private PageIndexes CalculateVisibleIndexesForDesiredLastVisibleIndex( int desiredLastVisibleIndex )
{
PageIndexes layoutedIndexes = new PageIndexes();
int stickyFooterCountForLastVisibleIndex = this.GetStickyFooterCountForIndex( desiredLastVisibleIndex );
layoutedIndexes.EndIndex = desiredLastVisibleIndex + stickyFooterCountForLastVisibleIndex;
int minVisibleIndex = layoutedIndexes.EndIndex
- this.CalculateFlooredPageItemCount( this.AnimatedScrollInfo.ViewportHeight );
layoutedIndexes.StartIndex = minVisibleIndex;
// Process indexes from bottom to top up to an index for which
// the number of required sticky headers will force a visible index
// larger than the maximal acceptable last visible index
for( int i = desiredLastVisibleIndex - 1; i >= minVisibleIndex; i-- )
{
int stickyHeaderCountForIndex = this.GetStickyHeaderCountForIndex( i );
// If the index of the container - its sticky header count
// is less than the minimal acceptable visible index, we ensure
// the next container index as the minimal one to set as current
if( minVisibleIndex > ( i - stickyHeaderCountForIndex ) )
{
layoutedIndexes.StartIndex = i + 1;
break;
}
}
return layoutedIndexes;
}
private void CalculateLayoutedIndexes( double verticalOffset, double viewportHeight, out PageIndexes layoutedIndexes )
{
layoutedIndexes = new PageIndexes();
int itemCount = this.CustomItemContainerGenerator.ItemCount;
if( itemCount > 0 )
{
layoutedIndexes.StartIndex = Math.Min(
this.GetContainerIndexFromOffset( verticalOffset, false ),
itemCount - 1 );
layoutedIndexes.EndIndex = Math.Min(
this.GetContainerIndexFromOffset( verticalOffset + viewportHeight - m_containerHeight, true ),
itemCount - 1 );
layoutedIndexes.EndIndex = Math.Max(
layoutedIndexes.StartIndex,
layoutedIndexes.EndIndex );
}
}
private PageIndexes CalculateVisibleIndexesForDesiredFirstVisibleIndex( int desiredFirstVisibleIndex )
{
PageIndexes layoutedIndexes = new PageIndexes();
// Get the sticky header count for the desiredFirstVisibleIndex
// and set the StartIndex
int stickyHeaderCountForFirstVisibleIndex = this.GetStickyHeaderCountForIndex( desiredFirstVisibleIndex );
layoutedIndexes.StartIndex = desiredFirstVisibleIndex - stickyHeaderCountForFirstVisibleIndex;
// Get the index of the maximal visible index according
// to the number of container the viewport can display
// and the number of sticky header the desiredFirstVisibleIndex
// must display
int maxLastVisibleIndex = layoutedIndexes.StartIndex
+ this.CalculateFlooredPageItemCount( this.AnimatedScrollInfo.ViewportHeight );
layoutedIndexes.EndIndex = maxLastVisibleIndex;
// Process indexes from top to bottom up to an index for which
// the number of required sticky footers will force a visible index
// larger than the maximal acceptable last visible index
for( int i = desiredFirstVisibleIndex + 1; i <= maxLastVisibleIndex; i++ )
{
int stickyFooterCountForIndex = this.GetStickyFooterCountForIndex( i );
// The index of the container + its sticky footer count
// is greater than the last acceptable visible index, we ensure
// the previous container as the maximal one to set as current
if( maxLastVisibleIndex < ( i + stickyFooterCountForIndex ) )
{
layoutedIndexes.EndIndex = i - 1;
break;
}
}
return layoutedIndexes;
}
private void GeneratePageAndUpdateIScrollInfoValues(
Size availableSize,
bool measureInvalidated,
ref double viewportHeight )
{
PageIndexes generatedPage;
// We must ensure the VerticalOffset is valid according
// to the actual viewport height in case the VerticalOffset
// is greater than the new viewportHeight.
IScrollInfo scrollInfo = this as IScrollInfo;
double maxOffset = Math.Max( 0d, scrollInfo.ExtentHeight - 1 );
double offset = Math.Max( Math.Min( m_verticalOffset, maxOffset ), 0d );
if( offset != m_verticalOffset )
this.SetVerticalOffsetCore( offset );
int verticalOffset = ( int )m_verticalOffset;
if( m_indexToBringIntoView != -1 )
{
int intOffset = Math.Min( m_indexToBringIntoView, ( int )maxOffset );
if( intOffset < m_lastLayoutedPage.StartIndex )
{
generatedPage = new PageIndexes( intOffset, -1 );
}
else
{
generatedPage = new PageIndexes( -1, intOffset );
}
}
else
{
generatedPage = new PageIndexes( verticalOffset, -1 );
}
// CALCULATE THE VIEWPORT HEIGHT AND GENERATE CONTAINERS
this.GeneratePage( availableSize.Height, measureInvalidated, ref generatedPage, out viewportHeight );
// CALCULATE THE EXTENT WIDTH
m_extentWidth = Math.Max( this.GetMaxDesiredWidth(), this.GetSynchronizedExtentWidth() );
// CALCULATE THE VIEWPORT WIDTH
m_viewportWidth = Double.IsInfinity( availableSize.Width )
? m_extentWidth : Math.Min( m_extentWidth, availableSize.Width );
this.SetVerticalOffsetCore( generatedPage.StartIndex );
this.InvalidateScrollInfo();
}
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 GeneratePage(
double availableHeight,
bool measureInvalidated,
ref PageIndexes generatedPage,
out double containersHeight )
{
containersHeight = 0d;
ICustomItemContainerGenerator generator = this.CustomItemContainerGenerator;
// The generator can be null if we're in design mode.
