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.

/**
 * Sets the width (in pixels) on a DOM node.
 * @param {!HtmlNode} node The node whose width is being set.
 * @param {number} widthPx The width in pixels.
 */
function setNodeWidth(node, widthPx) {
  node.style.width = widthPx.toFixed(0) + 'px';
}

/**
 * Sets the height (in pixels) on a DOM node.
 * @param {!HtmlNode} node The node whose height is being set.
 * @param {number} heightPx The height in pixels.
 */
function setNodeHeight(node, heightPx) {
  node.style.height = heightPx.toFixed(0) + 'px';
}

/**
 * Sets the position and size of a DOM node (in pixels).
 * @param {!HtmlNode} node The node being positioned.
 * @param {number} leftPx The left position in pixels.
 * @param {number} topPx The top position in pixels.
 * @param {number} widthPx The width in pixels.
 * @param {number} heightPx The height in pixels.
 */
function setNodePosition(node, leftPx, topPx, widthPx, heightPx) {
  node.style.left = leftPx.toFixed(0) + 'px';
  node.style.top = topPx.toFixed(0) + 'px';
  setNodeWidth(node, widthPx);
  setNodeHeight(node, heightPx);
}

/**
 * Sets the visibility for a DOM node.
 * @param {!HtmlNode} node The node being positioned.
 * @param {boolean} isVisible Whether to show the node or not.
 */
function setNodeDisplay(node, isVisible) {
  node.style.display = isVisible ? '' : 'none';
}

/**
 * Toggles the visibility of a DOM node.
 * @param {!HtmlNode} node The node to show or hide.
 */
function toggleNodeDisplay(node) {
  setNodeDisplay(node, !getNodeDisplay(node));
}

/**
 * Returns the visibility of a DOM node.
 * @param {!HtmlNode} node The node to query.
 */
function getNodeDisplay(node) {
  return node.style.display != 'none';
}

/**
 * Adds a node to |parentNode|, of type |tagName|.
 * @param {!HtmlNode} parentNode The node that will be the parent of the new
 *     element.
 * @param {string} tagName the tag name of the new element.
 * @return {!HtmlElement} The newly created element.
 */
function addNode(parentNode, tagName) {
  var elem = parentNode.ownerDocument.createElement(tagName);
  parentNode.appendChild(elem);
  return elem;
}

/**
 * Adds |text| to node |parentNode|.
 * @param {!HtmlNode} parentNode The node to add text to.
 * @param {string} text The text to be added.
 * @return {!Object} The newly created text node.
 */
function addTextNode(parentNode, text) {
  var textNode = parentNode.ownerDocument.createTextNode(text);
  parentNode.appendChild(textNode);
  return textNode;
}

/**
 * Adds a node to |parentNode|, of type |tagName|.  Then adds
 * |text| to the new node.
 * @param {!HtmlNode} parentNode The node that will be the parent of the new
 *     element.
 * @param {string} tagName the tag name of the new element.
 * @param {string} text The text to be added.
 * @return {!HtmlElement} The newly created element.
 */
function addNodeWithText(parentNode, tagName, text) {
  var elem = parentNode.ownerDocument.createElement(tagName);
  parentNode.appendChild(elem);
  addTextNode(elem, text);
  return elem;
}

/**
 * Returns the key such that map[key] == value, or the string '?' if
 * there is no such key.
 * @param {!Object} map The object being used as a lookup table.
 * @param {Object} value The value to be found in |map|.
 * @return {string} The key for |value|, or '?' if there is no such key.
 */
function getKeyWithValue(map, value) {
  for (var key in map) {
    if (map[key] == value)
      return key;
  }
  return '?';
}

/**
 * Returns a new map with the keys and values of the input map inverted.
 * @param {!Object} map The object to have its keys and values reversed.  Not
 *     modified by the function call.
 * @return {Object} The new map with the reversed keys and values.
 */
function makeInverseMap(map) {
  var reversed = {};
  for (var key in map)
    reversed[map[key]] = key;
  return reversed;
}

/**
 * Looks up |key| in |map|, and returns the resulting entry, if there is one.
 * Otherwise, returns |key|.  Intended primarily for use with incomplete
 * tables, and for reasonable behavior with system enumerations that may be
 * extended in the future.
 * @param {!Object} map The table in which |key| is looked up.
 * @param {string} key The key to look up.
 * @return {Object|string} map[key], if it exists, or |key| if it doesn't.
 */
function tryGetValueWithKey(map, key) {
  if (key in map)
    return map[key];
  return key;
}

/**
 * Builds a string by repeating |str| |count| times.
 * @param {string} str The string to be repeated.
 * @param {number} count The number of times to repeat |str|.
 * @return {string} The constructed string
 */
function makeRepeatedString(str, count) {
  var out = [];
  for (var i = 0; i < count; ++i)
    out.push(str);
  return out.join('');
}

/**
 * Clones a basic POD object.  Only a new top level object will be cloned.  It
 * will continue to reference the same values as the original object.
 * @param {Object} object The object to be cloned.
 * @return {Object} A copy of |object|.
 */
function shallowCloneObject(object) {
  if (!(object instanceof Object))
    return object;
  var copy = {};
  for (var key in object) {
    copy[key] = object[key];
  }
  return copy;
}

/**
 * Helper to make sure singleton classes are not instantiated more than once.
 * @param {Function} ctor The constructor function being checked.
 */
function assertFirstConstructorCall(ctor) {
  // This is the variable which is set by cr.addSingletonGetter().
  if (ctor.hasCreateFirstInstance_) {
    throw Error(
        'The class ' + ctor.name + ' is a singleton, and should ' +
        'only be accessed using ' + ctor.name + '.getInstance().');
  }
  ctor.hasCreateFirstInstance_ = true;
}

function hasTouchScreen() {
  return 'ontouchstart' in window;
}