private void GenerateContainers(
ICustomItemContainerGenerator generator,
double pageHeight,
HashSet<UIElement> layoutedContainersToRecycle,
bool measureInvalidated,
ref PageIndexes pageIndexes,
out double containersHeight )
{
int currentIndex = pageIndexes.StartIndex;
GeneratorDirection direction;
if( currentIndex == -1 )
{
currentIndex = pageIndexes.EndIndex;
Debug.Assert( currentIndex != -1 );
direction = GeneratorDirection.Backward;
}
else
{
direction = GeneratorDirection.Forward;
}
int startIndex = currentIndex;
int endIndex = currentIndex;
containersHeight = 0d;
GeneratorPosition position;
position = generator.GeneratorPositionFromIndex( currentIndex );
int itemCount = generator.ItemCount;
using( generator.StartAt( position, direction, true ) )
{
while( ( ( direction == GeneratorDirection.Forward )
? ( currentIndex < itemCount ) : ( currentIndex >= 0 ) ) && ( pageHeight > 0 ) )
{
UIElement container = this.GenerateContainer( generator, currentIndex, measureInvalidated );
if( container == null )
break;
double containerHeight = container.DesiredSize.Height;
m_layoutedContainers.Add( new LayoutedContainerInfo( currentIndex, container ) );
layoutedContainersToRecycle.Remove( container );
m_layoutedContainersToRecycle.Remove( container );
if( ( direction == GeneratorDirection.Backward ) && ( ( pageHeight - containerHeight ) < 0 ) )
{
// We do not want to recycle the container since it will cause a re-invalidation of the measure and
// may cause an infinit loop. This case has been observed with a MaxHeight set on the DataGridControl.
break;
}
pageHeight -= containerHeight;
containersHeight += containerHeight;
endIndex = currentIndex;
currentIndex += ( direction == GeneratorDirection.Forward ) ? 1 : -1;
}
}
if( pageHeight > 0 )
{
if( direction == GeneratorDirection.Forward )
{
direction = GeneratorDirection.Backward;
}
else
{
direction = GeneratorDirection.Forward;
}
DataGridContext dataGridContext = DataGridControl.GetDataGridContext( this );
if( ( direction == GeneratorDirection.Forward ) || ( ( dataGridContext == null ) || ( TableView.GetAutoFillLastPage( dataGridContext ) ) ) )
{
currentIndex = ( direction == GeneratorDirection.Forward ) ? startIndex + 1 : startIndex - 1;
if( ( direction == GeneratorDirection.Forward ) ? ( currentIndex < itemCount ) : ( currentIndex >= 0 ) )
{
position = generator.GeneratorPositionFromIndex( currentIndex );
using( generator.StartAt( position, direction, true ) )
{
// If we still have more space, try to get more container to fill up the page.
while( ( ( direction == GeneratorDirection.Forward ) ?
( currentIndex < itemCount ) : ( currentIndex >= 0 ) ) && ( pageHeight > 0 ) )
{
UIElement container = this.GenerateContainer( generator, currentIndex, measureInvalidated );
if( container == null )
break;
double containerHeight = container.DesiredSize.Height;
pageHeight -= containerHeight;
m_layoutedContainers.Add( new LayoutedContainerInfo( currentIndex, container ) );
layoutedContainersToRecycle.Remove( container );
m_layoutedContainersToRecycle.Remove( container );
if( ( direction == GeneratorDirection.Backward ) && ( pageHeight < 0 ) )
{
// We do not want to recycle the container since it will cause a re-invalidation of the measure and
// may cause an infinit loop. This case has been observed with a MaxHeight set on the DataGridControl.
break;
}
containersHeight += containerHeight;
startIndex = currentIndex;
currentIndex += ( direction == GeneratorDirection.Forward ) ? 1 : -1;
}
}
}
}
}
m_layoutedContainers.Sort();
if( startIndex > endIndex )
{
pageIndexes = new PageIndexes( endIndex, startIndex );
}
else
{
pageIndexes = new PageIndexes( startIndex, endIndex );
}
}
private void GenerateContainers(
ICustomItemContainerGenerator generator,
int pageStartIndex,
int pageEndIndex,
bool measureInvalidated,
ref UIElement focusedElement )
{
HashSet<UIElement> unusedLayoutedContainers = new HashSet<UIElement>( m_layoutedContainers.Select( item => item.Container ) );
m_layoutedContainers.Clear();
ScrollDirection scrollDirection = this.AnimatedScrollInfo.VerticalScrollingDirection;
GeneratorPosition position;
GeneratorDirection direction;
int currentIndex;
int step;
if( ( scrollDirection == ScrollDirection.Forward )
|| ( scrollDirection == ScrollDirection.None ) )
{
position = generator.GeneratorPositionFromIndex( pageStartIndex );
direction = GeneratorDirection.Forward;
currentIndex = pageStartIndex;
step = 1;
}
else
{
position = generator.GeneratorPositionFromIndex( pageEndIndex );
direction = GeneratorDirection.Backward;
currentIndex = pageEndIndex;
step = -1;
}
using( generator.StartAt( position, direction, true ) )
{
while( ( currentIndex >= pageStartIndex ) && ( currentIndex <= pageEndIndex ) )
{
UIElement container = this.GenerateContainer( generator, currentIndex, measureInvalidated, true );
if( container == null )
break;
if( focusedElement == container )
{
focusedElement = null;
}
// The container is now part of the page layout. Add it to the list.
