private void RefreshScrollTipContent(ScrollBar scrollBar)
{
const int MaxItemToVisit = 100;
DataGridContext dataGridContext = DataGridControl.GetDataGridContext(this);
if (dataGridContext == null)
{
return;
}
DataGridControl parentGridControl = dataGridContext.DataGridControl;
if (parentGridControl == null)
{
return;
}
if (scrollBar.Orientation != m_itemsScrollingOrientation)
{
return;
}
double maxOffset = 0;
if (scrollBar.Orientation == Orientation.Vertical)
{
maxOffset = parentGridControl.ScrollViewer.ExtentHeight;
}
else
{
maxOffset = parentGridControl.ScrollViewer.ExtentWidth;
}
double offset = scrollBar.Track.Value;
int itemMaxOffset = 0;
int itemOffset = 0;
if (this.IsPixelScrolling)
{
// Calculate the offset ratio to get the item from the Generator
int itemsCount = parentGridControl.CustomItemContainerGenerator.ItemCount;
itemMaxOffset = itemsCount;
if ((maxOffset > 0) && (itemsCount > 0))
{
itemOffset = ( int )(offset / (maxOffset / itemsCount));
}
else
{
itemOffset = 0;
}
}
else
{
itemMaxOffset = ( int )maxOffset;
itemOffset = ( int )offset;
}
object newValue = null;
DataGridContext itemContext = null;
// If data is grouped, we do not want to keep the next data item if a HeaderFooterItem
// is the current item returned. So we increment the scroll up to the next item in order
// to get the real item that will be visible when the user will release the mouse
ItemContextVisitor visitor = new ItemContextVisitor(parentGridControl.ItemsHost is TableflowViewItemsHost);
int endOffset = Math.Min(itemOffset + MaxItemToVisit, itemMaxOffset);
bool visitWasStopped;
(( IDataGridContextVisitable )parentGridControl.DataGridContext).AcceptVisitor(itemOffset, endOffset, visitor, DataGridContextVisitorType.Items, out visitWasStopped);
object tempValue = visitor.Item;
if (visitor.VisitSuccessful)
{
newValue = tempValue;
itemContext = visitor.ParentDataGridContext;
}
else
{
//Set the ItemContext as the ScrollTip's DataGridContext, this is to ensure the
//ScrollTip will not change the ScrollContentTemplate ( by invalidation of the binding).
itemContext = DataGridControl.GetDataGridContext(this);
newValue = null; //show nothing in the ScrollTip.
}
// The TippedItemDataGridContext PropertChanged callback will take care of refreshing the ScrollTip CellContentTemplate.
if (itemContext != DataGridControl.GetDataGridContext(this))
{
DataGridControl.SetDataGridContext(this, itemContext);
}
if (this.Content != newValue)
{
this.Content = newValue;
}
}
private void RefreshScrollTipContent( ScrollBar scrollBar )
{
const int MaxItemToVisit = 100;
DataGridContext dataGridContext = DataGridControl.GetDataGridContext( this );
if( dataGridContext == null )
return;
DataGridControl parentGridControl = dataGridContext.DataGridControl;
if( parentGridControl == null )
return;
if( scrollBar.Orientation != m_itemsScrollingOrientation )
return;
double maxOffset = 0;
if( scrollBar.Orientation == Orientation.Vertical )
{
maxOffset = parentGridControl.ScrollViewer.ExtentHeight;
}
else
{
maxOffset = parentGridControl.ScrollViewer.ExtentWidth;
}
double offset = scrollBar.Track.Value;
int itemMaxOffset = 0;
int itemOffset = 0;
if( this.IsPixelScrolling )
{
// Calculate the offset ratio to get the item from the Generator
int itemsCount = parentGridControl.CustomItemContainerGenerator.ItemCount;
itemMaxOffset = itemsCount;
if( ( maxOffset > 0 ) && ( itemsCount > 0 ) )
{
itemOffset = ( int )( offset / ( maxOffset / itemsCount ) );
}
else
{
itemOffset = 0;
}
}
else
{
itemMaxOffset = ( int )maxOffset;
itemOffset = ( int )offset;
}
object newValue = null;
DataGridContext itemContext = null;
// If data is grouped, we do not want to keep the next data item if a HeaderFooterItem
// is the current item returned. So we increment the scroll up to the next item in order
// to get the real item that will be visible when the user will release the mouse
ItemContextVisitor visitor = new ItemContextVisitor( parentGridControl.ItemsHost is TableflowViewItemsHost );
int endOffset = Math.Min( itemOffset + MaxItemToVisit, itemMaxOffset );
bool visitWasStopped;
( ( IDataGridContextVisitable )parentGridControl.DataGridContext ).AcceptVisitor( itemOffset, endOffset, visitor, DataGridContextVisitorType.Items, out visitWasStopped );
object tempValue = visitor.Item;
if( visitor.VisitSuccessful )
{
newValue = tempValue;
itemContext = visitor.ParentDataGridContext;
}
else
{
//Set the ItemContext as the ScrollTip's DataGridContext, this is to ensure the
//ScrollTip will not change the ScrollContentTemplate ( by invalidation of the binding).
itemContext = DataGridControl.GetDataGridContext( this );
newValue = null; //show nothing in the ScrollTip.
}
// The TippedItemDataGridContext PropertChanged callback will take care of refreshing the ScrollTip CellContentTemplate.
if( itemContext != DataGridControl.GetDataGridContext( this ) )
DataGridControl.SetDataGridContext( this, itemContext );
if( this.Content != newValue )
this.Content = newValue;
}