Implement local NTP for fallback.

chrome/browser/resources/local_ntp/local_ntp.js

+// Copyright 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+(function() {
+/**
+ * The element used to vertically position the most visited section on
+ * window resize.
+ * @type {Element}
+ */
+var topMarginElement;
+
+/**
+ * The container for the tile elements.
+ * @type {Element}
+ */
+var tilesContainer;
+
+/**
+ * The notification displayed when a page is blacklisted.
+ * @type {Element}
+ */
+var notification;
+
+/**
+ * The array of rendered tiles, ordered by appearance.
+ * @type {Array.<Tile>}
+ */
+var tiles = [];
+
+/**
+ * The last blacklisted tile if any, which by definition should not be filler.
+ * @type {?Tile}
+ */
+var lastBlacklistedTile = null;
+
+/**
+ * The index of the last blacklisted tile, if any. Used to determine where to
+ * re-insert a tile on undo.
+ * @type {number}
+ */
+var lastBlacklistedIndex = -1;
+
+/**
+ * True if a page has been blacklisted and we're waiting on the
+ * onmostvisitedchange callback. See onMostVisitedChange() for how this
+ * is used.
+ * @type {boolean}
+ */
+var isBlacklisting = false;
+
+/**
+ * True if a blacklist has been undone and we're waiting on the
+ * onmostvisitedchange callback. See onMostVisitedChange() for how this
+ * is used.
+ * @type {boolean}
+ */
+var isUndoing = false;
+
+/**
+ * Current number of tiles shown based on the window width, including filler.
+ * @type {number}
+ */
+var numTilesShown = 0;
+
+/**
+ * The browser embeddedSearch.newTabPage object.
+ * @type {Object}
+ */
+var apiHandle;
+
+/**
+ * Possible background-colors of a non-custom theme. Used to determine whether
+ * the homepage should be updated to support custom or non-custom themes.
+ * @type {!Array.<string>}
+ * @const
+ */
+var WHITE = ['rgba(255,255,255,1)', 'rgba(0,0,0,0)'];
+
+/**
+ * Should be equal to mv-tile's -webkit-margin-start + width.
+ * @type {number}
+ * @const
+ */
+var TILE_WIDTH = 160;
+
+/**
+ * The height of the most visited section.
+ * @type {number}
+ * @const
+ */
+var MOST_VISITED_HEIGHT = 156;
+
+/** @type {number} @const */
+var MAX_NUM_TILES_TO_SHOW = 4;
+
+/** @type {number} @const */
+var MIN_NUM_TILES_TO_SHOW = 2;
+
+/**
+ * Minimum total padding to give to the left and right of the most visited
+ * section. Used to determine how many tiles to show.
+ * @type {number}
+ * @const
+ */
+var MIN_TOTAL_HORIZONTAL_PADDING = 188;
+
+/**
+ * Enum for classnames.
+ * @enum {string}
+ * @const
+ */
+var CLASSES = {
+  TILE: 'mv-tile',
+  PAGE: 'mv-page',  // page tiles
+  TITLE: 'mv-title',
+  THUMBNAIL: 'mv-thumb',
+  DOMAIN: 'mv-domain',
+  BLACKLIST_BUTTON: 'mv-x',
+  FAVICON: 'mv-favicon',
+  FILLER: 'mv-filler',  // filler tiles
+  BLACKLIST: 'mv-blacklist',  // triggers tile blacklist animation
+  HIDE_TILE: 'mv-tile-hide', // hides tiles on small browser width
+  HIDE_BLACKLIST_BUTTON: 'mv-x-hide', // hides blacklist button during animation
+  DELAYED_HIDE_NOTIFICATION: 'mv-notice-delayed-hide',
+  HIDE_NOTIFICATION: 'mv-notice-hide'
+};
+
+/**
+ * Enum for ids.
+ * @enum {string}
+ * @const
+ */
+var IDS = {
+  TOP_MARGIN: 'mv-top-margin',
+  TILES: 'mv-tiles',
+  NOTIFICATION: 'mv-notice',
+  NOTIFICATION_MESSAGE: 'mv-msg',
+  UNDO_LINK: 'mv-undo',
+  RESTORE_ALL_LINK: 'mv-restore',
+  NOTIFICATION_CLOSE_BUTTON: 'mv-notice-x'
+};
+
+/**
+ * A Tile is either a rendering of a Most Visited page or "filler" used to
+ * pad out the section when not enough pages exist.
+ *
+ * @param {Element} elem The element for rendering the tile.
+ * @param {number=} opt_rid The RID for the corresponding Most Visited page.
+ *     Should only be left unspecified when creating a filler tile.
+ * @constructor
+ */
+function Tile(elem, opt_rid) {
+  /** @type {Element} */
+  this.elem = elem;
+
+  /** @type {number|undefined} */
+  this.rid = opt_rid;
+}
+
+/**
+ * Updates the NTP based on the current theme.
+ * @private
+ */
+function onThemeChange() {
+  var info = apiHandle.themeBackgroundInfo;
+  if (!info)
+    return;
+  var background = [info.colorRgba,
+                    info.imageUrl,
+                    info.imageTiling,
+                    info.imageHorizontalAlignment,
+                    info.imageVerticalAlignment].join(' ').trim();
+  document.body.style.background = background;