m_layoutedContainers.Add( new LayoutedContainerInfo( currentIndex, container ) );
m_layoutedContainersToRecycle.Remove( container );
unusedLayoutedContainers.Remove( container );
currentIndex += step;
}
}
// A ScrollViewer may measure forever if the containers that are "underneath" the horizontal
// scrollbar are the ones that required the scrollbar in the first place.
if( m_lastVisiblePageIndexes != PageIndexes.Empty )
{
int remainingItemCount = ( m_lastVisiblePageIndexes.EndIndex - m_lastVisiblePageIndexes.StartIndex )
- ( pageEndIndex - pageStartIndex );
if( ( remainingItemCount > 0 ) && ( this.GetMaxDesiredWidth() < this.AnimatedScrollInfo.ExtentWidth ) )
{
int itemCount = generator.ItemCount;
if( ( currentIndex >= 0 ) && ( currentIndex < itemCount ) )
{
position = generator.GeneratorPositionFromIndex( currentIndex );
using( generator.StartAt( position, direction, true ) )
{
while( ( remainingItemCount > 0 ) && ( currentIndex >= 0 ) && ( currentIndex < itemCount ) )
{
UIElement container = this.GenerateContainer( generator, currentIndex, measureInvalidated, true );
if( container == null )
break;
if( focusedElement == container )
{
focusedElement = null;
}
// The container is now part of the page layout. Add it to the list.
m_layoutedContainers.Add( new LayoutedContainerInfo( currentIndex, container ) );
m_layoutedContainersToRecycle.Remove( container );
unusedLayoutedContainers.Remove( container );
currentIndex += step;
remainingItemCount--;
}
}
}
}
}
m_layoutedContainers.Sort();
// Recycle the containers that have not been reused in the current page.
foreach( var container in unusedLayoutedContainers )
{
// We do not recycle the focused element!
if( container.IsKeyboardFocusWithin )
{
Debug.Assert( focusedElement == null );
focusedElement = container;
}
else
{
int index = generator.GetRealizedIndexForContainer( container );
this.RecycleContainer( generator, index, container );
m_layoutedContainersToRecycle.Add( container );
}
}
}
private void GenerateContainers(
ICustomItemContainerGenerator generator,
int pageStartIndex,
int pageEndIndex,
bool measureInvalidated,
ref UIElement focusedElement )
{
ScrollDirection scrollDirection = this.AnimatedScrollInfo.VerticalScrollingDirection;
GeneratorPosition position;
GeneratorDirection direction;
if( ( scrollDirection == ScrollDirection.Forward )
|| ( scrollDirection == ScrollDirection.None ) )
{
position = generator.GeneratorPositionFromIndex( pageStartIndex );
direction = GeneratorDirection.Forward;
}
else
{
position = generator.GeneratorPositionFromIndex( pageEndIndex );
direction = GeneratorDirection.Backward;
}
using( generator.StartAt( position, direction, true ) )
{
int currentIndex = ( direction == GeneratorDirection.Forward )
? pageStartIndex
: pageEndIndex;
while( ( direction == GeneratorDirection.Forward )
? ( currentIndex <= pageEndIndex )
: ( currentIndex >= pageStartIndex ) )
{
UIElement container = this.GenerateContainer( generator, currentIndex, measureInvalidated, true );
if( container == null )
return;
if( ( focusedElement != null ) && ( focusedElement == container ) )
{
focusedElement = null;
}
// The container is now part of the page layout. Add it to the list.
m_layoutedContainers.Add( new LayoutedContainerInfo( currentIndex, container ) );
m_layoutedContainersToRecycle.Remove( container );
currentIndex += ( direction == GeneratorDirection.Forward ) ? 1 : -1;
}
}
m_layoutedContainers.Sort();
}