Ensure that GenericL10n works if the locale files cannot be loaded

- Ensure that localization works in the GENERIC viewer, even if the necessary locale files cannot be loaded.
   This was the behaviour prior to the introduction of Fluent, and it seems worthwhile to keep that (especially since we already bundle the en-US strings anyway).

 - Let the `GenericL10n`-implementation use the *bundled* en-US strings directly when no language is provided.

 - Remove the `NullL10n`-implementation, and simply fallback to `GenericL10n`, to reduce the maintenance burden of viewer-components localization.

 - Indirectly, given the previous point, stop exporting `NullL10n` in the viewer-components since it's now removed.
   Note that it was never really intended to be used directly and only existed as a fallback.

*Please note:* This doesn't affect the Firefox PDF Viewer, thanks to the use of import maps.

examples/mobile-viewer/viewer.mjs

@@ -272,7 +272,7 @@ const PDFViewerApplication = {
     });
     this.pdfLinkService = linkService;
 
-    this.l10n = pdfjsViewer.NullL10n;
+    this.l10n = new pdfjsViewer.GenericL10n();
 
     const container = document.getElementById("viewerContainer");
     const pdfViewer = new pdfjsViewer.PDFViewer({

gulpfile.mjs

@@ -272,7 +272,7 @@ function createWebpackConfig(
     "web-com": "",
     "web-download_manager": "",
     "web-external_services": "",
-    "web-l10n_utils": "web/stubs.js",
+    "web-null_l10n": "",
     "web-pdf_attachment_viewer": "web/pdf_attachment_viewer.js",
     "web-pdf_cursor_tools": "web/pdf_cursor_tools.js",
     "web-pdf_document_properties": "web/pdf_document_properties.js",
@@ -294,6 +294,7 @@ function createWebpackConfig(
     viewerAlias["web-com"] = "web/chromecom.js";
     viewerAlias["web-download_manager"] = "web/download_manager.js";
     viewerAlias["web-external_services"] = "web/chromecom.js";
+    viewerAlias["web-null_l10n"] = "web/l10n.js";
     viewerAlias["web-preferences"] = "web/chromecom.js";
     viewerAlias["web-print_service"] = "web/pdf_print_service.js";
   } else if (bundleDefines.GENERIC) {
@@ -308,13 +309,12 @@ function createWebpackConfig(
     viewerAlias["web-com"] = "web/genericcom.js";
     viewerAlias["web-download_manager"] = "web/download_manager.js";
     viewerAlias["web-external_services"] = "web/genericcom.js";
-    viewerAlias["web-l10n_utils"] = "web/l10n_utils.js";
+    viewerAlias["web-null_l10n"] = "web/genericl10n.js";
     viewerAlias["web-preferences"] = "web/genericcom.js";
     viewerAlias["web-print_service"] = "web/pdf_print_service.js";
   } else if (bundleDefines.MOZCENTRAL) {
     if (bundleDefines.GECKOVIEW) {
       const gvAlias = {
-        "web-l10n_utils": "web/stubs.js",
         "web-toolbar": "web/toolbar-geckoview.js",
       };
       for (const key in viewerAlias) {
@@ -324,6 +324,7 @@ function createWebpackConfig(
     viewerAlias["web-com"] = "web/firefoxcom.js";
     viewerAlias["web-download_manager"] = "web/firefoxcom.js";
     viewerAlias["web-external_services"] = "web/firefoxcom.js";
+    viewerAlias["web-null_l10n"] = "web/l10n.js";
     viewerAlias["web-preferences"] = "web/firefoxcom.js";
     viewerAlias["web-print_service"] = "web/firefox_print_service.js";
   }
@@ -1616,7 +1617,7 @@ function buildLibHelper(bundleDefines, inputStream, outputDir) {
       "display-node_utils": "./node_utils.js",
       "fluent-bundle": "../../../node_modules/@fluent/bundle/esm/index.js",
       "fluent-dom": "../../../node_modules/@fluent/dom/esm/index.js",
-      "web-l10n_utils": "../web/l10n_utils.js",
+      "web-null_l10n": "../web/genericl10n.js",
     },
   };
   const licenseHeaderLibre = fs

