internal double GetStickyFootersRegionHeight( StickyContainerInfoList stickyFooters )
{
int count = stickyFooters.Count;
double lastStickyFooterOffset = m_viewportHeight;
for( int i = 0; i < count; i++ )
{
double desiredOffset = this.ComputeStickyFooterDesiredOffset( stickyFooters[ i ], lastStickyFooterOffset );
lastStickyFooterOffset = Math.Min( desiredOffset, lastStickyFooterOffset );
}
return lastStickyFooterOffset;
}
internal double GetStickyHeadersRegionHeight( StickyContainerInfoList stickyHeaders )
{
int count = stickyHeaders.Count;
double lastStickyHeaderOffset = -m_containerHeight;
for( int i = 0; i < count; i++ )
{
double desiredOffset = this.ComputeStickyHeaderDesiredOffset( stickyHeaders[ i ], lastStickyHeaderOffset );
lastStickyHeaderOffset = Math.Max( desiredOffset, lastStickyHeaderOffset );
}
return lastStickyHeaderOffset + m_containerHeight;
}
private void GenerateStickyHeaders( ICustomItemContainerGenerator generator, bool measureInvalidated, ref UIElement focusedElement )
{
CustomItemContainerGenerator customGenerator = ( CustomItemContainerGenerator )generator;
if( !this.AreHeadersStickyCache && !this.AreGroupHeadersStickyCache && !this.AreParentRowsStickyCache )
{
this.RecycleUnusedStickyContainers( generator, m_stickyHeaders, null, ref focusedElement );
m_stickyHeaders.Clear();
return;
}
int numberOfContainerChecked = 0;
StickyContainerInfoList newStickyHeaders = new StickyContainerInfoList();
foreach( LayoutedContainerInfo layoutedContainerInfo in m_layoutedContainers )
{
UIElement container = layoutedContainerInfo.Container;
// For each visible container, we must find what headers should be sticky for it.
List<StickyContainerGenerated> stickyHeaders =
customGenerator.GenerateStickyHeaders( container, this.AreHeadersStickyCache, this.AreGroupHeadersStickyCache, this.AreParentRowsStickyCache );
stickyHeaders.Sort( StickyContainerGeneratedComparer.Singleton );
// For each sticky headers returned, we must get the index of the last container
// that could need that container to be sticky.
foreach( StickyContainerGenerated stickyHeaderInfo in stickyHeaders )
{
UIElement stickyContainer = ( UIElement )stickyHeaderInfo.StickyContainer;
if( newStickyHeaders.ContainsContainer( stickyContainer ) )
continue;
int lastContainerIndex = customGenerator.GetLastHoldingContainerIndexForStickyHeader( stickyContainer );
StickyContainerInfo stickyContainerInfo = new StickyContainerInfo( stickyContainer, stickyHeaderInfo.Index, lastContainerIndex );
newStickyHeaders.Add( stickyContainerInfo );
if( focusedElement == stickyContainer )
{
focusedElement = null;
}
this.HandleGeneratedStickyContainerPreparation( stickyHeaderInfo, measureInvalidated );
}
// We only need to find the sticky headers for one
// more element than what is already sticky.
int visibleStickyHeadersCount = ( int )Math.Ceiling( this.GetStickyHeadersRegionHeight( newStickyHeaders ) / m_containerHeight );
if( ( ++numberOfContainerChecked - visibleStickyHeadersCount ) >= 1 )
break;
}
foreach( StickyContainerInfo stickyHeaderInfo in newStickyHeaders )
{
UIElement container = stickyHeaderInfo.Container;
int index = m_layoutedContainers.IndexOfContainer( container );
if( index > -1 )
{
m_layoutedContainers.RemoveAt( index );
}
m_layoutedContainersToRecycle.Remove( container );
}
this.RecycleUnusedStickyContainers( generator, m_stickyHeaders, newStickyHeaders, ref focusedElement );
m_stickyHeaders.Clear();
m_stickyHeaders.AddRange( newStickyHeaders );
m_stickyHeaders.Sort( StickyContainerInfoComparer.Singleton );
}
private void GenerateStickyFooters( ICustomItemContainerGenerator generator, bool measureInvalidated, ref UIElement focusedElement )
{
if( !this.AreFootersStickyCache && !this.AreGroupFootersStickyCache )
{
this.RecycleUnusedStickyContainers( generator, m_stickyFooters, null, ref focusedElement );
m_stickyFooters.Clear();
return;
}
CustomItemContainerGenerator customGenerator = ( CustomItemContainerGenerator )generator;
int numberOfContainerChecked = 0;
StickyContainerInfoList newStickyFooters = new StickyContainerInfoList();
int layoutedContainerCount = m_layoutedContainers.Count;
if( layoutedContainerCount > 0 )
{
// We must not generate sticky footers if the last container is not even at the bottom of the view!
