Rust Hover Preview

A Windows 11 tray app inspired by QTTabBar and QuickLook. Hover over a file in File Explorer for an instant preview, or press Space to lock open a pinned preview window. Works with keyboard navigation, and customizes easily via the tray icon or a simple config.ini

Showcase.webm

Highlights

• Mouse-hover and keyboard-navigation previews in Explorer, beside the cursor or the focused item and kept on screen.
• Press a key (SPACE by default) and a preview becomes a window of its own — captioned, movable, resizable, always on top, where it stays until you close it.
• Supports images, videos, audios, ebooks, Office documents, design documents, text/code, archives, camera raw, vector drawings, fonts, and more.
• Granular display scaling: Flexible sizing (fit-to-screen, percentage-based, or 25%–400% native scale) with independent scaling profiles for media vs. text, vectors, and documents.
• Tray menu and hand-editable config.ini; DPI aware, single-instance, sleep/resume resilient, and light on idle CPU.
• Plugs into what you have: built-in decoders and Windows codecs cover the basics; ImageMagick, FFmpeg, mpv, LibreOffice, Office, WebView2, PeaZip, Calibre, and the Windows PDF engine extend it where installed — nothing bundled. For video, mpv is recommended for performance, hardware acceleration, reliability, and subtitles (embedded tracks and sidecar .srt) that just work.

Supported Formats

Images

Engine	config.ini	Default extensions
This app's own decoders and the codecs Windows ships	[image]	apng, avci, avif, bmp, dds, exr, ff, gif, hdr, heic, heif, ico, jfif, jpe, jpeg, jpg, jxl, pam, pbm, pgm, png, pnm, ppm, qoi, tga, tif, tiff, webp
ImageMagick	[magick]	3fr, aai, art, arw, ase, aseprite, bayer, bayera, bgr, bgra, bgro, c2pa, cal, cals, cmyk, cmyka, cr2, cr3, crw, cube, cur, cut, dcm, dcr, dcx, dng, dpx, dxt1, dxt5, erf, fax, fff, fit, fits, fl32, fts, ftxt, g3, g4, gray, graya, group4, hrz, icb, iiq, ipl, j2c, j2k, jng, jnx, jp2, jpc, jpm, jpt, k25, kdc, mac, map, mat, mdc, mef, miff, mng, mono, mos, mpc, mrw, mtv, nef, nrw, orf, otb, pal, palm, pango, pcds, pef, pes, pfm, pgx, phm, picon, pict, pix, pwp, raf, raw, rgb, rgb565, rgba, rgbo, rgf, rla, rle, rmf, rw2, rwl, scr, sct, sf3, sfw, sgi, six, sixel, sr2, srf, srw, stegano, sun, tim, tm2, uyvy, vda, vicar, viff, vips, vst, wbinfo, wbmp, x3f, xbm, xcf, xpm, xv, ycbcr, ycbcra, yuv

heic, heif, avif, avci, jxl and a still webp are decoded by a codec Windows provides rather than one this app carries, so each of those six stills needs its Store extension installed once; every other entry of [image] needs nothing installed.

Videos

Engine	config.ini	Default extensions
The media engine Windows 11 ships	[video]	3g2, 3gp, 3gpp, asf, avi, dvr-ms, m1v, m2t, m2ts, m2v, m4v, mkv, mov, mp4, mpe, mpeg, mpg, mts, qt, ts, vob, webm, wmv
FFmpeg's player (ffplay)	[ffmpeg]	264, 265, 266, apv, av1, avc, avs, avs2, avs3, bik, bk2, c93, cavs, cdg, cdxl, cin, cpk, dav, dif, divx, drc, dv, evc, f4v, flm, flv, gxf, h261, h263, h264, h265, h266, h26l, hevc, ifv, imx, ismv, ivf, ivr, kux, m2p, mj2, mjpeg, mjpg, mk3d, moflex, mpv, mve, mvi, mxf, mxg, nsv, nut, obu, ogm, ogv, pmp, psp, rcv, rm, rmvb, roq, rsd, smk, str, swf, thp, tod, tp, tr, ty, ty+, usm, vc1, vc2, viv, vro, vvc, vw, wtv, xl, xmv, y4m, yop
mpv	— (no list of its own)	union of [video] + [ffmpeg] above (23 + 84 = 107 names)

Audio

Engine	config.ini	Default extensions
The media engine Windows ships, then FFmpeg's player — the machine's answer, not a setting	[audio]	aac, ac3, aif, aifc, aiff, amr, ape, au, awb, caf, dff, dsf, dts, dtshd, eac3, flac, m4a, m4b, mka, mp2, mp3, mpa, mpc, oga, ogg, ofr, ofs, opus, ra, shn, snd, spx, tak, tta, voc, wav, wave, wma, wv

Text

Engine	config.ini	Default extensions
This app, syntax-highlighted	[text] extensions	adb, adoc, ads, asciidoc, asm, asp, aspx, astro, awk, bash, bat, bib, bzl, c, cc, cfg, cg, cjs, clj, cljc, cljs, cmake, cmd, comp, conf, cpp, cs, csh, cshtml, css, csv, csx, cts, cxx, d, dart, diff, diz, edn, ejs, el, elm, env, erb, erl, ex, exs, f, f03, f77, f90, f95, fish, for, frag, fs, fsi, fsx, ftn, fx, geom, glsl, go, gql, gradle, graphql, groovy, h, haml, hbs, hcl, hh, hlsl, hpp, hrl, hs, htm, html, hxx, inc, ini, ipynb, java, jl, js, json, json5, jsonc, jsonl, jsp, jsx, ksh, kt, kts, latex, less, lhs, liquid, lisp, ll, lock, log, lsp, lua, m, mak, man, markdown, md, mdown, metal, mjs, mk, mkd, ml, mli, mm, mts, mustache, nasm, nfo, nim, ninja, nix, njk, org, pas, patch, php, phtml, pl, plist, pm, properties, proto, ps1, psd1, psm1, py, pyi, pyw, r, rake, rb, rkt, rmd, rs, rst, rtf, s, sass, scala, scm, scss, sh, slim, sol, sql, srt, ss, styl, sv, svelte, svh, swift, tcl, tex, text, tf, tfvars, toml, ts, tsv, tsx, twig, txt, v, vbs, vert, vhd, vhdl, vtt, vue, wat, wgsl, xhtml, xml, xsd, xsl, xslt, yaml, yml, zig, zsh
This app, as plain text	[text] names	authors, .babelrc, brewfile, caddyfile, changelog, changes, .clang-format, .clang-tidy, cmakelists.txt, code_of_conduct, containerfile, contributing, contributors, copying, copyright, dockerfile, .dockerignore, .editorconfig, .env, .env.example, .env.local, .eslintignore, .eslintrc, gemfile, .gitattributes, .gitconfig, .gitignore, .gitkeep, .gitmodules, gnumakefile, .golangci.yml, history, .htaccess, install, jenkinsfile, justfile, licence, license, .mailmap, makefile, makefile.am, makefile.in, notice, .npmignore, .prettierignore, .prettierrc, procfile, rakefile, readme, .rustfmt.toml, security, .stylelintrc, unlicense, vagrantfile

