private void SelectAndSnapTo(LoopingSelectorItem item)
{
if (item == null)
{
return;
}
if (_selectedItem != null)
{
_selectedItem.SetState(IsExpanded ? LoopingSelectorItem.State.Expanded : LoopingSelectorItem.State.Normal, true);
}
if (_selectedItem != item)
{
_selectedItem = item;
// Update DataSource.SelectedItem aynchronously so that animations have a chance to start.
Dispatcher.BeginInvoke(() =>
{
_isSelecting = true;
DataSource.SelectedItem = item.DataContext;
_isSelecting = false;
});
}
_selectedItem.SetState(LoopingSelectorItem.State.Selected, true);
TranslateTransform transform = item.Transform;
if (transform != null)
{
if (Orientation == Orientation.Vertical)
{
double newPosition = -transform.Y - Math.Round(item.ActualHeight / 2);
if (_panningTransform.Y != newPosition)
{
AnimatePanel(_selectDuration, _selectEase, newPosition);
}
}
else
{
double newPosition = -transform.X - Math.Round(item.ActualWidth / 2);
if (_panningTransform.X != newPosition)
{
AnimatePanel(_selectDuration, _selectEase, newPosition);
}
}
}
}
/// <summary>
/// Balances the items.
/// </summary>
private void Balance()
{
if (!IsReady)
{
return;
}
double actualItemWidth = ActualItemWidth;
double actualItemHeight = ActualItemHeight;
if (Orientation == Orientation.Vertical)
{
_additionalItemsCount = (int)Math.Round((ActualHeight * 1.5) / actualItemHeight);
}
else
{
_additionalItemsCount = (int)Math.Round((ActualWidth * 1.5) / actualItemWidth);
}
LoopingSelectorItem closestToMiddle = null;
int closestToMiddleIndex = -1;
if (_itemsPanel.Children.Count == 0)
{
// We need to get the selection and start from there
closestToMiddleIndex = 0;
_selectedItem = closestToMiddle = CreateAndAddItem(_itemsPanel, DataSource.SelectedItem);
if (Orientation == Orientation.Vertical)
{
closestToMiddle.Transform.Y = -actualItemHeight / 2;
closestToMiddle.Transform.X = (ActualWidth - actualItemWidth) / 2;
}
else
{
closestToMiddle.Transform.X = -actualItemWidth / 2;
closestToMiddle.Transform.Y = (ActualHeight - actualItemHeight) / 2;
}
closestToMiddle.SetState(LoopingSelectorItem.State.Selected, false);
}
else
{
closestToMiddleIndex = GetClosestItem();
closestToMiddle = (LoopingSelectorItem)_itemsPanel.Children[closestToMiddleIndex];
}
int itemsBeforeCount;
LoopingSelectorItem firstItem = GetFirstItem(closestToMiddle, out itemsBeforeCount);
int itemsAfterCount;
LoopingSelectorItem lastItem = GetLastItem(closestToMiddle, out itemsAfterCount);
// Does the top need items?
if (itemsBeforeCount < itemsAfterCount || itemsBeforeCount < _additionalItemsCount)
{
while (itemsBeforeCount < _additionalItemsCount)
{
object newData = DataSource.GetPrevious(firstItem.DataContext);
if (newData == null)
{
// There may be room to display more items, but there is no more data.
if (Orientation == Orientation.Vertical)
{
_maximumPanelScroll = -firstItem.Transform.Y - actualItemHeight / 2;
}
else
{
_maximumPanelScroll = -firstItem.Transform.X - actualItemWidth / 2;
}
if (_panelAnimation.To != null && (_isAnimating && _panelAnimation.To.Value > _maximumPanelScroll))
{
Brake(_maximumPanelScroll);
}
break;
}
LoopingSelectorItem newItem = null;
// Can an item from the bottom be re-used?
if (itemsAfterCount > _additionalItemsCount)
{
newItem = lastItem;
lastItem = lastItem.Previous;
newItem.Remove();
newItem.Content = newItem.DataContext = newData;
}
else
{
// Make a new item
newItem = CreateAndAddItem(_itemsPanel, newData);
if (Orientation == Orientation.Vertical)
{
newItem.Transform.X = (ActualWidth - actualItemWidth) / 2;
}
else
{
newItem.Transform.Y = (ActualHeight - actualItemHeight) / 2;
}
}
// Put the new item on the top
if (Orientation == Orientation.Vertical)
{
newItem.Transform.Y = firstItem.Transform.Y - actualItemHeight;
}
else
{
newItem.Transform.X = firstItem.Transform.X - actualItemWidth;
}
newItem.InsertBefore(firstItem);
firstItem = newItem;
++itemsBeforeCount;
}
}
// Does the bottom need items?
if (itemsAfterCount < itemsBeforeCount || itemsAfterCount < _additionalItemsCount)
{
while (itemsAfterCount < _additionalItemsCount)
{
object newData = DataSource.GetNext(lastItem.DataContext);
if (newData == null)
{
// There may be room to display more items, but there is no more data.
if (Orientation == Orientation.Vertical)
{
_minimumPanelScroll = -lastItem.Transform.Y - actualItemHeight / 2;
}
else
{
_minimumPanelScroll = -lastItem.Transform.X - actualItemWidth / 2;
}
if (_panelAnimation.To != null && (_isAnimating && _panelAnimation.To.Value < _minimumPanelScroll))
{
Brake(_minimumPanelScroll);
}
break;
}
LoopingSelectorItem newItem = null;
// Can an item from the top be re-used?
if (itemsBeforeCount > _additionalItemsCount)
{
newItem = firstItem;
firstItem = firstItem.Next;
newItem.Remove();
newItem.Content = newItem.DataContext = newData;
}
else
{
// Make a new item
newItem = CreateAndAddItem(_itemsPanel, newData);
if (Orientation == Orientation.Vertical)
{
newItem.Transform.X = (ActualWidth - actualItemWidth) / 2;
}
else
{
newItem.Transform.Y = (ActualHeight - ActualItemHeight) / 2;
}
}
// Put the new item on the bottom
if (Orientation == Orientation.Vertical)
{
newItem.Transform.Y = lastItem.Transform.Y + actualItemHeight;
}
else
{
newItem.Transform.X = lastItem.Transform.X + actualItemWidth;
}
newItem.InsertAfter(lastItem);
lastItem = newItem;
++itemsAfterCount;
}
}
_temporaryItemsPool = null;
}