[Editor] Add the possibility to query some ML stuff to guess an alt text for an image

It's only for an experimental purpose.

extensions/chromium/preferences_schema.json

@@ -45,6 +45,10 @@
       "type": "boolean",
       "default": false
     },
+    "enableML": {
+      "type": "boolean",
+      "default": false
+    },
     "cursorToolOnLoad": {
       "title": "Cursor tool on load",
       "description": "The cursor tool that is enabled upon load.\n 0 = Text selection tool.\n 1 = Hand tool.",

src/display/editor/alt_text.js

@@ -76,6 +76,10 @@ class AltText {
     this.#altTextWasFromKeyBoard = false;
   }
 
+  isEmpty() {
+    return !this.#altText && !this.#altTextDecorative;
+  }
+
   get data() {
     return {
       altText: this.#altText,

src/display/editor/editor.js

@@ -970,6 +970,10 @@ class AnnotationEditor {
     this.#altText.data = data;
   }
 
+  hasAltText() {
+    return !this.#altText?.isEmpty();
+  }
+
   /**
    * Render this editor in a div.
    * @returns {HTMLDivElement | null}

src/display/editor/stamp.js

@@ -431,6 +431,42 @@ class StampEditor extends AnnotationEditor {
     const bitmap = this.#isSvg
       ? this.#bitmap
       : this.#scaleBitmap(width, height);
+
+    if (this._uiManager.hasMLManager && !this.hasAltText()) {
+      const offscreen = new OffscreenCanvas(width, height);
+      const ctx = offscreen.getContext("2d");
+      ctx.drawImage(
+        bitmap,
+        0,
+        0,
+        bitmap.width,
+        bitmap.height,
+        0,
+        0,
+        width,
+        height
+      );
+      offscreen.convertToBlob().then(blob => {
+        const fileReader = new FileReader();
+        fileReader.onload = () => {
+          const url = fileReader.result;
+          this._uiManager
+            .mlGuess({
+              service: "image-to-text",
+              request: {
+                imageData: url,
+              },
+            })
+            .then(response => {
+              const altText = response?.output || "";
+              if (this.parent && altText && !this.hasAltText()) {
+                this.altTextData = { altText, decorative: false };
+              }
+            });
+        };
+        fileReader.readAsDataURL(blob);
+      });
+    }
     const ctx = canvas.getContext("2d");
     ctx.filter = this._uiManager.hcmFilter;
     ctx.drawImage(

src/display/editor/tools.js

@@ -563,6 +563,8 @@ class AnnotationEditorUIManager {
 
   #mainHighlightColorPicker = null;
 
+  #mlManager = null;
+
   #mode = AnnotationEditorType.NONE;
 
   #selectedEditors = new Set();
@@ -749,7 +751,8 @@ class AnnotationEditorUIManager {
     eventBus,
     pdfDocument,
     pageColors,
-    highlightColors
+    highlightColors,
+    mlManager
   ) {
     this.#container = container;
     this.#viewer = viewer;
@@ -763,6 +766,7 @@ class AnnotationEditorUIManager {
     this.#filterFactory = pdfDocument.filterFactory;
     this.#pageColors = pageColors;
     this.#highlightColors = highlightColors || null;
+    this.#mlManager = mlManager || null;
     this.viewParameters = {
       realScale: PixelsPerInch.PDF_TO_CSS_UNITS,
       rotation: 0,
@@ -797,6 +801,14 @@ class AnnotationEditorUIManager {
     }
   }
 
+  async mlGuess(data) {
+    return this.#mlManager?.guess(data) || null;
+  }
+
+  get hasMLManager() {
+    return !!this.#mlManager;
+  }
+
   get hcmFilter() {
     return shadow(
       this,

web/app.js

@@ -53,7 +53,7 @@ import {
 } from "pdfjs-lib";
 import { AppOptions, OptionKind } from "./app_options.js";
 import { AutomationEventBus, EventBus } from "./event_utils.js";
-import { ExternalServices, initCom } from "web-external_services";
+import { ExternalServices, initCom, MLManager } from "web-external_services";
 import { LinkTarget, PDFLinkService } from "./pdf_link_service.js";
 import { AltTextManager } from "web-alt_text_manager";
 import { AnnotationEditorParams } from "web-annotation_editor_params";
@@ -420,6 +420,7 @@ const PDFViewerApplication = {
       maxCanvasPixels: AppOptions.get("maxCanvasPixels"),
       enablePermissions: AppOptions.get("enablePermissions"),
       pageColors,
+      mlManager: this.mlManager,
     });
     this.pdfViewer = pdfViewer;
 
@@ -682,6 +683,14 @@ const PDFViewerApplication = {
     return shadow(this, "externalServices", new ExternalServices());
   },
 
+  get mlManager() {
+    return shadow(
+      this,
+      "mlManager",
+      AppOptions.get("enableML") === true ? new MLManager() : null
+    );
+  },
+
   get initialized() {
     return this._initializedCapability.settled;
   },

web/app_options.js

@@ -143,6 +143,11 @@ const defaultOptions = {
     value: typeof PDFJSDev === "undefined" || PDFJSDev.test("TESTING"),
     kind: OptionKind.VIEWER + OptionKind.PREFERENCE,
   },
+  enableML: {
+    /** @type {boolean} */
+    value: false,
+    kind: OptionKind.VIEWER + OptionKind.PREFERENCE,
+  },
   enablePermissions: {
     /** @type {boolean} */
     value: false,

web/chromecom.js

@@ -435,4 +435,10 @@ class ExternalServices extends BaseExternalServices {
   }
 }
 
-export { ExternalServices, initCom, Preferences };
+class MLManager {
+  async guess() {
+    return null;
+  }
+}
+
+export { ExternalServices, initCom, MLManager, Preferences };

web/firefoxcom.js

@@ -314,6 +314,12 @@ class FirefoxScripting {
   }
 }
 
+class MLManager {
+  guess(data) {
+    return FirefoxCom.requestAsync("mlGuess", data);
+  }
+}
+
 class ExternalServices extends BaseExternalServices {
   updateFindControlState(data) {
     FirefoxCom.request("updateFindControlState", data);
@@ -415,4 +421,4 @@ class ExternalServices extends BaseExternalServices {
   }
 }
 
-export { DownloadManager, ExternalServices, initCom, Preferences };
+export { DownloadManager, ExternalServices, initCom, MLManager, Preferences };

web/genericcom.js

@@ -47,4 +47,10 @@ class ExternalServices extends BaseExternalServices {
   }
 }
 
-export { ExternalServices, initCom, Preferences };
+class MLManager {
+  async guess() {
+    return null;
+  }
+}
+
+export { ExternalServices, initCom, MLManager, Preferences };

web/pdf_viewer.js

@@ -216,6 +216,8 @@ class PDFViewer {
 
   #enablePermissions = false;
 
+  #mlManager = null;
+
   #getAllTextInProgress = false;
 
   #hiddenCopyElement = null;
@@ -292,6 +294,7 @@ class PDFViewer {
     }
     this.#enablePermissions = options.enablePermissions || false;
     this.pageColors = options.pageColors || null;
+    this.#mlManager = options.mlManager || null;
 
     this.defaultRenderingQueue = !options.renderingQueue;
     if (
@@ -857,7 +860,8 @@ class PDFViewer {
               this.eventBus,
               pdfDocument,
               this.pageColors,
-              this.#annotationEditorHighlightColors
+              this.#annotationEditorHighlightColors,
+              this.#mlManager
             );
             this.eventBus.dispatch("annotationeditoruimanager", {
               source: this,