Ebook

Engine	config.ini	Default extensions
The Windows PDF engine for the PDF's three spellings; this app's own readers for the three comic containers	[ebook]	cbc, cbr, cbz, epdf, pdf, pdfa
Calibre, which converts the book to a PDF first	[calibre]	azw, azw3, azw4, djvu, epub, fb2, htmlz, lit, lrf, mobi, pml, prc, snb, tcr

Archives

Engine	config.ini	Default extensions
This app, from each archive's own table of contents	[archive]	7z, apk, jar, rar, tar, tar.gz, tgz, xpi, zip, zipx
PeaZip	[peazip]	001, apfs, ar, arc, arj, bcm, br, bz2, bzip2, cab, chm, cpio, cramfs, deb, dmg, esd, gz, gzip, hfs, hfsx, hxs, iso, lha, lpaq8, lzh, lzma, msi, msp, pkg, ppkg, qcow, qcow2, rpm, squashfs, swm, taz, tbz, tbz2, tpz, txz, tzst, udf, udeb, vdi, vhd, vhdx, vmdk, wim, xar, xip, xz, z, zpaq, zst

Document

Engine	config.ini	Default extensions
Microsoft Office, falling back to LibreOffice where Office is absent	[office]	doc, docm, docx, dot, dotm, dotx, pot, potm, potx, pps, ppsm, ppsx, ppt, pptm, pptx, xls, xlsb, xlsm, xlsx, xlt, xltm, xltx
LibreOffice	[libre]	123, 602, abw, cdr, cgm, cmx, cwk, dbf, dif, dxf, fodg, fodp, fodt, gnm, gnumeric, hwp, key, lwp, mcw, met, mw, numbers, odb, odc, odf, odg, odm, odp, ods, odt, oth, otg, otm, otp, ots, ott, pages, pcd, pct, pcx, pdb, pm6, pmd, psw, pub, ras, sda, sdc, sdd, sdw, slk, stc, std, sti, stw, svm, sxd, sxg, sxi, sxm, sxw, vdx, vsd, vsdm, vsdx, vstx, wb2, wk1, wk3, wk4, wks, wpg, wq1, wq2, wpd, wps, wri, xlw, zabw, zmf

Vector

Engine	config.ini	Default extensions
WebView2 for svg and svgz; the drawing layer for the metafiles and the preview picture an EPS carries	[vector]	emf, epi, eps, epsf, epsi, ept, ept2, ept3, svg, svgz, wmf

Fonts

Engine	config.ini	Default extensions
WebView2 — a specimen page with the font in it	[font]	otf, ttc, ttf, woff, woff2

Design

Engine	config.ini	Default extensions
This app, from the flattened picture each format keeps of the whole document	[design]	ai, fig, kra, ora, procreate, psb, psd, sketch, xd

Installation

Each release provides two options:

• rust-hover-preview_<version>_x64-setup.exe — NSIS installer. Installs to %LOCALAPPDATA%\rust-hover-preview with an optional startup entry.
• rust-hover-preview.exe — portable standalone binary. Run it from any folder.

1. Open Releases.
2. Download your preferred asset.
3. Run the installer, or place the portable binary wherever you like.
4. Launch Rust Hover Preview.

No Rust toolchain is needed.

Optional: Enable Video Preview with mpv

For smoother playback and a better picture, install mpv: videos then play through it automatically, using your graphics card, with subtitles just working — including any .srt file beside the video.

The app finds mpv.exe beside itself, in your PATH, in MPV Player under Program Files, and in SVP 4's mpv64; where more than one is found, Codecs → Videos → MPV lets you pick which one plays.

mpv ships no installer of its own, so grab a Windows build from mpv's own installation page.

Option A: winget

winget install --id shinchiro.mpv -e

Option B: manual

1. Download a Windows build from https://mpv.io/installation/
2. Extract it, for example to C:\mpv
3. Add C:\mpv to your user PATH

Verify either way:

mpv --version

Optional: Enable Video Preview and Advanced Audio Processing with FFmpeg

FFmpeg adds the video formats and the audio ones Windows does not decode — the [ffmpeg] list, and the [audio] names Windows' own decoders do not reach. It also plays any [video] name the media engine turns down, or every video there is, where Engine → Video Engine names FFmpeg. ffplay and ffprobe need to be in your PATH.

Option A: winget

winget install --id Gyan.FFmpeg -e

Option B: manual

1. Download a Windows build from https://ffmpeg.org/download.html
2. Extract it, for example to C:\ffmpeg
3. Add C:\ffmpeg\bin to your user PATH

Verify either way:

ffplay -version
ffprobe -version

Optional: Enable More Video Codecs (Windows Codecs)

The media engine decodes H.264, MPEG-4, and WMV out of the box; each codec below is a separate free extension from the Microsoft Store, and none of them is needed while FFmpeg is installed.

Codec	Needs
HEVC (H.265)	HEVC Video Extensions
VP9	VP9 Video Extensions
AV1	AV1 Video Extension
MPEG-1 and MPEG-2	MPEG-2 Video Extension
Theora, Vorbis and Opus in an Ogg file	Web Media Extensions

All are free, official from Microsoft. Windows 11 usually has HEVC, VP9, and AV1 already. Installing one takes effect the next time the tray's Codecs menu is opened — no restart, nothing to configure.

Optional: Enable HEIC, AVIF, JPEG XL and WebP Preview (Windows Codecs)

A still heic, heif, avif, jxl, and still webp is decoded by a codec Windows provides rather than one shipped with the app. Each still needs its extension installed once from the Microsoft Store:

Still format	Needs
heic, heif	HEIF Image Extension + HEVC Video Extensions
avif	HEIF Image Extension + AV1 Video Extension
jxl	JPEG XL Image Extension, or the JXL support optional feature on Windows 11 24H2
webp	WebP Image Extension — optional: the app decodes WebP without it

All are free, official from Microsoft. Windows 11 often has HEIF, AV1, and WebP already. Where one is missing, hovering such a file shows no preview rather than an error.

