pdf.js/web/new_alt_text_manager.js

/* Copyright 2024 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.
 */

class NewAltTextManager {
  #boundCancel = this.#cancel.bind(this);

  #createAutomaticallyButton;

  #currentEditor = null;

  #cancelButton;

  #descriptionContainer;

  #dialog;

  #disclaimer;

  #firstTime = false;

  #guessedAltText;

  #isEditing = null;

  #imagePreview;

  #imageData;

  #isAILoading = false;

  #wasAILoading = false;

  #learnMore;

  #notNowButton;

  #overlayManager;

  #textarea;

  #title;

  #uiManager;

  #previousAltText = null;

  #telemetryData = null;

  constructor(
    {
      descriptionContainer,
      dialog,
      imagePreview,
      cancelButton,
      disclaimer,
      notNowButton,
      saveButton,
      textarea,
      learnMore,
      errorCloseButton,
      createAutomaticallyButton,
      title,
    },
    overlayManager
  ) {
    this.#cancelButton = cancelButton;
    this.#createAutomaticallyButton = createAutomaticallyButton;
    this.#descriptionContainer = descriptionContainer;
    this.#dialog = dialog;
    this.#disclaimer = disclaimer;
    this.#notNowButton = notNowButton;
    this.#imagePreview = imagePreview;
    this.#textarea = textarea;
    this.#learnMore = learnMore;
    this.#title = title;
    this.#overlayManager = overlayManager;

    dialog.addEventListener("close", this.#close.bind(this));
    dialog.addEventListener("contextmenu", event => {
      if (event.target !== this.#textarea) {
        event.preventDefault();
      }
    });
    cancelButton.addEventListener("click", this.#boundCancel);
    notNowButton.addEventListener("click", this.#boundCancel);
    saveButton.addEventListener("click", this.#save.bind(this));
    errorCloseButton.addEventListener("click", () => {
      this.#toggleError(false);
    });
    createAutomaticallyButton.addEventListener("click", async () => {
      const checked =
        createAutomaticallyButton.getAttribute("aria-pressed") !== "true";
      if (this.#uiManager) {
        this.#uiManager.setPreference("enableGuessAltText", checked);
        await this.#uiManager.mlManager.toggleService("altText", checked);
      }
      this.#toggleGuessAltText(checked, /* isInitial = */ false);
    });
    textarea.addEventListener("focus", () => {
      this.#wasAILoading = this.#isAILoading;
      this.#toggleLoading(false);
    });
    textarea.addEventListener("blur", () => {
      if (textarea.value) {
        return;
      }
      this.#toggleLoading(this.#wasAILoading);
    });
    textarea.addEventListener("input", () => {
      this.#toggleTitle();
      this.#toggleDisclaimer();
    });

    this.#overlayManager.register(dialog);
  }

  #toggleLoading(value) {
    if (!this.#uiManager || this.#isAILoading === value) {
      return;
    }
    this.#isAILoading = value;
    this.#descriptionContainer.classList.toggle("loading", value);
  }

  #toggleError(value) {
    if (!this.#uiManager) {
      return;
    }
    this.#dialog.classList.toggle("error", value);
  }

  #toggleTitle() {
    const isEditing = this.#isAILoading || !!this.#textarea.value;
    if (this.#isEditing === isEditing) {
      return;
    }
    this.#isEditing = isEditing;
    this.#title.setAttribute(
      "data-l10n-id",
      `pdfjs-editor-new-alt-text-dialog-${isEditing ? "edit" : "add"}-label`
    );
  }

  async #toggleGuessAltText(value, isInitial = false) {
    if (!this.#uiManager) {
      return;
    }
    this.#dialog.classList.toggle("aiDisabled", !value);
    this.#createAutomaticallyButton.setAttribute("aria-pressed", value);

    if (value) {
      const { altTextLearnMoreUrl } = this.#uiManager.mlManager;
      if (altTextLearnMoreUrl) {
        this.#learnMore.href = altTextLearnMoreUrl;
      }
      this.#mlGuessAltText(isInitial);
    } else {
      this.#toggleLoading(false);
      this.#isAILoading = false;
      this.#toggleTitle();
      this.#toggleDisclaimer();
    }
  }

  #toggleNotNow() {
    this.#notNowButton.classList.toggle("hidden", !this.#firstTime);
    this.#cancelButton.classList.toggle("hidden", this.#firstTime);
  }

  #toggleAI(value) {
    this.#dialog.classList.toggle("noAi", !value);
    this.#toggleTitle();
  }

