text encoding

Question

Could you please be so kind and help me in the following situation:
I am coding a simple text editor program whichwould  convert an UTF-8 text file from one unicode range to another (for example, Devanagari into Latin). I have built a table of character correspondences but I am not sure which method to use on this table. So, the problem is to read the text opened in a child window, change it in accordance with my encoding table and open the result in the second MDI window.

I will be thankful for any advice.