Created attachment 129630 [details] Sample image take with Canon PowerShot A700 Gwenview does not show thumbnails for Canon PowerShot A700 photos when in low resource mode (see Screenshot and sample image). Maybe the problem is an invalid exif thumbnail size (exiftool prints "Thumbnail Image Valid Area: 0 0 0 0" for these images). STEPS TO REPRODUCE 1. Switch gwenview to "Low resource usage mode" 2. Restart gwenview to clear thumbnail cache 3. Open gwenview in folder with sample image OBSERVED RESULT The thumbnail for the sample image is only unicolor. EXPECTED RESULT The thumbnail should be a small version of the actual photo. SOFTWARE/OS VERSIONS Linux/KDE Plasma: Kubuntu 20.04 LTS KDE Plasma Version: 5.18.5 KDE Frameworks Version: 5.68.0 Qt Version: 5.12.8 ADDITIONAL INFORMATION
Created attachment 129631 [details] Gwenview showing a unicolor thumbnail
The problem seems to be in lib/jpegcontent.cpp line 581 (https://github.com/KDE/gwenview/blob/master/lib/jpegcontent.cpp#L581). As stated here https://exiftool.org/TagNames/Canon.html, the four zeros mean 'no crop'. If the validArea rect is created by two QPoint(0, 0) it results in a QRect(0,0 1x1). I think this should be QRect(0,0 0x0). Maybe this is a Qt bug?
Created attachment 134952 [details] Personal fix for this bug I fixed the bug for myself with this change.
Bug still exists in current Kubuntu 22.10 installation running Gwenview 22.08.2.
*** Bug 428013 has been marked as a duplicate of this bug. ***
Problem also occurs with a Canon Ixus 255 camera. An example image file from that camera is attached to this duplicate bug report: https://bugs.kde.org/show_bug.cgi?id=428013
Thank you for the bug report. Unfortunately we were not able to get to it yet. Can we ask you to please check if this is still an issue with Gwenview 25.08.0?
Created attachment 184308 [details] Gwenview 23.08.5 screenshot - small thumbnails
Created attachment 184309 [details] Gwenview 23.08.5 screenshot - bigger thumbnails The bug still exists in version Gwenview 23.08.5 (Kubuntu 24.04.3 LTS), but now I can reproduce it only at bigger thumbnail sizes. Using smaller thumbnail overview, the image is correct (see first screenshot), scaling up the thumbnails it changes to the wrong preview (see second screenshot).
Created attachment 184310 [details] Gwenview 25.04.3 screenshot Just tested with current Neon setup (Gwenview 25.04.3): The bug still exists and shows up at any thumbnail size. I had to delete ~/.cache/thumbnails after switching to "low resource" mode - "low resource" does not store new thumbnails, but does not delete already existing.
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