internal TableViewPageResult Generate( IEnumerable<LayoutedContainerInfo> layoutedContainers, TableViewPage lastGeneratedPage )
{
m_generator = m_itemsHost.CustomItemContainerGenerator;
Debug.Assert( m_generator != null );
m_generator.IsRecyclingEnabled = true;
m_itemCount = m_generator.ItemCount;
m_focusedContainer = DataGridItemsHost.GetItemsHostContainerFromElement( m_itemsHost, Keyboard.FocusedElement as DependencyObject );
var lastGeneratedPageSize = lastGeneratedPage.OuterPage.Length;
m_oldLayoutedContainers = new Dictionary<UIElement, int>( lastGeneratedPageSize );
m_newLayoutedContainers = null;
// Figure out the realized index of all currently layouted containers.
foreach( var container in layoutedContainers.Select( item => item.Container ) )
{
var newRealizedIndex = m_generator.GetRealizedIndexForContainer( container );
if( ( newRealizedIndex >= 0 ) || ( container == m_focusedContainer ) )
{
m_oldLayoutedContainers.Add( container, newRealizedIndex );
}
// The container is lost, recycle it.
else
{
m_itemsHost.RecycleContainer( m_generator, new LayoutedContainerInfo( newRealizedIndex, container ) );
}
}
TableViewPageResult result;
if( m_itemCount > 0 )
{
m_newLayoutedContainers = new List<LayoutedContainerInfo>( lastGeneratedPageSize );
var extendedHeight = Math.Max( m_availableHeight, lastGeneratedPage.ViewportHeight );
this.PrepareRecycleCandidates( extendedHeight );
var dataGridContext = DataGridControl.GetDataGridContext( m_itemsHost );
var fillLastPage = ( dataGridContext != null ) && TableView.GetAutoFillLastPage( dataGridContext );
var pageInfo = this.GenerateContainers( m_startIndex, m_itemCount, m_availableHeight, extendedHeight, fillLastPage );
// Keep the focused container active by putting it in the layouted containers collection.
if( m_focusedContainer != null )
{
int newRealizedIndex;
if( m_oldLayoutedContainers.TryGetValue( m_focusedContainer, out newRealizedIndex ) )
{
m_oldLayoutedContainers.Remove( m_focusedContainer );
m_newLayoutedContainers.Add( new LayoutedContainerInfo( newRealizedIndex, m_focusedContainer ) );
}
}
result = new TableViewPageResult( pageInfo, m_newLayoutedContainers );
}
else
{
result = new TableViewPageResult( TableViewPage.Empty, Enumerable.Empty<LayoutedContainerInfo>() );
}
// Recycle the containers that have not been reused.
foreach( var entry in m_oldLayoutedContainers )
{
m_itemsHost.RecycleContainer( m_generator, new LayoutedContainerInfo( entry.Value, entry.Key ) );
}
return result;
}
private Size GetNewDesiredSize( TableViewPage pageInfo )
{
double desiredHeight;
double availableHeight = m_lastMeasureAvailableSize.Height;
if( pageInfo == TableViewPage.Empty )
{
desiredHeight = 0d;
}
// The current generated page displays only a subset of the data source.
else if( pageInfo.InnerPage.Length < this.ScrollInfo.ExtentHeight )
{
if( double.IsPositiveInfinity( availableHeight ) )
{
desiredHeight = pageInfo.InnerPage.Size;
}
else
{
desiredHeight = availableHeight;
}
}
// The current generated page displays all containers.
else
{
var pageHeight = pageInfo.OuterPage.Size;
if( double.IsPositiveInfinity( availableHeight ) )
{
desiredHeight = pageHeight;
}
else
{
desiredHeight = Math.Min( availableHeight, pageHeight );
}
}
return new Size( m_viewportWidth, desiredHeight );
}
internal TableViewPageResult( TableViewPage pageInfo, IEnumerable<LayoutedContainerInfo> layoutedContainers )
{
if( pageInfo == null )
throw new ArgumentNullException( "pageInfo" );
if( layoutedContainers == null )
throw new ArgumentNullException( "layoutedContainers" );
m_pageInfo = pageInfo;
m_layoutedContainers = layoutedContainers;
}