A complete, single-file text editor written in Odin with raylib. Under 1,000 lines, zero external dependencies beyond the Odin toolchain.

• Text input (ASCII + UTF-8: Hiragana, Katakana, Latin-1, CJK symbols)
• Enter, Tab (4 spaces), Backspace, Delete
• Unlimited undo / redo (delta-based operation stack)

• ← → ↑ ↓ (up/down preserves preferred column)
• Home / End — line start / end
• Ctrl+Home / Ctrl+End — document start / end
• PageUp / PageDown

• Shift + any movement key
• Mouse click + drag
• Ctrl+A — select all

• Ctrl+C copy, Ctrl+X cut, Ctrl+V paste (system clipboard)

• Open file from command-line argument
• Ctrl+O — open (minibuffer prompt)
• Ctrl+S — save
• Ctrl+Shift+S — save as

• Line numbers gutter
• Status bar: filename, dirty marker *, line/column, total lines, rune count
• Minibuffer prompt for Open / Save As (Esc to cancel)
• Transient message line (fades to help text after 3s)
• Mouse wheel scrolling
• Resizable window
• Auto-detects a system monospace font (Menlo → SFNSMono → DejaVuSansMono → Consolas)

# macOS
brew install odin

# Or download from https://odin-lang.org/docs/install/

git clone https://github.com/<your-user>/odin-editor.git
cd odin-editor

# Run directly
odin run .

# Open a file
odin run . -- path/to/file.txt

# Optimized release build
odin build . -o:speed -out:editor
./editor path/to/file.txt

Single file: main.odin (~800 LOC).

• Buffer: [dynamic]rune — simple, correct for UTF-8. O(n) inserts but fine for typical editing sessions.
• Undo/redo: pair of operation stacks. Each Op stores the inserted/deleted runes plus cursor/anchor snapshots, so redo is free.
• Selection: tracked as an anchor rune index (-1 = no selection) plus the cursor. sel_range() returns the normalized [lo, hi).
• Rendering: only the visible line range is drawn each frame. Line positions are recomputed from scratch each frame — acceptable for small files, would be replaced by a line-index cache for larger ones.

• No horizontal scrolling (long lines overflow the right edge)
• CJK ideographs (0x4E00..0x9FFF) aren't in the default codepoint atlas — extend build_codepoints() to include them, at the cost of a larger font texture
• Full-width characters are rendered at half-width cursor columns, so Japanese-heavy lines will have a cursor-position offset
• No syntax highlighting

• Gap buffer or piece table (current [dynamic]rune is slow on multi-MB files)
• Find / replace (Ctrl+F)
• Multiple buffers / tabs
• Syntax highlighting
• Configurable keybindings
• Soft line wrap

MIT