Which of these a moving file needs is under Supported Formats above.

A .webp is the exception: it needs none of them, because the app carries its own libwebp decoder, so WebP previews even on Windows 10.

Optional: Enable CorelDRAW and Other Documents (LibreOffice)

cdr and everything else in the [libre] list is drawn by LibreOffice, which this app drives where it finds it — nothing is bundled with the app and there is nothing to configure. Install it once:

winget install -e --id TheDocumentFoundation.LibreOffice

Or download the official installer from https://www.libreoffice.org/download/ and run the suggested file (LibreOffice_*_Win_x86-64.msi; LibreOffice ships an .msi, not an .exe).

Optional: Enable Camera Raw and More Pictures (ImageMagick)

nef and everything else in the [magick] list is developed by ImageMagick, which this app runs where it finds it — nothing is bundled with the app and there is nothing to configure. Install it once:

winget install -e --id ImageMagick.ImageMagick

Or download the official installer from https://imagemagick.org/download/ and run the suggested file (ImageMagick-*-Q16-HDRI-x64-dll.exe).

Optional: Enable Niche Archives (PeaZip)

cab and everything else in the [peazip] list is listed by PeaZip, which this app runs where it finds it — nothing is bundled with the app and there is nothing to configure. Install it once:

winget install -e --id Giorgiotani.Peazip

Or download the official installer from https://peazip.github.io/peazip-64bit.html and run the suggested file (peazip-*.WIN64.exe).

Optional: Enable Ebooks (Calibre)

mobi and everything else in the [calibre] list is converted by Calibre, which this app runs where it finds it — nothing is bundled with the app and there is nothing to configure. Install it once:

winget install -e --id calibre.calibre

Or download the official installer from https://calibre-ebook.com/download_windows and run the suggested file (calibre-*-64bit.msi).

Warning

If winget reports an error, the package sources are usually why: run winget source reset --force.

If that is refused as well, open Terminal as administrator (right-click the Start button → Terminal (Admin)) and run the same command from there.

Usage

1. Start the app — a tray icon appears.
2. Hover media files in Explorer to preview them.
3. Or navigate with the keyboard — arrow keys, Tab, or a file's name typed to jump to it — to preview the focused item.
4. Use SPACE (by default) to pin the preview.
5. Right-click the tray icon to configure behavior.

Pin mode works like Quick Look: pressing Space (pin_key, watched while pin_enabled) turns the settled preview into an always-on-top window. Space in a focused pin pauses and resumes a sound; a minimized pin sits in a draggable bubble that Space in Explorer brings back. Arrow keys walk siblings, Escape closes.

System Tray Menu

A setting marked (Default) is what an untouched setting would be. The check or radio mark shows what is set now.