+  var isCustom = !!background && WHITE.indexOf(background) == -1;
+  document.body.classList.toggle('custom-theme', isCustom);
+}
+
+/**
+ * Handles a new set of Most Visited page data.
+ */
+function onMostVisitedChange() {
+  var pages = apiHandle.mostVisited;
+
+  if (isBlacklisting) {
+    // If this was called as a result of a blacklist, add a new replacement
+    // (possibly filler) tile at the end and trigger the blacklist animation.
+    var replacementTile = createTile(pages[MAX_NUM_TILES_TO_SHOW - 1]);
+
+    tiles.push(replacementTile);
+    tilesContainer.appendChild(replacementTile.elem);
+
+    var lastBlacklistedTileElement = lastBlacklistedTile.elem;
+    lastBlacklistedTileElement.addEventListener(
+        'webkitTransitionEnd', blacklistAnimationDone);
+    lastBlacklistedTileElement.classList.add(CLASSES.BLACKLIST);
+    // In order to animate the replacement tile sliding into place, it must
+    // be made visible.
+    updateTileVisibility(numTilesShown + 1);
+
+  } else if (isUndoing) {
+    // If this was called as a result of an undo, re-insert the last blacklisted
+    // tile in its old location and trigger the undo animation.
+    tiles.splice(
+        lastBlacklistedIndex, 0, lastBlacklistedTile);
+    var lastBlacklistedTileElement = lastBlacklistedTile.elem;
+    tilesContainer.insertBefore(
+        lastBlacklistedTileElement,
+        tilesContainer.childNodes[lastBlacklistedIndex]);
+    lastBlacklistedTileElement.addEventListener(
+        'webkitTransitionEnd', undoAnimationDone);
+    // Force the removal to happen synchronously.
+    lastBlacklistedTileElement.scrollTop;
+    lastBlacklistedTileElement.classList.remove(CLASSES.BLACKLIST);
+  } else {
+    // Otherwise render the tiles using the new data without animation.
+    tiles = [];
+    for (var i = 0; i < MAX_NUM_TILES_TO_SHOW; ++i) {
+      tiles.push(createTile(pages[i]));
+    }
+    renderTiles();
+  }
+}
+
+/**
+ * Renders the current set of tiles without animation.
+ */
+function renderTiles() {
+  removeChildren(tilesContainer);
+  for (var i = 0, length = tiles.length; i < length; ++i) {
+    tilesContainer.appendChild(tiles[i].elem);
+  }
+}
+
+/**
+ * Creates a Tile with the specified page data. If no data is provided, a
+ * filler Tile is created.
+ * @param {Object} page The page data.
+ * @return {Tile} The new Tile.
+ */
+function createTile(page) {
+  var tileElement = document.createElement('div');
+  tileElement.classList.add(CLASSES.TILE);
+
+  if (page) {
+    var rid = page.rid;
+    tileElement.classList.add(CLASSES.PAGE);
+
+    // The click handler for navigating to the page identified by the RID.
+    tileElement.addEventListener('click', function() {
+      apiHandle.navigateContentWindow(rid);
+    });
+
+    // The shadow DOM which renders the page title.
+    var titleElement = page.titleElement;
+    if (titleElement) {
+      titleElement.classList.add(CLASSES.TITLE);
+      tileElement.appendChild(titleElement);
+    }
+
+    // Render the thumbnail if present. Otherwise, fall back to a shadow DOM
+    // which renders the domain.
+    var thumbnailUrl = page.thumbnailUrl;
+
+    var showDomainElement = function() {
+      var domainElement = page.domainElement;
+      if (domainElement) {
+        domainElement.classList.add(CLASSES.DOMAIN);
+        tileElement.appendChild(domainElement);
+      }
+    };
+    if (thumbnailUrl) {
+      var image = new Image();
+      image.onload = function() {
+        var thumbnailElement = createAndAppendElement(
+            tileElement, 'div', CLASSES.THUMBNAIL);
+        thumbnailElement.style.backgroundImage = 'url(' + thumbnailUrl + ')';
+      };
+
+      image.onerror = showDomainElement;
+      image.src = thumbnailUrl;
+    } else {
+      showDomainElement();
+    }
+
+    // The button used to blacklist this page.
+    var blacklistButton = createAndAppendElement(
+        tileElement, 'div', CLASSES.BLACKLIST_BUTTON);
+    blacklistButton.addEventListener('click', generateBlacklistFunction(rid));
+    // TODO(jeremycho): i18n. See
+    // https://code.google.com/p/chromium/issues/detail?id=190223

[Dan Beam, 2013/03/25 21:37:39]

nit: this is fine, but http://crbug.com/190223 is shorter

[jeremycho, 2013/03/25 21:51:20]

Done.

