Public Property IsBlank As Boolean

Dim instance As BlankConditionalFormattingRule
Dim value As Boolean
 
instance.IsBlank = value
 
value = instance.IsBlank

public bool IsBlank {get; set;}

protected void Page_Load(object sender, System.EventArgs e)
                       {
                           FpSpread1.Sheets[0].Cells[0, 0].Value = 3;
                           FpSpread1.Sheets[0].Cells[1, 0].Value = 2;
                           FpSpread1.Sheets[0].Cells[1, 1].Value = 10;
                           FpSpread1.Sheets[0].Cells[0, 2].Value = 1;    
                       }

protected void Button1_Click(object sender, EventArgs e)
        {
            //Blank and NonBlank CF
            FarPoint.Web.Spread.BlankConditionalFormattingRule blank = new FarPoint.Web.Spread.BlankConditionalFormattingRule(true);
            blank.IsBlank = true;
            blank.BackColor = Color.LimeGreen;
            FpSpread1.ActiveSheetView.SetConditionalFormatting(0, 1, blank);
            //or
            //Blank and NonBlank CF
            //FarPoint.Web.Spread.BlankConditionalFormattingRule blank = new FarPoint.Web.Spread.BlankConditionalFormattingRule(true);
            //blank.IsBlank = false;
            //blank.FontStyle = new FarPoint.Web.Spread.SpreadFontStyle(FarPoint.Web.Spread.UnderlineFontStyle.None);
            //blank.FontStyle.RegularBoldItalic = FarPoint.Web.Spread.RegularBoldItalicFontStyle.Bold;
            //blank.BackColor = Color.LimeGreen;
            //FpSpread1.ActiveSheetView.SetConditionalFormatting(0, 0, 3, 3, blank);
        }

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
            FpSpread1.Sheets(0).Cells(0, 0).Value = 3
            FpSpread1.Sheets(0).Cells(1, 0).Value = 2
            FpSpread1.Sheets(0).Cells(1, 1).Value = 10
            FpSpread1.Sheets(0).Cells(0, 2).Value = 1
        End Sub

Protected Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
            'Blank and NonBlank CF
            Dim blank As New FarPoint.Web.Spread.BlankConditionalFormattingRule(True)
            blank.IsBlank = True
            blank.BackColor = Drawing.Color.LimeGreen
            FpSpread1.ActiveSheetView.SetConditionalFormatting(0, 1, blank)
            'or
            'Blank and NonBlank CF
            'Dim blank As New FarPoint.Web.Spread.BlankConditionalFormattingRule(True)
            'blank.IsBlank = False
            'blank.FontStyle = New FarPoint.Web.Spread.SpreadFontStyle(FarPoint.Web.Spread.UnderlineFontStyle.None)
            'blank.FontStyle.RegularBoldItalic = FarPoint.Web.Spread.RegularBoldItalicFontStyle.Bold            
            'blank.BackColor = Drawing.Color.LimeGreen
            'FpSpread1.ActiveSheetView.SetConditionalFormatting(0, 0, 3, 3, blank)
        End Sub