Componentize IDR_NET_ERROR_HTML for sharing it with iOS.

chrome/renderer/resources/offline.js

-// Copyright (c) 2014 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() {
-'use strict';
-/**
- * T-Rex runner.
- * @param {string} outerContainerId Outer containing element id.
- * @param {Object} opt_config
- * @constructor
- * @export
- */
-function Runner(outerContainerId, opt_config) {
-  // Singleton
-  if (Runner.instance_) {
-    return Runner.instance_;
-  }
-  Runner.instance_ = this;
-
-  this.outerContainerEl = document.querySelector(outerContainerId);
-  this.containerEl = null;
-  this.snackbarEl = null;
-  this.detailsButton = this.outerContainerEl.querySelector('#details-button');
-
-  this.config = opt_config || Runner.config;
-
-  this.dimensions = Runner.defaultDimensions;
-
-  this.canvas = null;
-  this.canvasCtx = null;
-
-  this.tRex = null;
-
-  this.distanceMeter = null;
-  this.distanceRan = 0;
-
-  this.highestScore = 0;
-
-  this.time = 0;
-  this.runningTime = 0;
-  this.msPerFrame = 1000 / FPS;
-  this.currentSpeed = this.config.SPEED;
-
-  this.obstacles = [];
-
-  this.started = false;
-  this.activated = false;
-  this.crashed = false;
-  this.paused = false;
-  this.inverted = false;
-  this.invertTimer = 0;
-  this.resizeTimerId_ = null;
-
-  this.playCount = 0;
-
-  // Sound FX.
-  this.audioBuffer = null;
-  this.soundFx = {};
-
-  // Global web audio context for playing sounds.
-  this.audioContext = null;
-
-  // Images.
-  this.images = {};
-  this.imagesLoaded = 0;
-
-  if (this.isDisabled()) {
-    this.setupDisabledRunner();
-  } else {
-    this.loadImages();
-  }
-}
-window['Runner'] = Runner;
-
-
-/**
- * Default game width.
- * @const
- */
-var DEFAULT_WIDTH = 600;
-
-/**
- * Frames per second.
- * @const
- */
-var FPS = 60;
-
-/** @const */
-var IS_HIDPI = window.devicePixelRatio > 1;
-
-/** @const */
-var IS_IOS = window.navigator.userAgent.indexOf('CriOS') > -1 ||
-    window.navigator.userAgent == 'UIWebViewForStaticFileContent';
-
-/** @const */
-var IS_MOBILE = window.navigator.userAgent.indexOf('Mobi') > -1 || IS_IOS;
-
-/** @const */
-var IS_TOUCH_ENABLED = 'ontouchstart' in window;
-
-/**
- * Default game configuration.
- * @enum {number}
- */
-Runner.config = {
-  ACCELERATION: 0.001,
-  BG_CLOUD_SPEED: 0.2,
-  BOTTOM_PAD: 10,
-  CLEAR_TIME: 3000,
-  CLOUD_FREQUENCY: 0.5,
-  GAMEOVER_CLEAR_TIME: 750,
-  GAP_COEFFICIENT: 0.6,
-  GRAVITY: 0.6,
-  INITIAL_JUMP_VELOCITY: 12,
-  INVERT_FADE_DURATION: 12000,
-  INVERT_DISTANCE: 700,
-  MAX_CLOUDS: 6,
-  MAX_OBSTACLE_LENGTH: 3,
-  MAX_OBSTACLE_DUPLICATION: 2,
-  MAX_SPEED: 13,
-  MIN_JUMP_HEIGHT: 35,
-  MOBILE_SPEED_COEFFICIENT: 1.2,
-  RESOURCE_TEMPLATE_ID: 'audio-resources',
-  SPEED: 6,
-  SPEED_DROP_COEFFICIENT: 3
-};
-
-
-/**
- * Default dimensions.
- * @enum {string}
- */
-Runner.defaultDimensions = {
-  WIDTH: DEFAULT_WIDTH,
-  HEIGHT: 150
-};
-
-
-/**
- * CSS class names.
- * @enum {string}
- */
-Runner.classes = {
-  CANVAS: 'runner-canvas',
-  CONTAINER: 'runner-container',
-  CRASHED: 'crashed',
-  ICON: 'icon-offline',
-  INVERTED: 'inverted',
-  SNACKBAR: 'snackbar',
-  SNACKBAR_SHOW: 'snackbar-show',
-  TOUCH_CONTROLLER: 'controller'
-};
-
-
-/**
- * Sprite definition layout of the spritesheet.
- * @enum {Object}
- */
-Runner.spriteDefinition = {
-  LDPI: {
-    CACTUS_LARGE: {x: 332, y: 2},
-    CACTUS_SMALL: {x: 228, y: 2},
-    CLOUD: {x: 86, y: 2},
-    HORIZON: {x: 2, y: 54},
-    MOON: {x: 484, y: 2},
-    PTERODACTYL: {x: 134, y: 2},
-    RESTART: {x: 2, y: 2},
-    TEXT_SPRITE: {x: 655, y: 2},
-    TREX: {x: 848, y: 2},
-    STAR: {x: 645, y: 2}
-  },
-  HDPI: {
-    CACTUS_LARGE: {x: 652, y: 2},
-    CACTUS_SMALL: {x: 446, y: 2},
-    CLOUD: {x: 166, y: 2},
-    HORIZON: {x: 2, y: 104},
-    MOON: {x: 954, y: 2},
-    PTERODACTYL: {x: 260, y: 2},
-    RESTART: {x: 2, y: 2},
-    TEXT_SPRITE: {x: 1294, y: 2},
-    TREX: {x: 1678, y: 2},
-    STAR: {x: 1276, y: 2}
-  }
-};
-
-
-/**
- * Sound FX. Reference to the ID of the audio tag on interstitial page.
- * @enum {string}
- */
-Runner.sounds = {
-  BUTTON_PRESS: 'offline-sound-press',
-  HIT: 'offline-sound-hit',
-  SCORE: 'offline-sound-reached'
-};
-
-
-/**
- * Key code mapping.
- * @enum {Object}
- */
-Runner.keycodes = {
-  JUMP: {'38': 1, '32': 1},  // Up, spacebar
-  DUCK: {'40': 1},  // Down
-  RESTART: {'13': 1}  // Enter
-};
-
-
-/**
- * Runner event names.
- * @enum {string}
- */
-Runner.events = {
-  ANIM_END: 'webkitAnimationEnd',
-  CLICK: 'click',
-  KEYDOWN: 'keydown',
-  KEYUP: 'keyup',
-  MOUSEDOWN: 'mousedown',
-  MOUSEUP: 'mouseup',
-  RESIZE: 'resize',
-  TOUCHEND: 'touchend',
-  TOUCHSTART: 'touchstart',
-  VISIBILITY: 'visibilitychange',
-  BLUR: 'blur',
-  FOCUS: 'focus',
-  LOAD: 'load'
-};
-
-
-Runner.prototype = {
-  /**
-   * Whether the easter egg has been disabled. CrOS enterprise enrolled devices.
-   * @return {boolean}
-   */
-  isDisabled: function() {
-    return loadTimeData && loadTimeData.valueExists('disabledEasterEgg');
-  },
-
-  /**
-   * For disabled instances, set up a snackbar with the disabled message.
-   */
-  setupDisabledRunner: function() {
-    this.containerEl = document.createElement('div');
-    this.containerEl.className = Runner.classes.SNACKBAR;
-    this.containerEl.textContent = loadTimeData.getValue('disabledEasterEgg');
-    this.outerContainerEl.appendChild(this.containerEl);
-
-    // Show notification when the activation key is pressed.
-    document.addEventListener(Runner.events.KEYDOWN, function(e) {
-      if (Runner.keycodes.JUMP[e.keyCode]) {
-        this.containerEl.classList.add(Runner.classes.SNACKBAR_SHOW);
-        document.querySelector('.icon').classList.add('icon-disabled');
-      }
-    }.bind(this));
-  },
-
-  /**
-   * Setting individual settings for debugging.
-   * @param {string} setting
-   * @param {*} value
-   */
-  updateConfigSetting: function(setting, value) {
-    if (setting in this.config && value != undefined) {
-      this.config[setting] = value;
-
-      switch (setting) {
-        case 'GRAVITY':
-        case 'MIN_JUMP_HEIGHT':
-        case 'SPEED_DROP_COEFFICIENT':
-          this.tRex.config[setting] = value;
-          break;
-        case 'INITIAL_JUMP_VELOCITY':
-          this.tRex.setJumpVelocity(value);
-          break;
-        case 'SPEED':
-          this.setSpeed(value);
-          break;
-      }
-    }
-  },
-
-  /**
-   * Cache the appropriate image sprite from the page and get the sprite sheet
-   * definition.
-   */
-  loadImages: function() {
-    if (IS_HIDPI) {
-      Runner.imageSprite = document.getElementById('offline-resources-2x');
-      this.spriteDef = Runner.spriteDefinition.HDPI;
-    } else {
-      Runner.imageSprite = document.getElementById('offline-resources-1x');
-      this.spriteDef = Runner.spriteDefinition.LDPI;
-    }
-
-    this.init();
-  },
-
-  /**
-   * Load and decode base 64 encoded sounds.
-   */
-  loadSounds: function() {
-    if (!IS_IOS) {
-      this.audioContext = new AudioContext();
-
-      var resourceTemplate =
-          document.getElementById(this.config.RESOURCE_TEMPLATE_ID).content;
-
-      for (var sound in Runner.sounds) {
-        var soundSrc =
-            resourceTemplate.getElementById(Runner.sounds[sound]).src;
-        soundSrc = soundSrc.substr(soundSrc.indexOf(',') + 1);
-        var buffer = decodeBase64ToArrayBuffer(soundSrc);
-
-        // Async, so no guarantee of order in array.
-        this.audioContext.decodeAudioData(buffer, function(index, audioData) {
-            this.soundFx[index] = audioData;
-          }.bind(this, sound));
-      }
-    }
-  },
-
-  /**
-   * Sets the game speed. Adjust the speed accordingly if on a smaller screen.
