pdf.js/src/display/editor/alt_text.js

/* Copyright 2023 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.
 */

import { noContextMenu } from "../display_utils.js";

class AltText {
  #altText = null;

  #altTextDecorative = false;

  #altTextButton = null;

  #altTextTooltip = null;

  #altTextTooltipTimeout = null;

  #altTextWasFromKeyBoard = false;

  #badge = null;

  #editor = null;

  #guessedText = null;

  #textWithDisclaimer = null;

  #useNewAltTextFlow = false;

  static _l10nPromise = null;

  constructor(editor) {
    this.#editor = editor;
    this.#useNewAltTextFlow = editor._uiManager.useNewAltTextFlow;
  }

  static initialize(l10nPromise) {
    AltText._l10nPromise ||= l10nPromise;
  }

  async render() {
    const altText = (this.#altTextButton = document.createElement("button"));
    altText.className = "altText";
    let msg;
    if (this.#useNewAltTextFlow) {
      altText.classList.add("new");
      msg = await AltText._l10nPromise.get(
        "pdfjs-editor-new-alt-text-missing-button-label"
      );
    } else {
      msg = await AltText._l10nPromise.get(
        "pdfjs-editor-alt-text-button-label"
      );
    }
    altText.textContent = msg;
    altText.setAttribute("aria-label", msg);
    altText.tabIndex = "0";
    const signal = this.#editor._uiManager._signal;
    altText.addEventListener("contextmenu", noContextMenu, { signal });
    altText.addEventListener("pointerdown", event => event.stopPropagation(), {
      signal,
    });

    const onClick = event => {
      event.preventDefault();
      this.#editor._uiManager.editAltText(this.#editor);
      if (this.#useNewAltTextFlow) {
        this.#editor._reportTelemetry({
          action: "pdfjs.image.alt_text.image_status_label_clicked",
          label: this.#label,
        });
      }
    };
    altText.addEventListener("click", onClick, { capture: true, signal });
    altText.addEventListener(
      "keydown",
      event => {
        if (event.target === altText && event.key === "Enter") {
          this.#altTextWasFromKeyBoard = true;
          onClick(event);
        }
      },
      { signal }
    );
    await this.#setState();

    return altText;
  }

  get #label() {
    return (
      (this.#altText && "added") ||
      (this.#altText === null && this.guessedText && "review") ||
      "missing"
    );
  }

  finish() {
    if (!this.#altTextButton) {
      return;
    }
    this.#altTextButton.focus({ focusVisible: this.#altTextWasFromKeyBoard });
    this.#altTextWasFromKeyBoard = false;
  }

  isEmpty() {
    if (this.#useNewAltTextFlow) {
      return this.#altText === null;
    }
    return !this.#altText && !this.#altTextDecorative;
  }

  hasData() {
    if (this.#useNewAltTextFlow) {
      return this.#altText !== null || !!this.#guessedText;
    }
    return this.isEmpty();
  }

  get guessedText() {
    return this.#guessedText;
  }

  async setGuessedText(guessedText) {
    if (this.#altText !== null) {
      // The user provided their own alt text, so we don't want to overwrite it.
      return;
    }
    this.#guessedText = guessedText;
    this.#textWithDisclaimer = await AltText._l10nPromise.get(
      "pdfjs-editor-new-alt-text-generated-alt-text-with-disclaimer"
    )({ generatedAltText: guessedText });
    this.#setState();
  }

  toggleAltTextBadge(visibility = false) {
    if (!this.#useNewAltTextFlow || this.#altText) {
      this.#badge?.remove();
      this.#badge = null;
      return;
    }
    if (!this.#badge) {
      const badge = (this.#badge = document.createElement("div"));
      badge.className = "noAltTextBadge";
      this.#editor.div.append(badge);
    }
    this.#badge.classList.toggle("hidden", !visibility);
  }

  serialize(isForCopying) {
    let altText = this.#altText;
    if (!isForCopying && this.#guessedText === altText) {
      altText = this.#textWithDisclaimer;
    }
    return {
      altText,
      decorative: this.#altTextDecorative,
      guessedText: this.#guessedText,
      textWithDisclaimer: this.#textWithDisclaimer,
    };
  }

  get data() {
    return {
      altText: this.#altText,
      decorative: this.#altTextDecorative,
    };
  }

