Adds a new NTP endpoint for the single frame of the fast NTP

chrome/browser/resources/local_ntp/most_visited_single.js

+/* Copyright 2015 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. */
+
+ // Single iframe for NTP tiles.
+(function() {
+'use strict';
+
+
+/**
+ * The different types of events that are logged from the NTP.  This enum is
+ * used to transfer information from the NTP JavaScript to the renderer and is
+ * not used as a UMA enum histogram's logged value.
+ * Note: Keep in sync with common/ntp_logging_events.h
+ * @enum {number}
+ * @const
+ */
+var LOG_TYPE = {
+  // The suggestion is coming from the server. Unused here.
+  NTP_SERVER_SIDE_SUGGESTION: 0,
+  // The suggestion is coming from the client.
+  NTP_CLIENT_SIDE_SUGGESTION: 1,
+  // Indicates a tile was rendered, no matter if it's a thumbnail, a gray tile
+  // or an external tile.
+  NTP_TILE: 2,
+  // The tile uses a local thumbnail image.
+  NTP_THUMBNAIL_TILE: 3,
+  // Used when no thumbnail is specified and a gray tile with the domain is used
+  // as the main tile. Unused here.
+  NTP_GRAY_TILE: 4,
+  // The visuals of that tile are handled externally by the page itself.
+  // Unused here.
+  NTP_EXTERNAL_TILE: 5,
+  // There was an error in loading both the thumbnail image and the fallback
+  // (if it was provided), resulting in a gray tile.
+  NTP_THUMBNAIL_ERROR: 6,
+  // Used a gray tile with the domain as the fallback for a failed thumbnail.
+  // Unused here.
+  NTP_GRAY_TILE_FALLBACK: 7,
+  // The visuals of that tile's fallback are handled externally. Unused here.
+  NTP_EXTERNAL_TILE_FALLBACK: 8,
+  // The user moused over an NTP tile or title.

[huangs, 2015/03/13 03:49:52]

Can remove "or title".

[fserb, 2015/03/13 17:22:44]

Done.

+  NTP_MOUSEOVER: 9
+};
+
+
+/**
+ * Total number of tiles to show at any time. If the host page doesn't send
+ * enough tiles, we fill them blank.
+ * @const {number}
+ */
+var NUMBER_OF_TILES = 8;
+
+
+/**
+ * The origin of this request.
+ * @const {string}
+ */
+var DOMAIN_ORIGIN = '{{ORIGIN}}';
+
+
+/**
+ * Counter for DOM elements that we are waiting to finish loading.
+ * @type {number}
+ */
+var loadedCounter = 1;
+
+
+/**
+ * DOM element containing the tiles we are going to present next.
+ * Works as a double-buffer that is shown when we receive a "show" postMessage.
+ * @type {Element}
+ */
+var tiles = null;
+
+
+/**
+ * Log an event on the NTP.
+ * @param {number} eventType Event from NTP_LOGGING_EVENT_TYPE.

[huangs, 2015/03/13 03:49:52]

NTP_LOGGING_EVENT_TYPE => LOG_TYPE

[fserb, 2015/03/13 17:22:45]

Done.

+ */
+var logEvent = function(eventType) {
+  chrome.embeddedSearch.newTabPage.logEvent(eventType);
+};
+
+
+/**
+ * Down count the DOM elements that we are waiting for the page to load.

[huangs, 2015/03/13 03:49:52]

NIT: "Down counts" -- if a function comment starts with verb, there's an
implicit "This function..".

[fserb, 2015/03/13 17:22:45]

Done.

+ * When we get to 0, we send a message to the parent window.
+ * This is usually used as an EventListener of onload/onerror.
+ */
+var countLoad = function() {
+  loadedCounter -= 1;
+  if (loadedCounter <= 0) {
+    window.parent.postMessage({cmd: 'loaded'}, DOMAIN_ORIGIN);
+    loadedCounter = 1;
+  }
+};
+
+
+/**
+ * Handle postMessages coming from the host page to the iframe.

