pdf.js/web/toolbar.js

/* Copyright 2016 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 {
  animationStarted,
  DEFAULT_SCALE,
  DEFAULT_SCALE_VALUE,
  MAX_SCALE,
  MIN_SCALE,
  noContextMenuHandler,
  NullL10n,
} from "./ui_utils.js";

const PAGE_NUMBER_LOADING_INDICATOR = "visiblePageIsLoading";
// Keep the two values below up-to-date with the values in `web/viewer.css`:
const SCALE_SELECT_CONTAINER_WIDTH = 140; // px
const SCALE_SELECT_WIDTH = 162; // px

/**
 * @typedef {Object} ToolbarOptions
 * @property {HTMLDivElement} container - Container for the secondary toolbar.
 * @property {HTMLSpanElement} numPages - Label that contains number of pages.
 * @property {HTMLInputElement} pageNumber - Control for display and user input
 *   of the current page number.
 * @property {HTMLSpanElement} scaleSelectContainer - Container where scale
 *   controls are placed. The width is adjusted on UI initialization.
 * @property {HTMLSelectElement} scaleSelect - Scale selection control.
 * @property {HTMLOptionElement} customScaleOption - The item used to display
 *   a non-predefined scale.
 * @property {HTMLButtonElement} previous - Button to go to the previous page.
 * @property {HTMLButtonElement} next - Button to go to the next page.
 * @property {HTMLButtonElement} zoomIn - Button to zoom in the pages.
 * @property {HTMLButtonElement} zoomOut - Button to zoom out the pages.
 * @property {HTMLButtonElement} viewFind - Button to open find bar.
 * @property {HTMLButtonElement} openFile - Button to open a new document.
 * @property {HTMLButtonElement} presentationModeButton - Button to switch to
 *   presentation mode.
 * @property {HTMLButtonElement} download - Button to download the document.
 * @property {HTMLAElement} viewBookmark - Element to link current url of
 *   the page view.
 */

class Toolbar {
  /**
   * @param {ToolbarOptions} options
   * @param {EventBus} eventBus
   * @param {IL10n} l10n - Localization service.
   */
  constructor(options, eventBus, l10n = NullL10n) {
    this.toolbar = options.container;
    this.eventBus = eventBus;
    this.l10n = l10n;
    this.buttons = [
      { element: options.previous, eventName: "previouspage" },
      { element: options.next, eventName: "nextpage" },
      { element: options.zoomIn, eventName: "zoomin" },
      { element: options.zoomOut, eventName: "zoomout" },
      { element: options.openFile, eventName: "openfile" },
      { element: options.print, eventName: "print" },
      {
        element: options.presentationModeButton,
        eventName: "presentationmode",
      },
      { element: options.download, eventName: "download" },
      { element: options.viewBookmark, eventName: null },
    ];
    this.items = {
      numPages: options.numPages,
      pageNumber: options.pageNumber,
      scaleSelectContainer: options.scaleSelectContainer,
      scaleSelect: options.scaleSelect,
      customScaleOption: options.customScaleOption,
      previous: options.previous,
      next: options.next,
      zoomIn: options.zoomIn,
      zoomOut: options.zoomOut,
    };

    this._wasLocalized = false;
    this.reset();

    // Bind the event listeners for click and various other actions.
    this._bindListeners();
  }

  setPageNumber(pageNumber, pageLabel) {
    this.pageNumber = pageNumber;
    this.pageLabel = pageLabel;
    this._updateUIState(false);
  }

  setPagesCount(pagesCount, hasPageLabels) {
    this.pagesCount = pagesCount;
    this.hasPageLabels = hasPageLabels;
    this._updateUIState(true);
  }

  setPageScale(pageScaleValue, pageScale) {
    this.pageScaleValue = (pageScaleValue || pageScale).toString();
    this.pageScale = pageScale;
    this._updateUIState(false);
  }

  reset() {
    this.pageNumber = 0;
    this.pageLabel = null;
    this.hasPageLabels = false;
    this.pagesCount = 0;
    this.pageScaleValue = DEFAULT_SCALE_VALUE;
    this.pageScale = DEFAULT_SCALE;
    this._updateUIState(true);
    this.updateLoadingIndicatorState();
  }

  _bindListeners() {
    const { pageNumber, scaleSelect } = this.items;
    const self = this;