• Enable Preview — Turn previews on or off.
• Pin Mode — Everything about pinning, in one place.
  • Enable (Space) — Turn pinning on or off.
    • Pressing the key while a preview is up turns it into a window of its own: captioned, movable, resizable, always on top, and still there when the pointer leaves.
    • The caption carries Previous, Next, Open With, and Open With....
      • Previous / Next — Step the pin through the sibling files in the folder it was taken up in, in the order the listing is showing them; step over any one that will not open rather than stopping there.
      • Open With — Opens the file in whatever program Windows has registered for it.
      • Open With... — Asks you to pick one from the list Windows keeps of the programs that could.
      • The two hand-off buttons name themselves while the pointer rests on them; Open With names the program it would use.
    • Its edges resize it; what that does depends on what is inside.
      • A picture, video, or rendered page keeps its own shape.
      • A document or listing is laid out to whatever box it is given.
      • A sound's card keeps the size Audio names, and a video ffplay has is not resized at all.
    • A picture's caption and bar are drawn over the media rather than in bands around it, and fade in as the pointer arrives; only the strip under the pointer is shown.
    • A pinned video carries a transport bar of its own: play/pause, a draggable seek bar, and the two clocks.
      • Where FFmpeg's player is the one playing it, a read-out bar appears instead, since that player can be told nothing.
    • A pinned sound's card carries four buttons of its own: Previous, Play/Pause, Next, and Volume.
      • Space holds a sound where it stood and sets it going again from there.
      • A click on a sound's bar takes the file to that second.
      • A right-click on the card opens the card's own menu in a panel of its own over the screen: the whole of what a pin does — the two ways out, the file's own playback, then Shuffle, End of File and Seek.
    • A pinned text preview comes up in full mode, so it scrolls and its text can be selected and copied.
      • Ctrl+A selects all of it; Ctrl+C copies what is selected.
    • A pinned video has a transport bar with a volume of its own, set on the window; it does not change Volume → Video.
    • Maximize fits the window to the screen.
    • Minimize puts the window away, either into a round bubble on the desktop that can be dragged anywhere and clicked to bring the window back (a right-click on the bubble opens its own menu: the same playback rows, then Pause on Minimize where the kind behind it plays something, then the ways out; Play there gives back a park the collapse made, without waiting for the window), or into the app's own taskbar button — see Minimize under Pin Mode below.
    • Clicking the window gives it the keyboard; then the arrow keys step it and Escape closes it.
    • The pin key itself only ever puts a pin up and brings back a bubble; it never hides one.
    • The key is named in the item and can be changed in config.ini (pin_key).
  • Update Preview — Whether a pin that is up is shown the file you pick next.
    • Follow Selection — On by default.
      • A file you click, or one the keyboard selects, is shown where the window already stands, rather than as a second preview beside it.
      • A file named this way that cannot be shown leaves the window on the file it already had.
      • Stepping over a file that will not open belongs to the caption's own Previous and Next, which you pressed.
      • A sound's card is drawn at the size its Audio setting names, in the middle of that box; it follows System → Theme, and no longer Font Size.
      • The keyboard half follows Explorer, so it pauses while a pinned window holds the keyboard; click back into the listing and it carries on.
    • On Hover — Off by default.
      • On, the pointer's own hover is one of the ways a pin is told about a file, the way a Quick Look window follows a listing.
      • Greyed while Follow Selection is off.
  • Minimize — Where a window put away by its Minimize button goes, and what it does with what it was playing while it is away.
    • To Bubble (Default) — The window collapses into the round bubble on the desktop, and this app never appears in the taskbar.
    • To Taskbar — The window leaves the screen and the app appears in the taskbar as its own button, titled Rust Preview; clicking the button brings the pinned window back where it stood, and a right-click on the button closes the window.
    • A window is away either way, so previews stay held back until it is brought back, whichever place the setting names.
    • What a window put away holds where it is is Pause on Minimize at the top of each kind's own Pin Mode — one under Preview Settings → Video, one under Preview Settings → Audio — because what should go quiet while a pin is away is a question about one kind of file.
  • Navigation — What Previous and Next on the caption step through: three anchors — Video, Audio, Others — each with All Files / Same Category. The walk is anchored on the first file pinned, so a video walks videos while a document walks end to end.
    • The walk is the pin's own: one playlist spawned when the pin is taken up and stepped along, so a Previous is the file the walk came from and the Next after it is the file it was interrupted on. A file picked in the listing inside that folder carries the playlist on; one anywhere else starts fresh.
    • Video and Audio start at Same Category, Others at All Files.
    • Both work with Update Preview off; they are a thing you pressed, and no setting asks for them.
    • The arrow keys step the same way, and are asked for by nothing at all — but only once you have clicked the pinned window, which gives it the keyboard. Until you do, the arrows belong to whatever is in front.
    • Space in a pinned sound pauses and resumes it, on the same terms.
    • Escape in a pinned window closes it.
    • All Files — Every file this build can preview, in the folder the pin was taken up in and not any subfolder of it, in the order the Explorer listing is showing them. A video sits beside a sound.
    • Same Category — Only the files of the walk's anchor category: video, audio, or the anchor's own kind for Others.
      • A camera raw is a picture and a book is a document, because that is what you call them.
      • A kind switched off under Preview Types, or one with no engine installed on the machine, is not a step either way.
      • A file this build could preview but that will not open is a step the window steps over rather than one it stops on.
• Preview Types — Choose which file kinds can preview: Image, Video, Audio, Text, Ebook, Archive, Document, Vector, Font, Design.
  • A switch is a switch over behaviour, not over files: the lists deciding which files are previewed are untouched, so switching a kind off and back on restores what was configured.
  • One switch covers both the original file and the engine-drawn preview.
    • Camera raw uses Images.
    • A LibreOffice document uses Document.
    • A PeaZip archive uses Archives.
    • A Calibre book uses Ebook, as do the app-drawn PDF and comic pages.
• Preview Settings — What each kind's previews are like, below Preview Types: one half per kind that has settings beyond whether it previews at all, named for the kind and nothing else. What a film and a sound are heard at is the Volume submenu below Background, since the level is the one question both kinds answer the same way.
  • Video — What a film's previews are like: whether a hovered one goes round, and what a pinned one does.
    • Subtitles — Whether a film's own subtitle tracks are probed for and copied out at all, which is what General (Disk) holds between hovers; 0 there draws a film without them.
      • Where the engine that will play is mpv the row reads Subtitles (MPV) and is not about a copy at all: mpv finds a film's own tracks and the .srt beside it and draws them itself, so nothing is extracted and the pinned T key does nothing on that route.
    • Loop — On by default: a hovered film goes round at the end of its file. Off, it stops there.
    • Pin Mode — What a pinned film does.
      • Pause on Minimize — On by default: a film put away by the Minimize button is held where it stood and started again at the second it stopped at when the window comes back, rather than playing on behind a bubble nobody can see.
      • Shuffle — Off by default: whether a forward step of the walk takes a random film of the anchor's kind rather than the one beside it. A step back is the file the walk came from.
      • End of File — What a pinned film does at the end of its file: Loop (default), Pause (the file left where it ended, the bar and the play button standing there), or Jump — the walk's next file, which the Shuffle row decides between the file beside it and a random one of the same kind.
  • Audio — The same questions for a sound, and the two places a sound starts: where a hovered one does and where a pinned one does.
  • Loop — On by default: a hovered sound goes round at the end of its file. Off, it stops there.
  • Seek — Where in a file a hovered sound starts playing.
    • Remember (default) — Picks it up where the last hover left it.
    • From the Start — Always begins at the beginning.
    • From the Middle — Drops it half way in.
    • Random — Anywhere at all.
    • The remembered positions are kept in a small file under %TEMP%\rust-hover-preview\audio, so they survive a restart; nothing is remembered while another mode is chosen.
    • A video is always played from its beginning.
  • Pin Mode — What a pinned sound does.
    • Pause on Minimize — On by default: the sound a pin put away was playing is held where it stood and started again at the second it stopped at when the window comes back.
    • Shuffle and End of File — the same two rows as a film's, asked of a sound: a forward step takes a random sound rather than the one beside it, and a file that ends goes round, holds where it stopped, or steps on to the next.
    • Seek — Where in a file a pinned sound starts playing: From the Start (default), Remember, From the Middle, or Random.
  • Text — What a text preview is painted with: the font size, how Markdown is shown, and whether a page of HTML runs.
    • Font Size — 400% at the top down to 70% at the bottom.
    • Markdown — Rendered or Source.
    • Render HTML — Off by default.
