Legacy Encodings support in Opera Presto 2.7

Although Opera works with the Unicode character set and its character encodings of UTF-16 and UTF-8, most text on the Internet is encoded in legacy encodings, for instance:

• ISO 8859-1
• Windows-1251
• Shift_JIS (MIME name)
• EUC-KR

Opera handles this by detecting the character encoding used, and converting it to UTF-16. The user has three options for how to handle these pages.

• Auto-detect: in this mode Opera will attempt to detect the encoding used by the page
  • If the transport protocol provides an encoding name, that is used
  • If not, Opera will look at the page for a charset declaration
  • If this is missing, Opera will attempt to auto-detect the encoding, using the domain name to see if the script is a CJK script, and if so which one
  • Opera can also auto-detect UTF-8
• Writing script auto-detect: In this mode the user can tell that this is a Japanese or Chinese page, but that the encoding is unknown. Opera will then analyze the text in the page to determine which encoding is used.
• Encoding override: In this mode the user selects an encoding. This encoding will be used by Opera, regardless of what the page and transport protocol claims is the encoding for the page.

Opera Presto includes support for Unicode 5.2 character properties (class, casing, bidirectionality, mirroring, normalization) from 5.0.

• See UAX#14 linebreaking
• See UAX#29 text segmentation

Big5-HKSCS support for the HKSCS-2008 encoding standard has been updated.

• See iana.org: Character sets
• See ogcio.gov: hkscs 2008 summary

Charset CP51932 is now implemented as an alias of euc-jp.

• See iana.org: CP51932

Encoding	Category	Comments	Support
ISO 8859-1	Latin		Yes
ISO 8859-2	Latin	Used in Eastern Europe	Yes
ISO 8859-3	Latin	Rare	Yes
ISO 8859-4	Latin	Sami and Baltic country	Yes
ISO 8859-9	Latin	Turkish	Yes
ISO 8859-10	Latin	Inuit, Sami, and Icelandic	Yes
ISO 8859-13	Latin	Rare	Yes
ISO 8859-14	Latin	Celtic	Yes
ISO 8859-15	Latin	Intended to supersede 8859-1	Yes
Windows-1250	Latin	Used in Eastern Europe	Yes
Windows-1252	Latin		Yes
Windows-1254	Latin	Turkish	Yes
Windows-1257	Latin	Baltic	Yes
Windows-1258	Latin	Vietnamese	Yes
VISCII	Latin	Vietnamese	Yes
IBM 866	Cyrillic		Yes
ISO 8859-5	Cyrillic		Yes
koi8-r	Cyrillic		Yes
koi8-u	Cyrillic	Ukrainian version of koi8-r	Yes
Windows-1251	Cyrillic		Yes
ISO 8859-6	Arabic		Yes
Windows-1256	Arabic		Yes
ISO 8859-7	Greek		Yes
Windows-1253	Greek		Yes
ISO 8859-8	Hebrew		Yes
Windows-1255	Hebrew		Yes
ISO 8859-11	Thai	Also known as TIS-620	Yes
Windows-874	Thai	Extension of ISO 8859-11	Yes
utf-8	Unicode		Yes
utf-16	Unicode		Yes
Shift-JIS	Japanese		Yes
ISO-2022-JP	Japanese		Yes
EUC-JP	Japanese		Yes
Big 5	Chinese		Yes
EUC-CN	Chinese	Also erroneously known as GB 2312	Yes
HZ-GB-2312	Chinese	Primarily used in e-mail	Yes
EUC-TW	Chinese		Yes
GBK	Chinese	EUC-CN extension	Yes
EUC-KR	Korean		Yes