dtourolle 9717e59909 Add RAW decode and a working image viewer
dr-decode exposes four entry points rather than one decode, because
callers differ sharply in what they need (ARCH §3.2): culling wants a
preview, the grid wants metadata, only develop and export touch sensor
data. Fusing them forces a full decode where a header read suffices,
which is why Lightroom stalls ~2s per image while culling.

Smoke-tested against 1,852 real Canon CR2 files (EOS 6D, ~27MB each):

  metadata      0.2ms   from a 256KB header read, no full decode
  preview     ~250ms   5472x3648, downscaled to 2048 for display
  jpeg          3.0ms

Two findings worth recording:

rawler 0.7.2's CR2 decoder implements only full_image; thumbnail_image
and preview_image are unimplemented trait defaults returning None. So
every rung of the preview ladder resolves to a full-resolution decode at
~250ms — 5x over NFR-P13's 50ms budget. CR2 does carry smaller IFDs, so
the fix is our own IFD walk or an upstream contribution. The ladder is
written now so that fixing it is a decoder change, not a change to every
caller. Recorded in milestone-v0.1 risks.

Preview.downscale_to bounds memory: a 5472x3648 RGBA preview is 79.8MB,
which exhausts a phone's budget after a handful of images. Box-filtered
so downscaled thumbnails do not alias.

Also fixed a RefCell double-borrow that panicked on first navigation —
`*x.borrow_mut() = *x.borrow() + 1` holds both borrows at once. Verified
with 10,000 programmatic navigations.

58 tests passing. Traceability 20.3% (29/143).
2026-08-09 08:28:26 +02:00

DarkRoom

A cross-platform, non-destructive RAW photo editor for Linux and Android.

Status: early. v0.1 is a remote library viewer — see docs/milestone-v0.1.md.

Documentation

Document Contents
requirements.md What the software must do — 122 numbered requirements
architecture.md How it is built — crates, GPU pipeline, data model, sync
milestone-v0.1.md The first buildable milestone

Building

Desktop:

cargo run -p darkroom-desktop

Android (containerised toolchain, see docker/android):

./docker/android/build.sh cargo ndk -t arm64-v8a build --release

Current state

Working: workspace, GPU context and compute pass, adaptive Slint shell, Android cross-compilation of the core crates.

Not yet working: the zero-copy display path. The build currently uploads frames through the CPU, which is exactly what ARCH §6.1 forbids — measured at 96% of frame time at 4K. Replacing it is spike S1, the project's highest priority.

cargo run -p dr-gpu --example bench --features readback

reproduces that measurement.

Licence

GPL-3.0-or-later.

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2026-10-07 11:27:59 +00:00
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