[gthumb-list] Display IPTC comment in the sidebar

[John Burke <johnburke firemail cc>]

Hello!
This is the first time I write to the list. I'm using gThumb 3.6.1 on
Ubuntu 18.04. I think it is very nice and user-friendly.

For some images, I added a text comment:

$ wrjpgcom -comment "This is my test comment" testimage.jpg > testimage.jpg

This has the result of writing the `Comment' field in the image
metadata. IIUC, it should be an IPTC field in this case. I would like to
display the comment of this image in gThumb's sidebar.

In `Preferences' -> `Extensions', `Support for EXIF, IPTC, XMP' is
enabled. However, the sidebar currently shows only Name, File size, File
modification Date/Time, File Type, MIME Type, File path, File Type and
Image Size. I did not find a way to add other fields, and therefore
my comment is not shown.

Apparently, sidebar only displays comments which have been added by
gThumb itself, pressing `c'. Instead, comments already stored with the
above example of `wrjpgcom' are not shown.

This situation is really like the one described in a previous e-mail on
this list:

https://mail.gnome.org/archives/gthumb-list/2012-January/msg00012.html

Is it possible to make comments written with `wrjpgcom' appear on the
sidebar on gThumb?

Thank you anyway,

John



If it can help, this is the output of `exiftool testimage.jpg' before
adding a comment with `c' in gThumb:

ExifTool Version Number         : 10.80
File Name                       : testimage.jpg
Directory                       : .
File Size                       : 366 kB
File Modification Date/Time     : 2019:05:30 12:41:02+02:00
File Access Date/Time           : 2019:05:30 12:41:05+02:00
File Inode Change Date/Time     : 2019:05:30 12:41:02+02:00
File Permissions                : rw-r--r--
File Type                       : JPEG
File Type Extension             : jpg
MIME Type                       : image/jpeg
JFIF Version                    : 1.01
Resolution Unit                 : None
X Resolution                    : 72
Displayed Units X               : inches
Y Resolution                    : 72
Displayed Units Y               : inches
Comment                         : This is my test comment
Image Width                     : 1280
Image Height                    : 899
Encoding Process                : Baseline DCT, Huffman coding
Bits Per Sample                 : 8
Color Components                : 3
Y Cb Cr Sub Sampling            : YCbCr4:2:0 (2 2)
Image Size                      : 1280x899
Megapixels                      : 1.2

"This is my test comment" appears in the `Comment' field.

This is the output of `exiftool testimage.jpg' after adding a comment
``Alternative comment'' with `c' in gThumb:

ExifTool Version Number         : 10.80
File Name                       : testimage.jpg
Directory                       : .
File Size                       : 369 kB
File Modification Date/Time     : 2019:05:30 12:41:02+02:00
File Access Date/Time           : 2019:05:30 15:08:33+02:00
File Inode Change Date/Time     : 2019:05:30 15:08:32+02:00
File Permissions                : rw-r--r--
File Type                       : JPEG
File Type Extension             : jpg
MIME Type                       : image/jpeg
JFIF Version                    : 1.01
Exif Byte Order                 : Little-endian (Intel, II)
X Resolution                    : 72
Y Resolution                    : 72
Resolution Unit                 : inches
Modify Date                     : 2019:05:30 15:08:32
Y Cb Cr Positioning             : Centered
Exif Version                    : 0221
Components Configuration        : Y, Cb, Cr, -
Warning                         : Invalid EXIF text encoding for UserComment
User Comment                    : Alternative comment
Flashpix Version                : 0100
Color Space                     : sRGB
XMP Toolkit                     : XMP Core 4.4.0-Exiv2
Description                     : Alternative comment
Current IPTC Digest             : 0e7c990bbcb8cd6d818ee33ec1afa70d
Caption-Abstract                : Alternative comment
Urgency                         : 0 (reserved)
Displayed Units X               : inches
Displayed Units Y               : inches
Image Width                     : 1280
Image Height                    : 899
Encoding Process                : Baseline DCT, Huffman coding
Bits Per Sample                 : 8
Color Components                : 3
Y Cb Cr Sub Sampling            : YCbCr4:2:0 (2 2)
Image Size                      : 1280x899
Megapixels                      : 1.2

The previous comment "This is my test comment" has disappeared. Three
fields have instead been created, with the same text "Alternative
comment": `User Comment', `Description', `Caption-Abstract'.