Supplementary Character Support in Microsoft Products Michael S. Kaplan Software Design Engineer Microsoft

12 September 2002San Jose, California (IUC22) What are supplementary characters? " a coded character representation for a single abstract character that consists of a sequence of two code units, where the first unit of the pair is a high surrogate and the second is a low surrogate "

12 September 2002San Jose, California (IUC22) High/low surrogate? High: U+D800 - U+DBFF Low: U+DC00 - U+DFFF Terminology: – "surrogate pair" preferred over "surrogate character“ See 16to32AndBack.asp

12 September 2002San Jose, California (IUC22) Conversion example #1 Example #1: – The first character in the Surrogate range (D800, DC00) as UTF-32: 1. D800: binary (lower ten bits: ) 2.DC00: binary (lower ten bits: ) 3.Concatenate = x Add x10000 Result: U This makes sense, since the first character in the Surrogate range follows immediately after the last character in the 16-bit Unicode range (U+FFFF)

12 September 2002San Jose, California (IUC22) Conversion example #2 Example #2. – You have a Unicode character such as U+2040A (a CJK character in Plane 2) and wish to encode it in UTF-16 1.Subtract x Result: 1040A 2.Split into two ten-bit pieces: Add (D800) to the high 10 bits piece ( ) - Result: (D841) 4.Add (DC00) to the low 10 bits piece ( ) - Result: (DC0A) Your surrogate pair: D841, DC0A

12 September 2002San Jose, California (IUC22) UTF-8 conversions Illegal conversions: six-byte UTF-8 (two surrogate code points of UTF-16, converted separately) legal conversions: four-byte UTF-8 (one UTF-32 code point) CESU-8 is the the inverse of the above

12 September 2002San Jose, California (IUC22) UTF-8 example Unicode surrogate pair: aaaabbbbbbcccccc, zzzzyyyyyyxxxxxx becomes incorrect UTF-8 total 6 bytes: 1110aaaa 10bbbbbb 10cccccc 1110zzzz 10yyyyyy 10xxxxxx Instead, you should take a Unicode surrogate pair: wwwwzzzzyy, yyyyxxxxxx and convert it to UTF-8 totaling 4 bytes (below, uuuuu is defined as = wwww+1): 11110uuu 10uuzzzz 10yyyyyy 10xxxxxx

12 September 2002San Jose, California (IUC22) Encoding choices for MS UTF-16, mostly Occasionally UTF-8 Even more occasionally, UTF-32 REASONS: There was obviously an existing, well-tested set of APIs that support UCS-2, which is a subset of UTF-16. A completely new API set was not required. A move to UTF-32 would require twice as much space for all characters. A move to UTF-8 would require even more than twice as much space in many cases.

12 September 2002San Jose, California (IUC22) The products... Mostly the new generation of products: – Windows 2000/XP – Office XP (some support in Office 2000) – Visual Studio.Net Most (all) of these products supported Unicode already – a little bit of extra work needed for supplementary characters – usually just UTF-8 changes were needed

12 September 2002San Jose, California (IUC22) Windows 2000 Uniscribe support for rendering Each surrogate pair is a single grapheme APIs like CharPrev/CharNext not changed No specific surrogate font/IME Must be turned on:

12 September 2002San Jose, California (IUC22) Windows XP *.* from Windows 2000 Turned on by default! GDI+ support for rendering Font CMAP extensions Lots of UTF-8 issues fixed No specific surrogate font/IME (yet) Extensions to fallback fonts [limited]: HKLM\Software\Microsoft\Windows NT\CurrentVersion\LanguagePack\SurrogateFallback\Plane1 HKLM\Software\Microsoft\Windows NT\CurrentVersion\LanguagePack\SurrogateFallback\Plane2 HKLM\Software\Microsoft\Windows NT\CurrentVersion\LanguagePack\SurrogateFallback\Plane3 (etc.)

12 September 2002San Jose, California (IUC22) Other system components MLang Internet Explorer IIS 5.0/6.0

12 September 2002San Jose, California (IUC22) The downlevel story No good support for Unicode, let along supplementary characters Uniscribe/RichEdit does improve the downlevel story for display purposes Officially, no support on Win9x

12 September 2002San Jose, California (IUC22) The Office suite Word Frontpage Excel/Access Outlook RichEdit 4.0

12 September 2002San Jose, California (IUC22) Office - Specific Features Insertion/Deletion of text - All Cursor movement - All Font linking/fallback - All (Word's is best) UTF-8 issues fixed - All Enhanced word breaking - All (Word/RichEdit) Vertical text - Word/PowerPoint/Publisher/RichEdit Direct entry (Alt+nnnnnn, hhhhh + Alt+x) - Word/RichEdit

12 September 2002San Jose, California (IUC22) CHS/CHT/CHP Office The product and the langpacks support an extended Unicode IME that handles supplementary characters An Extension B font is also included

12 September 2002San Jose, California (IUC22) Visual Studio[.NET] String class and globalization namespace StringInfo GetTextElementEnumerator – Handles supplementary characters – Also handles composite characters GDI+ IDE support

12 September 2002San Jose, California (IUC22) SQL Server Past - no support (for Unicode, even!) Present - surrogate "safe" (neutral) Future - surrogate “aware”

12 September 2002San Jose, California (IUC22) Items not [currently] supported Character Map Graph 10 Outlook 10 mail headers Fonts/IMEs “Collations” for supplementary characters

12 September 2002San Jose, California (IUC22) Collation plan for supplementary characters in the UCA? All Plane-1 (non-ideographic) characters sort after all the other non-ideographic scripts but before the ideographs. All Plane 2 (ideographic) characters will be sorted after all the ideographs on the BMP. All Plane 3-14 (currently not assigned) will be treated like any other unassigned characters. Plane 14 language tags will be treated as if they were unassigned. All characters encoded in Plane (private use) will be sorted after all other characters.

12 September 2002San Jose, California (IUC22) Questions?

12 September 2002San Jose, California (IUC22) Supplementary Character Support in Microsoft Products Don’t forget to fill out your evals!