Implement feature dropping in spacing derivation.

doc/custom-build.md

@@ -73,7 +73,7 @@ Inside the plan, top-level properties include:
         - `U+27F6` LONG RIGHTWARDS ARROW
         - `U+27FB` LONG LEFTWARDS ARROW FROM BAR
         - `U+27FC` LONG RIGHTWARDS ARROW FROM BAR
-  - `fixed`: Apply `fontconfig-mono` changes and further remove ligations.
+  - `fixed`: Apply `fontconfig-mono` changes and further remove ligations, `NWID` and `WWID` typographic features.
 * `serifs`: Optional, String, configures style of serifs.
   - When set to `slab`, the font will be converted into slab-serif.
   - Otherwise the font will be sans-serif.

font-src/derive-spacing.mjs

@@ -1,11 +1,15 @@
 import fs from "fs";
+import path from "path";
+import url from "url";
 
-import { FontIo, Ot } from "ot-builder";
+import * as Toml from "@iarna/toml";
+import { FontIo, Ot, CliProc } from "ot-builder";
 
 import { assignFontNames, createNamingDictFromArgv } from "./gen/meta/naming.mjs";
 
-export default main;
+const __dirname = url.fileURLToPath(new URL(".", import.meta.url));
 
+export default main;
 async function main(argv) {
 	const font = await readTTF(argv);
 
@@ -14,11 +18,19 @@ async function main(argv) {
 
 	switch (argv.shape.spacing) {
 		case "term":
-			deriveTerm(font);
+			await deriveTerm(font);
+			break;
+		case "fontconfig-mono":
+			await deriveTerm(font);
+			await deriveFixed_DropWideChars(font);
+			await deriveFixed_DropFeatures(font, false);
+			CliProc.gcFont(font, Ot.ListGlyphStoreFactory);
 			break;
 		case "fixed":
-			deriveTerm(font);
-			deriveFixed(font);
+			await deriveTerm(font);
+			await deriveFixed_DropWideChars(font);
+			await deriveFixed_DropFeatures(font, true);
+			CliProc.gcFont(font, Ot.ListGlyphStoreFactory);
 			break;
 	}
 
@@ -26,7 +38,7 @@ async function main(argv) {
 }
 
 // To derive -Term variants, simply apply NWID
-function deriveTerm(font) {
+async function deriveTerm(font) {
 	const gsub = font.gsub;
 	let nwidMap = new Map();
 	for (const feature of gsub.features) {
@@ -52,7 +64,7 @@ function deriveTerm(font) {
 // In FontConfig, a font is considered "monospace" if and only if all encoded non-combining
 // characters  (AW > 0) have the same width. We use this method to validate whether our
 // "Fixed" subfamilies are properly built.
-function deriveFixed(font) {
+async function deriveFixed_DropWideChars(font) {
 	const unitWidth = font.os2.xAvgCharWidth;
 	for (const [ch, g] of [...font.cmap.unicode.entries()]) {
 		const advanceWidth = g.horizontal.end - g.horizontal.start;
@@ -64,6 +76,62 @@ function deriveFixed(font) {
 	}
 }
 
