Cram v1.1.0

Mostly work on finding duplicates, and on what you can see and do with the result. The engine gains
progress reporting and a verification pass; Cram Studio gains a gallery, a full-size viewer and the
ability to delete. As with every release here, the Cram Studio installer ships as an asset and is a
separate proprietary product under its own EULA.

Added

• A duplicate scan reports what it has found while it is still running. A scan over a whole
  drive spends minutes walking before it can group anything, and until now it said nothing for all
  of it, which is indistinguishable from being hung. Progress::on_scan_progress(files, dirs) is
  called at most every 250 ms, and Studio shows the running counts.

• Photos and video open in their own tab in Cram Studio, as a gallery. A duplicate set of
  images cannot be judged from a list of paths, so image and video sets now go to a separate tab
  with thumbnails, per-file or whole-row selection, and identical and look-alike kept on separate
  panes. Everything that is not an image or a video stays where it was: a thumbnail of a .dll
  tells you nothing.

• A full-size preview behind every thumbnail, from the magnifier on hover or a double-click.
  The arrows step through the set with both neighbours prefetched, and the image is contained in a
  fixed stage so two near-identical shots land in the same place and only the difference moves.
  Where the file is small enough and the format is one the view can draw directly, the original
  bytes are shown rather than a re-encode, so nothing you are judging is an artefact of the
  preview; when it does have to downscale, it says so.

• Duplicates can be deleted from Cram Studio, to the Recycle Bin. Deliberately not a button you
  can hit in passing: it has to be held, it says how many and how much, and everything goes to the
  Recycle Bin so a mistake is recoverable from Explorer. Selecting every copy in a set raises a
  warning rather than being forbidden.

• The hard-link option explains itself, behind a ? beside it, and a duplicate can be shown in
  its folder rather than only named.

Fixed

• A look-alike group could swallow hundreds of unrelated images. One scan put 936 different
  terminal screenshots in a single group. Grouping was by perceptual hash alone, unioned, which is
  single-linkage clustering: A joins B and B joins C, so one bridging pair merges two sets that
  resemble each other not at all. Tightening the hash threshold could not have fixed it, because
  single-linkage always finds a bridge. A candidate pair is now verified against the pixels — same
  aspect ratio within 10%, and a mean absolute difference no greater than 0.007 over a 64-pixel
  colour render. Colour matters here: discarding chroma is what makes a hash robust, and it is
  also what makes two unrelated dark terminals look identical. The threshold sits between the
  noisiest thing that must stay together (a photo resized and re-encoded at JPEG q40, 0.0037) and
  the closest thing that must separate (two different terminals, 0.0132) — about 1.9x from each. A
  retake of the same terminal with one word changed scores 0.0009 and stays grouped. Those are
  synthetic images, so treat the margin as real but not generous.

• A cancelled extraction took back more than it wrote. It now removes only files and directories
  that did not exist when it created them, so cancelling an extraction into a folder that already
  held a file of the same name leaves that file alone.

• A directory cycle walked forever. Past 1,000 levels the walk checks file identity and stops
  when it reaches somewhere it has already been. Legitimately deep trees are unaffected, which has
  a test.

• Thumbnails were drawn at roughly a quarter of the resolution they were displayed at. The
  request was sized in CSS pixels rather than device pixels, the result was then cropped to fill and
  upscaled again, the fast integer resampler aliased text, and JPEG's default quality rang around
  every glyph edge. Now: sized from the display's pixel ratio, Lanczos3, quality 90, and the whole
  image shown rather than a crop. Against a perfect render at the display size, 12.4x closer for
  4.1x the bytes.

• Installing a new version over an old one failed with Cram Studio closed. cram shell install
  registers cram_shell.dll as an in-process context-menu handler, so the first right-click after
  an install maps it into explorer.exe, which does not let go; the installer then could not open
  it for writing. Explorer is not something an installer can close, and the check for a running app
  looks for Studio rather than Explorer. A mapped file can still be renamed, so the installer now
  moves the old one aside and writes the new one over the name it vacated. Explorer keeps serving
  right-clicks from the previous version until it next restarts, which is a better outcome than an
  install that will not proceed.

• The browser hand-off left Firefox's own copy of every download on disk. The add-on called
  downloads.erase(), which removes the entry from Firefox's history and never touches the file.
  Deleting the bytes is downloads.removeFile(), which was not called at all. The leftover file
  also explains the file(1).type names: Cram found its own destination taken and uniquified around
  it. The add-on updates separately from Cram itself: install cram-handoff-v1.1.0.xpi below. It
  will not update on its own, because the add-on is unlisted and carries no update URL.