-   * @param {number} opt_speed
-   */
-  setSpeed: function(opt_speed) {
-    var speed = opt_speed || this.currentSpeed;
-
-    // Reduce the speed on smaller mobile screens.
-    if (this.dimensions.WIDTH < DEFAULT_WIDTH) {
-      var mobileSpeed = speed * this.dimensions.WIDTH / DEFAULT_WIDTH *
-          this.config.MOBILE_SPEED_COEFFICIENT;
-      this.currentSpeed = mobileSpeed > speed ? speed : mobileSpeed;
-    } else if (opt_speed) {
-      this.currentSpeed = opt_speed;
-    }
-  },
-
-  /**
-   * Game initialiser.
-   */
-  init: function() {
-    // Hide the static icon.
-    document.querySelector('.' + Runner.classes.ICON).style.visibility =
-        'hidden';
-
-    this.adjustDimensions();
-    this.setSpeed();
-
-    this.containerEl = document.createElement('div');
-    this.containerEl.className = Runner.classes.CONTAINER;
-
-    // Player canvas container.
-    this.canvas = createCanvas(this.containerEl, this.dimensions.WIDTH,
-        this.dimensions.HEIGHT, Runner.classes.PLAYER);
-
-    this.canvasCtx = this.canvas.getContext('2d');
-    this.canvasCtx.fillStyle = '#f7f7f7';
-    this.canvasCtx.fill();
-    Runner.updateCanvasScaling(this.canvas);
-
-    // Horizon contains clouds, obstacles and the ground.
-    this.horizon = new Horizon(this.canvas, this.spriteDef, this.dimensions,
-        this.config.GAP_COEFFICIENT);
-
-    // Distance meter
-    this.distanceMeter = new DistanceMeter(this.canvas,
-          this.spriteDef.TEXT_SPRITE, this.dimensions.WIDTH);
-
-    // Draw t-rex
-    this.tRex = new Trex(this.canvas, this.spriteDef.TREX);
-
-    this.outerContainerEl.appendChild(this.containerEl);
-
-    if (IS_MOBILE) {
-      this.createTouchController();
-    }
-
-    this.startListening();
-    this.update();
-
-    window.addEventListener(Runner.events.RESIZE,
-        this.debounceResize.bind(this));
-  },
-
-  /**
-   * Create the touch controller. A div that covers whole screen.
-   */
-  createTouchController: function() {
-    this.touchController = document.createElement('div');
-    this.touchController.className = Runner.classes.TOUCH_CONTROLLER;
-  },
-
-  /**
-   * Debounce the resize event.
-   */
-  debounceResize: function() {
-    if (!this.resizeTimerId_) {
-      this.resizeTimerId_ =
-          setInterval(this.adjustDimensions.bind(this), 250);
-    }
-  },
-
-  /**
-   * Adjust game space dimensions on resize.
-   */
-  adjustDimensions: function() {
-    clearInterval(this.resizeTimerId_);
-    this.resizeTimerId_ = null;
-
-    var boxStyles = window.getComputedStyle(this.outerContainerEl);
-    var padding = Number(boxStyles.paddingLeft.substr(0,
-        boxStyles.paddingLeft.length - 2));
-
-    this.dimensions.WIDTH = this.outerContainerEl.offsetWidth - padding * 2;
-
-    // Redraw the elements back onto the canvas.
-    if (this.canvas) {
-      this.canvas.width = this.dimensions.WIDTH;
-      this.canvas.height = this.dimensions.HEIGHT;
-
-      Runner.updateCanvasScaling(this.canvas);
-
-      this.distanceMeter.calcXPos(this.dimensions.WIDTH);
-      this.clearCanvas();
-      this.horizon.update(0, 0, true);
-      this.tRex.update(0);
-
-      // Outer container and distance meter.
-      if (this.activated || this.crashed || this.paused) {
-        this.containerEl.style.width = this.dimensions.WIDTH + 'px';
-        this.containerEl.style.height = this.dimensions.HEIGHT + 'px';
-        this.distanceMeter.update(0, Math.ceil(this.distanceRan));
-        this.stop();
-      } else {
-        this.tRex.draw(0, 0);
-      }
-
-      // Game over panel.
-      if (this.crashed && this.gameOverPanel) {
-        this.gameOverPanel.updateDimensions(this.dimensions.WIDTH);
-        this.gameOverPanel.draw();
-      }
-    }
-  },
-
-  /**
-   * Play the game intro.
-   * Canvas container width expands out to the full width.
-   */
-  playIntro: function() {
-    if (!this.started && !this.crashed) {
-      this.playingIntro = true;
-      this.tRex.playingIntro = true;
-
-      // CSS animation definition.
-      var keyframes = '@-webkit-keyframes intro { ' +
-            'from { width:' + Trex.config.WIDTH + 'px }' +
-            'to { width: ' + this.dimensions.WIDTH + 'px }' +
-          '}';
-      document.styleSheets[0].insertRule(keyframes, 0);
-
-      this.containerEl.addEventListener(Runner.events.ANIM_END,
-          this.startGame.bind(this));
-
-      this.containerEl.style.webkitAnimation = 'intro .4s ease-out 1 both';
-      this.containerEl.style.width = this.dimensions.WIDTH + 'px';
-
-      if (this.touchController) {
-        this.outerContainerEl.appendChild(this.touchController);
-      }
-      this.activated = true;
-      this.started = true;
-    } else if (this.crashed) {
-      this.restart();
-    }
-  },
-
-
-  /**
-   * Update the game status to started.
-   */
-  startGame: function() {
-    this.runningTime = 0;
-    this.playingIntro = false;
-    this.tRex.playingIntro = false;
-    this.containerEl.style.webkitAnimation = '';
-    this.playCount++;
-
-    // Handle tabbing off the page. Pause the current game.
-    document.addEventListener(Runner.events.VISIBILITY,
-          this.onVisibilityChange.bind(this));
-
-    window.addEventListener(Runner.events.BLUR,
-          this.onVisibilityChange.bind(this));
-
-    window.addEventListener(Runner.events.FOCUS,
-          this.onVisibilityChange.bind(this));
-  },
-
-  clearCanvas: function() {
-    this.canvasCtx.clearRect(0, 0, this.dimensions.WIDTH,
-        this.dimensions.HEIGHT);
-  },
-
-  /**
-   * Update the game frame.
-   */
-  update: function() {
-    this.drawPending = false;
-
-    var now = getTimeStamp();
-    var deltaTime = now - (this.time || now);
-    this.time = now;
-
-    if (this.activated) {
-      this.clearCanvas();
-
-      if (this.tRex.jumping) {
-        this.tRex.updateJump(deltaTime);
-      }
-
-      this.runningTime += deltaTime;
-      var hasObstacles = this.runningTime > this.config.CLEAR_TIME;
-
-      // First jump triggers the intro.
-      if (this.tRex.jumpCount == 1 && !this.playingIntro) {
-        this.playIntro();
-      }
-
-      // The horizon doesn't move until the intro is over.
-      if (this.playingIntro) {
-        this.horizon.update(0, this.currentSpeed, hasObstacles);
-      } else {
-        deltaTime = !this.started ? 0 : deltaTime;
-        this.horizon.update(deltaTime, this.currentSpeed, hasObstacles,
-            this.inverted);
-      }
-
-      // Check for collisions.
-      var collision = hasObstacles &&
-          checkForCollision(this.horizon.obstacles[0], this.tRex);
-
-      if (!collision) {
-        this.distanceRan += this.currentSpeed * deltaTime / this.msPerFrame;
-
-        if (this.currentSpeed < this.config.MAX_SPEED) {
-          this.currentSpeed += this.config.ACCELERATION;
-        }
-      } else {
-        this.gameOver();
-      }
-
-      var playAchievementSound = this.distanceMeter.update(deltaTime,
-          Math.ceil(this.distanceRan));
-
-      if (playAchievementSound) {
-        this.playSound(this.soundFx.SCORE);
-      }
-
-      // Night mode.
-      if (this.invertTimer > this.config.INVERT_FADE_DURATION) {
-        this.invertTimer = 0;
-        this.invertTrigger = false;
-        this.invert();
-      } else if (this.invertTimer) {
-        this.invertTimer += deltaTime;
-      } else {
-        var actualDistance =
-            this.distanceMeter.getActualDistance(Math.ceil(this.distanceRan));
-
-        if (actualDistance > 0) {
-          this.invertTrigger = !(actualDistance %
-              this.config.INVERT_DISTANCE);
-
-          if (this.invertTrigger && this.invertTimer === 0) {
-            this.invertTimer += deltaTime;
-            this.invert();
-          }
-        }
-      }
-    }
-
-    if (!this.crashed) {
-      this.tRex.update(deltaTime);
-      this.raq();
-    }
-  },
-
-  /**
-   * Event handler.
-   */
-  handleEvent: function(e) {
-    return (function(evtType, events) {
-      switch (evtType) {
-        case events.KEYDOWN:
-        case events.TOUCHSTART:
-        case events.MOUSEDOWN:
-          this.onKeyDown(e);
-          break;
-        case events.KEYUP:
-        case events.TOUCHEND:
-        case events.MOUSEUP:
-          this.onKeyUp(e);
-          break;
-      }
-    }.bind(this))(e.type, Runner.events);
-  },
-
-  /**
-   * Bind relevant key / mouse / touch listeners.
-   */
-  startListening: function() {
-    // Keys.
-    document.addEventListener(Runner.events.KEYDOWN, this);
-    document.addEventListener(Runner.events.KEYUP, this);
-
-    if (IS_MOBILE) {
-      // Mobile only touch devices.
-      this.touchController.addEventListener(Runner.events.TOUCHSTART, this);
-      this.touchController.addEventListener(Runner.events.TOUCHEND, this);
-      this.containerEl.addEventListener(Runner.events.TOUCHSTART, this);
-    } else {
-      // Mouse.
-      document.addEventListener(Runner.events.MOUSEDOWN, this);
-      document.addEventListener(Runner.events.MOUSEUP, this);
-    }
-  },
-
-  /**
-   * Remove all listeners.
