisplayedItem to be non-null if we physically move
// its content. This will only happen if DisplayedItem == SelectedItem
DisplayedItem = ItemContainerGenerator.ContainerFromIndex(SelectedIndex) as ComboBoxItem;
SelectionBoxItem = content;
SelectionBoxItemTemplate = ItemTemplate;
// If displayed item is avaiable, we can get the right template from there. Otherwise
// we need to create a container, read the template and destroy it.
if (DisplayedItem != null)
{
SelectionBoxItemTemplate = DisplayedItem.ContentTemplate;
if (content is UIElement)
{
DisplayedItem.Content = null;
}
else
{
DisplayedItem = null;
}
}
else
{
bool fresh;
ComboBoxItem container = ItemContainerGenerator.ContainerFromIndex(SelectedIndex) as ComboBoxItem;
if (container == null)
{
var index = ItemContainerGenerator.GeneratorPositionFromIndex(SelectedIndex);
using (ItemContainerGenerator.StartAt(index, GeneratorDirection.Forward, true))
container = ItemContainerGenerator.GenerateNext(out fresh) as ComboBoxItem;
ItemContainerGenerator.PrepareItemContainer(container);
}
SelectionBoxItemTemplate = container.ContentTemplate;
}
_contentPresenter.Content = SelectionBoxItem;
_contentPresenter.ContentTemplate = SelectionBoxItemTemplate;
}