[huangs, 2015/03/13 03:49:52]

NIT: Handles

[fserb, 2015/03/13 17:22:45]

Done.

+ * We try to keep the logic here to a minimum and just dispatch to the relevant
+ * functions.
+ **/
+var handlePostMessage = function(event) {
+  var cmd = event.data.cmd;
+
+  if (cmd == 'tile') {
+    addTile(event.data);
+  } else if (cmd == 'show') {
+    showTiles();
+    countLoad();
+  } else {
+    console.error('Unknown command: ' + event.data);
+  }
+};
+
+
+/**
+ * Called when the host page has finished sending us tile information and
+ * we are ready to show the new tiles and drop the old ones.
+ */
+var showTiles = function() {
+  // Store the tiles on the current closure.
+  var cur = tiles;
+
+  // Create empty tiles until we have NUMBER_OF_TILES.
+  while (cur.childNodes.length < NUMBER_OF_TILES) {
+    addTile({});
+  }
+
+  var parent = document.querySelector('#most-visited');
+
+  // Mark old tile DIV for removal after the transition animation is done.
+  var old = parent.querySelector('#mv-tiles');
+  if (old) {
+    old.id = 'mv-tiles-old';
+    cur.addEventListener('webkitTransitionEnd', function(ev) {
+      if (ev.target === cur) {
+        parent.removeChild(old);
+      }
+    });
+  }
+
+  // Add new tileset.
+  cur.id = 'mv-tiles';
+  parent.appendChild(cur);
+  // We want the CSS transition to trigger, so need to add to the DOM before
+  // setting the style.
+  setTimeout(function() {

[huangs, 2015/03/13 03:49:52]

Would requestAnimationFrame() do the same thing?

[fserb, 2015/03/13 17:22:45]

not the same thing.

+    cur.style.opacity = 1.0;
+  }, 0);
+
+  // Make sure the tiles variable contain the next tileset we may use.
+  tiles = document.createElement('div');
+};
+
+
+/**
+ * Called when the host page wants to add a suggestion tile.
+ * For Most Visited, it grabs the data from Chrome and pass on.
+ * For host page generated it just passes the data.
+ * @param {object} args Data for the tile to be rendered.
+ */
+var addTile = function(args) {
+  if (args.rid) {
+    var data = chrome.embeddedSearch.searchBox.getMostVisitedItemData(args.rid);
+    tiles.appendChild(renderTile(data));
+    logEvent(LOG_TYPE.NTP_CLIENT_SIDE_SUGGESTION);
+  } else {
+    tiles.appendChild(renderTile(null));

[huangs, 2015/03/13 03:49:52]

Would you need to log NTP_SERVER_SIDE_SUGGESTION ?

[fserb, 2015/03/13 17:22:45]

When I handle it, yes.

+  }
+};
+
+
+/**
+ * Called when the user decided to add a tile to the blacklist.
+ * It sets of the animation for the blacklist and sends the blacklisted id
+ * to the host page.
+ * @param {Element} tile DOM node of the tile we want to remove.
+ */
+var blacklistTile = function(tile) {
+  tile.classList.add('blacklisted');
+  var sent = false;
+  tile.addEventListener('webkitTransitionEnd', function() {
+    if (sent) return;
+    sent = true;
+    window.parent.postMessage({cmd: 'tileBlacklisted',
+                               rid: Number(tile.getAttribute('data-rid'))},
+                              DOMAIN_ORIGIN);
+  });
+};
+
+
+/**
+ * Renders a MostVisited tile to the DOM.
+ * @param {object} data Object containing rid, url, title, favicon, thumbnail.
+ *     data is null if you want to construct an empty tile.
+ */
+var renderTile = function(data) {
+  var tile = document.createElement('a');
+
+  if (data == null) {
+    tile.className = 'mv-empty-tile';
+    return tile;
+  }
+
+  logEvent(LOG_TYPE.NTP_TILE);
+
+  tile.className = 'mv-tile';
+  tile.setAttribute('data-rid', data.rid);
+  tile.innerHTML = '<div class="mv-favicon"></div>' +
+    '<div class="mv-title"></div><div class="mv-thumb"></div>' +
+    '<div title="' + configData['removeThumbnailTooltip'] +
+    '" class="mv-x"></div>';
+
+  tile.href = data.url;
+  tile.title = data.title;
+  tile.addEventListener('keypress', function(ev) {
+    if (ev.keyCode == 127) { // DELETE
+      blacklistTile(tile);
+      ev.stopPropagation();
+      return false;
+    }
+  });
+  // TODO(fserb): remove this or at least change to mouseenter.
+  tile.addEventListener('mouseover', function() {
+    logEvent(LOG_TYPE.NTP_MOUSEOVER);
+  });
+
+  var title = tile.querySelector('.mv-title');
+  title.innerText = data.title;
+  title.style.direction = data.direction || 'ltr';
+
+  var thumb = tile.querySelectorAll('.mv-thumb')[0];