-   */
-  stopListening: function() {
-    document.removeEventListener(Runner.events.KEYDOWN, this);
-    document.removeEventListener(Runner.events.KEYUP, this);
-
-    if (IS_MOBILE) {
-      this.touchController.removeEventListener(Runner.events.TOUCHSTART, this);
-      this.touchController.removeEventListener(Runner.events.TOUCHEND, this);
-      this.containerEl.removeEventListener(Runner.events.TOUCHSTART, this);
-    } else {
-      document.removeEventListener(Runner.events.MOUSEDOWN, this);
-      document.removeEventListener(Runner.events.MOUSEUP, this);
-    }
-  },
-
-  /**
-   * Process keydown.
-   * @param {Event} e
-   */
-  onKeyDown: function(e) {
-    // Prevent native page scrolling whilst tapping on mobile.
-    if (IS_MOBILE) {
-      e.preventDefault();
-    }
-
-    if (e.target != this.detailsButton) {
-      if (!this.crashed && (Runner.keycodes.JUMP[e.keyCode] ||
-           e.type == Runner.events.TOUCHSTART)) {
-        if (!this.activated) {
-          this.loadSounds();
-          this.activated = true;
-          errorPageController.trackEasterEgg();
-        }
-
-        if (!this.tRex.jumping && !this.tRex.ducking) {
-          this.playSound(this.soundFx.BUTTON_PRESS);
-          this.tRex.startJump(this.currentSpeed);
-        }
-      }
-
-      if (this.crashed && e.type == Runner.events.TOUCHSTART &&
-          e.currentTarget == this.containerEl) {
-        this.restart();
-      }
-    }
-
-    if (this.activated && !this.crashed && Runner.keycodes.DUCK[e.keyCode]) {
-      e.preventDefault();
-      if (this.tRex.jumping) {
-        // Speed drop, activated only when jump key is not pressed.
-        this.tRex.setSpeedDrop();
-      } else if (!this.tRex.jumping && !this.tRex.ducking) {
-        // Duck.
-        this.tRex.setDuck(true);
-      }
-    }
-  },
-
-
-  /**
-   * Process key up.
-   * @param {Event} e
-   */
-  onKeyUp: function(e) {
-    var keyCode = String(e.keyCode);
-    var isjumpKey = Runner.keycodes.JUMP[keyCode] ||
-       e.type == Runner.events.TOUCHEND ||
-       e.type == Runner.events.MOUSEDOWN;
-
-    if (this.isRunning() && isjumpKey) {
-      this.tRex.endJump();
-    } else if (Runner.keycodes.DUCK[keyCode]) {
-      this.tRex.speedDrop = false;
-      this.tRex.setDuck(false);
-    } else if (this.crashed) {
-      // Check that enough time has elapsed before allowing jump key to restart.
-      var deltaTime = getTimeStamp() - this.time;
-
-      if (Runner.keycodes.RESTART[keyCode] || this.isLeftClickOnCanvas(e) ||
-          (deltaTime >= this.config.GAMEOVER_CLEAR_TIME &&
-          Runner.keycodes.JUMP[keyCode])) {
-        this.restart();
-      }
-    } else if (this.paused && isjumpKey) {
-      // Reset the jump state
-      this.tRex.reset();
-      this.play();
-    }
-  },
-
-  /**
-   * Returns whether the event was a left click on canvas.
-   * On Windows right click is registered as a click.
-   * @param {Event} e
-   * @return {boolean}
-   */
-  isLeftClickOnCanvas: function(e) {
-    return e.button != null && e.button < 2 &&
-        e.type == Runner.events.MOUSEUP && e.target == this.canvas;
-  },
-
-  /**
-   * RequestAnimationFrame wrapper.
-   */
-  raq: function() {
-    if (!this.drawPending) {
-      this.drawPending = true;
-      this.raqId = requestAnimationFrame(this.update.bind(this));
-    }
-  },
-
-  /**
-   * Whether the game is running.
-   * @return {boolean}
-   */
-  isRunning: function() {
-    return !!this.raqId;
-  },
-
-  /**
-   * Game over state.
-   */
-  gameOver: function() {
-    this.playSound(this.soundFx.HIT);
-    vibrate(200);
-
-    this.stop();
-    this.crashed = true;
-    this.distanceMeter.acheivement = false;
-
-    this.tRex.update(100, Trex.status.CRASHED);
-
-    // Game over panel.
-    if (!this.gameOverPanel) {
-      this.gameOverPanel = new GameOverPanel(this.canvas,
-          this.spriteDef.TEXT_SPRITE, this.spriteDef.RESTART,
-          this.dimensions);
-    } else {
-      this.gameOverPanel.draw();
-    }
-
-    // Update the high score.
-    if (this.distanceRan > this.highestScore) {
-      this.highestScore = Math.ceil(this.distanceRan);
-      this.distanceMeter.setHighScore(this.highestScore);
-    }
-
-    // Reset the time clock.
-    this.time = getTimeStamp();
-  },
-
-  stop: function() {
-    this.activated = false;
-    this.paused = true;
-    cancelAnimationFrame(this.raqId);
-    this.raqId = 0;
-  },
-
-  play: function() {
-    if (!this.crashed) {
-      this.activated = true;
-      this.paused = false;
-      this.tRex.update(0, Trex.status.RUNNING);
-      this.time = getTimeStamp();
-      this.update();
-    }
-  },
-
-  restart: function() {
-    if (!this.raqId) {
-      this.playCount++;
-      this.runningTime = 0;
-      this.activated = true;
-      this.crashed = false;
-      this.distanceRan = 0;
-      this.setSpeed(this.config.SPEED);
-      this.time = getTimeStamp();
-      this.containerEl.classList.remove(Runner.classes.CRASHED);
-      this.clearCanvas();
-      this.distanceMeter.reset(this.highestScore);
-      this.horizon.reset();
-      this.tRex.reset();
-      this.playSound(this.soundFx.BUTTON_PRESS);
-      this.invert(true);
-      this.update();
-    }
-  },
-
-  /**
-   * Pause the game if the tab is not in focus.
-   */
-  onVisibilityChange: function(e) {
-    if (document.hidden || document.webkitHidden || e.type == 'blur' ||
-      document.visibilityState != 'visible') {
-      this.stop();
-    } else if (!this.crashed) {
-      this.tRex.reset();
-      this.play();
-    }
-  },
-
-  /**
-   * Play a sound.
-   * @param {SoundBuffer} soundBuffer
-   */
-  playSound: function(soundBuffer) {
-    if (soundBuffer) {
-      var sourceNode = this.audioContext.createBufferSource();
-      sourceNode.buffer = soundBuffer;
-      sourceNode.connect(this.audioContext.destination);
-      sourceNode.start(0);
-    }
-  },
-
-  /**
-   * Inverts the current page / canvas colors.
-   * @param {boolean} Whether to reset colors.
-   */
-  invert: function(reset) {
-    if (reset) {
-      document.body.classList.toggle(Runner.classes.INVERTED, false);
-      this.invertTimer = 0;
-      this.inverted = false;
-    } else {
-      this.inverted = document.body.classList.toggle(Runner.classes.INVERTED,
-          this.invertTrigger);
-    }
-  }
-};
-
-
-/**
- * Updates the canvas size taking into
- * account the backing store pixel ratio and
- * the device pixel ratio.
- *
- * See article by Paul Lewis:
- * http://www.html5rocks.com/en/tutorials/canvas/hidpi/
- *
- * @param {HTMLCanvasElement} canvas
- * @param {number} opt_width
- * @param {number} opt_height
- * @return {boolean} Whether the canvas was scaled.
- */
-Runner.updateCanvasScaling = function(canvas, opt_width, opt_height) {
-  var context = canvas.getContext('2d');
-
-  // Query the various pixel ratios
-  var devicePixelRatio = Math.floor(window.devicePixelRatio) || 1;
-  var backingStoreRatio = Math.floor(context.webkitBackingStorePixelRatio) || 1;
-  var ratio = devicePixelRatio / backingStoreRatio;
-
-  // Upscale the canvas if the two ratios don't match
-  if (devicePixelRatio !== backingStoreRatio) {
-    var oldWidth = opt_width || canvas.width;
-    var oldHeight = opt_height || canvas.height;
-
-    canvas.width = oldWidth * ratio;
-    canvas.height = oldHeight * ratio;
-
-    canvas.style.width = oldWidth + 'px';
-    canvas.style.height = oldHeight + 'px';
-
-    // Scale the context to counter the fact that we've manually scaled
-    // our canvas element.
-    context.scale(ratio, ratio);
-    return true;
-  } else if (devicePixelRatio == 1) {
-    // Reset the canvas width / height. Fixes scaling bug when the page is
-    // zoomed and the devicePixelRatio changes accordingly.
-    canvas.style.width = canvas.width + 'px';
-    canvas.style.height = canvas.height + 'px';
-  }
-  return false;
-};
-
-
-/**
- * Get random number.
- * @param {number} min
- * @param {number} max
- * @param {number}
- */
-function getRandomNum(min, max) {
-  return Math.floor(Math.random() * (max - min + 1)) + min;
-}
-
-
-/**
- * Vibrate on mobile devices.
- * @param {number} duration Duration of the vibration in milliseconds.
- */
-function vibrate(duration) {
-  if (IS_MOBILE && window.navigator.vibrate) {
-    window.navigator.vibrate(duration);
-  }
-}
-
-
-/**
- * Create canvas element.
- * @param {HTMLElement} container Element to append canvas to.
- * @param {number} width
- * @param {number} height
- * @param {string} opt_classname
- * @return {HTMLCanvasElement}
- */
-function createCanvas(container, width, height, opt_classname) {
-  var canvas = document.createElement('canvas');
-  canvas.className = opt_classname ? Runner.classes.CANVAS + ' ' +
-      opt_classname : Runner.classes.CANVAS;
-  canvas.width = width;
-  canvas.height = height;
-  container.appendChild(canvas);
-
-  return canvas;
-}
-
-
-/**
- * Decodes the base 64 audio to ArrayBuffer used by Web Audio.
