Hello Joakim, glad you found out what to do. This would make for a good addition to the user guide. Would you like to contribute your findings?
Benedikt Joakim Knudsen <joakim.gr...@gmail.com> schrieb am Di., 31. Mai 2016 um 19:21 Uhr: > Btw, ENCODING_UTF16 is just a String = "UTF-16LE" (Little Endian) > > On 31 May 2016 at 19:20, Joakim Knudsen <joakim.gr...@gmail.com> wrote: > > > Following a post on the User-Commons-Apache log (from 2012), I ended up > > with the following code which seems to work. > > It writes proper Unicode, which I can read back successfully using > > ExifTool. I also see the comment nicely in Windows Explorer, and under > File > > > Properties. > > Note I changed the field type from ASCII to FIELD_TYPE_UNDEFINED, > > otherwise (with ASCII) it did not work. At least Windows couldn't make > > sense of the EXIF data. > > > > // http://osdir.com/ml/user-commons-apache/2012-03/msg00046.html > > byte[] unicodeMarker = new byte[]{ 0x55, 0x4E, 0x49, 0x43, 0x4F, 0x44, > > 0x45, 0x00 }; > > byte[] comment = textToSet.getBytes(ENCODING_UTF16); // OR UTF-16BE if > the file is big-endian! > > byte[] bytesComment = new byte[unicodeMarker.length + comment.length]; > > System.arraycopy(unicodeMarker, 0, bytesComment, 0, > unicodeMarker.length); > > System.arraycopy(comment, 0, bytesComment, unicodeMarker.length, > comment.length); > > > > TiffOutputField exif_comment = new > TiffOutputField(TiffConstants.EXIF_TAG_USER_COMMENT, > > TiffFieldTypeConstants.FIELD_TYPE_UNDEFINED, > bytesComment.length, bytesComment); > > > > > > I can now write UserComment: "æøå" without problems :) > > > > > > > > - Joakim > > > > > > On 31 May 2016 at 17:39, Benedikt Ritter <brit...@apache.org> wrote: > > > >> Hello Joachim, > >> > >> Joakim Knudsen <joakim.gr...@gmail.com> schrieb am Sa., 28. Mai 2016 um > >> 21:10 Uhr: > >> > >> > Hi Benedikt, and thanks for replying! > >> > > >> > So, if FieldType is unused, maybe the alternative, simpler constructor > >> is > >> > more appropriate/correct to use? > >> > > >> > // try using the approach given in the example (modified from the GPS > >> tag): > >> > TiffOutputField exif_comment = TiffOutputField.create( > >> > TiffConstants.EXIF_TAG_USER_COMMENT, > >> > outputSet.byteOrder, textToSet); > >> > > >> > However, now Sanselan throws an ImageWriteException: > >> > org.apache.sanselan.ImageWriteException: Tag has unexpected data type. > >> > > >> > So are you 100% sure field type should not be set (to ASCII)? > >> > > >> > >> No, I'm just saying that it uses a hard coded encoding anyway :-) > >> > >> > >> > > >> > Next, you're saying the string to set (textToSet) is converted > >> internally > >> > to byte array, using US-ASCII encoding. > >> > If I try writing "æøåæøå" to a file, I get "쎦쎸쎥쎦쎸쎥" when I copy the > JPEG > >> > out and check Properties in Windows Explorer. > >> > If I write only ASCII characters, e.g. "Test", then that comes through > >> just > >> > fine. > >> > > >> > In summary, here is the code that works for me (except non-ASCII > >> > characters): > >> > > >> > > >> > *// > >> > > >> > > >> > http://mail-archives.apache.org/mod_mbox/commons-user/201203.mbox/%3CCAJm2B-mYCXYKuyu=Hs8UAZCpw-B=kwuz4gszfuobvzwun0l...@mail.gmail.com%3E > >> > < > >> > > >> > http://mail-archives.apache.org/mod_mbox/commons-user/201203.mbox/%3CCAJm2B-mYCXYKuyu=Hs8UAZCpw-B=kwuz4gszfuobvzwun0l...@mail.gmail.com%3E > >> > >*byte > >> > b[] = ExifTagConstants.EXIF_TAG_USER_COMMENT.encodeValue( > >> > TiffFieldTypeConstants.FIELD_TYPE_ASCII, > >> > textToSet, outputSet. > >> > *byteOrder*); > >> > > >> > // constructor arguments: taginfo tag fieldtype count bytes > >> > TiffOutputField exif_comment = new > >> > TiffOutputField(TiffConstants.EXIF_TAG_USER_COMMENT.tag, > >> > TiffConstants.EXIF_TAG_USER_COMMENT, > >> > TiffFieldTypeConstants.FIELD_TYPE_UNDEFINED, > >> > b.length, b); > >> > > >> > >> The provided links indicate to me, that it is possible to write non > ASCII > >> characters. Are you sure your code looks like what Damjan suggested? > >> > >> Benedikt > >> > >> > >> > > >> > > >> > > >> > Joakim > >> > > >> > > >> > > >> > On 22 May 2016 at 15:29, Benedikt Ritter <brit...