The NullReference exception occurs when the LayoutChanged method is called

Hello Ruud,

Despite the fact that these issues have similar call stacks, each time they occur under different circumstances. That is why we extract such issues in separate threads. I would like to note, that we inspected our code for possible weak points, but all the information provided in these tickets indicate that the issue occurs because of accessing UI controls from non-UI threads. Since none of our customers can provide us with a compilable sample illustrating the problematic behavior, we are unable to give a precise answer why this occurs and modify our source codes correspondingly.

Hi Support team,

I was going to raise a ticket for the same issue until i found this ticket already opened by Steven (feel free if you want me to raise a ticket instead of commenting this).

We are using the "BeginInvoke" and this issue still happens to us in our product, we are using a common method that takes a Control and a string as parameters, then sets the Control.Text = string, here's the method:

internal void SetDisplayText(Control control, string text)
{
try
{
if (control == null)
return;

if (!control.IsHandleCreated)
return;

if (this.InvokeRequired || control.InvokeRequired)
{
BeginInvoke(new UIMarshallingThreadDelegates.ParameterLessTaskDelegate(
delegate
{
control.Text = text;
}));
}
else
{
control.Text = text;
}
}
catch (Exception exception)
{
ServiceLocator.LoggerService.Error("TopOfBook.SetDisplayText => error : " + exception);
}
}

The method above can be called from several threads.

Here's the exception callStack:

2020-05-04 14:27:45:832, P:29220, TH:62308, [Error,Error,4] : TopOfBook.SetDisplayText => error : System.NullReferenceException: Object reference not set to an instance of an object.
at DevExpress.Utils.Text.FontsCache.GetFontCacheByFont(Graphics graphics, Font font)
at DevExpress.Utils.Text.TextUtils.GetStringSize(Graphics g, String text, Font font, StringFormat stringFormat, Int32 maxWidth, Int32 maxHeight, IWordBreakProvider wordBreakProvider, Boolean& isCropped)
at DevExpress.Utils.Paint.XPaintMixed.CalcTextSize(Graphics g, String s, Font font, StringFormat strFormat, Int32 maxWidth, Int32 maxHeight, Boolean& isCropped)
at DevExpress.Utils.Paint.XPaintMixed.CalcTextSize(Graphics g, String s, Font font, StringFormat strFormat, Int32 maxWidth)
at DevExpress.Utils.AppearanceObject.CalcTextSize(GraphicsCache cache, StringFormat sf, String s, Int32 width)
at DevExpress.XtraEditors.ViewInfo.LabelControlViewInfo.CalcSimpleTextSize(String Text, Boolean useHotkeyPrefix, LabelAutoSizeMode mode, Int32 predWidth, Int32 predHeight)
at DevExpress.XtraEditors.ViewInfo.LabelControlViewInfo.CalcTextSize(String Text, Boolean useHotkeyPrefix, LabelAutoSizeMode mode, Int32 predWidth, Int32 predHeight)
at DevExpress.XtraEditors.ViewInfo.LabelControlViewInfo.CalcTextSize(String Text, Boolean useHotkeyPrefix, LabelAutoSizeMode mode)
at DevExpress.XtraEditors.ViewInfo.LabelControlViewInfo.CalcTextSize(Boolean useHotkeyPrefix)
at DevExpress.XtraEditors.ViewInfo.LabelControlViewInfo.CalcTextPoints()
at DevExpress.XtraEditors.ViewInfo.LabelControlViewInfo.CalcContentRect(Rectangle bounds)
at DevExpress.XtraEditors.ViewInfo.BaseControlViewInfo.CalcRects()
at DevExpress.XtraEditors.ViewInfo.BaseControlViewInfo.CalcViewInfo(Graphics g)
at DevExpress.XtraEditors.LabelControl.LayoutChanged(Boolean isVisualUpdate)
at DevExpress.XtraEditors.LabelControl.OnTextChanged(EventArgs e)
at System.Windows.Forms.Control.set_Text(String value)
at Com.QuodFinancial.FrontEnd.Gui.Mvp.Views.ForEx.InstrumentSummary.InstrumentSummaryTopOfBook.SetDisplayText(Control control, String text)

The exception is very rare to happen, but in the context we are working at, this should never happen as we can miss big opportunities.
We are using DevExpress 18.2.5.

Thank you,
Chams

Hello,

I've created a separate ticket on your behalf (T888808: NullReferenceException is thrown in the GetFontCacheByFont method). It has been placed in our processing queue and will be answered shortly.