      • On, a .htm or .html file is previewed as the page it holds rather than as its markup, run by the browser engine.
      • A page is the one thing previewed as a page rather than as a picture, so it is the one thing that runs, and a page that draws itself with script has nothing to show without a run.
      • What it may still do is bounded: the frame it is shown in cannot open forms or popups or navigate, and nothing a page links to is fetched.
      • SVG documents and font specimens, which a browser is handed as an image, are still drawn rather than run.
      • A running page can be pointed at, clicked into and typed into; a document, a specimen and every other preview still cannot.
    • Without the engine on the machine it stays a text preview.
  • Image — Pin Mode, and the whole of it: Shuffle, whether a pinned picture's walk takes the next file at random. A picture has no level, no end of file and nowhere in it to start, and a hover has no next file, so the shuffle is the one thing a picture answers.
• Timing
  • Prioritize Keyboard — On by default.
    • The file under a pointer that has not been moved does not preview of its own while the keyboard is driving Explorer, so pressing a key onto a file with no preview of its own behaves like pressing one onto a file that has a preview.
    • The pointer takes the screen back when it is moved, when the wheel is turned, or when a folder change hands it over.
    • Off, the pointer's own hover always wins.
  • Trigger Key (Alt) — The key is named in the item.
    • Enable Trigger Key — Whether the key is watched.
    • Affect Pin Mode — Off by default, and off at the start.
      • A pinned window is one you put there, so the key that holds back hovers is not read while one is up.
      • On, holding it brings the pin down along with the previews it stops.
      • It speaks for Hold to Disable Preview.
    • Hold to Disable Preview / Hold to Enable Preview — What holding the key does.
  • Hover Delay — How long the pointer rests before a preview opens: 0 ms at the top down to 1000 ms at the bottom. Default 0 ms.
  • Rehover Delay — Wait before the same file can preview again. Default 200 ms.
  • Settling Delay — How still the pointer must be before previewing what it is on.
    • Default 0 ms means a new file can preview while the hand is still moving.
    • Keyboard previews ignore this.
• Placement
  • Position — Follow Cursor or Best Position. Default Best Position.
  • Avoid — Nothing, Filename (default), Filename Column, or Details.
    • Keeps a preview off the item it is about.
    • Keyboard previews have no cursor, so Nothing acts like Filename.
• Scaling
  • Image — Fit to Screen, a share of the display's fitted size (75%, 50%, 25%, 10%), or a share of the image's own size (400%–25%). The two groups are listed under By Screen and By Own Size. Default 100%.
  • Video — Same shares for a video, except that Fit to Screen is the display's room: a film smaller than the screen fills it, as a pinned window and a maximize already do. Default 100%.
  • Animated — Same shares for an animated GIF, WebP, or PNG — and for an animated JPEG XL, which plays through the same machinery.
    • A still GIF or PNG uses Image.
    • Default 100%.
  • Audio — 25%, 20%, 15%, 10% (default), 7%, or 5% of the display, for a sound's card — the whole card scales with the share: font, height and width, the way Windows scaling sizes a window.
    • The card at any share is the 10% card uniformly smaller or larger (~188×50 at 5% to ~936×250 at 25% on a 3440×1440 display), its seek bar stretching with the width, its height what its content measures at the share's font.
    • Built at the share's own font (the default text size, 125%, at the 10% anchor), so Font Size does not resize it; a pinned sound's card is the same size as the hover's.
  • Vector — Fit to Screen (default), or 75%, 50%, 25%, 10% of the display.
  • Text — Same display shares for a text preview — a plain text file, code, or Markdown.
    • It caps how much of the screen the preview box may take when it opens; a short file still gets the small box its own text needs.
    • Default Fit to Screen.
  • Ebook — Fit to Screen (default), or the same display shares for a PDF page, a comic's first page, and a Calibre-converted book.
  • Document — Same display shares for a document drawn as a page, whether by its own Office app or by LibreOffice.
    • A workbook's fallback bitmap is never enlarged.
  • Font — Same shares for a font specimen. Default 50%.
  • Design — Same display shares for design documents: Photoshop, Illustrator, Krita, OpenRaster, Procreate. Default Fit to Screen.
• Background
  • Image — Transparent, Black, White, or Checkerboard. Default Checkerboard.
  • Vector — Same backdrops for an SVG document or metafile. Default Checkerboard.
  • HTML — White, Black, or Checkerboard for a page of HTML. Default White.
    • The see-through backdrop is not offered: a page is drawn on a page, whether it runs or not, and the backdrop is behind the page rather than behind what it paints.
  • Font — Same backdrops for a font specimen. Default White.
  • DDS — Black or White for .dds textures. Default White.
    • The two see-through backdrops are not offered.
  • Design — Same as picture backdrops for a design document. Default Checkerboard.
• Volume — What a film and a sound are heard at: one menu with a Video half and an Audio half, below Background and above Performance. Each half carries Normalize (Expensive) (loudness measured and brought to -14 LUFS; greyed without FFmpeg) and Remember Level above its levels.
  • Video — 100% down to 0%, loudest first. A film's soundtrack starts at 0%, so a hover never makes a sound the pointer did not ask for.
  • Audio — The same levels; a sound file starts at 10%, and a sound at 0% still shows its card, silently.
• Performance
  • Cache — What a preview may cost between hovers: 2 GB down to 0 MB.
    • Image (RAM) = decoded frames kept in memory.
    • Document (Disk) = engine-drawn pages kept as temp files.
    • Image (Disk) = the pictures ImageMagick developed, kept as temp files.
    • General (Disk) = the subtitle tracks a film's embedded ones are copied into, kept as temp files; 0 draws a film without its subtitles.
  • Decode Budget — 16 GB down to 512 MB; default 1 GB. A file past it gets no preview.
  • Explorer Poll — How often the app checks Explorer while a folder window is focused: 15 ms (default), 31, 47, 63, or 78 ms.
    • Lower answers a move sooner; higher is lighter on CPU and Explorer.
  • Hardware Acceleration (Video) — checked by default: a video FFmpeg's player has is decoded on the graphics card rather than on a core.
    • It is a setting about this build's FFmpeg rather than about a kind of file — a file the media engine plays is decoded by Windows either way.
    • A machine with no device FFmpeg can decode on is the one the setting is for, where FFmpeg falls back by itself.
• Engine
  • Away Timer — How long Explorer may be unreachable before a non-Persistent engine is let go: 1 hour, 30 minutes, 10 minutes, 5 minutes, 1 minute (default), 30 seconds, 15 seconds.
    • Counts time when no Explorer window is reachable on any monitor.
    • A second Explorer window keeps engines warm.
    • Each … TTL submenu has a Persistent toggle at the top.
  • Video Engine — Which engine plays a video.
    • Best (default) — The machine's own answer: mpv for every video where it is installed, and otherwise the media engine for a film at or under 3.2 megapixels and FFmpeg's player for a larger one or one it could not measure.
    • MPV — mpv alone.
    • Native — The media engine alone.
    • FFmpeg — ffplay alone.
    • Native (FFmpeg above 3.2MP) — That size rule stated plainly.
    • A Fallback switch at the top (default on) lets a chosen engine that cannot play a given file fall through to the engines it may: MPV reaches both of the others, while Native and FFmpeg still only reach each other. Off, the engine you chose stands alone.
    • MPV is greyed out where mpv is not installed; FFmpeg and Native (FFmpeg above 3.2MP) where ffplay is not.
  • Office Engine — Which engine draws Office documents.
    • Microsoft Office (default) — Uses the format's own app and falls back to LibreOffice.
    • LibreOffice — Draws every Office document.
    • LibreOffice is greyed out if not installed.
  • Microsoft Office TTL — With Persistent on: how long a family's Office app stays warm: Indefinitely, 1 hour, 30 minutes, 10 minutes (default), 5 minutes, 1 minute, 0 seconds.
    • Off: kept while Explorer is reachable, then let go by Away Timer.
  • LibreOffice TTL — Same for the engine that draws CorelDRAW and nearby formats.
    • A kept engine converts the next document faster: 1.2 s cold vs 0.2 s, but uses a few hundred MB.
    • 0 seconds means one engine per document.
    • Both TTLs apply to Persistent engines; non-persistent ones use Away Timer.
    • Greyed out if LibreOffice is not installed.
  • WebView2 TTL — With Persistent on: how long the SVG browser stays warm.
    • Off: let go by Away Timer.
    • Greyed out if WebView2 is missing.
  • No ImageMagick TTL, PeaZip TTL, or Calibre TTL: those tools run once and exit, so idle time cannot bound them. A second hover is a cache hit.
• Codecs — What this machine has: Videos, Audio, Images, Engines.
  • A missing one carries a cross, and where the README names a page for it, picking the row offers to open that page — nothing is installed or downloaded by the app itself.
  • Videos → MPV opens a submenu of every mpv this machine has where there is more than one — the standalone install and SVP's own, say — each named by its path, with the one in use marked. Picking one is remembered as mpv_path.
• System (vX.Y.Z)
  • Check for Updates — Whether the app asks GitHub for a newer release on its own, at startup and when the menu is opened. On by default; at most once every six hours. Where one is found, the Update Available row appears above this submenu on the menu's next opening; where none is, nothing happens. Turning it on asks at once.
  • Run at Startup — Add or remove the Windows startup entry.
    • On every start, an entry that names another copy of the app — a portable copy, an older version, a path that has moved — is pointed back at the one you are running.
  • Theme — Atom One Light, One Dark Pro, or any .tmTheme in %APPDATA%\rust-hover-preview\theme. The look is the app's own rather than a text preview's, so it sits beside the rows about the app.
  • Edit Config.ini — Open the configuration file in its default editor.
• Exit — Close the app.

