[Editor] Allow the user to add and save an alt-text for images (bug 1844952)

src/display/editor/editor.js

@@ -34,8 +34,14 @@ import { FeatureTest, shadow, unreachable } from "../../shared/util.js";
  * Base class for editors.
  */
 class AnnotationEditor {
+  #altText = "";
+
+  #altTextDecorative = false;
+
   #altTextButton = null;
 
+  #altTextAriaDescription = null;
+
   #keepAspectRatio = false;
 
   #resizersDiv = null;
@@ -810,7 +816,7 @@ class AnnotationEditor {
     if (this.#altTextButton) {
       return;
     }
-    const altText = (this.#altTextButton = document.createElement("span"));
+    const altText = (this.#altTextButton = document.createElement("button"));
     altText.className = "altText";
     AnnotationEditor._l10nPromise.get("alt_text_button_label").then(msg => {
       altText.textContent = msg;
@@ -820,14 +826,17 @@ class AnnotationEditor {
       "click",
       event => {
         event.preventDefault();
+        this._uiManager.editAltText(this);
       },
       { capture: true }
     );
     altText.addEventListener("keydown", event => {
       if (event.target === altText && event.key === "Enter") {
         event.preventDefault();
+        this._uiManager.editAltText(this);
       }
     });
+    this.#setAltTextButtonState();
     this.div.append(altText);
     if (!AnnotationEditor.SMALL_EDITOR_SIZE) {
       // We take the width of the alt text button and we add 40% to it to be
@@ -840,6 +849,55 @@ class AnnotationEditor {
     }
   }
 
+  #setAltTextButtonState() {
+    const button = this.#altTextButton;
+    if (!button) {
+      return;
+    }
+    // TODO: remove the aria-describedby once the tooltip stuff is implemented:
+    // the tooltip willl contain a span with the description, hence we could use
+    // it.
+    if (this.#altTextDecorative) {
+      button.classList.add("done");
+      button.title = "";
+      if (this.#altTextAriaDescription) {
+        button.removeAttribute("aria-describedby");
+        this.#altTextAriaDescription.remove();
+        this.#altTextAriaDescription = null;
+      }
+    } else if (this.#altText) {
+      button.classList.add("done");
+      button.title = this.#altText;
+      let description = this.#altTextAriaDescription;
+      if (!description) {
+        this.#altTextAriaDescription = description =
+          document.createElement("span");
+        description.className = "description";
+        const id = (description.id = `${this.id}-alt-text`);
+        button.append(description);
+        button.setAttribute("aria-describedby", id);
+      }
+      description.innerText = this.#altText;
+    }
+  }
+
+  getClientDimensions() {
+    return this.div.getBoundingClientRect();
+  }
+
+  get altTextData() {
+    return {
+      altText: this.#altText,
+      decorative: this.#altTextDecorative,
+    };
+  }
+
+  set altTextData({ altText, decorative }) {
+    this.#altText = altText;
+    this.#altTextDecorative = decorative;
+    this.#setAltTextButtonState();
+  }
+
   /**
    * Render this editor in a div.
    * @returns {HTMLDivElement}

src/display/editor/stamp.js

@@ -484,7 +484,7 @@ class StampEditor extends AnnotationEditor {
       return null;
     }
     const editor = super.deserialize(data, parent, uiManager);
-    const { rect, bitmapUrl, bitmapId, isSvg } = data;
+    const { rect, bitmapUrl, bitmapId, isSvg, accessibilityData } = data;
     if (bitmapId && uiManager.imageManager.isValidId(bitmapId)) {
       editor.#bitmapId = bitmapId;
     } else {
@@ -496,6 +496,10 @@ class StampEditor extends AnnotationEditor {
     editor.width = (rect[2] - rect[0]) / parentWidth;
     editor.height = (rect[3] - rect[1]) / parentHeight;
 
+    if (accessibilityData) {
+      editor.altTextData = accessibilityData;
+    }
+
     return editor;
   }
 
@@ -520,9 +524,15 @@ class StampEditor extends AnnotationEditor {
       // of this annotation and the clipboard doesn't support ImageBitmaps,
       // hence we serialize the bitmap to a data url.
       serialized.bitmapUrl = this.#serializeBitmap(/* toUrl = */ true);
+      serialized.accessibilityData = this.altTextData;
       return serialized;
     }
 
+    const { decorative, altText } = this.altTextData;
+    if (!decorative && altText) {
+      serialized.accessibilityData = { type: "Figure", alt: altText };
+    }
+
     if (context === null) {
       return serialized;
     }

src/display/editor/tools.js

@@ -525,6 +525,8 @@ class AnnotationEditorUIManager {
 
   #allLayers = new Map();
 
+  #altTextManager = null;
+
   #annotationStorage = null;
 
   #commandManager = new CommandManager();
@@ -693,9 +695,17 @@ class AnnotationEditorUIManager {
     );
   }
 
-  constructor(container, viewer, eventBus, pdfDocument, pageColors) {
+  constructor(
+    container,
+    viewer,
+    altTextManager,
+    eventBus,
+    pdfDocument,
+    pageColors
+  ) {
     this.#container = container;
     this.#viewer = viewer;
+    this.#altTextManager = altTextManager;
     this.#eventBus = eventBus;
     this.#eventBus._on("editingaction", this.#boundOnEditingAction);
     this.#eventBus._on("pagechanging", this.#boundOnPageChanging);
@@ -711,7 +721,7 @@ class AnnotationEditorUIManager {
   }
 
   destroy() {
-    this.#removeKeyboardManager();
+    this.removeKeyboardManager();
     this.#removeFocusManager();
     this.#eventBus._off("editingaction", this.#boundOnEditingAction);
     this.#eventBus._off("pagechanging", this.#boundOnPageChanging);
@@ -726,6 +736,7 @@ class AnnotationEditorUIManager {
     this.#activeEditor = null;
     this.#selectedEditors.clear();
     this.#commandManager.destroy();
+    this.#altTextManager.destroy();
   }
 
   get hcmFilter() {
@@ -749,6 +760,10 @@ class AnnotationEditorUIManager {
     );
   }
 
+  editAltText(editor) {
+    this.#altTextManager?.editAltText(this, editor);
+  }
+
   onPageChanging({ pageNumber }) {
     this.#currentPageIndex = pageNumber - 1;
   }
@@ -860,13 +875,13 @@ class AnnotationEditorUIManager {
     lastActiveElement.focus();
   }
 
-  #addKeyboardManager() {
+  addKeyboardManager() {
     // The keyboard events are caught at the container level in order to be able
     // to execute some callbacks even if the current page doesn't have focus.
     window.addEventListener("keydown", this.#boundKeydown, { capture: true });
   }
 
-  #removeKeyboardManager() {
+  removeKeyboardManager() {
     window.removeEventListener("keydown", this.#boundKeydown, {
       capture: true,
     });
@@ -1039,7 +1054,7 @@ class AnnotationEditorUIManager {
   setEditingState(isEditing) {
     if (isEditing) {
       this.#addFocusManager();
-      this.#addKeyboardManager();
+      this.addKeyboardManager();
       this.#addCopyPasteListeners();
       this.#dispatchUpdateStates({
         isEditing: this.#mode !== AnnotationEditorType.NONE,
@@ -1050,7 +1065,7 @@ class AnnotationEditorUIManager {
       });
     } else {
       this.#removeFocusManager();
-      this.#removeKeyboardManager();
+      this.removeKeyboardManager();
       this.#removeCopyPasteListeners();
       this.#dispatchUpdateStates({
         isEditing: false,