if( generator == null )
return;
// Make sure that container recycling is currently enabled on the generator.
generator.IsRecyclingEnabled = true;
bool pageChanged =
( generatedPage.StartIndex != m_lastGeneratedPage.StartIndex )
|| ( m_lastGeneratedPageViewPortHeight != availableHeight );
if( ( pageChanged ) || ( measureInvalidated ) )
{
UIElement focusedContainer = DataGridItemsHost.GetItemsHostContainerFromElement( this, Keyboard.FocusedElement as DependencyObject );
HashSet<UIElement> layoutedContainersToRecycle = new HashSet<UIElement>();
int newPageLengthApproximation = Math.Max( 1, m_lastGeneratedPage.Length );
foreach( LayoutedContainerInfo containerInfo in m_layoutedContainers )
{
int realizedIndex = containerInfo.RealizedIndex;
UIElement container = containerInfo.Container;
bool waitForRecycle = ( ( generatedPage.StartIndex != -1 ) && ( realizedIndex >= generatedPage.StartIndex ) && ( realizedIndex <= generatedPage.StartIndex + newPageLengthApproximation ) )
|| ( ( generatedPage.EndIndex != -1 ) && ( realizedIndex >= generatedPage.EndIndex - newPageLengthApproximation ) && ( realizedIndex <= generatedPage.EndIndex ) );
// Mark the container has a candidate for recycling.
if( ( waitForRecycle ) || ( container == focusedContainer ) )
{
layoutedContainersToRecycle.Add( container );
}
// The element will probably not be on the generated page. Recycle its container immediatly
// to minimize the number of new containers created.
else
{
this.TrySafeRecycleContainer( generator, realizedIndex, container );
m_layoutedContainersToRecycle.Add( container );
}
}
m_layoutedContainers.Clear();
this.GenerateContainers( generator, availableHeight, layoutedContainersToRecycle, measureInvalidated, ref generatedPage, out containersHeight );
// We do not recycle the focused element!
if( layoutedContainersToRecycle.Contains( focusedContainer ) )
{
layoutedContainersToRecycle.Remove( focusedContainer );
m_layoutedContainersToRecycle.Remove( focusedContainer );
m_layoutedContainers.Add( new LayoutedContainerInfo( generator.GetRealizedIndexForContainer( focusedContainer ), focusedContainer ) );
}
// Recycle the containers for the current page.
this.RecycleContainers( layoutedContainersToRecycle, generator );
foreach( UIElement container in layoutedContainersToRecycle )
{
m_layoutedContainersToRecycle.Add( container );
}
m_lastGeneratedPage = generatedPage;
m_lastGeneratedPageViewPortHeight = availableHeight;
m_lastGeneratedPageContainersHeight = containersHeight;
}
else
{
generatedPage = m_lastGeneratedPage;
containersHeight = m_lastGeneratedPageContainersHeight;
}
}
protected override void HandlePageDownKey( KeyEventArgs e )
{
if( e.Handled )
return;
e.Handled = true;
DataGridControl dataGridControl = this.ParentDataGridControl;
NavigationBehavior navigationBehavior = dataGridControl.NavigationBehavior;
bool changeCurrentColumn = ( navigationBehavior == NavigationBehavior.CellOnly );
// CTRL + PageDown
if( ( e.KeyboardDevice.Modifiers & ModifierKeys.Control ) == ModifierKeys.Control )
{
// Simply scroll to bottom and set last index as current
this.ScrollInfo.ScrollOwner.ScrollToBottom();
this.SetCurrent( this.CustomItemContainerGenerator.ItemCount - 1, changeCurrentColumn );
return;
}
UIElement focusedContainer = DataGridItemsHost.GetItemsHostContainerFromElement( this, Keyboard.FocusedElement as DependencyObject );
// No focused container or no navigation allowed
if( ( focusedContainer == null ) || ( navigationBehavior == NavigationBehavior.None ) )
{
// We just need to scroll one page down.