Configuration

Settings are stored at:

%APPDATA%\rust-hover-preview\config.ini

The file is watched, and changes apply without a restart. A read takes what the file says and puts right in the app what it cannot read — the file itself is left alone until the next start, so a hand edit is never written over while it is being made. A save writes the whole file beside it, flushed to the disk, and moves it into place, so a save cut short leaves the file that was there; a file holding no setting of its own is not read as a configuration, and is left exactly where it is.

Example, trimmed:

[settings]
; General
check_for_updates=true
pin_enabled=true
pin_key=space
pin_nav_audio=category
pin_nav_others=all
pin_nav_video=category
pin_update_enabled=true
pin_update_on_hover=false
preview_enabled=true
run_at_startup=true
theme=light

; Minimize
pin_minimize_to=bubble
pin_pause_audio=true
pin_pause_video=true

; Preview Types
archive_preview_enabled=true
audio_preview_enabled=true
design_preview_enabled=true
document_preview_enabled=true
ebook_preview_enabled=true
font_preview_enabled=true
image_preview_enabled=true
text_preview_enabled=true
vector_preview_enabled=true
video_preview_enabled=true

; Text Preview
markdown_mode=rendered
render_html=false
text_font_scale=125

; Timing
hover_delay_ms=0
prioritize_keyboard=true
same_file_rehover_delay_ms=200
settling_delay_ms=0
trigger_key=alt
trigger_key_affect_pin_mode=false
trigger_key_enabled=true
trigger_key_mode=disable

; Placement
avoid_mode=filename
follow_cursor=false

; Scaling
animated_scale=100
audio_scale=10
design_scale=fit
document_scale=fit
ebook_scale=fit
font_scale=50
preview_scale=100
text_scale=fit
vector_scale=fit
video_scale=100

; Background
dds_background=white
design_background=checkerboard
font_background=white
html_background=white
image_background=checkerboard
vector_background=checkerboard

; Volume
audio_loop=true
audio_seek=remember
audio_volume=10
normalize_video_volume=false
normalize_volume=false
pin_mode_audio_end_of_file=loop
pin_mode_audio_seek=start
pin_mode_audio_shuffle=false
pin_mode_image_shuffle=false
pin_mode_video_end_of_file=loop
pin_mode_video_shuffle=false
remember_audio_volume=true
remember_video_volume=true
video_loop=true
video_volume=0

; Performance
decode_budget_gb=1
document_cache_mb=256
general_disk_cache_mb=128
image_cache_mb=64
image_disk_cache_mb=512
tick_ms=15
video_hw_accel=true

; Engine
afk_timer_seconds=60
libreoffice_idle=600
libreoffice_persistent=false
office_engine=microsoft_office
office_engine_idle=600
office_engine_persistent=false
video_engine=best
video_engine_fallback=true
webview_idle=600
webview_persistent=false

; Advanced
hdr_exposure=0
hdr_tone_map=reinhard
spinner_delay_ms=250

Here's what this .INI does:

Look and text

• theme: light, dark, or custom:<name>.
• markdown_mode: show Markdown as rendered or source.
• text_font_scale: 1–1000%, default 125; archive lists follow it too.
• render_html: false by default.
  • On, .htm and .html files are run as the pages they hold by the browser engine, at the share of the screen Document Scaling names.
  • That is the one kind of preview a pointer and a keyboard reach: the page's own box holds the pointer, and a click into it gives the keys.
  • Without that engine, they are text like before.

What can preview

• *_preview_enabled: turn each preview type on or off. File lists stay normal.
• extensions under each kind's section: which files that kind previews.
  • Kinds: image, video, ffmpeg, audio, text (which also carries a names key for files with no extension), archive, office, font, design, vector, ebook, libre, magick, peazip, calibre.
  • No dots.
  • An entry with a dot, like tar.gz, matches the end of the file name.
  • A name two sections hold belongs to the earlier kind, so the kind decides which switch applies to it.
• Which engine plays a sound is the machine's answer rather than a setting: the media engine Windows has is asked first and an installed FFmpeg second.

Video and audio

• video_loop / audio_loop: whether a hovered film or sound goes round at the end of its file. Both default true; off, it stops at the end.
• pin_mode_video_end_of_file / pin_mode_audio_end_of_file: what a pinned film or sound does at the end of its file — loop (default), pause (the file left where it ended, the card holding it with a play button), or continue (the walk's next file).
• pin_mode_video_shuffle / pin_mode_audio_shuffle: whether a forward step of a pinned walk takes a random file of the anchor's kind rather than the one beside it. Both default false; a step back is the file the walk came from.
• pin_mode_image_shuffle: the same question asked of a pinned picture's walk, which has no end of file to jump from — its shuffle is the caption's buttons and the keyboard's alone. Default false.
• pin_mode_audio_seek: where in a file a pinned sound starts playing — start (default), remember, middle, or random.
• audio_seek: where in a file a hovered sound starts playing.
  • remember (default) picks it up where the last hover left it, start always begins at the beginning, middle drops it half way in, and random anywhere at all.
  • The remembered positions are kept in a small file under %TEMP%\rust-hover-preview\audio, so they survive a restart; nothing is remembered while another mode is chosen.
  • A video is always played from its beginning.
• A video's engine is the video_engine setting; the two lists decide which engine is asked about a name — the media engine takes only [video] names, and an [ffmpeg] name is FFmpeg's alone.