LayoutedContainerInfo bottomMostContainerInfo = m_layoutedContainers[ layoutedContainerCount - 1 ];
double bottomMostContainerOffset = this.GetContainerOffsetFromIndex( bottomMostContainerInfo.RealizedIndex );
if( ( bottomMostContainerOffset + m_containerHeight ) >= m_viewportHeight )
{
for( int i = layoutedContainerCount - 1; i >= 0; i-- )
{
LayoutedContainerInfo layoutedContainerInfo = m_layoutedContainers[ i ];
UIElement layoutedContainer = layoutedContainerInfo.Container;
// For each visible container, we must find what footers should be sticky for it.
List<StickyContainerGenerated> stickyFooters =
customGenerator.GenerateStickyFooters( layoutedContainer, this.AreFootersStickyCache, this.AreGroupFootersStickyCache );
stickyFooters.Sort( StickyContainerGeneratedReverseComparer.Singleton );
// For each sticky headers returned, we must get the index of the last container
// that could need that container to be sticky.
foreach( StickyContainerGenerated stickyFooterInfo in stickyFooters )
{
UIElement stickyContainer = ( UIElement )stickyFooterInfo.StickyContainer;
if( newStickyFooters.ContainsContainer( stickyContainer ) )
continue;
int firstContainerIndex = customGenerator.GetFirstHoldingContainerIndexForStickyFooter( stickyContainer );
StickyContainerInfo stickyContainerInfo = new StickyContainerInfo( stickyContainer, stickyFooterInfo.Index, firstContainerIndex );
newStickyFooters.Add( stickyContainerInfo );
if( focusedElement == stickyContainer )
{
focusedElement = null;
}
this.HandleGeneratedStickyContainerPreparation( stickyFooterInfo, measureInvalidated );
}
// We only need to find the sticky footers for one
// more element than what is already sticky.
int visibleStickyFootersCount = ( int )Math.Ceiling( ( this.AnimatedScrollInfo.ViewportHeight - this.GetStickyFootersRegionHeight( newStickyFooters ) ) / m_containerHeight );
if( ( ++numberOfContainerChecked - visibleStickyFootersCount ) >= 1 )
break;
}
}
}
foreach( StickyContainerInfo stickyFooterInfo in newStickyFooters )
{
int indexOf = m_layoutedContainers.IndexOfContainer( stickyFooterInfo.Container );
if( indexOf > -1 )
{
m_layoutedContainers.RemoveAt( indexOf );
}
}
this.RecycleUnusedStickyContainers( generator, m_stickyFooters, newStickyFooters, ref focusedElement );
m_stickyFooters.Clear();
m_stickyFooters.AddRange( newStickyFooters );
m_stickyFooters.Sort( StickyContainerInfoReverseComparer.Singleton );
}
private void RecycleUnusedStickyContainers(
ICustomItemContainerGenerator generator,
StickyContainerInfoList stickyContainers,
StickyContainerInfoList stickyContainersToExclude,
ref UIElement focusedElement )
{
for( int i = stickyContainers.Count - 1; i >= 0; i-- )
{
StickyContainerInfo stickyHeaderInfo = stickyContainers[ i ];
UIElement container = stickyHeaderInfo.Container;
if( m_layoutedContainers.ContainsContainer( container ) )
continue;
if( ( stickyContainersToExclude != null ) && ( stickyContainersToExclude.ContainsContainer( container ) ) )
continue;
if( container.IsKeyboardFocusWithin )
{
Debug.Assert( ( focusedElement == null ) || ( focusedElement == container ) );
focusedElement = container;
continue;
}
int index = generator.GetRealizedIndexForContainer( container );
this.RecycleContainer( generator, index, container );
stickyContainers.RemoveAt( i );
}
}