集保罕字 Big5 轉 Unicode

TdccBig5.cs

using System;
using System.IO;
using System.Text;
using System.Collections.Generic;
using System.Text.RegularExpressions;
using System.Globalization;

namespace TdccBig5
{
    public static class TdccBig5ToUnicode
    {
        // https://www.tdcc.com.tw/portal/zh/download/downloadArea?offset=&title=&subTitle=&parent=402897956c6bbcd6016c6bbd6bee0261&subCategory=0081f82f6c4b1d8f016c4b221a3a0002&keywords=
        // 罕用字型及對照檔
        private readonly static Dictionary<string, string> _mapping = new Dictionary<string, string>()
        {
            // big5 code, unicode codepoint, string, pinyin
	    // ...
            { "994B", "05553" }, // 啓 #### ㄑㄧˇ
	    // ...
        };

        public static string Transform(string tdccString)
        {
            Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
            // big5 custom fonts blocks
            // FA40-FEFE ＋ 8E40-A0FE ＋ 8140-8DFE
            int range1Begin = Convert.ToInt32(0xFA40);
            int range1End = Convert.ToInt32(0xFEFE);
            int range2Begin = Convert.ToInt32(0x8E40);
            int range2End = Convert.ToInt32(0xA0FE);
            int range3Begin = Convert.ToInt32(0x8140);
            int range3End = Convert.ToInt32(0x8DFE);
            try
            {
                string unicodeString = "";
                for (int i = 0; i < tdccString.Length; i++)
                {
                    string word = tdccString.Substring(i, 1);
                    byte[] big5Bytes = Encoding.GetEncoding("BIG5").GetBytes(word);
                    if (BitConverter.IsLittleEndian)
                    {
                        Array.Reverse(big5Bytes);
                    }
                    int value = BitConverter.ToUInt16(big5Bytes, 0);
                    if (
                        (value >= range1Begin && value <= range1End) ||
                        (value >= range2Begin && value <= range2End) ||
                        (value >= range3Begin && value <= range3End))
                    {
                        string key = value.ToString("X");
                        if (TdccBig5ToUnicode._mapping.ContainsKey(key))
                        {
                            int codepoint = int.Parse(TdccBig5ToUnicode._mapping[key], NumberStyles.HexNumber);
                            unicodeString += Char.ConvertFromUtf32(codepoint);
                        }
                        else {
                            unicodeString += word;
                        }
                    }
                    else
                    {
                        unicodeString += word;
                    }
                }
                return unicodeString;
            }
            catch (Exception ex)
            {
                // fallback
                return tdccString;
            }
        }

    }
}