Add configurable letterbox fill for sleep screen cover images that don't
match the display aspect ratio. Four fill modes are available: Solid
(single dominant edge shade), Blended (per-pixel edge colors), Gradient
(edge colors interpolated toward white/black), and None.
Enable upscaling of cover images smaller than the display in Fit mode by
modifying drawBitmap/drawBitmap1Bit to support both up and downscaling
via a unified block-fill approach.
Edge sampling data is cached to .crosspoint alongside the cover BMP to
avoid redundant bitmap scanning on subsequent sleeps. Cache is validated
against screen dimensions and auto-regenerated when stale.
New settings: Letterbox Fill (None/Solid/Blended/Gradient) and Gradient
Direction (To White/To Black).
Co-authored-by: Cursor <cursoragent@cursor.com>
## Summary
This is an updated version of @itsthisjustin's #346 that builds on
current master and also deduplicates the settings list so we don't have
two copies of the settings. In the Web UI, it should organize the
settings a little closer to what you see on device.
## Additional Context
I tested this live on device and it seems to play nicely for me. It's
re-based on master since master's settings stuff has moved somewhat
since the original PR and addresses the sole review comment #346 - it
also means that I don't need to manually key in the URL for my OPDS
server. :)
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### AI Usage
My changes were implemented with Claude Opus 4.5 and Claude Code 2.1.25.
I don't know if @itsthisjustin's original work used AI assistance.
Co-authored-by: Dave Allie <dave@daveallie.com>