- * @param {string} base64String
- */
-function decodeBase64ToArrayBuffer(base64String) {
-  var len = (base64String.length / 4) * 3;
-  var str = atob(base64String);
-  var arrayBuffer = new ArrayBuffer(len);
-  var bytes = new Uint8Array(arrayBuffer);
-
-  for (var i = 0; i < len; i++) {
-    bytes[i] = str.charCodeAt(i);
-  }
-  return bytes.buffer;
-}
-
-
-/**
- * Return the current timestamp.
- * @return {number}
- */
-function getTimeStamp() {
-  return IS_IOS ? new Date().getTime() : performance.now();
-}
-
-
-//******************************************************************************
-
-
-/**
- * Game over panel.
- * @param {!HTMLCanvasElement} canvas
- * @param {Object} textImgPos
- * @param {Object} restartImgPos
- * @param {!Object} dimensions Canvas dimensions.
- * @constructor
- */
-function GameOverPanel(canvas, textImgPos, restartImgPos, dimensions) {
-  this.canvas = canvas;
-  this.canvasCtx = canvas.getContext('2d');
-  this.canvasDimensions = dimensions;
-  this.textImgPos = textImgPos;
-  this.restartImgPos = restartImgPos;
-  this.draw();
-};
-
-
-/**
- * Dimensions used in the panel.
- * @enum {number}
- */
-GameOverPanel.dimensions = {
-  TEXT_X: 0,
-  TEXT_Y: 13,
-  TEXT_WIDTH: 191,
-  TEXT_HEIGHT: 11,
-  RESTART_WIDTH: 36,
-  RESTART_HEIGHT: 32
-};
-
-
-GameOverPanel.prototype = {
-  /**
-   * Update the panel dimensions.
-   * @param {number} width New canvas width.
-   * @param {number} opt_height Optional new canvas height.
-   */
-  updateDimensions: function(width, opt_height) {
-    this.canvasDimensions.WIDTH = width;
-    if (opt_height) {
-      this.canvasDimensions.HEIGHT = opt_height;
-    }
-  },
-
-  /**
-   * Draw the panel.
-   */
-  draw: function() {
-    var dimensions = GameOverPanel.dimensions;
-
-    var centerX = this.canvasDimensions.WIDTH / 2;
-
-    // Game over text.
-    var textSourceX = dimensions.TEXT_X;
-    var textSourceY = dimensions.TEXT_Y;
-    var textSourceWidth = dimensions.TEXT_WIDTH;
-    var textSourceHeight = dimensions.TEXT_HEIGHT;
-
-    var textTargetX = Math.round(centerX - (dimensions.TEXT_WIDTH / 2));
-    var textTargetY = Math.round((this.canvasDimensions.HEIGHT - 25) / 3);
-    var textTargetWidth = dimensions.TEXT_WIDTH;
-    var textTargetHeight = dimensions.TEXT_HEIGHT;
-
-    var restartSourceWidth = dimensions.RESTART_WIDTH;
-    var restartSourceHeight = dimensions.RESTART_HEIGHT;
-    var restartTargetX = centerX - (dimensions.RESTART_WIDTH / 2);
-    var restartTargetY = this.canvasDimensions.HEIGHT / 2;
-
-    if (IS_HIDPI) {
-      textSourceY *= 2;
-      textSourceX *= 2;
-      textSourceWidth *= 2;
-      textSourceHeight *= 2;
-      restartSourceWidth *= 2;
-      restartSourceHeight *= 2;
-    }
-
-    textSourceX += this.textImgPos.x;
-    textSourceY += this.textImgPos.y;
-
-    // Game over text from sprite.
-    this.canvasCtx.drawImage(Runner.imageSprite,
-        textSourceX, textSourceY, textSourceWidth, textSourceHeight,
-        textTargetX, textTargetY, textTargetWidth, textTargetHeight);
-
-    // Restart button.
-    this.canvasCtx.drawImage(Runner.imageSprite,
-        this.restartImgPos.x, this.restartImgPos.y,
-        restartSourceWidth, restartSourceHeight,
-        restartTargetX, restartTargetY, dimensions.RESTART_WIDTH,
-        dimensions.RESTART_HEIGHT);
-  }
-};
-
-
-//******************************************************************************
-
-/**
- * Check for a collision.
- * @param {!Obstacle} obstacle
- * @param {!Trex} tRex T-rex object.
- * @param {HTMLCanvasContext} opt_canvasCtx Optional canvas context for drawing
- *    collision boxes.
- * @return {Array<CollisionBox>}
- */
-function checkForCollision(obstacle, tRex, opt_canvasCtx) {
-  var obstacleBoxXPos = Runner.defaultDimensions.WIDTH + obstacle.xPos;
-
-  // Adjustments are made to the bounding box as there is a 1 pixel white
-  // border around the t-rex and obstacles.
-  var tRexBox = new CollisionBox(
-      tRex.xPos + 1,
-      tRex.yPos + 1,
-      tRex.config.WIDTH - 2,
-      tRex.config.HEIGHT - 2);
-
-  var obstacleBox = new CollisionBox(
-      obstacle.xPos + 1,
-      obstacle.yPos + 1,
-      obstacle.typeConfig.width * obstacle.size - 2,
-      obstacle.typeConfig.height - 2);
-
-  // Debug outer box
-  if (opt_canvasCtx) {
-    drawCollisionBoxes(opt_canvasCtx, tRexBox, obstacleBox);
-  }
-
-  // Simple outer bounds check.
-  if (boxCompare(tRexBox, obstacleBox)) {
-    var collisionBoxes = obstacle.collisionBoxes;
-    var tRexCollisionBoxes = tRex.ducking ?
-        Trex.collisionBoxes.DUCKING : Trex.collisionBoxes.RUNNING;
-
-    // Detailed axis aligned box check.
-    for (var t = 0; t < tRexCollisionBoxes.length; t++) {
-      for (var i = 0; i < collisionBoxes.length; i++) {
-        // Adjust the box to actual positions.
-        var adjTrexBox =
-            createAdjustedCollisionBox(tRexCollisionBoxes[t], tRexBox);
-        var adjObstacleBox =
-            createAdjustedCollisionBox(collisionBoxes[i], obstacleBox);
-        var crashed = boxCompare(adjTrexBox, adjObstacleBox);
-
-        // Draw boxes for debug.
-        if (opt_canvasCtx) {
-          drawCollisionBoxes(opt_canvasCtx, adjTrexBox, adjObstacleBox);
-        }
-
-        if (crashed) {
-          return [adjTrexBox, adjObstacleBox];
-        }
-      }
-    }
-  }
-  return false;
-};
-
-
-/**
- * Adjust the collision box.
- * @param {!CollisionBox} box The original box.
- * @param {!CollisionBox} adjustment Adjustment box.
- * @return {CollisionBox} The adjusted collision box object.
- */
-function createAdjustedCollisionBox(box, adjustment) {
-  return new CollisionBox(
-      box.x + adjustment.x,
-      box.y + adjustment.y,
-      box.width,
-      box.height);
-};
-
-
-/**
- * Draw the collision boxes for debug.
- */
-function drawCollisionBoxes(canvasCtx, tRexBox, obstacleBox) {
-  canvasCtx.save();
-  canvasCtx.strokeStyle = '#f00';
-  canvasCtx.strokeRect(tRexBox.x, tRexBox.y, tRexBox.width, tRexBox.height);
-
-  canvasCtx.strokeStyle = '#0f0';
-  canvasCtx.strokeRect(obstacleBox.x, obstacleBox.y,
-      obstacleBox.width, obstacleBox.height);
-  canvasCtx.restore();
-};
-
-
-/**
- * Compare two collision boxes for a collision.
- * @param {CollisionBox} tRexBox
- * @param {CollisionBox} obstacleBox
- * @return {boolean} Whether the boxes intersected.
- */
-function boxCompare(tRexBox, obstacleBox) {
-  var crashed = false;
-  var tRexBoxX = tRexBox.x;
-  var tRexBoxY = tRexBox.y;
-
-  var obstacleBoxX = obstacleBox.x;
-  var obstacleBoxY = obstacleBox.y;
-
-  // Axis-Aligned Bounding Box method.
-  if (tRexBox.x < obstacleBoxX + obstacleBox.width &&
-      tRexBox.x + tRexBox.width > obstacleBoxX &&
-      tRexBox.y < obstacleBox.y + obstacleBox.height &&
-      tRexBox.height + tRexBox.y > obstacleBox.y) {
-    crashed = true;
-  }
-
-  return crashed;
-};
-
-
-//******************************************************************************
-
-/**
- * Collision box object.
- * @param {number} x X position.
- * @param {number} y Y Position.
- * @param {number} w Width.
- * @param {number} h Height.
- */
-function CollisionBox(x, y, w, h) {
-  this.x = x;
-  this.y = y;
-  this.width = w;
-  this.height = h;
-};
-
-
-//******************************************************************************
-
-/**
- * Obstacle.
- * @param {HTMLCanvasCtx} canvasCtx
- * @param {Obstacle.type} type
- * @param {Object} spritePos Obstacle position in sprite.
- * @param {Object} dimensions
- * @param {number} gapCoefficient Mutipler in determining the gap.
- * @param {number} speed
- * @param {number} opt_xOffset
- */
-function Obstacle(canvasCtx, type, spriteImgPos, dimensions,
-    gapCoefficient, speed, opt_xOffset) {
-
-  this.canvasCtx = canvasCtx;
-  this.spritePos = spriteImgPos;
-  this.typeConfig = type;
-  this.gapCoefficient = gapCoefficient;
-  this.size = getRandomNum(1, Obstacle.MAX_OBSTACLE_LENGTH);
-  this.dimensions = dimensions;
-  this.remove = false;
-  this.xPos = dimensions.WIDTH + (opt_xOffset || 0);
-  this.yPos = 0;
-  this.width = 0;
-  this.collisionBoxes = [];
-  this.gap = 0;
-  this.speedOffset = 0;
-
-  // For animated obstacles.
-  this.currentFrame = 0;
-  this.timer = 0;
-
-  this.init(speed);
-};
-
-/**
- * Coefficient for calculating the maximum gap.
