gecko/browser/base/content/newtab/page.js

#ifdef 0
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this file,
 * You can obtain one at http://mozilla.org/MPL/2.0/. */
#endif

/**
 * This singleton represents the whole 'New Tab Page' and takes care of
 * initializing all its components.
 */
let gPage = {
  /**
   * Initializes the page.
   */
  init: function Page_init() {
    // Add ourselves to the list of pages to receive notifications.
    gAllPages.register(this);

    // Listen for 'unload' to unregister this page.
    addEventListener("unload", this, false);

    // Listen for toggle button clicks.
    let button = document.getElementById("newtab-toggle");
    button.addEventListener("click", this, false);

    // Check if the new tab feature is enabled.
    let enabled = gAllPages.enabled;
    if (enabled)
      this._init();

    this._updateAttributes(enabled);
  },

  /**
   * True if the page is allowed to capture thumbnails using the background
   * thumbnail service.
   */
  get allowBackgroundCaptures() {
    return document.documentElement.getAttribute("allow-background-captures") ==
           "true";
  },

  /**
   * Listens for notifications specific to this page.
   */
  observe: function Page_observe(aSubject, aTopic, aData) {
    if (aTopic == "nsPref:changed") {
      let enabled = gAllPages.enabled;
      this._updateAttributes(enabled);

      // Initialize the whole page if we haven't done that, yet.
      if (enabled) {
        this._init();
      } else {
        gUndoDialog.hide();
      }
    } else if (aTopic == "page-thumbnail:create" && gGrid.ready) {
      for (let site of gGrid.sites) {
        if (site && site.url === aData) {
          site.refreshThumbnail();
        }
      }
    }
  },

  /**
   * Updates the whole page and the grid when the storage has changed.
   */
  update: function Page_update() {
    // The grid might not be ready yet as we initialize it asynchronously.
    if (gGrid.ready) {
      gGrid.refresh();
    }
  },

  /**
   * Internally initializes the page. This runs only when/if the feature
   * is/gets enabled.
   */
  _init: function Page_init() {
    if (this._initialized)
      return;

    this._initialized = true;

    this._mutationObserver = new MutationObserver(() => {
      if (this.allowBackgroundCaptures) {
        for (let site of gGrid.sites) {
          if (site) {
            site.captureIfMissing();
          }
        }
      }
    });
    this._mutationObserver.observe(document.documentElement, {
      attributes: true,
      attributeFilter: ["allow-background-captures"],
    });

    gLinks.populateCache(function () {
      // Initialize and render the grid.
      gGrid.init();

      // Initialize the drop target shim.
      gDropTargetShim.init();

#ifdef XP_MACOSX
      // Workaround to prevent a delay on MacOSX due to a slow drop animation.
      document.addEventListener("dragover", this, false);
      document.addEventListener("drop", this, false);
#endif
    }.bind(this));
  },

  /**
   * Updates the 'page-disabled' attributes of the respective DOM nodes.
   * @param aValue Whether the New Tab Page is enabled or not.
   */
  _updateAttributes: function Page_updateAttributes(aValue) {
    // Set the nodes' states.
    let nodeSelector = "#newtab-scrollbox, #newtab-toggle, #newtab-grid";
    for (let node of document.querySelectorAll(nodeSelector)) {
      if (aValue)
        node.removeAttribute("page-disabled");
      else
        node.setAttribute("page-disabled", "true");
    }

    // Enables/disables the control and link elements.
    let inputSelector = ".newtab-control, .newtab-link";
    for (let input of document.querySelectorAll(inputSelector)) {
      if (aValue) 
        input.removeAttribute("tabindex");
      else
        input.setAttribute("tabindex", "-1");
    }

    // Update the toggle button's title.
    let toggle = document.getElementById("newtab-toggle");
    toggle.setAttribute("title", newTabString(aValue ? "hide" : "show"));
  },

  /**
   * Handles all page events.
   */
  handleEvent: function Page_handleEvent(aEvent) {
    switch (aEvent.type) {
      case "unload":
        if (this._mutationObserver)
          this._mutationObserver.disconnect();
        gAllPages.unregister(this);
        break;
      case "click":
        gAllPages.enabled = !gAllPages.enabled;
        break;
      case "dragover":
        if (gDrag.isValid(aEvent) && gDrag.draggedSite)
          aEvent.preventDefault();
        break;
      case "drop":
        if (gDrag.isValid(aEvent) && gDrag.draggedSite) {
          aEvent.preventDefault();
          aEvent.stopPropagation();
        }
        break;
    }
  }
};