@apache.org> wrote: > >> > > >> > > Hello Joakim > >> > > > >> > > Joakim Knudsen <joakim.gr...@gmail.com> schrieb am Sa., 21. Mai > 2016 > >> um > >> > > 19:29 Uhr: > >> > > > >> > > > Hi List! > >> > > > > >> > > > I'm working on an Android app, where I want to read and write > "EXIF > >> > tags" > >> > > > to JPEG files on the device. Sanselan 0.97 seems to work > perfectly, > >> > > > although it's a bit complicated to work with EXIF > tags/directories. > >> > > > > >> > > > The specific tags I'm interested in, is EXIF_TAG_USER_COMMENT and > >> > > > EXIF_TAG_IMAGE_DESCRIPTION. > >> > > > According to the documentation I could find, UserComment is of > field > >> > type > >> > > > "undefined", whereas ImageDescription is of field type ASCII. > >> > > > > >> > > > > >> > > > >> > > >> > http://www.awaresystems.be/imaging/tiff/tifftags/privateifd/exif/usercomment.html > >> > > > > >> http://www.awaresystems.be/imaging/tiff/tifftags/imagedescription.html > >> > > > > >> > > > What's the proper way of creating those tags, wrt. charset etc? I > >> want > >> > as > >> > > > wide as possible character support (æøå etc). > >> > > > > >> > > > I find different discussions online, with different advice. Seems > >> two > >> > > > constructors are going around, where the simpler one does not deal > >> with > >> > > > charset/encoding at all. This one uses the .create method: > >> > > > > >> > > > String textToSet = "Some Text æøå"; > >> > > > > >> > > > TiffOutputField exif_comment = TiffOutputField.create( > >> > > > TiffConstants.EXIF_TAG_USER_COMMENT, > >> > > > outputSet.byteOrder, textToSet); > >> > > > > >> > > > > >> > > > while this one uses the standard constructor: > >> > > > > >> > > > byte b[] = ExifTagConstants.EXIF_TAG_USER_COMMENT.encodeValue( > >> > > > TiffFieldTypeConstants.FIELD_TYPE_ASCII, > >> > > > textToSet, outputSet.byteOrder > >> > > > ); > >> > > > > >> > > > // constructor arguments: taginfo tag fieldtype count bytes > >> > > > TiffOutputField exif_comment2 = new > >> > > > TiffOutputField(TiffConstants.EXIF_TAG_USER_COMMENT.tag, > >> > > > TiffConstants.EXIF_TAG_USER_COMMENT, > >> > > > TiffFieldTypeConstants.FIELD_TYPE_UNDEFINED, > >> > > > b.length, b); > >> > > > > >> > > > In this last one, the string to set has been converted to a byte > >> array > >> > > > first. But can/should I set the encoding anywhere? > >> > > > > >> > > > Is the field type even ASCII? This information seems to indicate > >> it's > >> > > > not ASCII... > >> > > > > >> > > > > >> > > > >> > > >> > http://www.awaresystems.be/imaging/tiff/tifftags/privateifd/exif/usercomment.html > >> > > > > >> > > > > >> > > > Need some help here, as you can see, to get this right. The second > >> > > > approach above does seem to work in my app, but I'd like to be > sure > >> > > > I'm not somehow messing up the JPEGs on the deviced. > >> > > > > >> > > > >> > > I've looked at the code of > >> > > org.apache.commons.imaging.formats.tiff.taginfos.TagInfoGpsText > >> > > (ExifTagConstants.EXIF_TAG_USER_COMMENT is an instance of > >> > TagInfoGpsText). > >> > > Here are my observations: > >> > > > >> > > - The FieldType parameter, which you have set to > >> > > TiffFieldTypeConstants.FIELD_TYPE_ASCII is never used in the > >> > implemenation > >> > > of encodeValue(FieldType, Object, ByteOrder) > >> > > - When converting the input String to byte array, > >> String.getBytes(String > >> > > charsetName) is used > >> > > - For charsetName "US-ASCII" is always used (it can not be > configured > >> by > >> > > the user) > >> > > > >> > > So my guess is, that the code will not handle characters not in the > >> > > US-ASCII charset correctly. > >> > > > >> > > Benedikt > >> > > > >> > > > >> > > > > >> > > > > >> > > > > >> > > > Joakim > >> > > > > >> > > > >> > > >> > > > > >
