forked from akai/readest
Huang Xin
f805477091
Opening the Library with a large grouped library was slow because each folder's 2x2 cover mosaic was recomposed from scratch on every paint (up to 4 MuPDF cover decodes plus scales per cell). On a 685-book library this dominated the synchronous open path (254ms of 300ms) and ran again on the post-sync refresh. Navigation felt fast only because drilling into a group shows single covers, not mosaics. Mirror cloud_covers' async pattern in group_covers: - Cache the composed master bb per group, keyed by a signature that flips when the child set or any child's cover availability changes; serve cheap copies on a hit. Cache a nil result too, so a group whose covers are not ready yet keeps its placeholder without recomposing on every refresh; a later cover download flips the signature and recomposes once. - Compose off the first-paint path: a miss enqueues a background job (one mosaic per UI tick) and returns nil so the cell paints its FakeCover placeholder immediately; finished mosaics coalesce into one refresh. - Free cached masters when the Library closes. Measured synchronous open path drops from 300ms to 151ms on a 685-book library; mosaic compositing moves off the blocking paint and fills in progressively. Adds open-path timing logs to librarywidget and localscanner for on-device diagnosis of future large-library reports. Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>