Async load of image file should `.continueWith(loadTilesForImage)`

[bbappserver]

Hydrus version

650

Qt major version

Qt 6

Operating system

Linux (specify distro and version in comments)

Install method

Running from source

Install and OS comments

Ubuntu 24

Bug description and reproduction

Right now there is a noticeable hitch in displaying large (>~1MiB) image in the archive-delete filter. Inserting a a log into the imageCache tryGet (I forget what it's actually called it' like "GetOrNull" or something), shows that the issue is a cache miss in the image tile renderer cache for one or more tiles (as reported in the Discord), despite the fact that there i plenty of available space. This suggests an that an image that will be rendered imminently has not been sufficiently loaded an so needs to synchronously generate tiles, or there is an off by one because it tends to be that just about 4 tiles seem to be missing, or that rendering tiles is simply not prioritized in the jobs queue an hydrus can't cope under load.

As a diagnostic test I go back and then forward once tile generation is complete and it is instant, so certainly once tiles are ready it is blazingly fast.

Log output

v650, 2025-12-04 17:40:05: Cache "image tile cache" MISS "(b'\xc4\xc2\xae\xb8\xf6At\xe9\xd3\xdc\xcb\xe8n\xdf\xd7Ac\xa3\xb2^\xf5\xafBMF\xcf\xa8Hv\xaav\xe9', 0, 0, 2090, 2090, 517, 517)"
v650, 2025-12-04 17:40:05: Cache "image tile cache" adding "(b'\xc4\xc2\xae\xb8\xf6At\xe9\xd3\xdc\xcb\xe8n\xdf\xd7Ac\xa3\xb2^\xf5\xafBMF\xcf\xa8Hv\xaav\xe9', 0, 0, 2090, 2090, 517, 517)" (783 KB). Current size 783 KB/80 MB.
v650, 2025-12-04 17:40:05: Cache "image tile cache" MISS "(b'\xc4\xc2\xae\xb8\xf6At\xe9\xd3\xdc\xcb\xe8n\xdf\xd7Ac\xa3\xb2^\xf5\xafBMF\xcf\xa8Hv\xaav\xe9', 0, 2091, 2090, 2999, 517, 225)"
v650, 2025-12-04 17:40:05: Cache "image tile cache" adding "(b'\xc4\xc2\xae\xb8\xf6At\xe9\xd3\xdc\xcb\xe8n\xdf\xd7Ac\xa3\xb2^\xf5\xafBMF\xcf\xa8Hv\xaav\xe9', 0, 2091, 2090, 2999, 517, 225)" (341 KB). Current size 1.1 MB/80 MB.
v650, 2025-12-04 17:40:05: Cache "image tile cache" MISS "(b'\xc4\xc2\xae\xb8\xf6At\xe9\xd3\xdc\xcb\xe8n\xdf\xd7Ac\xa3\xb2^\xf5\xafBMF\xcf\xa8Hv\xaav\xe9', 2091, 0, 3999, 2090, 472, 517)"
v650, 2025-12-04 17:40:05: Cache "image tile cache" adding "(b'\xc4\xc2\xae\xb8\xf6At\xe9\xd3\xdc\xcb\xe8n\xdf\xd7Ac\xa3\xb2^\xf5\xafBMF\xcf\xa8Hv\xaav\xe9', 2091, 0, 3999, 2090, 472, 517)" (715 KB). Current size 1.8 MB/80 MB.
v650, 2025-12-04 17:40:05: Cache "image tile cache" MISS "(b'\xc4\xc2\xae\xb8\xf6At\xe9\xd3\xdc\xcb\xe8n\xdf\xd7Ac\xa3\xb2^\xf5\xafBMF\xcf\xa8Hv\xaav\xe9', 2091, 2091, 3999, 2999, 472, 225)"
v650, 2025-12-04 17:40:06: Cache "image tile cache" adding "(b'\xc4\xc2\xae\xb8\xf6At\xe9\xd3\xdc\xcb\xe8n\xdf\xd7Ac\xa3\xb2^\xf5\xafBMF\xcf\xa8Hv\xaav\xe9', 2091, 2091, 3999, 2999, 472, 225)" (311 KB). Current size 2.1 MB/80 MB.
v650, 2025-12-04 17:40:06: Cache "image cache" HIT "b'\xc4\xc2\xae\xb8\xf6At\xe9\xd3\xdc\xcb\xe8n\xdf\xd7Ac\xa3\xb2^\xf5\xafBMF\xcf\xa8Hv\xaav\xe9'
v650, 2025-12-04 17:40:06: Cache "image cache" HIT "b'\xd4Z7\xe6\xe3\x93\xfb0\xf0\xcb\x1a\x12#\xd3f\x0bM\xfd\x15-\x9d\x97h\xf7\xaca\\\xe6L\x07\xcd\x1c'
v650, 2025-12-04 17:40:06: Cache "image cache" MISS "b'N\x11\x99\x00A\xe0NT\xf9\x13L\xc1D\xa0\xb1\x865\xbe\xd0\x16<?\x0bh?W\x95\x02E\xa6,\x9d'"
v650, 2025-12-04 17:40:06: Cache "image cache" MISS "b'N\x11\x99\x00A\xe0NT\xf9\x13L\xc1D\xa0\xb1\x865\xbe\xd0\x16<?\x0bh?W\x95\x02E\xa6,\x9d'"