I know how to create Custom Fields in a DataSet for a Report in DecExpress XtraReports. But I need to Declare a Custom Function in available function list for Calculated Fields. I do not know how to solve this problem.
source type : Date
result : Date String In other Calendar Formats
source type : TinyInt (Enumeration)
result : Custom Enumeration Value Name
As per Q232469 and S132091 it isn't supported without using Scripts. However in saying that the Expression Editor does allow for Custom Functions as per Implementing Custom Functions I would look at this sample How to: Implement a Custom Criteria Language Operator and see if it does what you need.
Otherwise the suggestion is to add a Calculated Field then in your Script override the returned value of that Calculated Field see Calculated Fields
Hope this helps