- * @const
- */
-Obstacle.MAX_GAP_COEFFICIENT = 1.5;
-
-/**
- * Maximum obstacle grouping count.
- * @const
- */
-Obstacle.MAX_OBSTACLE_LENGTH = 3,
-
-
-Obstacle.prototype = {
-  /**
-   * Initialise the DOM for the obstacle.
-   * @param {number} speed
-   */
-  init: function(speed) {
-    this.cloneCollisionBoxes();
-
-    // Only allow sizing if we're at the right speed.
-    if (this.size > 1 && this.typeConfig.multipleSpeed > speed) {
-      this.size = 1;
-    }
-
-    this.width = this.typeConfig.width * this.size;
-
-    // Check if obstacle can be positioned at various heights.
-    if (Array.isArray(this.typeConfig.yPos))  {
-      var yPosConfig = IS_MOBILE ? this.typeConfig.yPosMobile :
-          this.typeConfig.yPos;
-      this.yPos = yPosConfig[getRandomNum(0, yPosConfig.length - 1)];
-    } else {
-      this.yPos = this.typeConfig.yPos;
-    }
-
-    this.draw();
-
-    // Make collision box adjustments,
-    // Central box is adjusted to the size as one box.
-    //      ____        ______        ________
-    //    _|   |-|    _|     |-|    _|       |-|
-    //   | |<->| |   | |<--->| |   | |<----->| |
-    //   | | 1 | |   | |  2  | |   | |   3   | |
-    //   |_|___|_|   |_|_____|_|   |_|_______|_|
-    //
-    if (this.size > 1) {
-      this.collisionBoxes[1].width = this.width - this.collisionBoxes[0].width -
-          this.collisionBoxes[2].width;
-      this.collisionBoxes[2].x = this.width - this.collisionBoxes[2].width;
-    }
-
-    // For obstacles that go at a different speed from the horizon.
-    if (this.typeConfig.speedOffset) {
-      this.speedOffset = Math.random() > 0.5 ? this.typeConfig.speedOffset :
-          -this.typeConfig.speedOffset;
-    }
-
-    this.gap = this.getGap(this.gapCoefficient, speed);
-  },
-
-  /**
-   * Draw and crop based on size.
-   */
-  draw: function() {
-    var sourceWidth = this.typeConfig.width;
-    var sourceHeight = this.typeConfig.height;
-
-    if (IS_HIDPI) {
-      sourceWidth = sourceWidth * 2;
-      sourceHeight = sourceHeight * 2;
-    }
-
-    // X position in sprite.
-    var sourceX = (sourceWidth * this.size) * (0.5 * (this.size - 1)) +
-        this.spritePos.x;
-
-    // Animation frames.
-    if (this.currentFrame > 0) {
-      sourceX += sourceWidth * this.currentFrame;
-    }
-
-    this.canvasCtx.drawImage(Runner.imageSprite,
-      sourceX, this.spritePos.y,
-      sourceWidth * this.size, sourceHeight,
-      this.xPos, this.yPos,
-      this.typeConfig.width * this.size, this.typeConfig.height);
-  },
-
-  /**
-   * Obstacle frame update.
-   * @param {number} deltaTime
-   * @param {number} speed
-   */
-  update: function(deltaTime, speed) {
-    if (!this.remove) {
-      if (this.typeConfig.speedOffset) {
-        speed += this.speedOffset;
-      }
-      this.xPos -= Math.floor((speed * FPS / 1000) * deltaTime);
-
-      // Update frame
-      if (this.typeConfig.numFrames) {
-        this.timer += deltaTime;
-        if (this.timer >= this.typeConfig.frameRate) {
-          this.currentFrame =
-              this.currentFrame == this.typeConfig.numFrames - 1 ?
-              0 : this.currentFrame + 1;
-          this.timer = 0;
-        }
-      }
-      this.draw();
-
-      if (!this.isVisible()) {
-        this.remove = true;
-      }
-    }
-  },
-
-  /**
-   * Calculate a random gap size.
-   * - Minimum gap gets wider as speed increses
-   * @param {number} gapCoefficient
-   * @param {number} speed
-   * @return {number} The gap size.
-   */
-  getGap: function(gapCoefficient, speed) {
-    var minGap = Math.round(this.width * speed +
-          this.typeConfig.minGap * gapCoefficient);
-    var maxGap = Math.round(minGap * Obstacle.MAX_GAP_COEFFICIENT);
-    return getRandomNum(minGap, maxGap);
-  },
-
-  /**
-   * Check if obstacle is visible.
-   * @return {boolean} Whether the obstacle is in the game area.
-   */
-  isVisible: function() {
-    return this.xPos + this.width > 0;
-  },
-
-  /**
-   * Make a copy of the collision boxes, since these will change based on
-   * obstacle type and size.
-   */
-  cloneCollisionBoxes: function() {
-    var collisionBoxes = this.typeConfig.collisionBoxes;
-
-    for (var i = collisionBoxes.length - 1; i >= 0; i--) {
-      this.collisionBoxes[i] = new CollisionBox(collisionBoxes[i].x,
-          collisionBoxes[i].y, collisionBoxes[i].width,
-          collisionBoxes[i].height);
-    }
-  }
-};
-
-
-/**
- * Obstacle definitions.
- * minGap: minimum pixel space betweeen obstacles.
- * multipleSpeed: Speed at which multiples are allowed.
- * speedOffset: speed faster / slower than the horizon.
- * minSpeed: Minimum speed which the obstacle can make an appearance.
- */
-Obstacle.types = [
-  {
-    type: 'CACTUS_SMALL',
-    width: 17,
-    height: 35,
-    yPos: 105,
-    multipleSpeed: 4,
-    minGap: 120,
-    minSpeed: 0,
-    collisionBoxes: [
-      new CollisionBox(0, 7, 5, 27),
-      new CollisionBox(4, 0, 6, 34),
-      new CollisionBox(10, 4, 7, 14)
-    ]
-  },
-  {
-    type: 'CACTUS_LARGE',
-    width: 25,
-    height: 50,
-    yPos: 90,
-    multipleSpeed: 7,
-    minGap: 120,
-    minSpeed: 0,
-    collisionBoxes: [
-      new CollisionBox(0, 12, 7, 38),
-      new CollisionBox(8, 0, 7, 49),
-      new CollisionBox(13, 10, 10, 38)
-    ]
-  },
-  {
-    type: 'PTERODACTYL',
-    width: 46,
-    height: 40,
-    yPos: [ 100, 75, 50 ], // Variable height.
-    yPosMobile: [ 100, 50 ], // Variable height mobile.
-    multipleSpeed: 999,
-    minSpeed: 8.5,
-    minGap: 150,
-    collisionBoxes: [
-      new CollisionBox(15, 15, 16, 5),
-      new CollisionBox(18, 21, 24, 6),
-      new CollisionBox(2, 14, 4, 3),
-      new CollisionBox(6, 10, 4, 7),
-      new CollisionBox(10, 8, 6, 9)
-    ],
-    numFrames: 2,
-    frameRate: 1000/6,
-    speedOffset: .8
-  }
-];
-
-
-//******************************************************************************
-/**
- * T-rex game character.
- * @param {HTMLCanvas} canvas
- * @param {Object} spritePos Positioning within image sprite.
- * @constructor
- */
-function Trex(canvas, spritePos) {
-  this.canvas = canvas;
-  this.canvasCtx = canvas.getContext('2d');
-  this.spritePos = spritePos;
-  this.xPos = 0;
-  this.yPos = 0;
-  // Position when on the ground.
-  this.groundYPos = 0;
-  this.currentFrame = 0;
-  this.currentAnimFrames = [];
-  this.blinkDelay = 0;
-  this.animStartTime = 0;
-  this.timer = 0;
-  this.msPerFrame = 1000 / FPS;
-  this.config = Trex.config;
-  // Current status.
-  this.status = Trex.status.WAITING;
-
-  this.jumping = false;
-  this.ducking = false;
-  this.jumpVelocity = 0;
-  this.reachedMinHeight = false;
-  this.speedDrop = false;
-  this.jumpCount = 0;
-  this.jumpspotX = 0;
-
-  this.init();
-};
-
-
-/**
- * T-rex player config.
- * @enum {number}
- */
-Trex.config = {
-  DROP_VELOCITY: -5,
-  GRAVITY: 0.6,
-  HEIGHT: 47,
-  HEIGHT_DUCK: 25,
-  INIITAL_JUMP_VELOCITY: -10,
-  INTRO_DURATION: 1500,
-  MAX_JUMP_HEIGHT: 30,
-  MIN_JUMP_HEIGHT: 30,
-  SPEED_DROP_COEFFICIENT: 3,
-  SPRITE_WIDTH: 262,
-  START_X_POS: 50,
-  WIDTH: 44,
-  WIDTH_DUCK: 59
-};
-
-
-/**
- * Used in collision detection.
- * @type {Array<CollisionBox>}
- */
-Trex.collisionBoxes = {
-  DUCKING: [
-    new CollisionBox(1, 18, 55, 25)
-  ],
-  RUNNING: [
-    new CollisionBox(22, 0, 17, 16),
-    new CollisionBox(1, 18, 30, 9),
-    new CollisionBox(10, 35, 14, 8),
-    new CollisionBox(1, 24, 29, 5),
-    new CollisionBox(5, 30, 21, 4),
-    new CollisionBox(9, 34, 15, 4)
-  ]
-};
-
-
-/**
- * Animation states.
- * @enum {string}
- */
-Trex.status = {
-  CRASHED: 'CRASHED',
-  DUCKING: 'DUCKING',
-  JUMPING: 'JUMPING',
-  RUNNING: 'RUNNING',
-  WAITING: 'WAITING'
-};
-
-/**
- * Blinking coefficient.
- * @const
- */
-Trex.BLINK_TIMING = 7000;
-
-
-/**
- * Animation config for different states.
