Display active media players on chrome://media-internals.

chrome/browser/resources/media_internals/util.js

+// Copyright (c) 2011 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.
+
+cr.define('media', function() {
+
+  /**
+   * The width and height of a bar drawn on a file canvas in pixels.
+   */
+  BAR_WIDTH = 500;
+  BAR_HEIGHT = 15;
+
+  // Maximum display length of a url in characters. Lengthy urls will be clipped
+  // and postfixed with an ellipsis.
+  MAX_URL_LENGTH = 50;
+
+  /**
+   * Draws a 1px white horizontal line across |context|.
+   */
+  drawLine = function(context, top) {
+    context.moveTo(0, top);
+    context.lineTo(BAR_WIDTH, top);
+    context.strokeStyle = '#fff';
+    context.stroke();
+  };
+
+  /**
+   * Creates an HTMLElement of type |type| with textContent |content|.
+   * @param {string} type The type of element to create.
+   * @param {string} content The content to place in the element.
+   * @return {HTMLElement} A newly initialized element.
+   */
+  makeElement = function(type, content) {
+    var element = document.createElement(type);
+    element.textContent = content;
+    return element;
+  };
+
+  /**
+   * Truncates a URL to MAX_URL_LENGTH. If the URL was too long, the last
+   * three characters of the returned string will be '...', and its length will
+   * be MAX_URL_LENGTH.
+   * @param {string} url The url to truncate.
+   * @return {string} A truncated url.
+   */
+  clipURL = function(url) {
+    if (url && url.length > MAX_URL_LENGTH)
+      return url.slice(0, MAX_URL_LENGTH - 3) + '...';
+    return url;
+  };
+
+  /**
+   * Creates a new <li> containing a <details> with a <summary> and sets
+   * properties to reference them.
+   * @return {Object} The new <li>.
+   */
+  createDetailsLi = function() {
+    li = document.createElement('li');
+    li.details = document.createElement('details');
+    li.summary = document.createElement('summary');
+    li.appendChild(li.details);
+    li.details.appendChild(li.summary);
+    return li
+  };
+
+  /**
+   * Prints each key-value pair in a dictionary to a row in a table.
+   * @param {Object} dict The dictionary to print.
+   * @param {HTMLElement} table The <table> element to print to.
+   */
+  printDictionaryToTable = function(dict, table) {
+    table.textContent = '';
+    for (var key in dict) {
+      var tr = document.createElement('tr');
+      tr.appendChild(makeElement('td', key + ':'));
+      tr.appendChild(makeElement('td', dict[key]));
+      table.appendChild(tr);
+    }
+    return table;
+  };
+
+  /**
+   * Rounds a number, leaving the specified number of digits after the decimal;
+   * defaults to 1.
+   * @param {number} n The number to be rounded.
+   * @param {int} digits The number of digits to leave after the decimal.
+   * @return {number} |n| rounded to |digits| decimal places.
+   */
+  round = function(n, digits) {
+    digits = digits || 1;
+    factor = Math.pow(10, digits);
+    return Math.round(n * factor) / factor;
+  };
+
+  return {
+    BAR_WIDTH: BAR_WIDTH,
+    BAR_HEIGHT: BAR_HEIGHT,
+    drawLine: drawLine,
+    makeElement: makeElement,
+    clipURL: clipURL,
+    createDetailsLi: createDetailsLi,
+    printDictionaryToTable: printDictionaryToTable,
+    round: round,
+  };
+});