test/unit/pdf_viewer.component_spec.js

@@ -30,8 +30,6 @@ import { AnnotationLayerBuilder } from "../../web/annotation_layer_builder.js";
 import { DownloadManager } from "../../web/download_manager.js";
 import { EventBus } from "../../web/event_utils.js";
 import { GenericL10n } from "../../web/genericl10n.js";
-import { L10n } from "../../web/l10n.js";
-import { NullL10n } from "../../web/l10n_utils.js";
 import { PDFHistory } from "../../web/pdf_history.js";
 import { PDFPageView } from "../../web/pdf_page_view.js";
 import { PDFScriptingManager } from "../../web/pdf_scripting_manager.component.js";
@@ -54,7 +52,6 @@ describe("pdfviewer_api", function () {
       FindState,
       GenericL10n,
       LinkTarget,
-      NullL10n,
       parseQueryString,
       PDFFindController,
       PDFHistory,
@@ -73,14 +70,4 @@ describe("pdfviewer_api", function () {
       XfaLayerBuilder,
     });
   });
-
-  it("checks that `NullL10n` implements all methods", function () {
-    const methods = Object.getOwnPropertyNames(NullL10n).sort();
-
-    const baseMethods = Object.getOwnPropertyNames(L10n.prototype)
-      .filter(m => m !== "constructor" && !m.startsWith("_"))
-      .sort();
-
-    expect(methods).toEqual(baseMethods);
-  });
 });

test/unit/unit_test.html

@@ -30,7 +30,7 @@
         "web-com": "../../web/genericcom.js",
         "web-download_manager": "../../web/download_manager.js",
         "web-external_services": "../../web/genericcom.js",
-        "web-l10n_utils": "../../web/l10n_utils.js",
+        "web-null_l10n": "../../web/genericl10n.js",
         "web-pdf_attachment_viewer": "../../web/pdf_attachment_viewer.js",
         "web-pdf_cursor_tools": "../../web/pdf_cursor_tools.js",
         "web-pdf_document_properties": "../../web/pdf_document_properties.js",

tsconfig.json

@@ -16,7 +16,7 @@
       "display-node_utils": ["./src/display/node_utils"],
       "fluent-bundle": ["./node_modules/@fluent/bundle/esm/index.js"],
       "fluent-dom": ["./node_modules/@fluent/dom/esm/index.js"],
-      "web-l10n_utils": ["./web/l10n_utils"]
+      "web-null_l10n": ["../web/genericl10n.js"]
     }
   },
   "files": ["src/pdf.js", "web/pdf_viewer.component.js"]

web/annotation_editor_layer_builder.js

@@ -25,7 +25,7 @@
 /** @typedef {import("../src/display/annotation_layer.js").AnnotationLayer} AnnotationLayer */
 
 import { AnnotationEditorLayer } from "pdfjs-lib";
-import { NullL10n } from "web-l10n_utils";
+import { GenericL10n } from "web-null_l10n";
 
 /**
  * @typedef {Object} AnnotationEditorLayerBuilderOptions
@@ -55,7 +55,10 @@ class AnnotationEditorLayerBuilder {
     this.pageDiv = options.pageDiv;
     this.pdfPage = options.pdfPage;
     this.accessibilityManager = options.accessibilityManager;
-    this.l10n = options.l10n || NullL10n;
+    this.l10n = options.l10n;
+    if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
+      this.l10n ||= new GenericL10n();
+    }
     this.annotationEditorLayer = null;
     this.div = null;
     this._cancelled = false;

web/genericl10n.js

@@ -20,22 +20,34 @@ import { DOMLocalization } from "fluent-dom";
 import { fetchData } from "pdfjs-lib";
 import { L10n } from "./l10n.js";
 
+function createBundle(lang, text) {
+  const resource = new FluentResource(text);
+  const bundle = new FluentBundle(lang);
+  const errors = bundle.addResource(resource);
+  if (errors.length) {
+    console.error("L10n errors", errors);
+  }
+  return bundle;
+}
+
 /**
  * @implements {IL10n}
  */
 class GenericL10n extends L10n {
   constructor(lang) {
     super({ lang });
-    this._setL10n(
+
-      new DOMLocalization(
+    const generateBundles = !lang
-        [],
+      ? GenericL10n.#generateBundlesFallback.bind(
-        GenericL10n.#generateBundles.bind(
+          GenericL10n,
+          this.getLanguage()
+        )
+      : GenericL10n.#generateBundles.bind(
           GenericL10n,
           "en-us",
           this.getLanguage()
-        )
+        );
-      )
+    this._setL10n(new DOMLocalization([], generateBundles));
-    );
   }
 
