miter

miter is a lightweight, cross-platform Markdown editor built with Qt 6. It focuses on fast typing, stable highlighting, and predictable editing behavior.

Core Features

• Multi-tab Markdown editing workflow.
• Real-time Markdown highlighting with stateful block parsing.
• Extended inline syntax support:
  • ++underline++
  • ==highlight==
  • superscript ^text^
  • subscript ~text~
  • strikethrough ~~text~~ (strike-out font style)
• LaTeX support:
  • inline $...$
  • display $$ ... $$
  • environment blocks \begin{env} ... \end{env}
• Link and image support:
  • [text](url)
  • ![alt](url)
  • linked image [![alt](image-url)](link-url)
  • angle autolinks <https://example.com> and <user@example.com>
• Task list checkbox marker highlighting ([ ], [x], [X]).
• Blockquote styling with a distinct gray background and quote-border color.
• White theme readability tuning with deeper neutral-gray token colors.
• Shared parser/editor continuation rules (lists and blockquotes) to keep typing behavior and highlighting consistent.

Performance Notes

• Focus mode dims only visible viewport lines (avoids O(n) extra-selections on every cursor move).
• Enter auto-close for $$ and fenced blocks reuses highlighter context state when available.
• Word/char stats are debounced to reduce per-keystroke CPU wakeups in long writing sessions.
• Ordered-list renumbering is localized to nearby list runs instead of scanning the full document.

Autocomplete Behavior

• Pair autocomplete at line end (no non-space text after cursor):
  • (), [], {}
  • <>
  • $...$
  • `...`
• Closer skip-over behavior:
  • typing a closer on an existing closer moves cursor right instead of inserting.
• Enter-based multiline autocomplete:
  • $$ becomes:
    • opening $$
    • empty line
    • closing $$
  • lines starting with three backticks (for example, backtick-fence plus language tag like python) auto-insert a closing fence.
  • \\begin{env} auto-inserts matching \\end{env}.
• Enter line continuation:
  • list continuation for ordered/unordered/task items
  • blockquote continuation with preserved indentation and quote depth
  • continuation matching is shared with BlockParser line parsers
• Horizontal-rule safety:
  • ***, - - -, and * * * are not treated as lists on Enter.
• Setext heading underline variants:
  • === is always rendered as a visible underline marker.
  • --- (3+ dashes) applies setext H2 heading behavior when it follows a non-empty text line in the same container context (including same-level blockquotes).
  • ***, - - -, and * * * remain horizontal rules and do not apply setext H2 behavior.

Complete behavior details are documented in spec.md.

Project Structure

• src/editor: editor widgets, keyboard behaviors, tab/session/search management.
• src/highlight: MdHighlighter token-to-format rendering.
• src/parser: block parser, inline parser, LaTeX parser, context stack.
• src/config: settings/theme loading.
• themes: TOML theme files.
• tests: parser/editor/highlighter regression tests.
• scripts: platform packaging and local update scripts.

Build And Run

Linux

cmake -S . -B build
cmake --build build -j$(nproc)
./build/miter

Open files directly:

./build/miter notes.md todo.md

macOS

brew install cmake qt
cmake -S . -B build -DCMAKE_PREFIX_PATH="$(brew --prefix qt)"
cmake --build build -j$(sysctl -n hw.ncpu)
open build/miter.app

Windows (Developer PowerShell)

cmake -S . -B build -DCMAKE_PREFIX_PATH="C:/Qt/6.8.0/msvc2022_64"
cmake --build build --config Release
.\build\Release\miter.exe

Test

Run full test suite:

cmake --build build -j$(nproc)
cd build
ctest --output-on-failure

Markdown-focused tests:

cmake --build build -j$(nproc) --target test_block_parser test_inline_parser test_latex_parser test_md_editor test_highlighter
cd build
ctest --output-on-failure -R "test_block_parser|test_inline_parser|test_latex_parser|test_md_editor|test_highlighter"

Packaging

Run packaging on the target OS.

macOS package

./scripts/package-macos.sh

Output: .dmg in the macOS build directory (default build-macos/).

Windows package

powershell -ExecutionPolicy Bypass -File .\scripts\package-windows.ps1

Output: .zip in the Windows build directory (default build-win\).

Local Install Or Update (Linux)

./scripts/update-local.sh

Default install target: ~/.local.

Keyboard Shortcuts

• Ctrl+O: open/import file
• Ctrl+S: save
• Ctrl+Shift+S: save as
• Ctrl+T: new tab
• Ctrl+W: close tab
• Ctrl+Tab: next tab
• Ctrl+Shift+Tab: previous tab
• Ctrl+F: search
• Ctrl++ / Ctrl+- / Ctrl+0: zoom in/out/reset
• Ctrl+L: toggle line numbers
• Ctrl+Shift+W: toggle word wrap
• F11: focus mode
• F12: fullscreen

Themes And Settings

• Theme files live in themes.
• Use the toolbar theme button to switch dark/white themes.
• Settings are stored in:
  • Linux: ~/.config/miter/config.toml
  • macOS: ~/Library/Preferences/miter/config.toml
  • Windows: %LOCALAPPDATA%\\miter\\config.toml

Example:

[editor]
tab_size = 2

tab_size controls inserted spaces for Tab and list indentation logic.

Acknowledgements

See NOTICE for third-party references and notices.

License

GPL-3.0