    // The buttons within the toolbar.
    for (const { element, eventName } of this.buttons) {
      element.addEventListener("click", evt => {
        if (eventName !== null) {
          this.eventBus.dispatch(eventName, { source: this });
        }
      });
    }
    // The non-button elements within the toolbar.
    pageNumber.addEventListener("click", function() {
      this.select();
    });
    pageNumber.addEventListener("change", function() {
      self.eventBus.dispatch("pagenumberchanged", {
        source: self,
        value: this.value,
      });
    });

    scaleSelect.addEventListener("change", function() {
      if (this.value === "custom") {
        return;
      }
      self.eventBus.dispatch("scalechanged", {
        source: self,
        value: this.value,
      });
    });
    // Suppress context menus for some controls.
    scaleSelect.oncontextmenu = noContextMenuHandler;

    this.eventBus.on("localized", () => {
      this._wasLocalized = true;
      this._adjustScaleWidth();
      this._updateUIState(true);
    });
  }

  _updateUIState(resetNumPages = false) {
    if (!this._wasLocalized) {
      // Don't update the UI state until we localize the toolbar.
      return;
    }
    const { pageNumber, pagesCount, pageScaleValue, pageScale, items } = this;

    if (resetNumPages) {
      if (this.hasPageLabels) {
        items.pageNumber.type = "text";
      } else {
        items.pageNumber.type = "number";
        this.l10n
          .get("of_pages", { pagesCount }, "of {{pagesCount}}")
          .then(msg => {
            items.numPages.textContent = msg;
          });
      }
      items.pageNumber.max = pagesCount;
    }

    if (this.hasPageLabels) {
      items.pageNumber.value = this.pageLabel;
      this.l10n
        .get(
          "page_of_pages",
          { pageNumber, pagesCount },
          "({{pageNumber}} of {{pagesCount}})"
        )
        .then(msg => {
          items.numPages.textContent = msg;
        });
    } else {
      items.pageNumber.value = pageNumber;
    }

    items.previous.disabled = pageNumber <= 1;
    items.next.disabled = pageNumber >= pagesCount;

    items.zoomOut.disabled = pageScale <= MIN_SCALE;
    items.zoomIn.disabled = pageScale >= MAX_SCALE;

    const customScale = Math.round(pageScale * 10000) / 100;
    this.l10n
      .get("page_scale_percent", { scale: customScale }, "{{scale}}%")
      .then(msg => {
        let predefinedValueFound = false;
        for (const option of items.scaleSelect.options) {
          if (option.value !== pageScaleValue) {
            option.selected = false;
            continue;
          }
          option.selected = true;
          predefinedValueFound = true;
        }
        if (!predefinedValueFound) {
          items.customScaleOption.textContent = msg;
          items.customScaleOption.selected = true;
        }
      });
  }

  updateLoadingIndicatorState(loading = false) {
    const pageNumberInput = this.items.pageNumber;

    pageNumberInput.classList.toggle(PAGE_NUMBER_LOADING_INDICATOR, loading);
  }

  /**
   * Increase the width of the zoom dropdown DOM element if, and only if, it's
   * too narrow to fit the *longest* of the localized strings.
   * @private
   */
  async _adjustScaleWidth() {
    const { items, l10n } = this;

    const predefinedValuesPromise = Promise.all([
      l10n.get("page_scale_auto", null, "Automatic Zoom"),
      l10n.get("page_scale_actual", null, "Actual Size"),
      l10n.get("page_scale_fit", null, "Page Fit"),
      l10n.get("page_scale_width", null, "Page Width"),
    ]);

    // The temporary canvas is used to measure text length in the DOM.
    let canvas = document.createElement("canvas");
    if (
      typeof PDFJSDev === "undefined" ||
      PDFJSDev.test("MOZCENTRAL || GENERIC")
    ) {
      canvas.mozOpaque = true;
    }
    let ctx = canvas.getContext("2d", { alpha: false });

    await animationStarted;
    const { fontSize, fontFamily } = getComputedStyle(items.scaleSelect);
    ctx.font = `${fontSize} ${fontFamily}`;

    let maxWidth = 0;
    for (const predefinedValue of await predefinedValuesPromise) {
      const { width } = ctx.measureText(predefinedValue);
      if (width > maxWidth) {
        maxWidth = width;
      }
    }
    const overflow = SCALE_SELECT_WIDTH - SCALE_SELECT_CONTAINER_WIDTH;
    maxWidth += 1.5 * overflow;

    if (maxWidth > SCALE_SELECT_CONTAINER_WIDTH) {
      items.scaleSelect.style.width = `${maxWidth + overflow}px`;
      items.scaleSelectContainer.style.width = `${maxWidth}px`;
    }
    // Zeroing the width and height cause Firefox to release graphics resources
    // immediately, which can greatly reduce memory consumption.
    canvas.width = 0;
    canvas.height = 0;
    canvas = ctx = null;
  }
}

export { Toolbar };