- * @enum {Object}
- */
-Trex.animFrames = {
-  WAITING: {
-    frames: [44, 0],
-    msPerFrame: 1000 / 3
-  },
-  RUNNING: {
-    frames: [88, 132],
-    msPerFrame: 1000 / 12
-  },
-  CRASHED: {
-    frames: [220],
-    msPerFrame: 1000 / 60
-  },
-  JUMPING: {
-    frames: [0],
-    msPerFrame: 1000 / 60
-  },
-  DUCKING: {
-    frames: [262, 321],
-    msPerFrame: 1000 / 8
-  }
-};
-
-
-Trex.prototype = {
-  /**
-   * T-rex player initaliser.
-   * Sets the t-rex to blink at random intervals.
-   */
-  init: function() {
-    this.blinkDelay = this.setBlinkDelay();
-    this.groundYPos = Runner.defaultDimensions.HEIGHT - this.config.HEIGHT -
-        Runner.config.BOTTOM_PAD;
-    this.yPos = this.groundYPos;
-    this.minJumpHeight = this.groundYPos - this.config.MIN_JUMP_HEIGHT;
-
-    this.draw(0, 0);
-    this.update(0, Trex.status.WAITING);
-  },
-
-  /**
-   * Setter for the jump velocity.
-   * The approriate drop velocity is also set.
-   */
-  setJumpVelocity: function(setting) {
-    this.config.INIITAL_JUMP_VELOCITY = -setting;
-    this.config.DROP_VELOCITY = -setting / 2;
-  },
-
-  /**
-   * Set the animation status.
-   * @param {!number} deltaTime
-   * @param {Trex.status} status Optional status to switch to.
-   */
-  update: function(deltaTime, opt_status) {
-    this.timer += deltaTime;
-
-    // Update the status.
-    if (opt_status) {
-      this.status = opt_status;
-      this.currentFrame = 0;
-      this.msPerFrame = Trex.animFrames[opt_status].msPerFrame;
-      this.currentAnimFrames = Trex.animFrames[opt_status].frames;
-
-      if (opt_status == Trex.status.WAITING) {
-        this.animStartTime = getTimeStamp();
-        this.setBlinkDelay();
-      }
-    }
-
-    // Game intro animation, T-rex moves in from the left.
-    if (this.playingIntro && this.xPos < this.config.START_X_POS) {
-      this.xPos += Math.round((this.config.START_X_POS /
-          this.config.INTRO_DURATION) * deltaTime);
-    }
-
-    if (this.status == Trex.status.WAITING) {
-      this.blink(getTimeStamp());
-    } else {
-      this.draw(this.currentAnimFrames[this.currentFrame], 0);
-    }
-
-    // Update the frame position.
-    if (this.timer >= this.msPerFrame) {
-      this.currentFrame = this.currentFrame ==
-          this.currentAnimFrames.length - 1 ? 0 : this.currentFrame + 1;
-      this.timer = 0;
-    }
-
-    // Speed drop becomes duck if the down key is still being pressed.
-    if (this.speedDrop && this.yPos == this.groundYPos) {
-      this.speedDrop = false;
-      this.setDuck(true);
-    }
-  },
-
-  /**
-   * Draw the t-rex to a particular position.
-   * @param {number} x
-   * @param {number} y
-   */
-  draw: function(x, y) {
-    var sourceX = x;
-    var sourceY = y;
-    var sourceWidth = this.ducking && this.status != Trex.status.CRASHED ?
-        this.config.WIDTH_DUCK : this.config.WIDTH;
-    var sourceHeight = this.config.HEIGHT;
-
-    if (IS_HIDPI) {
-      sourceX *= 2;
-      sourceY *= 2;
-      sourceWidth *= 2;
-      sourceHeight *= 2;
-    }
-
-    // Adjustments for sprite sheet position.
-    sourceX += this.spritePos.x;
-    sourceY += this.spritePos.y;
-
-    // Ducking.
-    if (this.ducking && this.status != Trex.status.CRASHED) {
-      this.canvasCtx.drawImage(Runner.imageSprite, sourceX, sourceY,
-          sourceWidth, sourceHeight,
-          this.xPos, this.yPos,
-          this.config.WIDTH_DUCK, this.config.HEIGHT);
-    } else {
-      // Crashed whilst ducking. Trex is standing up so needs adjustment.
-      if (this.ducking && this.status == Trex.status.CRASHED) {
-        this.xPos++;
-      }
-      // Standing / running
-      this.canvasCtx.drawImage(Runner.imageSprite, sourceX, sourceY,
-          sourceWidth, sourceHeight,
-          this.xPos, this.yPos,
-          this.config.WIDTH, this.config.HEIGHT);
-    }
-  },
-
-  /**
-   * Sets a random time for the blink to happen.
-   */
-  setBlinkDelay: function() {
-    this.blinkDelay = Math.ceil(Math.random() * Trex.BLINK_TIMING);
-  },
-
-  /**
-   * Make t-rex blink at random intervals.
-   * @param {number} time Current time in milliseconds.
-   */
-  blink: function(time) {
-    var deltaTime = time - this.animStartTime;
-
-    if (deltaTime >= this.blinkDelay) {
-      this.draw(this.currentAnimFrames[this.currentFrame], 0);
-
-      if (this.currentFrame == 1) {
-        // Set new random delay to blink.
-        this.setBlinkDelay();
-        this.animStartTime = time;
-      }
-    }
-  },
-
-  /**
-   * Initialise a jump.
-   * @param {number} speed
-   */
-  startJump: function(speed) {
-    if (!this.jumping) {
-      this.update(0, Trex.status.JUMPING);
-      // Tweak the jump velocity based on the speed.
-      this.jumpVelocity = this.config.INIITAL_JUMP_VELOCITY - (speed / 10);
-      this.jumping = true;
-      this.reachedMinHeight = false;
-      this.speedDrop = false;
-    }
-  },
-
-  /**
-   * Jump is complete, falling down.
-   */
-  endJump: function() {
-    if (this.reachedMinHeight &&
-        this.jumpVelocity < this.config.DROP_VELOCITY) {
-      this.jumpVelocity = this.config.DROP_VELOCITY;
-    }
-  },
-
-  /**
-   * Update frame for a jump.
-   * @param {number} deltaTime
-   * @param {number} speed
-   */
-  updateJump: function(deltaTime, speed) {
-    var msPerFrame = Trex.animFrames[this.status].msPerFrame;
-    var framesElapsed = deltaTime / msPerFrame;
-
-    // Speed drop makes Trex fall faster.
-    if (this.speedDrop) {
-      this.yPos += Math.round(this.jumpVelocity *
-          this.config.SPEED_DROP_COEFFICIENT * framesElapsed);
-    } else {
-      this.yPos += Math.round(this.jumpVelocity * framesElapsed);
-    }
-
-    this.jumpVelocity += this.config.GRAVITY * framesElapsed;
-
-    // Minimum height has been reached.
-    if (this.yPos < this.minJumpHeight || this.speedDrop) {
-      this.reachedMinHeight = true;
-    }
-
-    // Reached max height
-    if (this.yPos < this.config.MAX_JUMP_HEIGHT || this.speedDrop) {
-      this.endJump();
-    }
-
-    // Back down at ground level. Jump completed.
-    if (this.yPos > this.groundYPos) {
-      this.reset();
-      this.jumpCount++;
-    }
-
-    this.update(deltaTime);
-  },
-
-  /**
-   * Set the speed drop. Immediately cancels the current jump.
-   */
-  setSpeedDrop: function() {
-    this.speedDrop = true;
-    this.jumpVelocity = 1;
-  },
-
-  /**
-   * @param {boolean} isDucking.
-   */
-  setDuck: function(isDucking) {
-    if (isDucking && this.status != Trex.status.DUCKING) {
-      this.update(0, Trex.status.DUCKING);
-      this.ducking = true;
-    } else if (this.status == Trex.status.DUCKING) {
-      this.update(0, Trex.status.RUNNING);
-      this.ducking = false;
-    }
-  },
-
-  /**
-   * Reset the t-rex to running at start of game.
-   */
-  reset: function() {
-    this.yPos = this.groundYPos;
-    this.jumpVelocity = 0;
-    this.jumping = false;
-    this.ducking = false;
-    this.update(0, Trex.status.RUNNING);
-    this.midair = false;
-    this.speedDrop = false;
-    this.jumpCount = 0;
-  }
-};
-
-
-//******************************************************************************
-
-/**
- * Handles displaying the distance meter.
- * @param {!HTMLCanvasElement} canvas
- * @param {Object} spritePos Image position in sprite.
- * @param {number} canvasWidth
- * @constructor
- */
-function DistanceMeter(canvas, spritePos, canvasWidth) {
-  this.canvas = canvas;
-  this.canvasCtx = canvas.getContext('2d');
-  this.image = Runner.imageSprite;
-  this.spritePos = spritePos;
-  this.x = 0;
-  this.y = 5;
-
-  this.currentDistance = 0;
-  this.maxScore = 0;
-  this.highScore = 0;
-  this.container = null;
-
-  this.digits = [];
-  this.acheivement = false;
-  this.defaultString = '';
-  this.flashTimer = 0;
-  this.flashIterations = 0;
-  this.invertTrigger = false;
-
-  this.config = DistanceMeter.config;
-  this.maxScoreUnits = this.config.MAX_DISTANCE_UNITS;
-  this.init(canvasWidth);
-};
-
-
-/**
- * @enum {number}
- */
-DistanceMeter.dimensions = {
-  WIDTH: 10,
-  HEIGHT: 13,
-  DEST_WIDTH: 11
-};
-
-
-/**
- * Y positioning of the digits in the sprite sheet.
- * X position is always 0.
- * @type {Array<number>}
- */
-DistanceMeter.yPos = [0, 13, 27, 40, 53, 67, 80, 93, 107, 120];
-
-
-/**
- * Distance meter config.
- * @enum {number}
- */
-DistanceMeter.config = {
-  // Number of digits.
-  MAX_DISTANCE_UNITS: 5,
-
-  // Distance that causes achievement animation.
-  ACHIEVEMENT_DISTANCE: 100,
-
-  // Used for conversion from pixel distance to a scaled unit.
-  COEFFICIENT: 0.025,
-
-  // Flash duration in milliseconds.
