Fonts and text

FreeType rasterization and HarfBuzz shaping for Otter Shell text.

Font (FreeType)

const font = try render.Font.init(allocator, .{});
defer font.deinit();

font.drawText(&surface, "Hello", .{ .x = 0, .y = 20 }, 16, render.Color.white);
const width = font.measureText("Hello", 16);

Loading priority: explicit font_path, then font_family discovery, then bundled fallback (IoskeleyMonoNerdFont-Regular.ttf). Fallback faces mmap lazily on first missing glyph. Glyph cache evicts least-recently-used entries at 65,536 entries and on allocation failure. Color emoji glyphs share the cache, so their bitmap decode is not repeated every frame. Failed Fontconfig fallback lookups also use a small negative cache.

TextSystem

For RTL, CJK, and mixed-direction labels:

var text_system = try render.TextSystem.init(allocator, &font);
defer text_system.deinit();

var scratch: render.ShapeScratch = .{};
const shaped = try text_system.shapeInto("مرحبا", &scratch, .{});

Helpers:

hasStrongRtlUtf8 / hasStrongRtlCodepoints: cheap bidi preflight
measure, wrap, truncate, cursorRect: layout-facing APIs
draw: FreeType fast path or shaped glyph rasterization

Pass text_system and text_scratch through otter-ui FrameOptions, or attach both to CommandList for direct rasterization. TextSystem reuses the latest shaped run when the text, font size, scale, direction, and scratch generation still match. Reuse the same scratch storage across measure and draw calls to take that fast path.

HiDPI text

drawTextScaled / measureTextScaled: logical coords via Surface
measureTextAtScale: explicit scale without a Surface

Build with -Denable_text=false to omit the text stack entirely.

Getting Started

Libraries

Font (FreeType)

TextSystem

HiDPI text

​Font (FreeType)

​TextSystem

​HiDPI text

Font (FreeType)

TextSystem

HiDPI text