this.ScrollInfo.ScrollOwner.PageDown();
return;
}
int generatorItemCount = this.CustomItemContainerGenerator.ItemCount;
int focusedContainerRealizedIndex = this.CustomItemContainerGenerator.GetRealizedIndexForContainer( focusedContainer );
int maxIndex = generatorItemCount - 1;
if( focusedContainerRealizedIndex == maxIndex )
{
this.MoveFocus( new TraversalRequest( FocusNavigationDirection.Down ) );
}
else
{
this.InvalidateMeasure();
double containersHeight;
PageIndexes generatedPage = new PageIndexes( focusedContainerRealizedIndex, -1 );
this.GeneratePage( this.RenderSize.Height, false, ref generatedPage, out containersHeight );
this.SetVerticalOffsetCore( generatedPage.StartIndex );
int initialDesiredIndex;
// Last row not totally visible, take the one before the last
if( ( containersHeight > this.RenderSize.Height ) && ( generatedPage.Length > 1 ) )
{
initialDesiredIndex = generatedPage.EndIndex - 1;
}
else
{
initialDesiredIndex = generatedPage.EndIndex;
}
if( focusedContainerRealizedIndex != initialDesiredIndex )
{
int desiredPageDownIndex = initialDesiredIndex;
bool isDataRow = false;
// SetCurrent on the index or up to focusedContainerRealizedIndex to a focusable index
while( ( !dataGridControl.HasValidationError )
&& ( !isDataRow )
&& ( desiredPageDownIndex > focusedContainerRealizedIndex ) )
{
if( this.SetCurrent( desiredPageDownIndex, changeCurrentColumn, out isDataRow ) )
return;
desiredPageDownIndex--;
}
if( ( dataGridControl.HasValidationError ) || ( isDataRow ) )
return;
//Debug.Assert( false, "When this will occur???" );
desiredPageDownIndex = initialDesiredIndex + 1;
isDataRow = false;
// No container were focused while processing indexes from focused to
// initialDesiredIndex, try SetCurrent on indexes higher than
// the initial down to maxIndex
while( ( !dataGridControl.HasValidationError )
&& ( !isDataRow )
&& ( desiredPageDownIndex <= maxIndex ) )
{
if( this.SetCurrent( desiredPageDownIndex, changeCurrentColumn, out isDataRow ) )
return;
desiredPageDownIndex++;
}
}
}
}
protected override void HandlePageUpKey( KeyEventArgs e )
{
if( e.Handled )
return;
e.Handled = true;
DataGridControl dataGridControl = this.ParentDataGridControl;
NavigationBehavior navigationBehavior = dataGridControl.NavigationBehavior;
bool changeCurrentColumn = ( navigationBehavior == NavigationBehavior.CellOnly );
if( ( e.KeyboardDevice.Modifiers & ModifierKeys.Control ) == ModifierKeys.Control )
{
// Simply scroll to top and set first index as current
this.ScrollInfo.ScrollOwner.ScrollToTop();
this.SetCurrent( 0, changeCurrentColumn );
return;
}
UIElement focusedContainer = DataGridItemsHost.GetItemsHostContainerFromElement( this, Keyboard.FocusedElement as DependencyObject );
if( ( focusedContainer == null ) || ( navigationBehavior == NavigationBehavior.None ) )
{
// We just need to scroll one page up.
this.ScrollInfo.ScrollOwner.PageUp();
return;
}
int focusedContainerRealizedIndex = this.CustomItemContainerGenerator.GetRealizedIndexForContainer( focusedContainer );
if( focusedContainerRealizedIndex == 0 )
{
this.MoveFocus( new TraversalRequest( FocusNavigationDirection.Up ) );
}
else
{
this.InvalidateMeasure();
double containersHeight;
PageIndexes generatedPage = new PageIndexes( -1, focusedContainerRealizedIndex );
this.GeneratePage( this.RenderSize.Height, false, ref generatedPage, out containersHeight );
this.SetVerticalOffsetCore( generatedPage.StartIndex );
int initialDesiredIndex = generatedPage.StartIndex;
if( focusedContainerRealizedIndex != initialDesiredIndex )
{
int desiredPageUpIndex = initialDesiredIndex;
bool isDataRow = false;
// SetCurrent on the index or down to a focusable index
while( ( !dataGridControl.HasValidationError )
&& ( !isDataRow )
&& ( desiredPageUpIndex < focusedContainerRealizedIndex ) )
{
if( this.SetCurrent( desiredPageUpIndex, changeCurrentColumn, out isDataRow ) )
return;
desiredPageUpIndex++;
}
if( ( dataGridControl.HasValidationError ) || ( isDataRow ) )
return;
// No container were focused while processing indexes from focused to
// initialDesiredIndex, try SetCurrent on indexes lower than
// the initial up to 0
desiredPageUpIndex = initialDesiredIndex - 1;
isDataRow = false;
while( ( !dataGridControl.HasValidationError )
&& ( !isDataRow )
&& ( desiredPageUpIndex > 0 ) )
{
if( this.SetCurrent( desiredPageUpIndex, changeCurrentColumn, out isDataRow ) )
return;
desiredPageUpIndex--;
}
}
}
}