+async function deriveFixed_DropFeatures(font, fFixed) {
+	if (!font.gsub) return;
+
+	const dropFeatureTagSet = new Set();
+	dropFeatureTagSet.add("NWID");
+	dropFeatureTagSet.add("WWID");
+
+	if (fFixed) {
+		const LIGATIONS_TOML = path.resolve(__dirname, "../params/ligation-set.toml");
+		const rawLigationData = Toml.parse(await fs.promises.readFile(LIGATIONS_TOML, "utf-8"));
+		for (const [_, comp] of Object.entries(rawLigationData.composite)) {
+			dropFeatureTagSet.add(comp.tag);
+		}
+	}
+
+	for (const feature of font.gsub.features) {
+		if (dropFeatureTagSet.has(feature.tag)) {
+			feature.lookups.length = 0;
+			feature.params = null;
+		}
+	}
+
+	markSweepLookups(font.gsub);
+}
+function markSweepLookups(table) {
+	let lookupSet = new Set();
+	for (const feature of table.features) {
+		for (const lookup of feature.lookups) {
+			lookupSet.add(lookup);
+		}
+	}
+
+	do {
+		let sizeBefore = lookupSet.size;
+		for (const lookup of table.lookups) {
+			if (lookup instanceof Ot.Gsub.Chaining || lookup instanceof Ot.Gpos.Chaining) {
+				for (const rule of lookup.rules) {
+					for (const app of rule.applications) lookupSet.add(app.apply);
+				}
+			}
+		}
+		let sizeAfter = lookupSet.size;
+		if (sizeBefore >= sizeAfter) break;
+	} while (true);
+
+	let front = 0;
+	for (let rear = 0; rear < table.lookups.length; rear++) {
+		if (lookupSet.has(table.lookups[rear])) {
+			table.lookups[front++] = table.lookups[rear];
+		}
+	}
+	table.lookups.length = front;
+
+	return lookupSet;
+}
+
 async function readTTF(argv) {
 	const buf = await fs.promises.readFile(argv.i);
 	const sfnt = FontIo.readSfntOtf(buf);

font-src/index.mjs

@@ -1,6 +1,6 @@
 import fs from "fs";
 import path from "path";
-import * as url from "url";
+import url from "url";
 import zlib from "zlib";
 
 import * as Toml from "@iarna/toml";
@@ -15,7 +15,6 @@ import { applyMetricOverride } from "./support/metric-override.mjs";
 import * as Parameters from "./support/parameters.mjs";
 import * as VariantData from "./support/variant-data.mjs";
 
-const __filename = url.fileURLToPath(import.meta.url);
 const __dirname = url.fileURLToPath(new URL(".", import.meta.url));
 
 // Parameter preparation

utility/export-data/index.mjs

@@ -1,6 +1,6 @@
 import fs from "fs";
 import path from "path";
-import * as url from "url";
+import url from "url";
 
 import { parseLigationData } from "./ligation-data.mjs";
 import { getCharMapAndSupportedLanguageList } from "./supported-languages.mjs";

utility/export-data/ligation-data.mjs

@@ -1,6 +1,6 @@
 import fs from "fs";
 import path from "path";
-import * as url from "url";
+import url from "url";
 
 import * as toml from "@iarna/toml";
 

utility/export-data/variants-data.mjs

@@ -1,6 +1,6 @@
 import fs from "fs";
 import path from "path";
-import * as url from "url";
+import url from "url";
 
 import * as toml from "@iarna/toml";
 

utility/generate-release-note/change-log.mjs

@@ -1,6 +1,6 @@
 import fs from "fs";
 import path from "path";
-import * as url from "url";
+import url from "url";
 
 import semver from "semver";
 

utility/generate-release-note/package-list.mjs

@@ -1,6 +1,6 @@
 import fs from "fs";
 import path from "path";
-import * as url from "url";
+import url from "url";
 
 import { Output } from "./shared/index.mjs";
 

utility/generate-release-note/release-note.mjs

@@ -1,6 +1,6 @@
 import fs from "fs";
 import path from "path";
-import * as url from "url";
+import url from "url";
 
 import SemVer from "semver";
 

utility/update-package-json-version/index.mjs

@@ -1,6 +1,6 @@
 import fs from "fs";
 import path from "path";
-import * as url from "url";
+import url from "url";
 
 import semver from "semver";
 

verdafile.mjs

@@ -25,6 +25,7 @@ const IMAGES = "images";
 const IMAGE_TASKS = ".build/image-tasks";
 const GLYF_TTC = ".build/glyf-ttc";
 
