blog/lib/tasks/fonts.ts

import tmp from "tmp";
import hashPaths from "../hash.ts";
import { dest, fromGlob } from "../rx-utils.ts";
import { lastValueFrom, mergeMap } from "rxjs";
import { VFile } from "vfile";

const FONT_PRESETS: { [variant: string]: { ranges: string[] } } = {
    mono: { ranges: ["20-7F", "2205", "2E22-2E25", "2713", "2717"] },
    text: { ranges: ["20-7F", "A0-FF", "2000-206F", "20AC"] },
};

async function compileFont(font: VFile): Promise<VFile> {
    const [, variant, weight] = /([A-Z][a-z]+)-(\w+)\.ttf$/.exec(font.basename!) as string[];
    const tmpOutput = tmp.fileSync({ discardDescriptor: true });
    const unicodes = FONT_PRESETS[variant.toLowerCase()].ranges;

    await new Deno.Command("pyftsubset", {
        args: [font.path, `--unicodes=${unicodes.join(",")}`, `--output-file=${tmpOutput.name}`, "--flavor=woff2"],
    }).output();

    font.path = `iosevka-adaedra-${variant.toLowerCase()}-${weight.toLowerCase()}.woff2`;
    font.value = await Deno.readFile(tmpOutput.name);

    await Deno.remove(tmpOutput.name);
    return font;
}

export const fonts = async () => {
    await lastValueFrom(
        fromGlob("vendor/*.ttf")
            .pipe(mergeMap(compileFont), hashPaths("fonts.manifest"), mergeMap(dest("dist/_assets"))),
    );
};