XCF issues and more

[leoutation at gmx.fr]

On 7/27/25 1:00 PM, Gilles Caulier wrote:
> Hi,
> 
> Look like the XCF Qt plugin from KImageFormats do not use the libgimp.
> There is no reference inside (no C header included about):
> 
> https://github.com/KDE/kimageformats/blob/master/src/imageformats/xcf_p.h
> https://github.com/KDE/kimageformats/blob/master/src/imageformats/xcf.cpp
> 
> Look also the XCF limitations:
> 
> https://github.com/KDE/kimageformats/blob/master/README.md#the-xcf-plugin
Yes, Gimp 3 uses now XCF 24 version. Old XCF 12 is used in Gimp 2.10

> 
> This can explain the dysfunctions here seen by Carol...

I guess this message concerns only Gimp 3 (XCF format version 24).
KImageformats doesn't display some XCF files but works for others.  I 
found why only some XCF files are not displayed.
Three causes for me now:
- when using "non destructive editing"
- using zlib compression (called "best")
- using tif format in layers
I recently reported issues details upstream
https://bugs.kde.org/show_bug.cgi?id=491795

> 
> Best regards
> 
> Gilles Caulier
> 
> Le sam. 26 juil. 2025 à 18:50, leoutation at gmx.fr <leoutation at gmx.fr> a écrit :
>>
>>
>>
>> On 7/25/25 12:06 PM, Gilles Caulier wrote:
>>> Le jeu. 24 juil. 2025 à 22:29, Carol C. Kankelborg
>>> <cckborg2 at kankelborg.net> a écrit :
>>>>
>>>> Hi,
>>>>      I recently upgraded to DigiKam 8.7.0 (Build Date 6/29/25 09:49), running on Sonoma 14.7.6. I ran the maintenance tools to clean up the database and rebuild thumbnails & fingerprints.
>>>>
>>>>     Before upgrading, there were a bunch of .xcf files that were grouped together under 100% similarity but were clearly very different from each other. After upgrading, these same files are grouped together in similarity, but the thumbnails and preview in Digikam is blank (all white). This doesn’t affect all of my .xcf files. As an example, I have one file I edited with Gimp from a scan from 11/3/22 that looks blank and another from 11/4/22 that looks fine. The blank one looks fine when I open it in GIMP.
>>>>
>>>>     Is this a bug I should report or is there some setting that is throwing DigiKam off?
>>>
>>> Hi Carol,
>>>
>>> The XCF support is delegate to a KDE framework component named
>>> KImageFormats. There is no specific code in digiKam to handle XCF
>>> files.
>>>
>>> https://invent.kde.org/frameworks/kimageformats
>>>
>>> XCF support have been problematic in the pass. Even if The Gimp is
>>> open Source, the file format change in time and support become broken
>>> while a period a time. The Gimp in the past provided a library to
>>> handle the file format. This library have been dropped and non
>>> supported since few years. So the people in charge to develop the XCF
>>> thumbnailer code fight against the complexity.
>>
>> Hi
>> Gimp – 3.0 library documentation is available here
>> https://developer.gimp.org/api/3.0/libgimp/
>>
>> Best regards
>>
>>>
>>> As you use MacOS, the KDE framworks is a little bits outdated in the
>>> 8.7.0 release. I will up-to-date this one in the current 8.8.0
>>> pre-release, probably this week end. Like this you will able to test
>>> is the new KImageFormats component fix your XCF problem.
>>>
>>>>
>>>>     I sent the above question with a sample .xcf file that was too big so it is awaiting moderator approval. I decided to scale down the image in GIMP and import it into DigiKam to see if it still had the problem, so I could resend my question within the size limits. I encoungered more bugs.
>>>
>>> If bug must be reported about XCF, no need to do it in the digiKam
>>> space. Use the KImageFormats component instead in bugzilla:
>>>
>>> https://bugs.kde.org/buglist.cgi?bug_status=UNCONFIRMED&bug_status=CONFIRMED&bug_status=ASSIGNED&bug_status=REOPENED&classification=Frameworks%20and%20Libraries&list_id=3209147&product=frameworks-kimageformats&query_format=advanced
>>>
>>> ... And as you can see there is 3 current reports about XCF...
>>>
>>>
>>>
>>>
>>>>
>>>> First, DigiKam crashes when I try to create a new album, even though it does successfully create the new album.
>>>> Second, when I try to “Add Images” to put the new .xcf file in DigiKam, it asks which album, then does nothing. The same thing happens when I try with a .jpg.
>>>
>>> Cannot reproduce the problem on my Macbook Pro M1 with Somona.
>>>
>>> Please follow instructions here to capture the digiKam trace from the
>>> Apple Terminal for future investiguations:
>>>
>>> https://www.digikam.org/contribute/#macos-host
>>>
>>> Best regards
>>>
>>> Gilles Caulier
>>