https://bugs.kde.org/show_bug.cgi?id=479726
Daichi Watanabe <[email protected]> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |[email protected] --- Comment #2 from Daichi Watanabe <[email protected]> --- This is not a Krita bug, and Halla is right that Krita cannot fix it. But the cause has now been identified and reported to Microsoft with a reproduction: https://github.com/microsoft/Windows-classic-samples/issues/429 For OneDrive cloud placeholders, the Windows shell hands thumbnail generation to the sync provider's ThumbnailProvider (registered per sync root) and never falls back to the per-extension handler that Krita -- or any other application -- registers. OneDrive renders a fixed set of formats server-side; anything else gets nothing. We reproduced this with Microsoft's own CloudMirror sample, modified by 15 lines, and measured three cases: 1. Sample as shipped (delegates to the registered handler) -> thumbnail rendered, with the cloud-only badge still present 2. Returning WTS_E_EXTRACTIONPENDING (0x8004B205) -> no thumbnail (this matches what OneDrive does) 3. Returning WTS_E_NOSTORAGEPROVIDERTHUMBNAILHANDLER (0x8004B207) -> no thumbnail, and the error is returned verbatim; no fallback happens Case 1 shows a sync provider *can* display thumbnails for cloud-only placeholders, so the limitation is not inherent to Files On-Demand. Case 3 shows that a constant naming exactly this situation exists, yet returning it produces no fallback. Your observation in comment #1 matches ours exactly: enabling "Always keep on this device" does not help, and moving the file outside the synced folder makes thumbnails appear. We measured the same for our own format (.mdp, MediBang Paint / FireAlpaca). The deciding factor is not whether the file content is present locally, but whether the file is still a cloud placeholder (a reparse point). Nothing for Krita to do here. Posting only so that anyone finding this report knows the cause is understood and where the upstream discussion is. -- You are receiving this mail because: You are watching all bug changes.