+    blacklistButton.title = "Don't show on this page";
+
+    // The page favicon, if any.
+    var faviconUrl = page.faviconUrl;
+    if (faviconUrl) {
+      var favicon = createAndAppendElement(
+          tileElement, 'div', CLASSES.FAVICON);
+      favicon.style.backgroundImage = 'url(' + faviconUrl + ')';
+    }
+    return new Tile(tileElement, rid);
+  } else {
+    tileElement.classList.add(CLASSES.FILLER);
+    return new Tile(tileElement);
+  }
+}
+
+/**
+ * Generates a function to be called when the page with the corresponding RID
+ * is blacklisted.
+ * @param {number} rid The RID of the page being blacklisted.
+ * @return {function(Event)} A function which handles the blacklisting of the
+ *     page by displaying the notification, updating state variables, and
+ *     notifying Chrome.
+ */
+function generateBlacklistFunction(rid) {
+  return function(e) {
+    // Prevent navigation when the page is being blacklisted.
+    e.stopPropagation();
+
+    showNotification();
+    isBlacklisting = true;
+    tilesContainer.classList.add(CLASSES.HIDE_BLACKLIST_BUTTON);
+    lastBlacklistedTile = getTileByRid(rid);
+    lastBlacklistedIndex = tiles.indexOf(lastBlacklistedTile);
+    apiHandle.deleteMostVisitedItem(rid);
+  };
+}
+
+/**
+ * Shows the blacklist notification and triggers a delay to hide it.
+ */
+function showNotification() {
+  notification.classList.remove(CLASSES.HIDE_NOTIFICATION);
+  notification.classList.remove(CLASSES.DELAYED_HIDE_NOTIFICATION);
+  notification.scrollTop;
+  notification.classList.add(CLASSES.DELAYED_HIDE_NOTIFICATION);
+}
+
+/**
+ * Hides the blacklist notification.
+ */
+function hideNotification() {
+  notification.classList.add(CLASSES.HIDE_NOTIFICATION);
+}
+
+/**
+ * Handles the end of the blacklist animation by removing the blacklisted tile.
+ */
+function blacklistAnimationDone() {
+  tiles.splice(lastBlacklistedIndex, 1);
+  removeNode(lastBlacklistedTile.elem);
+  updateTileVisibility(numTilesShown);
+  isBlacklisting = false;
+  tilesContainer.classList.remove(CLASSES.HIDE_BLACKLIST_BUTTON);
+  lastBlacklistedTile.elem.removeEventListener(
+      'webkitTransitionEnd', blacklistAnimationDone);
+}
+
+/**
+ * Handles a click on the notification undo link by hiding the notification and
+ * informing Chrome.
+ */
+function onUndo() {
+  hideNotification();
+  var lastBlacklistedRID = lastBlacklistedTile.rid;
+  if (typeof lastBlacklistedRID != 'undefined') {
+    isUndoing = true;
+    apiHandle.undoMostVisitedDeletion(lastBlacklistedRID);
+  }
+}
+
+/**
+ * Handles the end of the undo animation by removing the extraneous end tile.
+ */
+function undoAnimationDone() {
+  isUndoing = false;
+  tiles.splice(tiles.length - 1, 1);
+  removeNode(tilesContainer.lastElementChild);
+  updateTileVisibility(numTilesShown);
+  lastBlacklistedTile.elem.removeEventListener(
+      'webkitTransitionEnd', undoAnimationDone);
+}
+
+/**
+ * Handles a click on the restore all notification link by hiding the
+ * notification and informing Chrome.
+ */
+function onRestoreAll() {
+  hideNotification();
+  apiHandle.undoAllMostVisitedDeletions();
+}
+
+/**
+ * Handles a resize by vertically centering the most visited section
+ * and triggering the tile show/hide animation if necessary.
+ */
+function onResize() {
+  var clientHeight = document.documentElement.clientHeight;
+  topMarginElement.style.marginTop =
+      Math.max(0, (clientHeight - MOST_VISITED_HEIGHT) / 2) + 'px';
+
+  var clientWidth = document.documentElement.clientWidth;
+  var numTilesToShow = Math.floor(
+      (clientWidth - MIN_TOTAL_HORIZONTAL_PADDING) / TILE_WIDTH);
+  numTilesToShow = Math.max(MIN_NUM_TILES_TO_SHOW, numTilesToShow);
+  if (numTilesToShow != numTilesShown) {
+    updateTileVisibility(numTilesToShow);
+    numTilesShown = numTilesToShow;
+  }
+}
+
+/**
+ * Triggers an animation to show the first numTilesToShow tiles and hide the
+ * remaining.
+ * @param {number} numTilesToShow The number of tiles to show.
+ */
+function updateTileVisibility(numTilesToShow) {
+  for (var i = 0, length = tiles.length; i < length; ++i) {
+    tiles[i].elem.classList.toggle(CLASSES.HIDE_TILE, i >= numTilesToShow);
+  }
+}
+
+/**
+ * Returns the tile corresponding to the specified page RID.
+ * @param {number} rid The page RID being looked up.
+ * @return {Tile} The corresponding tile.
+ */
+function getTileByRid(rid) {
+  for (var i = 0, length = tiles.length; i < length; ++i) {
+    var tile = tiles[i];
+    if (tile.rid == rid)
+      return tile;
+  }
+  return null;
+}
+
+/**
+ * Utility function which creates an element with an optional classname and
+ * appends it to the specified parent.
+ * @param {Element} parent The parent to append the new element.
+ * @param {string} name The name of the new element.
+ * @param {string=} opt_class The optional classname of the new element.
+ * @return {Element} The new element.
+ */
+function createAndAppendElement(parent, name, opt_class) {
+  var child = document.createElement(name);
+  if (opt_class)
+    child.classList.add(opt_class);
+  parent.appendChild(child);
+  return child;
+}
+
+/**
+ * Removes a node from its parent.
+ * @param {Node} node The node to remove.
+ */
+function removeNode(node) {

