comic-img-compress/HANDOFF.md

HANDOFF.md

Current state of the comic compression toolchain as of 2026-06-28.

Repositories

Repo	Branch	Latest commit
comic-compress-new (CLI)	main	94f3fab
iMGcompress-core (library)	master	a03d0e5
iMGcompress (GUI)	master	7b7021a

What was done in this session (v3.1.0 / v2.0.0)

NuGet package updates (all three projects)

• SharpCompress 0.42 → 0.49.1 (CVE GHSA-6c8g-7p36-r338 fixed)
• Magick.NET-Q8-x64 → 14.14.0 (multiple CVEs fixed)
• Imazen.WebP → 11.0.0
• Imageflow.AllPlatforms + Imageflow.Net → 0.15.1
• iTextSharp → 5.5.13.5, itext → 9.6.0
• McMaster.Extensions.CommandLineUtils → 5.1.0
• System.Drawing.Common → 10.0.9

SharpCompress 0.49 breaking API migration (iMGcompress-core)

• ReaderFactory.Open → OpenReader(stream, new ReaderOptions())
• RarArchive/ZipArchive.Open → OpenArchive(filename, new ReaderOptions())
• ZipArchive.Create() → CreateArchive()
• SaveTo(path, CompressionType) → SaveTo(path, new ZipWriterOptions(CompressionType))
• Return type ZipArchive → IWritableArchive<ZipWriterOptions>
• Removed using ZstdSharp (internalized in 0.49)

Parallel within-archive compression (iMGcompress-core, -P flag)

• New ProcessArchivePAR2 + CompressEntrySync in Compressor.cs
• Batched 3-phase design: sequential read → Parallel.For (ProcessorCount/2 threads) → sequential write
• Ordering guaranteed by indexed pre-allocated result slots
• Measured speedup: ~3.4–5× vs serial on i7-12700KF (10 batch size)
• Memory bounded per batch; logs strictly in original entry order from write phase

MemoryStream pre-sizing (iMGcompress-core)

• All new MemoryStream() → new MemoryStream(entry.Size > 0 ? (int)entry.Size : 4096)
• Eliminates buffer-doubling reallocations on all 9 allocation sites in Compressor.cs

CLI fixes and new flags (ComicCompress)

• Fixed missing OnExecuteAsync — app was throwing InvalidOperationException on launch
• Added -w|--new-webp: use Imageflow encoder (experimental; benchmarked 8–15% slower than Imazen.WebP)
• Added -P|--par-archive: enable parallel within-archive compression

GUI (iMGcompress)

• Added checkBox_parArchive (flat-button, location 382,231, TabIndex 14)
• Default ON for COMIX and COMIX+PDF modes; OFF for IMAGE and ZEBRA
• Wired into FileProcessor.ProcessorFlags constructor
• Version bumped to 2.0.0 (28/06/2026)

Other

• Added CLAUDE.md to comic-compress-new with build commands and architecture notes

Current versions

• CLI (ComicCompress): 3.1.0 (28/06/2026) — see Program.cs
• GUI (iMGcompress): 2.0.0 (28/06/2026) — see MGCompress.cs

Known state / open items

• Imageflow encoder (-w flag) is wired and working but consistently slower than Imazen.WebP across all tested archive sizes. Kept as an experimental path only.
• libwebp.dll must be present alongside the executable — it is checked into the repo root of both comic-compress-new and iMGcompress-core.
• The GUI runs single-threaded on the UI thread (button_start_Click is synchronous). Long jobs block the window. Not addressed in this session.