[Editor] Make the focused stamp annotation more clear from a screen reader point of view (bug 1911994)

It has been tested with Voice Over (mac) and with NVDA (windows).

When an added stamp annotation is focused, the screen reader will announce
that it's a figure containing a graphic with the added alt-text.

src/display/editor/alt_text.js

@@ -279,8 +279,7 @@ class AltText {
       this.#altTextTooltip = tooltip = document.createElement("span");
       tooltip.className = "tooltip";
       tooltip.setAttribute("role", "tooltip");
-      const id = (tooltip.id = `alt-text-tooltip-${this.#editor.id}`);
-      button.setAttribute("aria-describedby", id);
+      tooltip.id = `alt-text-tooltip-${this.#editor.id}`;
 
       const DELAY_TO_SHOW_TOOLTIP = 100;
       const signal = this.#editor._uiManager._signal;

src/display/editor/editor.js

@@ -993,6 +993,15 @@ class AnnotationEditor {
     this.#altText?.destroy();
   }
 
+  addContainer(container) {
+    const editToolbarDiv = this._editToolbar?.div;
+    if (editToolbarDiv) {
+      editToolbarDiv.before(container);
+    } else {
+      this.div.append(container);
+    }
+  }
+
   getClientDimensions() {
     return this.div.getBoundingClientRect();
   }

src/display/editor/stamp.js

@@ -373,6 +373,7 @@ class StampEditor extends AnnotationEditor {
 
     super.render();
     this.div.hidden = true;
+    this.div.setAttribute("role", "figure");
 
     this.addAltTextButton();
 
@@ -425,7 +426,9 @@ class StampEditor extends AnnotationEditor {
 
     this._uiManager.enableWaiting(false);
     const canvas = (this.#canvas = document.createElement("canvas"));
-    div.append(canvas);
+    canvas.setAttribute("role", "img");
+    this.addContainer(canvas);
+
     if (
       !this._uiManager.useNewAltTextWhenAddingImage ||
       !this._uiManager.useNewAltTextFlow

src/display/editor/toolbar.js

@@ -62,6 +62,10 @@ class EditorToolbar {
     return editToolbar;
   }
 
+  get div() {
+    return this.#toolbar;
+  }
+
   static #pointerDown(e) {
     e.stopPropagation();
   }