Fix EXIF UserComment encoding for non-ASCII comments#353
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Fixes Ruben2776#324 The UserComment tag was decoded with Encoding.ASCII over the entire byte array, including the 8-byte EXIF encoding header. This garbled the header bytes into the output, discarded ASCII-prefixed comments, and never re-decoded UNICODE-prefixed comments as UTF-16LE (only a string Replace was applied), so CJK and other non-ASCII comments stayed mojibake. Read the 8-byte header and decode only the remaining bytes with the encoding it indicates per the EXIF UserComment spec: ASCII, UNICODE (UTF-16LE), JIS (UTF-8 fallback), or undefined (UTF-8). Trim trailing NUL padding and whitespace. No public API change; single method.
Owner
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Chinese characters just turn into question marks with your changes. It doesn't fix it. |
Owner
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Thank you for the PR, however it got fixed in #359 |
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Fixes #324
Root cause
GetUserCommentdecoded the entireUserCommentbyte array withEncoding.ASCII, including the 8-byte EXIF encoding identifier that prefixes the value. This caused three problems:ASCIIprefix were discarded (string.Emptyreturned).UNICODEprefix were never re-decoded as UTF-16LE — only a stringReplace("UNICODE", "")was performed on the already-ASCII-decoded text, so CJK and other non-ASCII comments stayed garbled.Fix
Read the first 8 bytes as the encoding identifier and decode only the remaining bytes (
commentBytes[8..]) with the encoding indicated by the header, per the EXIF UserComment specification:ASCII→Encoding.ASCIIUNICODE→Encoding.Unicode(UTF-16LE)JIS→ UTF-8 fallback (true JIS X0208 decoding is rare in the wild; UTF-8 is a safe best-effort)Encoding.UTF8Trailing NUL padding and whitespace are trimmed from the decoded result, which is returned as
string.Emptywhen null/empty/whitespace.Notes
System.Textencodings already imported (Encoding.ASCII,Encoding.Unicode,Encoding.UTF8).