Hi Mike,

Thanks for writing back.  The exception stack trace is included below.

The property is being accessed via a timer on the same thread as the UltraGrid (the main UI thread).  The exception causes my application to unexpectedly crash which is unfortunate as it can never be handled in my code.  Any thoughts?

Thanks, Steve

Exception details: Message=Index was outside the bounds of the array., StackTrace=   

   at Infragistics.Shared.SparseArray.GetItemAtScrollIndex(Int32 scrollIndex, ICreateItemCallback createItemCallback)
   at Infragistics.Win.UltraWinGrid.ScrollCountManagerSparseArray.GetItemAtScrollIndex(Int32 scrollIndex, Boolean allocate)
   at Infragistics.Win.UltraWinGrid.RowsCollection.GetRowAtScrollIndex(Int32 scrollIndex, Boolean allocate)
   at Infragistics.Win.UltraWinGrid.RowsCollection.GetRowAtScrollIndex(Int32 scrollIndex)
   at Infragistics.Win.UltraWinGrid.UltraGridLayout.GetRowAtScrollPos(Int32 pos)
   at Infragistics.Win.UltraWinGrid.ViewStyleBase.CreateRowsList_FixedRowsFeature(VisibleRowFetchRowContext& context, VisibleRow parentVisibleRow, UltraGridRow firstSibling)
   at Infragistics.Win.UltraWinGrid.ViewStyleBase.RecreateRowList(RowScrollRegion rsr)
   at Infragistics.Win.UltraWinGrid.RowScrollRegion.GetMaxScrollPosition(Boolean scrollToFill)
   at Infragistics.Win.UltraWinGrid.RowScrollRegion.EnsureScrollRegionFilled(Boolean calledFromRegenerateVisibleRows)
   at Infragistics.Win.UltraWinGrid.RowScrollRegion.RegenerateVisibleRows(Boolean resetScrollInfo)
   at Infragistics.Win.UltraWinGrid.RowScrollRegion.WillScrollbarBeShown(ScrollbarVisibility assumeColScrollbarsVisible)
   at Infragistics.Win.UltraWinGrid.RowScrollRegion.PositionScrollbar(Boolean resetScrollInfo)
   at Infragistics.Win.UltraWinGrid.ScrollRegionBase.SetOriginAndExtent(Int32 origin, Int32 extent)
   at Infragistics.Win.UltraWinGrid.RowScrollRegion.SetOriginAndExtent(Int32 origin, Int32 extent)
   at Infragistics.Win.UltraWinGrid.DataAreaUIElement.ResizeRowScrollRegions()
   at Infragistics.Win.UltraWinGrid.DataAreaUIElement.PositionChildElements()
   at Infragistics.Win.UIElement.VerifyChildElements(ControlUIElementBase controlElement, Boolean recursive)
   at Infragistics.Win.UltraWinGrid.DataAreaUIElement.VerifyChildElements(ControlUIElementBase controlElement, Boolean recursive)
   at Infragistics.Win.UltraWinGrid.DataAreaUIElement.set_Rect(Rectangle value)
   at Infragistics.Win.UltraWinGrid.UltraGridUIElement.PositionChildElements()
   at Infragistics.Win.UIElement.VerifyChildElements(ControlUIElementBase controlElement, Boolean recursive)
   at Infragistics.Win.UltraWinGrid.UltraGridUIElement.VerifyChildElements(ControlUIElementBase controlElement, Boolean recursive)
   at Infragistics.Win.UIElement.DrawHelper(Graphics graphics, Rectangle invalidRectangle, Boolean doubleBuffer, AlphaBlendMode alphaBlendMode, Boolean clipText, Boolean forceDrawAsFocused, Boolean preventAlphaBlendGraphics)
   at Infragistics.Win.UIElement.Draw(Graphics graphics, Rectangle invalidRectangle, Boolean doubleBuffer, AlphaBlendMode alphaBlendMode, Boolean forceDrawAsFocused, Boolean preventAlphaBlendGraphics)
   at Infragistics.Win.ControlUIElementBase.Draw(Graphics graphics, Rectangle invalidRectangle, Boolean doubleBuffer, AlphaBlendMode alphaBlendMode, Size elementSize, Boolean preventAlphaBlendGraphics)
   at Infragistics.Win.ControlUIElementBase.Draw(Graphics graphics, Rectangle invalidRectangle, Boolean doubleBuffer, AlphaBlendMode alphaBlendMode, Size elementSize)
   at Infragistics.Win.ControlUIElementBase.Draw(Graphics graphics, Rectangle invalidRectangle, Boolean doubleBuffer, AlphaBlendMode alphaBlendMode)
   at Infragistics.Win.UltraWinGrid.UltraGridUIElement.Draw(Graphics graphics, Rectangle invalidRectangle, Boolean doubleBuffer, AlphaBlendMode alphaBlendMode)
   at Infragistics.Win.UltraControlBase.OnPaint(PaintEventArgs pe)
   at Infragistics.Win.UltraWinGrid.UltraGrid.OnPaint(PaintEventArgs pe)
   at System.Windows.Forms.Control.PaintWithErrorHandling(PaintEventArgs e, Int16 layer, Boolean disposeEventArgs)
   at System.Windows.Forms.Control.WmPaint(Message& m)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam).