   /**
@@ -63,6 +75,9 @@ class GenericL10n extends L10n {
       if (bundle) {
         yield bundle;
       }
+      if (lang === "en-us") {
+        yield this.#createBundleFallback(lang);
+      }
     }
   }
 
@@ -74,20 +89,36 @@ class GenericL10n extends L10n {
     const url = new URL(path, baseURL);
     const text = await fetchData(url, /* type = */ "text");
 
-    const resource = new FluentResource(text);
+    return createBundle(lang, text);
-    const bundle = new FluentBundle(lang);
-    const errors = bundle.addResource(resource);
-    if (errors.length) {
-      console.error("L10n errors", errors);
-    }
-    return bundle;
   }
 
   static async #getPaths() {
-    const { href } = document.querySelector(`link[type="application/l10n"]`);
+    try {
-    const paths = await fetchData(href, /* type = */ "json");
+      const { href } = document.querySelector(`link[type="application/l10n"]`);
+      const paths = await fetchData(href, /* type = */ "json");
 
-    return { baseURL: href.replace(/[^/]*$/, "") || "./", paths };
+      return { baseURL: href.replace(/[^/]*$/, "") || "./", paths };
+    } catch {}
+    return { baseURL: "./", paths: Object.create(null) };
+  }
+
+  static async *#generateBundlesFallback(lang) {
+    yield this.#createBundleFallback(lang);
+  }
+
+  static async #createBundleFallback(lang) {
+    if (typeof PDFJSDev !== "undefined" && PDFJSDev.test("TESTING")) {
+      throw new Error("Not implemented: #createBundleFallback");
+    }
+    const text =
+      typeof PDFJSDev === "undefined"
+        ? await fetchData(
+            new URL(`./locale/${lang}/viewer.ftl`, window.location.href),
+            /* type = */ "text"
+          )
+        : PDFJSDev.eval("DEFAULT_FTL");
+
+    return createBundle(lang, text);
   }
 }
 

web/l10n.js

@@ -117,4 +117,6 @@ class L10n {
   }
 }
 
-export { L10n };
+const GenericL10n = null;
+
+export { GenericL10n, L10n };

web/l10n_utils.js

@@ -1,87 +0,0 @@
-/* Copyright 2021 Mozilla Foundation
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-/** @typedef {import("./interfaces").IL10n} IL10n */
-
-import { fetchData, shadow } from "pdfjs-lib";
-import { FluentBundle, FluentResource } from "fluent-bundle";
-import { DOMLocalization } from "fluent-dom";
-import { L10n } from "./l10n.js";
-
-/**
- * @implements {IL10n}
- */
-class ConstL10n extends L10n {
-  constructor(lang) {
-    super({ lang });
-    this._setL10n(
-      new DOMLocalization([], ConstL10n.#generateBundles.bind(ConstL10n, lang))
-    );
-  }
-
-  static async *#generateBundles(lang) {
-    const text =
-      typeof PDFJSDev === "undefined"
-        ? await fetchData(
-            new URL(`./locale/${lang}/viewer.ftl`, window.location.href),
-            /* type = */ "text"
-          )
-        : PDFJSDev.eval("DEFAULT_FTL");
-
-    const resource = new FluentResource(text);
-    const bundle = new FluentBundle(lang);
-    const errors = bundle.addResource(resource);
-    if (errors.length) {
-      console.error("L10n errors", errors);
-    }
-    yield bundle;
-  }
-
-  static get instance() {
-    return shadow(this, "instance", new ConstL10n("en-us"));
-  }
-}
-
-/**
- * No-op implementation of the localization service.
- * @implements {IL10n}
- */
-const NullL10n = {
-  getLanguage() {
-    return ConstL10n.instance.getLanguage();
-  },
-
-  getDirection() {
-    return ConstL10n.instance.getDirection();
-  },
-
-  async get(ids, args = null, fallback) {
-    return ConstL10n.instance.get(ids, args, fallback);
-  },
-
-  async translate(element) {
-    return ConstL10n.instance.translate(element);
-  },
-
-  pause() {
-    return ConstL10n.instance.pause();
-  },
-
-  resume() {
-    return ConstL10n.instance.resume();
-  },
-};
-
-export { NullL10n };