  /**
   * Set the alt text data.
   */
  set data({
    altText,
    decorative,
    guessedText,
    textWithDisclaimer,
    cancel = false,
  }) {
    if (guessedText) {
      this.#guessedText = guessedText;
      this.#textWithDisclaimer = textWithDisclaimer;
    }
    if (this.#altText === altText && this.#altTextDecorative === decorative) {
      return;
    }
    if (!cancel) {
      this.#altText = altText;
      this.#altTextDecorative = decorative;
    }
    this.#setState();
  }

  toggle(enabled = false) {
    if (!this.#altTextButton) {
      return;
    }
    if (!enabled && this.#altTextTooltipTimeout) {
      clearTimeout(this.#altTextTooltipTimeout);
      this.#altTextTooltipTimeout = null;
    }
    this.#altTextButton.disabled = !enabled;
  }

  destroy() {
    this.#altTextButton?.remove();
    this.#altTextButton = null;
    this.#altTextTooltip = null;
    this.#badge?.remove();
    this.#badge = null;
  }

  async #setState() {
    const button = this.#altTextButton;
    if (!button) {
      return;
    }

    if (this.#useNewAltTextFlow) {
      // If we've an alt text, we get an "added".
      // If we've a guessed text and the alt text has never been set, we get a
      // "to-review" been set.
      // Otherwise, we get a "missing".
      const label = this.#label;
      // TODO: Update the l10n keys to avoid this.
      const type = label === "review" ? "to-review" : label;
      this.#editor._reportTelemetry({
        action: "pdfjs.image.alt_text.image_status_label_displayed",
        label,
      });
      button.classList.toggle("done", !!this.#altText);
      AltText._l10nPromise
        .get(`pdfjs-editor-new-alt-text-${type}-button-label`)
        .then(msg => {
          button.setAttribute("aria-label", msg);
          // We can't just use button.textContent here, because it would remove
          // the existing tooltip element.
          for (const child of button.childNodes) {
            if (child.nodeType === Node.TEXT_NODE) {
              child.textContent = msg;
              break;
            }
          }
        });
      if (!this.#altText) {
        this.#altTextTooltip?.remove();
        return;
      }
    } else {
      if (!this.#altText && !this.#altTextDecorative) {
        button.classList.remove("done");
        this.#altTextTooltip?.remove();
        return;
      }
      button.classList.add("done");
      AltText._l10nPromise
        .get("pdfjs-editor-alt-text-edit-button-label")
        .then(msg => {
          button.setAttribute("aria-label", msg);
        });
    }

    let tooltip = this.#altTextTooltip;
    if (!tooltip) {
      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);

      const DELAY_TO_SHOW_TOOLTIP = 100;
      const signal = this.#editor._uiManager._signal;
      signal.addEventListener(
        "abort",
        () => {
          clearTimeout(this.#altTextTooltipTimeout);
          this.#altTextTooltipTimeout = null;
        },
        { once: true }
      );
      button.addEventListener(
        "mouseenter",
        () => {
          this.#altTextTooltipTimeout = setTimeout(() => {
            this.#altTextTooltipTimeout = null;
            this.#altTextTooltip.classList.add("show");
            this.#editor._reportTelemetry({
              action: "alt_text_tooltip",
            });
          }, DELAY_TO_SHOW_TOOLTIP);
        },
        { signal }
      );
      button.addEventListener(
        "mouseleave",
        () => {
          if (this.#altTextTooltipTimeout) {
            clearTimeout(this.#altTextTooltipTimeout);
            this.#altTextTooltipTimeout = null;
          }
          this.#altTextTooltip?.classList.remove("show");
        },
        { signal }
      );
    }
    tooltip.innerText = this.#altTextDecorative
      ? await AltText._l10nPromise.get(
          "pdfjs-editor-alt-text-decorative-tooltip"
        )
      : this.#altText;

    if (!tooltip.parentNode) {
      button.append(tooltip);
    }

    const element = this.#editor.getImageForAltText();
    element?.setAttribute("aria-describedby", tooltip.id);
  }
}

export { AltText };