Bind hb_ot_tags_from_script_and_language() and hb_ot_tags_to_script_and_language()

harfbuzz.symbols

@@ -127,6 +127,8 @@ _hb_ot_name_list_names
 _hb_ot_name_get_utf16
 _hb_ot_tag_to_language
 _hb_ot_tag_to_script
+_hb_ot_tags_from_script_and_language
+_hb_ot_tags_to_script_and_language
 _hb_ot_var_get_axis_infos
 _hb_script_from_string
 _hb_feature_from_string

src/shape.ts

@@ -4,6 +4,7 @@ import {
   hb_tag,
   hb_untag,
   utf8_ptr_to_string,
+  string_to_ascii_ptr,
   language_to_string,
   type ValueOf,
 } from "./helpers";
@@ -135,7 +136,7 @@ export function versionString(): string {
 }
 
 /**
- * Convert an OpenType script tag to HarfBuzz script.
+ * Convert an OpenType script tag to HarfBuzz script (ISO 15924).
  * @param tag The tag to convert.
  * @returns The script.
  */
@@ -146,7 +147,7 @@ export function otTagToScript(tag: string): string {
 }
 
 /**
- * Convert an OpenType language tag to HarfBuzz language.
+ * Convert an OpenType language tag to HarfBuzz language (BCP 47).
  * @param tag The tag to convert.
  * @returns The language.
  */
@@ -155,3 +156,86 @@ export function otTagToLanguage(tag: string): string {
   const language = exports.hb_ot_tag_to_language(hbTag);
   return language_to_string(language);
 }
+
+/** https://harfbuzz.github.io/harfbuzz-hb-ot-layout.html#HB-OT-MAX-TAGS-PER-LANGUAGE:CAPS */
+const HB_OT_MAX_TAGS_PER_LANGUAGE = 3;
+/** https://harfbuzz.github.io/harfbuzz-hb-ot-layout.html#HB-OT-MAX-TAGS-PER-SCRIPT:CAPS */
+const HB_OT_MAX_TAGS_PER_SCRIPT = 3;
+
+/**
+ * Convert a HarfBuzz script (ISO 15924) and a HarfBuzz language (BCP 47) to OpenType script tags and OpenType language tags.
+ * @param script A HarfBuzz script to convert.
+ * @param language A HarfBuzz language to convert.
+ * @returns An object with the OpenType script tags and the OpenType language tags.
+ */
+export function otTagsFromScriptAndLanguage(
+  script: string,
+  language: string,
+): {
+  scriptTags: string[];
+  languageTags: string[];
+} {
+  const sp = Module.stackSave();
+  const scriptStr = string_to_ascii_ptr(script);
+  const languageStr = string_to_ascii_ptr(language);
+  const scriptCountPtr = Module.stackAlloc(4);
+  Module.HEAPU32[scriptCountPtr / 4] = HB_OT_MAX_TAGS_PER_SCRIPT;
+  const scriptTagsPtr = Module.stackAlloc(HB_OT_MAX_TAGS_PER_SCRIPT * 4);
+  const languageCountPtr = Module.stackAlloc(4);
+  Module.HEAPU32[languageCountPtr / 4] = HB_OT_MAX_TAGS_PER_LANGUAGE;
+  const languageTagsPtr = Module.stackAlloc(HB_OT_MAX_TAGS_PER_LANGUAGE * 4);
+  exports.hb_ot_tags_from_script_and_language(
+    exports.hb_script_from_string(scriptStr.ptr, -1),
+    exports.hb_language_from_string(languageStr.ptr, -1),
+    scriptCountPtr,
+    scriptTagsPtr,
+    languageCountPtr,
+    languageTagsPtr,
+  );
+  scriptStr.free();
+  languageStr.free();
+  const scriptTags = Module.HEAPU32.subarray(
+    scriptTagsPtr / 4,
+    scriptTagsPtr / 4 + Module.HEAPU32[scriptCountPtr / 4],
+  );
+  const languageTags = Module.HEAPU32.subarray(
+    languageTagsPtr / 4,
+    languageTagsPtr / 4 + Module.HEAPU32[languageCountPtr / 4],
+  );
+  Module.stackRestore(sp);
+  return {
+    scriptTags: [...scriptTags].map(hb_untag),
+    languageTags: [...languageTags].map(hb_untag),
+  };
+}
+
+/**
+ * Convert an OpenType script tag and an OpenType language tag to a HarfBuzz script (ISO 15924) and a HarfBuzz language (BCP 47).
+ * @param scriptTag An OpenType script tag.
+ * @param languageTag An OpenType language tag.
+ * @returns An object with the HarfBuzz script and the HarfBuzz language.
+ */
+export function otTagsToScriptAndLanguage(
+  scriptTag: string,
+  languageTag: string,
+): {
+  script: string | undefined;
+  language: string | undefined;
+} {
+  const sp = Module.stackSave();
+  const scriptPtr = Module.stackAlloc(4);
+  const languagePtr = Module.stackAlloc(4);
+  exports.hb_ot_tags_to_script_and_language(
+    hb_tag(scriptTag),
+    hb_tag(languageTag),
+    scriptPtr,
+    languagePtr,
+  );
+  const script = Module.HEAPU32[scriptPtr / 4];
+  const language = Module.HEAPU32[languagePtr / 4];
+  Module.stackRestore(sp);
+  return {
+    script: hb_untag(script),
+    language: language_to_string(language),
+  };
+}

test/index.test.js

@@ -2084,6 +2084,32 @@ describe("misc", function () {
     expect(hb.otTagToLanguage("SYRE")).to.equal("und-syre");
   });
 
+  it(hb.otTagsFromScriptAndLanguage, () => {
+    // Single script to multiple tags:
+    expect(hb.otTagsFromScriptAndLanguage("Deva", "hin")).to.deep.equal({
+      scriptTags: ["dev3", "dev2", "deva"],
+      languageTags: ["HIN "],
+    });
+    // Single language to multiple tags:
+    expect(hb.otTagsFromScriptAndLanguage("Syrc", "syr")).to.deep.equal({
+      scriptTags: ["syrc"],
+      languageTags: ["SYR "], // In registry: "SYR ", SYRE, SYRJ, SYRN
+    });
+  });
+
+  it(hb.otTagsToScriptAndLanguage, () => {
+    // Multiple tags to single script:
+    expect(hb.otTagsToScriptAndLanguage("dev2", "HIN ")).to.deep.equal({
+      script: "Deva",
+      language: "hi-x-hbsc-64657632", // Private disambiguation
+    });
+    // Single tag to multiple languages:
+    expect(hb.otTagsToScriptAndLanguage("syrc", "SYR ")).to.deep.equal({
+      script: "Syrc",
+      language: "syr", // In registry: aii, amw, cld, syc, syr, tru
+    });
+  });
+
   it("test that calling functions repeatedly doesn't exhaust memory", function () {
     let blob = new hb.Blob(
       fs.readFileSync(path.join(__dirname, "fonts/noto/NotoSans-Regular.ttf")),