-  FLASH_DURATION: 1000 / 4,
-
-  // Flash iterations for achievement animation.
-  FLASH_ITERATIONS: 3
-};
-
-
-DistanceMeter.prototype = {
-  /**
-   * Initialise the distance meter to '00000'.
-   * @param {number} width Canvas width in px.
-   */
-  init: function(width) {
-    var maxDistanceStr = '';
-
-    this.calcXPos(width);
-    this.maxScore = this.maxScoreUnits;
-    for (var i = 0; i < this.maxScoreUnits; i++) {
-      this.draw(i, 0);
-      this.defaultString += '0';
-      maxDistanceStr += '9';
-    }
-
-    this.maxScore = parseInt(maxDistanceStr);
-  },
-
-  /**
-   * Calculate the xPos in the canvas.
-   * @param {number} canvasWidth
-   */
-  calcXPos: function(canvasWidth) {
-    this.x = canvasWidth - (DistanceMeter.dimensions.DEST_WIDTH *
-        (this.maxScoreUnits + 1));
-  },
-
-  /**
-   * Draw a digit to canvas.
-   * @param {number} digitPos Position of the digit.
-   * @param {number} value Digit value 0-9.
-   * @param {boolean} opt_highScore Whether drawing the high score.
-   */
-  draw: function(digitPos, value, opt_highScore) {
-    var sourceWidth = DistanceMeter.dimensions.WIDTH;
-    var sourceHeight = DistanceMeter.dimensions.HEIGHT;
-    var sourceX = DistanceMeter.dimensions.WIDTH * value;
-    var sourceY = 0;
-
-    var targetX = digitPos * DistanceMeter.dimensions.DEST_WIDTH;
-    var targetY = this.y;
-    var targetWidth = DistanceMeter.dimensions.WIDTH;
-    var targetHeight = DistanceMeter.dimensions.HEIGHT;
-
-    // For high DPI we 2x source values.
-    if (IS_HIDPI) {
-      sourceWidth *= 2;
-      sourceHeight *= 2;
-      sourceX *= 2;
-    }
-
-    sourceX += this.spritePos.x;
-    sourceY += this.spritePos.y;
-
-    this.canvasCtx.save();
-
-    if (opt_highScore) {
-      // Left of the current score.
-      var highScoreX = this.x - (this.maxScoreUnits * 2) *
-          DistanceMeter.dimensions.WIDTH;
-      this.canvasCtx.translate(highScoreX, this.y);
-    } else {
-      this.canvasCtx.translate(this.x, this.y);
-    }
-
-    this.canvasCtx.drawImage(this.image, sourceX, sourceY,
-        sourceWidth, sourceHeight,
-        targetX, targetY,
-        targetWidth, targetHeight
-      );
-
-    this.canvasCtx.restore();
-  },
-
-  /**
-   * Covert pixel distance to a 'real' distance.
-   * @param {number} distance Pixel distance ran.
-   * @return {number} The 'real' distance ran.
-   */
-  getActualDistance: function(distance) {
-    return distance ? Math.round(distance * this.config.COEFFICIENT) : 0;
-  },
-
-  /**
-   * Update the distance meter.
-   * @param {number} distance
-   * @param {number} deltaTime
-   * @return {boolean} Whether the acheivement sound fx should be played.
-   */
-  update: function(deltaTime, distance) {
-    var paint = true;
-    var playSound = false;
-
-    if (!this.acheivement) {
-      distance = this.getActualDistance(distance);
-      // Score has gone beyond the initial digit count.
-      if (distance > this.maxScore && this.maxScoreUnits ==
-        this.config.MAX_DISTANCE_UNITS) {
-        this.maxScoreUnits++;
-        this.maxScore = parseInt(this.maxScore + '9');
-      } else {
-        this.distance = 0;
-      }
-
-      if (distance > 0) {
-        // Acheivement unlocked
-        if (distance % this.config.ACHIEVEMENT_DISTANCE == 0) {
-          // Flash score and play sound.
-          this.acheivement = true;
-          this.flashTimer = 0;
-          playSound = true;
-        }
-
-        // Create a string representation of the distance with leading 0.
-        var distanceStr = (this.defaultString +
-            distance).substr(-this.maxScoreUnits);
-        this.digits = distanceStr.split('');
-      } else {
-        this.digits = this.defaultString.split('');
-      }
-    } else {
-      // Control flashing of the score on reaching acheivement.
-      if (this.flashIterations <= this.config.FLASH_ITERATIONS) {
-        this.flashTimer += deltaTime;
-
-        if (this.flashTimer < this.config.FLASH_DURATION) {
-          paint = false;
-        } else if (this.flashTimer >
-            this.config.FLASH_DURATION * 2) {
-          this.flashTimer = 0;
-          this.flashIterations++;
-        }
-      } else {
-        this.acheivement = false;
-        this.flashIterations = 0;
-        this.flashTimer = 0;
-      }
-    }
-
-    // Draw the digits if not flashing.
-    if (paint) {
-      for (var i = this.digits.length - 1; i >= 0; i--) {
-        this.draw(i, parseInt(this.digits[i]));
-      }
-    }
-
-    this.drawHighScore();
-    return playSound;
-  },
-
-  /**
-   * Draw the high score.
-   */
-  drawHighScore: function() {
-    this.canvasCtx.save();
-    this.canvasCtx.globalAlpha = .8;
-    for (var i = this.highScore.length - 1; i >= 0; i--) {
-      this.draw(i, parseInt(this.highScore[i], 10), true);
-    }
-    this.canvasCtx.restore();
-  },
-
-  /**
-   * Set the highscore as a array string.
-   * Position of char in the sprite: H - 10, I - 11.
-   * @param {number} distance Distance ran in pixels.
-   */
-  setHighScore: function(distance) {
-    distance = this.getActualDistance(distance);
-    var highScoreStr = (this.defaultString +
-        distance).substr(-this.maxScoreUnits);
-
-    this.highScore = ['10', '11', ''].concat(highScoreStr.split(''));
-  },
-
-  /**
-   * Reset the distance meter back to '00000'.
-   */
-  reset: function() {
-    this.update(0);
-    this.acheivement = false;
-  }
-};
-
-
-//******************************************************************************
-
-/**
- * Cloud background item.
- * Similar to an obstacle object but without collision boxes.
- * @param {HTMLCanvasElement} canvas Canvas element.
- * @param {Object} spritePos Position of image in sprite.
- * @param {number} containerWidth
- */
-function Cloud(canvas, spritePos, containerWidth) {
-  this.canvas = canvas;
-  this.canvasCtx = this.canvas.getContext('2d');
-  this.spritePos = spritePos;
-  this.containerWidth = containerWidth;
-  this.xPos = containerWidth;
-  this.yPos = 0;
-  this.remove = false;
-  this.cloudGap = getRandomNum(Cloud.config.MIN_CLOUD_GAP,
-      Cloud.config.MAX_CLOUD_GAP);
-
-  this.init();
-};
-
-
-/**
- * Cloud object config.
- * @enum {number}
- */
-Cloud.config = {
-  HEIGHT: 14,
-  MAX_CLOUD_GAP: 400,
-  MAX_SKY_LEVEL: 30,
-  MIN_CLOUD_GAP: 100,
-  MIN_SKY_LEVEL: 71,
-  WIDTH: 46
-};
-
-
-Cloud.prototype = {
-  /**
-   * Initialise the cloud. Sets the Cloud height.
-   */
-  init: function() {
-    this.yPos = getRandomNum(Cloud.config.MAX_SKY_LEVEL,
-        Cloud.config.MIN_SKY_LEVEL);
-    this.draw();
-  },
-
-  /**
-   * Draw the cloud.
-   */
-  draw: function() {
-    this.canvasCtx.save();
-    var sourceWidth = Cloud.config.WIDTH;
-    var sourceHeight = Cloud.config.HEIGHT;
-
-    if (IS_HIDPI) {
-      sourceWidth = sourceWidth * 2;
-      sourceHeight = sourceHeight * 2;
-    }
-
-    this.canvasCtx.drawImage(Runner.imageSprite, this.spritePos.x,
-        this.spritePos.y,
-        sourceWidth, sourceHeight,
-        this.xPos, this.yPos,
-        Cloud.config.WIDTH, Cloud.config.HEIGHT);
-
-    this.canvasCtx.restore();
-  },
-
-  /**
-   * Update the cloud position.
-   * @param {number} speed
-   */
-  update: function(speed) {
-    if (!this.remove) {
-      this.xPos -= Math.ceil(speed);
-      this.draw();
-
-      // Mark as removeable if no longer in the canvas.
-      if (!this.isVisible()) {
-        this.remove = true;
-      }
-    }
-  },
-
-  /**
-   * Check if the cloud is visible on the stage.
-   * @return {boolean}
-   */
-  isVisible: function() {
-    return this.xPos + Cloud.config.WIDTH > 0;
-  }
-};
-
-
-//******************************************************************************
-
-/**
- * Nightmode shows a moon and stars on the horizon.
- */
-function NightMode(canvas, spritePos, containerWidth) {
-  this.spritePos = spritePos;
-  this.canvas = canvas;
-  this.canvasCtx = canvas.getContext('2d');
-  this.xPos = containerWidth - 50;
-  this.yPos = 30;
-  this.currentPhase = 0;
-  this.opacity = 0;
-  this.containerWidth = containerWidth;
-  this.stars = [];
-  this.drawStars = false;
-  this.placeStars();
-};
-
-/**
- * @enum {number}
- */
-NightMode.config = {
-  FADE_SPEED: 0.035,
-  HEIGHT: 40,
-  MOON_SPEED: 0.25,
-  NUM_STARS: 2,
-  STAR_SIZE: 9,
-  STAR_SPEED: 0.3,
-  STAR_MAX_Y: 70,
-  WIDTH: 20
-};
-
-NightMode.phases = [140, 120, 100, 60, 40, 20, 0];
-
-NightMode.prototype = {
-  /**
-   * Update moving moon, changing phases.
-   * @param {boolean} activated Whether night mode is activated.
-   * @param {number} delta
-   */
-  update: function(activated, delta) {
-    // Moon phase.