  #toggleDisclaimer(value = null) {
    if (!this.#uiManager) {
      return;
    }
    const hidden =
      value === null
        ? !this.#guessedAltText || this.#guessedAltText !== this.#textarea.value
        : !value;
    this.#disclaimer.classList.toggle("hidden", hidden);
  }

  async #mlGuessAltText(isInitial) {
    if (this.#isAILoading) {
      // We're still loading the previous guess.
      return;
    }

    if (this.#textarea.value) {
      // The user has already set an alt text.
      return;
    }

    if (isInitial && this.#previousAltText !== null) {
      // The user has already set an alt text (empty or not).
      return;
    }

    this.#guessedAltText = this.#currentEditor.guessedAltText;
    if (this.#previousAltText === null && this.#guessedAltText) {
      // We have a guessed alt text and the user didn't change it.
      this.#addAltText(this.#guessedAltText);
      this.#toggleDisclaimer();
      this.#toggleTitle();
      return;
    }

    this.#toggleLoading(true);
    this.#toggleTitle();
    this.#toggleDisclaimer(true);

    let hasError = false;
    try {
      const { width, height, data } = this.#imageData;

      // Take a reference on the current editor, as it can be set to null (if
      // the dialog is closed before the end of the guess).
      // But in case we've an alt-text, we want to set it on the editor.
      const editor = this.#currentEditor;

      // 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({
        service: "moz-image-to-text",
        request: {
          data,
          width,
          height,
          channels: data.length / (width * height),
        },
      });
      if (!response || response.error || !response.output) {
        throw new Error("No valid response from the AI service.");
      }
      const altText = (this.#guessedAltText = response.output);
      await editor.setGuessedAltText(altText);
      this.#wasAILoading = this.#isAILoading;
      if (this.#isAILoading) {
        this.#addAltText(altText);
      }
    } catch (e) {
      console.error(e);
      hasError = true;
    }

    this.#toggleLoading(false);

    if (hasError && this.#uiManager) {
      this.#toggleError(true);
      this.#toggleTitle();
      this.#toggleDisclaimer();
    }
  }

  #addAltText(altText) {
    if (!this.#uiManager || this.#textarea.value) {
      return;
    }
    this.#textarea.value = altText;
  }

  async editAltText(uiManager, editor, firstTime) {
    if (this.#currentEditor || !editor) {
      return;
    }

    if (firstTime && editor.hasAltTextData()) {
      editor.altTextFinish();
      return;
    }

    this.#firstTime = firstTime;
    let { mlManager } = uiManager;
    if (!mlManager?.isReady("altText")) {
      mlManager = null;
    }
    const isAltTextEnabledPromise = mlManager?.isEnabledFor("altText");

    this.#currentEditor = editor;
    this.#uiManager = uiManager;
    this.#uiManager.removeEditListeners();

    ({ altText: this.#previousAltText } = editor.altTextData);
    this.#textarea.value = this.#previousAltText ?? "";

    // TODO: get this value from Firefox
    //   (https://bugzilla.mozilla.org/show_bug.cgi?id=1908184)
    const AI_MAX_IMAGE_DIMENSION = 224;

    // The max dimension of the preview in the dialog is 180px, so we keep 224px
    // and rescale it thanks to css.

    let canvas;
    if (mlManager) {
      ({ canvas, imageData: this.#imageData } = editor.copyCanvas(
        AI_MAX_IMAGE_DIMENSION,
        /* createImageData = */ true
      ));
      this.#toggleGuessAltText(
        await isAltTextEnabledPromise,
        /* isInitial = */ true
      );
    } else {
      ({ canvas } = editor.copyCanvas(
        AI_MAX_IMAGE_DIMENSION,
        /* createImageData = */ false
      ));
    }

    canvas.setAttribute("role", "presentation");
    this.#imagePreview.append(canvas);

    this.#toggleNotNow();
    this.#toggleAI(!!mlManager);
    this.#toggleError(false);

    try {
      await this.#overlayManager.open(this.#dialog);
    } catch (ex) {
      this.#close();
      throw ex;
    }
  }

  #cancel() {
    this.#currentEditor.altTextData = {
      cancel: true,
    };
    this.#finish();
  }

  #finish() {
    if (this.#overlayManager.active === this.#dialog) {
      this.#overlayManager.close(this.#dialog);
    }
  }

  #close() {
    const canvas = this.#imagePreview.firstChild;
    canvas.remove();
    canvas.width = canvas.height = 0;
    this.#imageData = null;

    this.#currentEditor._reportTelemetry(
      this.#telemetryData || {
        action: "alt_text_cancel",
      }
    );

    this.#telemetryData = null;
    this.#toggleLoading(false);

    this.#uiManager?.addEditListeners();
    this.#currentEditor.altTextFinish();
    this.#uiManager?.setSelected(this.#currentEditor);
    this.#currentEditor = null;
    this.#uiManager = null;
  }

  #save() {
    const altText = this.#textarea.value.trim();
    this.#currentEditor.altTextData = {
      altText,
      decorative: false,
    };
    this.#telemetryData = {
      action: "alt_text_save",
      alt_text_description: !!altText,
      alt_text_edit:
        !!this.#previousAltText && this.#previousAltText !== altText,
      alt_text_decorative: false,
      alt_text_altered:
        this.#guessedAltText && this.#guessedAltText !== altText,
    };
    this.#finish();
  }

  destroy() {
    this.#uiManager = null; // Avoid re-adding the edit listeners.
    this.#finish();
  }
}

export { NewAltTextManager };