 Hi Steve,

Well, that's a pretty clear indication that this is a threading issue. You say you are updaing the data source in a thread-safe manner. If you are updating the grid's data source on a thread other than the UI thread, then that's not safe under any circumstances because the data source may fire events that the grid is responding to on another thread. You must always suspend the notifications.

Hi Mike,

The method you provided works well, but I am still seeing the same exception.  I did notice one thing, though.  We have multiple threads updating the underlying datasource in a thread-safe manner.  Each update to the datasource conditionally calls SuspendBindingNotifications depending on the number of updates being done (let's say, more than 10).  If I remove that condition, and always suspend the binding notifications, I do not run into any unexpected exceptions with the stacktrace above.  When I include the condition to not suspend the binding notifications, I am able to reproduce the error after waiting an undeterministic amount of time.  The downside to always suspending the binding notifications is that the overall performance seems slower.

I know this is a rather vague description of the symptoms, but just throwing it out there.

Thanks for your help,

Steve

If you are concerned about getting the best possible efficiency, then you can use the UIElements of the grid directly. Here's some code that uses the UIElements to get the rows in the visible area. This code is assuming that there is only one ScrollRegion in the grid and that thereare no GroupByRows. 

private List<UltraGridRow> GetVisibleRows(UltraGrid grid)
        {
            List<UltraGridRow> rows = new List<UltraGridRow>();

            UIElement element = this.ultraGrid1.DisplayLayout.UIElement;
            if (element != null)
            {
                element = element.GetDescendant(typeof(DataAreaUIElement));
                if (element != null)
                {
                    element = element.GetDescendant(typeof(RowColRegionIntersectionUIElement));
                    if (element != null)
                    {
                        foreach (UIElement childElement in element.ChildElements)
                        {
                            if (childElement is RowUIElement)
                            {
                                UltraGridRow row = childElement.GetContext() as UltraGridRow;
                                if (row != null)
                                    rows.Add(row);
                            }
                        }
                    }
                }
            }

            return rows;
        }

Hi Mike, 

The timer is a Windwos.Forms.Timer.

In the body of the timer, I try to iterate through the VisibleRows collection of the ActiveRowScrollRegion.  Based on the time, we fade the color of the some of the cells in the row.  So, each iteration either calls ultraGridRow.Cells["column1"].Refresh() or sets ultraGridRow.Cells["column2"].ForeColor.  Is there a better approach to force a repaint of the cells? 

Unfortunately, I can't reproduce this reliably.  I have to run performance testing tool that creates a large amount of updates to the client application.

I am also running v7.2 of the toolset.  Do you think v7.3 would give me better results?

Thanks!

Steve