[huangs, 2015/03/13 03:49:52]

querySelector

[fserb, 2015/03/13 17:22:44]

Done.

+

[huangs, 2015/03/13 03:49:52]

NIT: Don't need this new line.

[fserb, 2015/03/13 17:22:45]

Done.

+  if (data.thumbnailUrl) {
+    var img = document.createElement('img');
+    img.title = data.title;
+    img.src = data.thumbnailUrl;
+    loadedCounter += 1;
+    img.addEventListener('load', countLoad);
+    img.addEventListener('error', countLoad);
+    img.addEventListener('error', function(ev) {
+      thumb.classList.add('failed-img');
+      thumb.removeChild(img);
+      logEvent(LOG_TYPE.NTP_THUMBNAIL_ERROR);
+    });
+    thumb.appendChild(img);
+    logEvent(LOG_TYPE.NTP_THUMBNAIL_TILE);
+  } else {
+    thumb.classList.add('failed-img');
+  }
+
+  var favicon = tile.querySelectorAll('.mv-favicon')[0];

[huangs, 2015/03/13 03:49:52]

querySelector

[fserb, 2015/03/13 17:22:45]

Done.

+  if (data.faviconUrl) {
+    var fi = document.createElement('img');
+    fi.src = '../' + data.faviconUrl;
+    // We set the title to empty, so it doesn't say the image name on chromevox.

[huangs, 2015/03/13 03:49:52]

NIT: // Set title to empty so screen readers won't say image name.

[fserb, 2015/03/13 17:22:45]

Done.

+    fi.title = '';
+    loadedCounter += 1;
+    fi.addEventListener('load', countLoad);
+    fi.addEventListener('error', countLoad);
+    fi.addEventListener('error', function(ev) {
+      favicon.classList.add('failed-favicon');
+    });
+    favicon.appendChild(fi);
+  } else {
+    favicon.classList.add('failed-favicon');
+  }
+
+  var mvx = tile.querySelectorAll('.mv-x')[0];

[huangs, 2015/03/13 03:49:52]

querySelector

[fserb, 2015/03/13 17:22:44]

Done.

+  mvx.addEventListener('click', function(ev) {
+    blacklistTile(tile);
+    ev.stopPropagation();
+    return false;
+  });
+
+  return tile;
+};
+
+
+/**
+ * Do some initialization and parses the query arguments passed to the iframe.
+ */
+var init = function() {
+  // Creates a new DOM element to hold the tiles.
+  tiles = document.createElement('div');
+
+  // Parse query arguments.
+  var query = window.location.search.substring(1).split('&');
+  var args = {};
+  for (var i = 0; i < query.length; ++i) {
+    var val = query[i].split('=');
+    if (val[0] == '') continue;
+    args[decodeURIComponent(val[0])] = decodeURIComponent(val[1]);
+  }
+
+  // Enable RTL.
+  if (args['rtl'] == '1') {
+    var html = document.querySelector('html');
+    html.dir = 'rtl';
+  }
+
+  window.addEventListener('message', handlePostMessage);
+};
+
+
+window.addEventListener('DOMContentLoaded', init);
+})();