public class CustomDrawDayNumberCellEventArgs :
    BaseEditCustomDrawArgs

Public Class CustomDrawDayNumberCellEventArgs
    Inherits BaseEditCustomDrawArgs

using DevExpress.XtraEditors.Calendar;

private bool IsHoliday(DateTime dt) {
   //the specified date is a Saturday or Holiday
   if(dt.DayOfWeek == DayOfWeek.Saturday || dt.DayOfWeek == DayOfWeek.Sunday) return true;
   //New Year's Day
   if(dt.Day == 1 && dt.Month == 1) return true;
   //Inauguration Day
   if(dt.Year >= 1789 && (dt.Year - 1789) % 4 == 0) {
      if(dt.Day == 20 && dt.Month == 1) return true;
   }
   //Independence Day
   if(dt.Day == 4 && dt.Month == 7) return true;
   //Veterans Day
   if(dt.Day == 11 && dt.Month == 11) return true;
   //Christmas
   if(dt.Day == 25 && dt.Month == 12) return true;
   return false;
}
private void dateEdit1_DrawItem(object sender, CustomDrawDayNumberCellEventArgs e) {
    if (e.View != DevExpress.XtraEditors.Controls.DateEditCalendarViewType.MonthInfo) return;
    //return if a given date is not a holiday
    //in this case the default drawing will be performed (e.Handled is false)
    if (!IsHoliday(e.Date)) return;
    //highlight the selected and hot-tracked dates
    bool isHotTracked = e.State == DevExpress.Utils.Drawing.ObjectState.Hot;
    if (e.Selected || isHotTracked) {
        e.Cache.FillRectangle(e.Style.GetBackBrush(e.Cache), e.Bounds);
    }
    //the brush for painting days
    Brush brush = (e.Inactive ? Brushes.LightPink : Brushes.Red);
    //specify formatting attributes for drawing text
    StringFormat strFormat = new StringFormat();
    strFormat.Alignment = StringAlignment.Center;
    strFormat.LineAlignment = StringAlignment.Center;
    //draw the day number
    e.Cache.DrawString(e.Date.Day.ToString(), e.Style.Font, brush, e.Bounds, strFormat);
    //no default drawing is required
    e.Handled = true;
}

Private Function IsHoliday(ByVal dt As DateTime) As Boolean
        'the specified date is a Saturday or Holiday
        If dt.DayOfWeek = DayOfWeek.Saturday Or dt.DayOfWeek = DayOfWeek.Sunday Then 
            Return True
        EndIf
        'New Year's Day
        If (dt.Day = 1 And dt.Month = 1) Then Return True
        'Inauguration Day
        If dt.Year >= 1789 And (dt.Year - 1789) Mod 4 = 0 Then
            If dt.Day = 20 And dt.Month = 1 Then Return True
        End If
        'Independence Day
        If dt.Day = 4 And dt.Month = 7 Then Return True
        'Veterans Day
        If dt.Day = 11 And dt.Month = 11 Then Return True
        'Christmas
        If dt.Day = 25 And dt.Month = 12 Then Return True
        Return False
End Function

Private Sub DateEdit1_DrawItem(ByVal sender As Object, _
  ByVal e As DevExpress.XtraEditors.Calendar.CustomDrawDayNumberCellEventArgs) _
  Handles DateEdit1.DrawItem
        If Not e.View = DevExpress.XtraEditors.Controls.DateEditCalendarViewType.MonthInfo Then Return
        'return if a given date is not a holiday
        'in this case the default drawing will be performed (e.Handled is false)
        If Not IsHoliday(e.Date) Then Return
        'highlight the selected and hot-tracked dates
        Dim isHotTracked As Boolean = (e.State = DevExpress.Utils.Drawing.ObjectState.Hot)
        If e.Selected Or isHotTracked Then e.Cache.FillRectangle(e.Style.GetBackBrush(e.Cache), e.Bounds)
        'the brush for painting days
        Dim brush As Brush = IIf(e.Inactive, Brushes.LightPink, Brushes.Red)
        'specify formatting attributes for drawing text
        Dim strFormat As StringFormat = New StringFormat
        strFormat.Alignment = StringAlignment.Center
        strFormat.LineAlignment = StringAlignment.Center
        'draw the day number
        e.Cache.DrawString(e.Date.Day.ToString(), e.Style.Font, brush, e.Bounds, strFormat)
        'no default drawing is required
        e.Handled = True
End Sub