web/pdf_page_view.js

@@ -43,7 +43,7 @@ import { AnnotationEditorLayerBuilder } from "./annotation_editor_layer_builder.
 import { AnnotationLayerBuilder } from "./annotation_layer_builder.js";
 import { compatibilityParams } from "./app_options.js";
 import { DrawLayerBuilder } from "./draw_layer_builder.js";
-import { NullL10n } from "web-l10n_utils";
+import { GenericL10n } from "web-null_l10n";
 import { SimpleLinkService } from "./pdf_link_service.js";
 import { StructTreeLayerBuilder } from "./struct_tree_layer_builder.js";
 import { TextAccessibilityManager } from "./text_accessibility.js";
@@ -157,7 +157,10 @@ class PDFPageView {
 
     this.eventBus = options.eventBus;
     this.renderingQueue = options.renderingQueue;
-    this.l10n = options.l10n || NullL10n;
+    this.l10n = options.l10n;
+    if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
+      this.l10n ||= new GenericL10n();
+    }
 
     this.renderTask = null;
     this.resume = null;
@@ -214,7 +217,7 @@ class PDFPageView {
       }
 
       // Ensure that Fluent is connected in e.g. the COMPONENTS build.
-      if (this.l10n === NullL10n) {
+      if (!options.l10n) {
         this.l10n.translate(this.div);
       }
     }

web/pdf_viewer.component.js

@@ -30,7 +30,6 @@ import { AnnotationLayerBuilder } from "./annotation_layer_builder.js";
 import { DownloadManager } from "./download_manager.js";
 import { EventBus } from "./event_utils.js";
 import { GenericL10n } from "./genericl10n.js";
-import { NullL10n } from "./l10n_utils.js";
 import { PDFHistory } from "./pdf_history.js";
 import { PDFPageView } from "./pdf_page_view.js";
 import { PDFScriptingManager } from "./pdf_scripting_manager.component.js";
@@ -54,7 +53,6 @@ export {
   FindState,
   GenericL10n,
   LinkTarget,
-  NullL10n,
   parseQueryString,
   PDFFindController,
   PDFHistory,

web/pdf_viewer.js

@@ -63,7 +63,7 @@ import {
   VERTICAL_PADDING,
   watchScroll,
 } from "./ui_utils.js";
-import { NullL10n } from "web-l10n_utils";
+import { GenericL10n } from "web-null_l10n";
 import { PDFPageView } from "./pdf_page_view.js";
 import { PDFRenderingQueue } from "./pdf_rendering_queue.js";
 import { SimpleLinkService } from "./pdf_link_service.js";
@@ -286,7 +286,10 @@ class PDFViewer {
       this.removePageBorders = options.removePageBorders || false;
     }
     this.maxCanvasPixels = options.maxCanvasPixels;
-    this.l10n = options.l10n || NullL10n;
+    this.l10n = options.l10n;
+    if (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) {
+      this.l10n ||= new GenericL10n();
+    }
     this.#enablePermissions = options.enablePermissions || false;
     this.pageColors = options.pageColors || null;
 
@@ -327,7 +330,7 @@ class PDFViewer {
 
     if (
       (typeof PDFJSDev === "undefined" || PDFJSDev.test("GENERIC")) &&
-      this.l10n === NullL10n
+      !options.l10n
     ) {
       // Ensure that Fluent is connected in e.g. the COMPONENTS build.
       this.l10n.translate(this.container);

web/stubs.js

@@ -1,18 +0,0 @@
-/* Copyright 2023 Mozilla Foundation
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-const NullL10n = null;
-
-export { NullL10n };

web/viewer-geckoview.html

@@ -63,7 +63,7 @@ See https://github.com/adobe-type-tools/cmap-resources
           "web-com": "./genericcom.js",
           "web-download_manager": "./download_manager.js",
           "web-external_services": "./genericcom.js",
-          "web-l10n_utils": "./l10n_utils.js",
+          "web-null_l10n": "./genericl10n.js",
           "web-pdf_attachment_viewer": "./stubs-geckoview.js",
           "web-pdf_cursor_tools": "./stubs-geckoview.js",
           "web-pdf_document_properties": "./stubs-geckoview.js",

web/viewer.html

@@ -72,7 +72,7 @@ See https://github.com/adobe-type-tools/cmap-resources
           "web-com": "./genericcom.js",
           "web-download_manager": "./download_manager.js",
           "web-external_services": "./genericcom.js",
-          "web-l10n_utils": "./l10n_utils.js",
+          "web-null_l10n": "./genericl10n.js",
           "web-pdf_attachment_viewer": "./pdf_attachment_viewer.js",
           "web-pdf_cursor_tools": "./pdf_cursor_tools.js",
           "web-pdf_document_properties": "./pdf_document_properties.js",