+const SHARED_CACHE = `${BUILD}/cache`;
 const DIST_TTC = "dist/.ttc";
 const DIST_SUPER_TTC = "dist/.super-ttc";
 const ARCHIVE_DIR = "release-archives";
@@ -157,10 +158,10 @@ function linkSpacingDerivableBuildPlans(bps) {
 	for (const pfxTo in bps) {
 		const planTo = bps[pfxTo];
 		const planToVal = rectifyPlanForSpacingDerivation(planTo);
-		if (!(planTo.spacing === "term" || planTo.spacing === "fixed")) continue;
+		if (!isLinkDeriveToSpacing(planTo.spacing)) continue;
 		for (const pfxFrom in bps) {
 			const planFrom = bps[pfxFrom];
-			if (!(planFrom.spacing === "normal" || !planFrom.spacing)) continue;
+			if (!isLinkDeriveFromSpacing(planFrom.spacing)) continue;
 			const planFromVal = rectifyPlanForSpacingDerivation(planFrom);
 			if (!deepEqual(planToVal, planFromVal)) continue;
 			planTo.spacingDeriveFrom = pfxFrom;
@@ -168,6 +169,13 @@ function linkSpacingDerivableBuildPlans(bps) {
 	}
 }
 
+function isLinkDeriveToSpacing(spacing) {
+	return spacing === "term" || spacing === "fontconfig-mono" || spacing === "fixed";
+}
+function isLinkDeriveFromSpacing(spacing) {
+	return !spacing || spacing === "normal";
+}
+
 function rectifyPlanForSpacingDerivation(p) {
 	return {
 		...p,
@@ -362,14 +370,16 @@ const ageKey = uuid.v4();
 const DistUnhintedTTF = file.make(
 	(gr, fn) => `${DIST}/${gr}/ttf-unhinted/${fn}.ttf`,
 	async (target, out, gr, fn) => {
-		await target.need(Scripts, Parameters, Dependencies);
-		const [fi] = await target.need(FontInfoOf(fn), de(out.dir));
+		await target.need(Scripts, Parameters, Dependencies, de(out.dir));
+		const [fi] = await target.need(FontInfoOf(fn));
 
 		if (fi.spacingDerive) {
 			// The font is a spacing variant, and is derivable form an existing
 			// normally-spaced variant.
 			const spD = fi.spacingDerive;
 			const [deriveFrom] = await target.need(DistUnhintedTTF(spD.prefix, spD.fileName));
+
+			echo.action(echo.hl.command(`Create TTF`), fn, echo.hl.operator("->"), out.full);
 			await silently.node(`font-src/derive-spacing.mjs`, {
 				i: deriveFrom.full,
 				o: out.full,
@@ -379,27 +389,30 @@ const DistUnhintedTTF = file.make(
 			// Ab-initio build
 			const charMapDir = `${BUILD}/ttf/${gr}`;
 			const charMapPath = `${charMapDir}/${fn}.charmap.mpz`;
-			await target.need(de(charMapDir));
 
-			await target.need(de(`${BUILD}/caches`));
 			const cacheFileName =
 				`${Math.round(1000 * fi.shape.weight)}-${Math.round(1000 * fi.shape.width)}-` +
 				`${Math.round(3600 * fi.shape.slopeAngle)}-${fi.shape.slope}`;
-			const cachePath = `${BUILD}/caches/${cacheFileName}.mpz`;
+			const cachePath = `${SHARED_CACHE}/${cacheFileName}.mpz`;
 			const cacheDiffPath = `${charMapDir}/${fn}.cache.mpz`;
 
-			echo.action(echo.hl.command(`Create TTF`), fn, echo.hl.operator("->"), out.full);
+			const [comps] = await target.need(
+				CompositesFromBuildPlan,
+				de(charMapDir),
+				de(SHARED_CACHE)
+			);
 
-			const [compositesFromBuildPlan] = await target.need(CompositesFromBuildPlan);
+			echo.action(echo.hl.command(`Create TTF`), fn, echo.hl.operator("->"), out.full);
 			const { cacheUpdated } = await silently.node("font-src/index.mjs", {
 				o: out.full,
 				oCharMap: charMapPath,
 				cacheFreshAgeKey: ageKey,
 				iCache: cachePath,
 				oCache: cacheDiffPath,
-				compositesFromBuildPlan,
+				compositesFromBuildPlan: comps,
 				...fi
 			});
+
 			if (cacheUpdated) {
 				const lock = build.locks.alloc(cacheFileName);
 				await lock.acquire();