Memory and cache

• image_cache_mb: memory for decoded image frames. Default 64, max 2048; 0 holds nothing.
• document_cache_mb: disk cache for rendered document pages. Default 256, max 2048; 0 keeps nothing between hovers but still draws the current one. Pages live under %TEMP%\rust-hover-preview\document; the least recently read page is removed first.
• image_disk_cache_mb: disk cache for the pictures ImageMagick developed. Default 512, max 2048; 0 keeps nothing between hovers but still develops the current one. Pictures live under %TEMP%\rust-hover-preview\image; the least recently read one is removed first, and they survive a restart.
• general_disk_cache_mb: disk cache for the subtitle tracks a film's embedded ones are copied into. Default 128, max 2048; 0 extracts nothing, and a film whose subtitles are embedded is drawn without them. Files live under %TEMP%\rust-hover-preview\general, least recently used first.
• decode_budget_gb: most memory one hover may use. Default 1, range 0.25–64. A file over the limit shows no preview.

Performance

• video_hw_accel: whether a video FFmpeg's player has is decoded on the graphics card rather than on a core — the tray's Performance → Hardware Acceleration → Video.
  • Default true.
  • It is a setting about this build's FFmpeg rather than about a kind of file: a file the media engine plays is decoded by Windows either way, and a machine with no device FFmpeg can decode on is the one the setting is for, where FFmpeg falls back by itself.

HDR

• hdr_tone_map: how HDR/EXR light becomes screen values: reinhard default, aces, srgb, or off. PNG/JPEG are not affected.
• hdr_exposure: stops shifted before that curve. Default 0, range -10 to 10.

Waiting and engines

• spinner_delay_ms: wait before showing the loading spinner. Default 250; 0 shows it immediately.
  • One delay covers all preview types, and a pinned window being shown another file with it.
  • A pin that has to wait shows a spinner of its own in the middle of itself, drawn over the file it is still showing rather than in place of it, and the window is never hidden while it waits.
• office_engine: microsoft_office default, falls back to LibreOffice when needed; or libreoffice, which always uses LibreOffice. If LibreOffice is missing, it falls back and the tray row is greyed out.
• video_engine: which engine plays a video: best (default), mpv, native, ffmpeg, or hybrid.
  • Best is the machine's own answer — mpv where it is installed, and otherwise hybrid where FFmpeg is installed (the media engine draws a film at or under 3.2 megapixels, FFmpeg's player takes a larger one or one it could not measure) and native where neither is.
  • mpv names mpv alone, native names the media engine alone, ffmpeg names ffplay alone, and hybrid states that size rule plainly.
  • A choice this machine cannot supply is read as best.
• mpv_path: which mpv.exe plays, written by Codecs → Videos → MPV where the machine has more than one. Empty, the default, means the first one found — beside the app, then the PATH, then MPV Player under Program Files, then SVP's mpv64. The only setting that holds a path.
• video_engine_fallback: true (default) lets a chosen engine that cannot play a given file fall through to the engines it may — a chosen mpv to both of the others, native and ffmpeg to each other — and false makes the engine you chose stand alone. Read only where video_engine names an engine; Best is its own walk either way.
• libreoffice_idle / office_engine_idle: seconds the engine is kept after its last page, or indefinitely. Default 600; 0 launches it per document.
• afk_timer_seconds: seconds with no Explorer window before a non-persistent engine is released. Default 60, max one day. 0 releases immediately.
• office_engine_persistent, libreoffice_persistent, webview_persistent: true keeps that engine always, bounded only by its …_idle time. false default keeps it while Explorer is reachable, bounded by afk_timer_seconds.

Trigger and position

• trigger_key / trigger_key_mode / trigger_key_enabled: the key (alt, ctrl, shift, win), what it does (disable or enable), and whether it is watched. Default true.
• trigger_key_affect_pin_mode: whether the trigger key reaches a pinned preview. Default false — the key is not read while a preview is pinned, up or collapsed into its bubble, since a pin is a window you put there rather than a hover for the key to hold back. true lets holding the key bring the pin down with the previews it stops. It speaks for disable; the enable mode is left as it is.
• pin_key / pin_enabled: the key that pins the preview on screen (space by default — the same spellings the trigger key takes: alt, f8, a, space, …), and whether it is watched. See Pin Mode above for what a pin does.
• pin_update_enabled: whether a pin that is up is shown the file picked next, by click or by keyboard, without moving the window. Default true.
  • Off, the pin keeps the file it was taken up on until it is closed — a pin is also a window to read in, and one that swapped its file out from under the hand on every keystroke would be unreadable.
  • The keyboard half follows Explorer, so it is inert while a pinned window holds the keyboard — click back into the listing and it resumes.
• pin_update_on_hover: whether that following includes the pointer's own hover, or only what a click or a key asks for. Default false; greyed in the tray while pin_update_enabled is off.
• pin_nav_video / pin_nav_audio / pin_nav_others: what the caption's Previous and Next buttons step through, by the walk's anchor — the first file pinned. Video and Audio default to category, Others to all.
  • all is every file this build can preview, so a video steps to the sound beside it.
  • category narrows the walk to the anchor's category — video, audio, or the anchor's own kind for Others, where a camera raw is a picture and a book is a document.
  • The walk is the folder the pin was taken up in and no subfolder of it, is in the order the Explorer listing is showing, wraps at both ends, and is held per folder, read on the first press rather than when the pin is taken up.
  • A file it reaches that the window cannot show is stepped over, and the walk is bounded by the folder: each other file is offered at most once, so a folder of nothing this build can read ends the walk instead of going round for ever.
  • A file holding only the old pin_nav_file_types seeds all three with it; a file written before any of them existed walks as the fresh defaults do.
• pin_minimize_to: where a pin put away by the window's own Minimize button goes. bubble (default) leaves the round bubble on the desktop and keeps this app out of the taskbar; taskbar takes the window off the screen and shows this app's own taskbar button (titled Rust Preview), which brings the pin back where it stood when clicked and closes it on a right-click. Read when the button is pressed, so a change reaches the next minimize; a file written before this setting existed is read as bubble.
• pin_pause_video / pin_pause_audio: whether a pin put away into its bubble or the taskbar holds what it was playing where it stands, and starts it again at the second it stopped at when the window comes back up. Both default true. They are two switches because a video and a sound are two different things to want quiet.
• follow_cursor: true = Follow Cursor; false = Best Position.
• avoid_mode: filename default, filename_column, details, or off — what the preview avoids.

