Big Hex Viewer

中文简介：HxD 风格的二进制查看/编辑器。偏移列 + 十六进制字节列 + ASCII 列经典布局，虚拟滚动支持超大文件（10GB+）流畅浏览，O(1) 偏移跳转、字节序列/文本查找、选区复制为十六进制或文本、覆盖式编辑与就地保存（不改文件长度）。默认只读，编辑需显式开启。

HxD-style hex viewer and in-place editor for any file — built for huge files.

Features

• Classic HxD layout, three-color columns: uppercase zero-padded offset column, hex byte column (8/16/32 bytes per row, optional grouping) and a decoded text column — offsets, hex and text each have their own theme-aware color. Unprintable code points render as .. Every row always renders the full row width, so the last short row stays aligned.
• Text encoding switch: the text column decodes with the selected encoding — auto-detect (BOM + 64 KB heuristic) or UTF-8, UTF-16LE/BE, GBK, GB18030, Big5, Shift-JIS, EUC-KR, Windows-1252, ISO-8859-1, ASCII. Multi-byte characters that straddle a row boundary are decoded with context, so CJK text stays intact.
• Huge-file ready: virtualized scrolling with a fixed-height scroll domain — a 10 GB file at 16 bytes/row is 625 million rows; rows are mapped linearly onto a 1 MiB-px spacer (Chromium clamps native scroll heights near 33.5M px, so native total height is not an option). Only the viewport + overscan rows exist in the DOM.
• O(1) offset navigation (Ctrl+G): jump with decimal (1048576), hex (0x100000) or size suffixes (16, 1KB, 2MB, 3G) — row = offset / bytesPerRow, no scan needed.
• Find (Ctrl+F / F3): plain-text search, or exact byte sequences with the hex: prefix (hex:DE AD BE EF); matches are highlighted and F3 cycles through them.
• Byte-accurate selection + right-click menu: click / drag / Shift+click in either the hex or the text column (both stay in sync); right-click never collapses the selection and opens a menu with Copy content and Copy byte string. In edit mode the menu also offers Cut (copy + zero-fill; overwrite semantics, the file length never changes) and Paste (hex bytes, or text when the selected encoding has an encoder). Ctrl+C / Ctrl+X / Ctrl+V follow the same rules; cut and paste are disabled outside edit mode.
• Top-anchored, draggable dialogs: Find (Ctrl+F) and Go to offset (Ctrl+G) open just below the toolbar — the rows you are inspecting stay visible and clickable while the dialog is open — and can still be dragged anywhere; transient messages appear in a centered, draggable toast.
• Overwrite editing (opt-in): toggle with a confirmation, then type hex nibbles in the hex column or ASCII characters in the text column; modified bytes are highlighted red (HxD style), Ctrl+Z undoes, Ctrl+S saves in place — the file size never changes.
• Safe save: before writing, the extension verifies the file's size and mtime are unchanged since it was opened; if anything touched the file externally, the save is refused with a clear message (reopen to pick up the new content). Hex saves are always in-place overwrites.
• Localized 中文/English UI strings follow VSCode's display language.

Extension Settings

Keyboard Shortcuts

Active while the hex viewer is focused:

Performance (measured)

Environment: Windows 11, AMD Ryzen 7 7840HS, NVMe SSD (F:), Node 26.4.0, VSCode 1.144.0. The 12.4 GB and 53.3 GB files are VMware disk images used as large binary stress files.

Open is O(1) (no index); random reads go through the 64 KB LRU, and the search column is a cold full scan (the 1 GiB log finds the planted needle 120 times; the other rows search for a needle that does not occur).

Limitations (by design, v0.2)

• Overwrite mode only: editing replaces byte values; inserting or deleting bytes (changing the file length) is not supported. Cut therefore copies and zero-fills the selected bytes; paste overwrites without changing the length.
• Backspace/Delete move the cursor without altering bytes.
• No automatic reload on external changes — detected and refused at save time instead.
• Text search/paste is encoded with the selected encoding. GBK/Big5/Shift-JIS/EUC-KR have no encoder in Node: ASCII text search/paste works, non-ASCII text is refused — use hex bytes (hex: prefix or the Hex bytes checkbox) for CJK content.

Build & install locally

Run from this directory:

npm install
npm run typecheck     # tsc --noEmit
npm run compile       # esbuild → out/extension.js + out/webview.bundle.js
npm test              # unit tests
npm run test:integration  # full stack in a real VSCode host
npx vsce package --allow-missing-repository
code --install-extension viewhexfile-0.2.1.vsix

Then right-click any file in the Explorer → Open with Big Hex Viewer.

Support

See SUPPORT.md, or write to fenyuesupport@163.com — please include your VSCode version (Help → About) and the steps to reproduce.

License

MIT — see the LICENSE file in the repository.