[Editor] Guess alt text even when showing the dialog is disabled

src/display/editor/stamp.js

@@ -133,8 +133,54 @@ class StampEditor extends AnnotationEditor {
     ) {
       this._editToolbar.hide();
       this._uiManager.editAltText(this, /* firstTime = */ true);
-    } else {
-      this.div.focus();
+      return;
+    }
+
+    if (
+      !this._uiManager.useNewAltTextWhenAddingImage &&
+      this._uiManager.useNewAltTextFlow &&
+      this.#bitmap
+    ) {
+      // The alt-text dialog isn't opened but we still want to guess the alt
+      // text.
+      this.#mlGuessAltText();
+    }
+
+    this.div.focus();
+  }
+
+  async #mlGuessAltText() {
+    if (this.hasAltTextData()) {
+      return;
+    }
+
+    const { mlManager } = this._uiManager;
+    if (!mlManager || !(await mlManager.isEnabledFor("altText"))) {
+      return;
+    }
+
+    // TODO: get this value from Firefox
+    //   (https://bugzilla.mozilla.org/show_bug.cgi?id=1908184)
+    const AI_MAX_IMAGE_DIMENSION = 224;
+    const {
+      imageData: { width, height, data },
+    } = this.copyCanvas(AI_MAX_IMAGE_DIMENSION, /* createImageData = */ true);
+    const response = await mlManager.guess({
+      name: "altText",
+      request: {
+        data,
+        width,
+        height,
+        channels: data.length / (width * height),
+      },
+    });
+    if (!response || response.error || !response.output) {
+      return;
+    }
+    const altText = response.output;
+    await this.setGuessedAltText(altText);
+    if (!this.hasAltTextData()) {
+      this.altTextData = { alt: altText, decorative: false };
     }
   }
 

src/display/editor/tools.js

@@ -856,18 +856,6 @@ class AnnotationEditorUIManager {
     }
   }
 
-  hasMLManager() {
-    return !!this.#mlManager;
-  }
-
-  async mlGuess(data) {
-    return this.#mlManager?.guess(data) || null;
-  }
-
-  async isMLEnabledFor(name) {
-    return !!(await this.#mlManager?.isEnabledFor(name));
-  }
-
   get mlManager() {
     return this.#mlManager;
   }

web/new_alt_text_manager.js

@@ -249,7 +249,7 @@ class NewAltTextManager {
 
       // When calling #mlGuessAltText we don't wait for it, so we must take care
       // that the alt text dialog can have been closed before the response is.
-      const response = await this.#uiManager.mlGuess({
+      const response = await this.#uiManager.mlManager.guess({
         name: "altText",
         request: {
           data,