[Dan Beam, 2013/03/25 21:37:39]

I don't really see the benefit of this method, but I guess it's fine to leave
here... seems to add more lines to this file for little benefit.

[jeremycho, 2013/03/25 21:51:20]

Acknowledged.  Thought it was a little cleaner than inlining, since node appears
twice.
On 2013/03/25 21:37:39, Dan Beam wrote:

+  node.parentNode.removeChild(node);
+}
+
+/**
+ * Removes all the child nodes on a DOM node.
+ * @param {Node} node Node to remove children from.
+ */
+function removeChildren(node) {
+  node.innerHTML = '';
+}
+
+/**
+ * @return {Object} the handle to the embeddedSearch API.
+ */
+function getEmbeddedSearchApiHandle() {
+  if (window.cideb)
+    return window.cideb;
+  if (window.chrome && window.chrome.embeddedSearch)
+    return window.chrome.embeddedSearch;
+  return null;
+}
+
+/**
+ * Prepares the New Tab Page by adding listeners, rendering the current
+ * theme, and the most visited pages section.
+ */
+function init() {
+  topMarginElement = document.getElementById(IDS.TOP_MARGIN);
+  tilesContainer = document.getElementById(IDS.TILES);
+  notification = document.getElementById(IDS.NOTIFICATION);
+
+  // TODO(jeremycho): i18n.
+  var notificationMessage = document.getElementById(IDS.NOTIFICATION_MESSAGE);
+  notificationMessage.innerText = 'Thumbnail removed.';
+  var undoLink = document.getElementById(IDS.UNDO_LINK);
+  undoLink.addEventListener('click', onUndo);
+  undoLink.innerText = 'Undo';
+  var restoreAllLink = document.getElementById(IDS.RESTORE_ALL_LINK);
+  restoreAllLink.addEventListener('click', onRestoreAll);
+  restoreAllLink.innerText = 'Restore all';
+  var notificationCloseButton =
+      document.getElementById(IDS.NOTIFICATION_CLOSE_BUTTON);
+  notificationCloseButton.addEventListener('click', hideNotification);
+
+  window.addEventListener('resize', onResize);
+  onResize();
+
+  var topLevelHandle = getEmbeddedSearchApiHandle();
+  // This is to inform Chrome that the NTP is instant-extended capable i.e.
+  // it should fire events like onmostvisitedchange.
+  topLevelHandle.searchBox.onsubmit = function() {};
+
+  apiHandle = topLevelHandle.newTabPage;
+  apiHandle.onthemechange = onThemeChange;
+  apiHandle.onmostvisitedchange = onMostVisitedChange;
+
+  onThemeChange();
+  onMostVisitedChange();
+}
+
+document.addEventListener('DOMContentLoaded', init);
+})();