Round-trip a raster preview through the DWG's embedded preview slot and
surface it to the OS file managers, so drawings show their contents in
Explorer / Finder / Nautilus instead of a generic document icon.
OCS:
* io::thumbnail — rasterize the scene to a BMP DIB on save (embedded via
acadrust's new Preview type) and read it back on open for the Start
page recent list; `--dwg-thumbnail IN OUT SIZE` CLI extracts a badged
PNG for external thumbnailers.
* io::file_association::install_thumbnailer — self-install the OS
integration on startup: Linux writes a .thumbnailer + hicolor mimetype
icons; Windows registers the IThumbnailProvider DLL under HKCU.
Shared core:
* crates/dwg-thumbnailer — lean (image-only) preview extractor + the
`badge_dwg` full-width "DWG" band, used by every platform so the
ribbon is single-sourced. Ships an rlib+staticlib.
* crates/dwg-thumbnailer-win — IThumbnailProvider COM in-proc server
(cfg(windows), CI-built as a workspace member).
* macos/ — QuickLook thumbnail extension (Swift + C-ABI bridge to the
core staticlib), assembled into a .appex.
Icons & packaging (single SVG source -> per-platform assets in CI):
* assets/mimetypes/image-vnd.{dwg,dxf}.svg — themed file icons.
* packaging: WiX ships dwg/dxf.ico + the thumbnail DLL and points the
ProgIds at them; Info.plist gets CFBundleTypeIconFile + the QuickLook
extension in Contents/PlugIns.
* release.yml — generate .ico (Windows) and .icns (macOS) from the SVGs,
build the QuickLook .appex, and bundle everything.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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