Scaling

• preview_scale: fit, a share of the display's fitted size (screen 75, screen 50, screen 25 or screen 10 — the display fitted to the media, reduced to that share of it), or a share of the picture's own size (25–400). Default 100.
• video_scale: same for video. Default 100.
• audio_scale: the share of the display a sound's card is laid out over — 25, 20, 15, 10, 7 or 5. Default 10. The whole card scales with the share (font, height, width), so it's the 10% card uniformly smaller or larger, and Text Size no longer resizes it. A hand-edited value is sanitized rather than fatal: 100 or more reads as 100, 0 reads as 10, an unrecognized value is ignored.
• animated_scale: same for animated GIF, WebP, or PNG — and for an animated JPEG XL, which is played as a picture rather than as a video. Default 100. Still GIF/PNG follow preview_scale.
• vector_scale: percentage or fit, based on the screen. Default fit; 100 or more reads as fit. Covers all Vector drawings. Old svg_scale is ignored and removed.
• text_scale: how much of the screen a text preview box may take when it opens, for plain text, code, and Markdown. Default fit; 100 or more reads as fit. Text Size still scales the text inside that box.
• ebook_scale: PDF page scale against the screen. Default fit; 100 or more reads as fit.
• document_scale: document page scale against the screen. Default fit. A workbook's fallback bitmap keeps its own size and is never enlarged.
• font_scale: font preview scale against the screen. Default 50; fit means all of it; 100 or more reads as fit.
• design_scale: design document scale against the screen. Default fit.

Fonts

• ttc_face: which face of a .ttc is drawn. 1 is first, max 10. The heading shows which face came out.

Backgrounds

• image_background: checkerboard default, black, white, or transparent. Also used for PDF pages, painted text frames, and document pages. Old transparent_background is ignored and removed.
• font_background: white default, black, checkerboard, or transparent.
• dds_background: white default or black, and only those two. Any other value reads as white.
• vector_background: checkerboard default, white, black, or transparent. Used for SVG pages and metafiles. Old svg_background is ignored and removed.
• html_background: white default, black, or checkerboard, and only those three — a page is drawn on a page, so transparency is not one of the backdrops it is offered. Used for a page of HTML previewed by render_html, run or not; any other value reads as white.
• design_background: checkerboard default, white, black, or transparent.

Old or removed names

• magick_preview_enabled and peazip_preview_enabled: not read. ImageMagick pictures use image_preview_enabled; PeaZip archives use archive_preview_enabled.
• libre_preview_enabled and libre_scale: gone. Use document_preview_enabled and document_scale.
• office_cache_mb and libre_cache_mb: gone. Use document_cache_mb. If both old ones exist, the larger is read once, then both are removed.
• text_preview_full_mode: gone. A pinned text preview comes up in full mode instead, so it scrolls and its text can be selected and copied.
• pin_nav_file_types: gone. Use pin_nav_video, pin_nav_audio and pin_nav_others; a file holding only the old key seeds all three with it.
• video_jump_enabled / audio_jump_enabled: gone. Use video_loop / audio_loop.
• pin_mode_video_jump_enabled, pin_mode_audio_jump_enabled, pin_mode_video_jump, pin_mode_audio_jump and pin_mode_audio_loop: gone, replaced by pin_mode_video_end_of_file/pin_mode_audio_end_of_file beside pin_mode_video_shuffle/pin_mode_audio_shuffle. A file holding one is read once into the settings that replaced it — …_jump_enabled = false as pause, …_jump = shuffle as continue with shuffle on, an old …_loop as continue — and the retired keys are dropped on the next save.
• No magick_idle, peazip_idle, or calibre_idle. ImageMagick, PeaZip, and Calibre are converters, not engines kept open. A second hover usually costs only a cache hit.

Extension list behavior

• A deleted extensions= line or whole section comes back with built-in entries.
• An extensions= line left empty stays empty.

Build from Source

Requirements: Windows 11, Rust 1.98.1+, Visual Studio Build Tools (MSVC / C++), and the Windows SDK.

cargo build            # debug
cargo build --release  # release

The release binary is written to target/release/rust-hover-preview.exe. A release build ends a running copy first, since Windows will not let the linker replace an open binary. Debug builds are left alone.

Architecture

See ARCHITECTURE.md for the full system overview. In short: Windows accessibility APIs and Shell COM identify the hovered or focused Explorer item, and GDI paints the preview into a topmost layered window. Text and code are highlighted with TextMate-style themes, Markdown is rendered, archive contents are listed from the archives' own tables of contents — or from the listing an installed PeaZip produces for the formats no reader here has — Office documents are drawn from a page Office renders in the background, WebView2 draws SVG documents and font specimens, and runs HTML pages where Render HTML is switched on, camera raw and the pictures beside it are developed by ImageMagick, and video is played by mpv where installed, and otherwise by Windows' own media engine for small films and FFmpeg's player for large ones. Pressing Space pins the preview into a captioned, always-on-top window of its own.

TODO

See TODO.md for planned work, known bugs, and other issues.

Privacy

Rust Hover Preview is local-first: previews work without an internet connection, and the only network request is an update check, which runs only at startup and when you open the tray menu, at most once every six hours, and never while Check for Updates is switched off. There is no telemetry, analytics, ads, accounts, or crash reporting; it reads only the item you hover or focus in Explorer, locally and only for enabled preview types, and cloud-only placeholders are skipped on purpose while password-protected files are never bypassed. Settings and themes live under %APPDATA%\rust-hover-preview; optional previews use locally installed mpv, FFmpeg, LibreOffice, or ImageMagick when available, plus Microsoft Office, Windows' own media engine, and the Windows PDF engine; caches are bounded by config.ini — decoded images stay in memory, while the page an engine drew for a document is kept as a file under the temp folder, where Windows is free to clear it. See PRIVACY.md for full details.

License

MIT. See LICENSE.

The app is built out of other people's code as much as its own — the Windows bindings, the image decoders, the syntax highlighter, the archive readers, the browser bindings — and each of those carries its own licence, with the notices MIT and BSD ask to be reproduced. THIRD-PARTY.md lists every dependency grouped by licence, with the copyright holders beside it, and the full texts are in LICENSES/. Both are generated from the dependency tree rather than kept by hand; generate-attribution.ps1 refreshes them.

RAR archives are handled through the official UnRAR sources compiled in by unrar_sys: that code is free to use for reading RAR archives, but it may not be used to build a RAR-compatible archiver or to recreate the RAR compression algorithm. See THIRD-PARTY.md (LicenseRef-UnRAR).