ArabicBitmapRenderer

A small toolkit for rendering Arabic text on tiny microcontroller displays (RP2040-class). Glyphs are pre-rendered from Noto Naskh Arabic on a Mac; the runtime is plain C99 with no allocation, no floats, and no curve math — just table lookups and bit-blitting.

• Generator (tools/GenerateArabicFont.swift) — CoreText renders each contextual form at a fixed pixel size and weight, packed into a C header: 1 bit/pixel bitmaps, tight bounding boxes, integer advances. The full alphabet in every form fits in a few KB of flash (~5.5 KB at 28 px).
• Shaper (src/ArabicShaper) — isolated/initial/medial/final forms, lam-alef ligatures, harakat, ZWJ/ZWNJ, and enough bidi to lay out mixed RTL/LTR lines in visual order.
• Renderer (src/ArabicRenderer) — one-pass width measurement and scanline or framebuffer blitting, suited to row-streaming LCD drivers.

Usage

swift tools/GenerateArabicFont.swift \
  fonts/noto-naskh-arabic/NotoNaskhArabic-VariableFont_wght.ttf \
  --size 28 --weight 400 --out src/generated

Compile src/*.c plus the generated header into your firmware. Shape once per content change, reuse the shaped array every frame; use arabicMeasureUtf8() for quick layout decisions. DESIGN.md has the data format, API, and edge-case notes.

Samples

Every letter in its contextual forms, and the classic Arabic pangram — both drawn by the actual runtime (scripts/render-samples.sh regenerates them):

Demo app

cd demo && swift run

A little macOS app for eyeballing spacing and joins: type Arabic text and compare the bitmap pipeline against CoreText rendering the vector font at the same size, zoomed in with a pixel grid and baseline guide.

License

Code: MIT (see LICENSE).

Font: Noto Naskh Arabic, © Google, under the SIL Open Font License 1.1 (fonts/noto-naskh-arabic/OFL.txt). Generated bitmap data is derived from the font and remains under the OFL; keep the license text alongside any distribution of the glyph data.