[polymer] Merge of master into polymer10-migration

netlog_viewer/time_util.js

+// Copyright (c) 2012 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.
+
+var timeutil = (function() {
+  'use strict';
+
+  /**
+   * Offset needed to convert event times to Date objects.
+   * Updated whenever constants are loaded.
+   */
+  var timeTickOffset = 0;
+
+  /**
+   * The time of the first observed event.  Used for more friendly time display.
+   */
+  var baseTime = 0;
+
+  /**
+   * Sets the offset used to convert tick counts to dates.
+   */
+  function setTimeTickOffset(offset) {
+    // Note that the subtraction by 0 is to cast to a number (probably a float
+    // since the numbers are big).
+    timeTickOffset = offset - 0;
+  }
+
+  /**
+   * The browser gives us times in terms of "time ticks" in milliseconds.
+   * This function converts the tick count to a Javascript "time", which is
+   * the UTC time in milliseconds.
+   *
+   * @param {string} timeTicks A time represented in "time ticks".
+   * @return {number} The Javascript time that |timeTicks| represents.
+   */
+  function convertTimeTicksToTime(timeTicks) {
+    return timeTickOffset + (timeTicks - 0);
+  }
+
+  /**
+   * The browser gives us times in terms of "time ticks" in milliseconds.
+   * This function converts the tick count to a Date() object.
+   *
+   * @param {string} timeTicks A time represented in "time ticks".
+   * @return {Date} The time that |timeTicks| represents.
+   */
+  function convertTimeTicksToDate(timeTicks) {
+    return new Date(convertTimeTicksToTime(timeTicks));
+  }
+
+  /**
+   * Returns the current time.
+   *
+   * @return {number} Milliseconds since the Unix epoch.
+   */
+  function getCurrentTime() {
+    return Date.now();
+  }
+
+  /**
+   * Returns the curent time in time ticks.
+   *
+   * @return {number} Current time, in TimeTicks.
+   */
+  function getCurrentTimeTicks() {
+    return getCurrentTime() - timeTickOffset;
+  }
+
+  /**
+   * Sets the base time more friendly display.
+   *
+   * @param {string} firstEventTime The time of the first event, as a Javascript
+   *     numeric time.  Other times can be displayed relative to this time.
+   */
+  function setBaseTime(firstEventTime) {
+    baseTime = firstEventTime;
+  }
+
+  /**
+   * Sets the base time more friendly display.
+   *
+   * @return {number} Time set by setBaseTime, or 0 if no time has been set.
+   */
+  function getBaseTime() {
+    return baseTime;
+  }
+
+  /**
+   * Clears the base time, so isBaseTimeSet() returns 0.
+   */
+  function clearBaseTime() {
+    baseTime = 0;
+  }
+
+  /**
+   * Returns true if the base time has been initialized.
+   *
+   * @return {bool} True if the base time is set.
+   */
+  function isBaseTimeSet() {
+    return baseTime != 0;
+  }
+
+  /**
+   * Takes in a "time ticks" and returns it as a time since the base time, in
+   * milliseconds.
+   *
+   * @param {string} timeTicks A time represented in "time ticks".
+   * @return {number} Milliseconds since the base time.
+   */
+  function convertTimeTicksToRelativeTime(timeTicks) {
+    return convertTimeTicksToTime(timeTicks) - baseTime;
+  }
+
+  /**
+   * Adds an HTML representation of |date| to |parentNode|.
+   *
+   * @param {DomNode} parentNode The node that will contain the new node.
+   * @param {Date} date The date to be displayed.
+   * @return {DomNode} The new node containing the date/time.
+   */
+  function addNodeWithDate(parentNode, date) {
+    var span = addNodeWithText(parentNode, 'span', dateToString(date));
+    span.title = 't=' + date.getTime();
+    return span;
+  }
+
+  /**
+   * Returns a string representation of |date|.
+   *
+   * @param {Date} date The date to be represented.
+   * @return {string} A string representation of |date|.
+   */
+  function dateToString(date) {
+    var dateStr = date.getFullYear() + '-' +
+                  zeroPad_(date.getMonth() + 1, 2) + '-' +
+                  zeroPad_(date.getDate(), 2);
+
+    var timeStr = zeroPad_(date.getHours(), 2) + ':' +
+                  zeroPad_(date.getMinutes(), 2) + ':' +
+                  zeroPad_(date.getSeconds(), 2) + '.' +
+                  zeroPad_(date.getMilliseconds(), 3);
+
+    return dateStr + ' ' + timeStr;
+  }
+
+  /**
+   * Prefixes enough zeros to |num| so that it has length |len|.
+   * @param {number} num The number to be padded.
+   * @param {number} len The desired length of the returned string.
+   * @return {string} The zero-padded representation of |num|.
+   */
+  function zeroPad_(num, len) {
+    var str = num + '';
+    while (str.length < len)
+      str = '0' + str;
+    return str;
+  }
+
+  return {
+    setTimeTickOffset: setTimeTickOffset,
+    convertTimeTicksToTime: convertTimeTicksToTime,
+    convertTimeTicksToDate: convertTimeTicksToDate,
+    getCurrentTime: getCurrentTime,
+    getCurrentTimeTicks: getCurrentTimeTicks,
+    setBaseTime: setBaseTime,
+    getBaseTime: getBaseTime,
+    clearBaseTime: clearBaseTime,
+    isBaseTimeSet: isBaseTimeSet,
+    convertTimeTicksToRelativeTime: convertTimeTicksToRelativeTime,
+    addNodeWithDate: addNodeWithDate,
+    dateToString: dateToString,
+  };
+})();