-    if (activated && this.opacity == 0) {
-      this.currentPhase++;
-
-      if (this.currentPhase >= NightMode.phases.length) {
-        this.currentPhase = 0;
-      }
-    }
-
-    // Fade in / out.
-    if (activated && (this.opacity < 1 || this.opacity == 0)) {
-      this.opacity += NightMode.config.FADE_SPEED;
-    } else if (this.opacity > 0) {
-      this.opacity -= NightMode.config.FADE_SPEED;
-    }
-
-    // Set moon positioning.
-    if (this.opacity > 0) {
-      this.xPos = this.updateXPos(this.xPos, NightMode.config.MOON_SPEED);
-
-      // Update stars.
-      if (this.drawStars) {
-         for (var i = 0; i < NightMode.config.NUM_STARS; i++) {
-            this.stars[i].x = this.updateXPos(this.stars[i].x,
-                NightMode.config.STAR_SPEED);
-         }
-      }
-      this.draw();
-    } else {
-      this.opacity = 0;
-      this.placeStars();
-    }
-    this.drawStars = true;
-  },
-
-  updateXPos: function(currentPos, speed) {
-    if (currentPos < -NightMode.config.WIDTH) {
-      currentPos = this.containerWidth;
-    } else {
-      currentPos -= speed;
-    }
-    return currentPos;
-  },
-
-  draw: function() {
-    var moonSourceWidth = this.currentPhase == 3 ? NightMode.config.WIDTH * 2 :
-         NightMode.config.WIDTH;
-    var moonSourceHeight = NightMode.config.HEIGHT;
-    var moonSourceX = this.spritePos.x + NightMode.phases[this.currentPhase];
-    var moonOutputWidth = moonSourceWidth;
-    var starSize = NightMode.config.STAR_SIZE;
-    var starSourceX = Runner.spriteDefinition.LDPI.STAR.x;
-
-    if (IS_HIDPI) {
-      moonSourceWidth *= 2;
-      moonSourceHeight *= 2;
-      moonSourceX = this.spritePos.x +
-          (NightMode.phases[this.currentPhase] * 2);
-      starSize *= 2;
-      starSourceX = Runner.spriteDefinition.HDPI.STAR.x;
-    }
-
-    this.canvasCtx.save();
-    this.canvasCtx.globalAlpha = this.opacity;
-
-    // Stars.
-    if (this.drawStars) {
-      for (var i = 0; i < NightMode.config.NUM_STARS; i++) {
-        this.canvasCtx.drawImage(Runner.imageSprite,
-            starSourceX, this.stars[i].sourceY, starSize, starSize,
-            Math.round(this.stars[i].x), this.stars[i].y,
-            NightMode.config.STAR_SIZE, NightMode.config.STAR_SIZE);
-      }
-    }
-
-    // Moon.
-    this.canvasCtx.drawImage(Runner.imageSprite, moonSourceX,
-        this.spritePos.y, moonSourceWidth, moonSourceHeight,
-        Math.round(this.xPos), this.yPos,
-        moonOutputWidth, NightMode.config.HEIGHT);
-
-    this.canvasCtx.globalAlpha = 1;
-    this.canvasCtx.restore();
-  },
-
-  // Do star placement.
-  placeStars: function() {
-    var segmentSize = Math.round(this.containerWidth /
-        NightMode.config.NUM_STARS);
-
-    for (var i = 0; i < NightMode.config.NUM_STARS; i++) {
-      this.stars[i] = {};
-      this.stars[i].x = getRandomNum(segmentSize * i, segmentSize * (i + 1));
-      this.stars[i].y = getRandomNum(0, NightMode.config.STAR_MAX_Y);
-
-      if (IS_HIDPI) {
-        this.stars[i].sourceY = Runner.spriteDefinition.HDPI.STAR.y +
-            NightMode.config.STAR_SIZE * 2 * i;
-      } else {
-        this.stars[i].sourceY = Runner.spriteDefinition.LDPI.STAR.y +
-            NightMode.config.STAR_SIZE * i;
-      }
-    }
-  },
-
-  reset: function() {
-    this.currentPhase = 0;
-    this.opacity = 0;
-    this.update(false);
-  }
-
-};
-
-
-//******************************************************************************
-
-/**
- * Horizon Line.
- * Consists of two connecting lines. Randomly assigns a flat / bumpy horizon.
- * @param {HTMLCanvasElement} canvas
- * @param {Object} spritePos Horizon position in sprite.
- * @constructor
- */
-function HorizonLine(canvas, spritePos) {
-  this.spritePos = spritePos;
-  this.canvas = canvas;
-  this.canvasCtx = canvas.getContext('2d');
-  this.sourceDimensions = {};
-  this.dimensions = HorizonLine.dimensions;
-  this.sourceXPos = [this.spritePos.x, this.spritePos.x +
-      this.dimensions.WIDTH];
-  this.xPos = [];
-  this.yPos = 0;
-  this.bumpThreshold = 0.5;
-
-  this.setSourceDimensions();
-  this.draw();
-};
-
-
-/**
- * Horizon line dimensions.
- * @enum {number}
- */
-HorizonLine.dimensions = {
-  WIDTH: 600,
-  HEIGHT: 12,
-  YPOS: 127
-};
-
-
-HorizonLine.prototype = {
-  /**
-   * Set the source dimensions of the horizon line.
-   */
-  setSourceDimensions: function() {
-
-    for (var dimension in HorizonLine.dimensions) {
-      if (IS_HIDPI) {
-        if (dimension != 'YPOS') {
-          this.sourceDimensions[dimension] =
-              HorizonLine.dimensions[dimension] * 2;
-        }
-      } else {
-        this.sourceDimensions[dimension] =
-            HorizonLine.dimensions[dimension];
-      }
-      this.dimensions[dimension] = HorizonLine.dimensions[dimension];
-    }
-
-    this.xPos = [0, HorizonLine.dimensions.WIDTH];
-    this.yPos = HorizonLine.dimensions.YPOS;
-  },
-
-  /**
-   * Return the crop x position of a type.
-   */
-  getRandomType: function() {
-    return Math.random() > this.bumpThreshold ? this.dimensions.WIDTH : 0;
-  },
-
-  /**
-   * Draw the horizon line.
-   */
-  draw: function() {
-    this.canvasCtx.drawImage(Runner.imageSprite, this.sourceXPos[0],
-        this.spritePos.y,
-        this.sourceDimensions.WIDTH, this.sourceDimensions.HEIGHT,
-        this.xPos[0], this.yPos,
-        this.dimensions.WIDTH, this.dimensions.HEIGHT);
-
-    this.canvasCtx.drawImage(Runner.imageSprite, this.sourceXPos[1],
-        this.spritePos.y,
-        this.sourceDimensions.WIDTH, this.sourceDimensions.HEIGHT,
-        this.xPos[1], this.yPos,
-        this.dimensions.WIDTH, this.dimensions.HEIGHT);
-  },
-
-  /**
-   * Update the x position of an indivdual piece of the line.
-   * @param {number} pos Line position.
-   * @param {number} increment
-   */
-  updateXPos: function(pos, increment) {
-    var line1 = pos;
-    var line2 = pos == 0 ? 1 : 0;
-
-    this.xPos[line1] -= increment;
-    this.xPos[line2] = this.xPos[line1] + this.dimensions.WIDTH;
-
-    if (this.xPos[line1] <= -this.dimensions.WIDTH) {
-      this.xPos[line1] += this.dimensions.WIDTH * 2;
-      this.xPos[line2] = this.xPos[line1] - this.dimensions.WIDTH;
-      this.sourceXPos[line1] = this.getRandomType() + this.spritePos.x;
-    }
-  },
-
-  /**
-   * Update the horizon line.
-   * @param {number} deltaTime
-   * @param {number} speed
-   */
-  update: function(deltaTime, speed) {
-    var increment = Math.floor(speed * (FPS / 1000) * deltaTime);
-
-    if (this.xPos[0] <= 0) {
-      this.updateXPos(0, increment);
-    } else {
-      this.updateXPos(1, increment);
-    }
-    this.draw();
-  },
-
-  /**
-   * Reset horizon to the starting position.
-   */
-  reset: function() {
-    this.xPos[0] = 0;
-    this.xPos[1] = HorizonLine.dimensions.WIDTH;
-  }
-};
-
-
-//******************************************************************************
-
-/**
- * Horizon background class.
- * @param {HTMLCanvasElement} canvas
- * @param {Object} spritePos Sprite positioning.
- * @param {Object} dimensions Canvas dimensions.
- * @param {number} gapCoefficient
- * @constructor
- */
-function Horizon(canvas, spritePos, dimensions, gapCoefficient) {
-  this.canvas = canvas;
-  this.canvasCtx = this.canvas.getContext('2d');
-  this.config = Horizon.config;
-  this.dimensions = dimensions;
-  this.gapCoefficient = gapCoefficient;
-  this.obstacles = [];
-  this.obstacleHistory = [];
-  this.horizonOffsets = [0, 0];
-  this.cloudFrequency = this.config.CLOUD_FREQUENCY;
-  this.spritePos = spritePos;
-  this.nightMode = null;
-
-  // Cloud
-  this.clouds = [];
-  this.cloudSpeed = this.config.BG_CLOUD_SPEED;
-
-  // Horizon
-  this.horizonLine = null;
-  this.init();
-};
-
-
-/**
- * Horizon config.
- * @enum {number}
- */
-Horizon.config = {
-  BG_CLOUD_SPEED: 0.2,
-  BUMPY_THRESHOLD: .3,
-  CLOUD_FREQUENCY: .5,
-  HORIZON_HEIGHT: 16,
-  MAX_CLOUDS: 6
-};
-
-
-Horizon.prototype = {
-  /**
-   * Initialise the horizon. Just add the line and a cloud. No obstacles.
-   */
-  init: function() {
-    this.addCloud();
-    this.horizonLine = new HorizonLine(this.canvas, this.spritePos.HORIZON);
-    this.nightMode = new NightMode(this.canvas, this.spritePos.MOON,
-        this.dimensions.WIDTH);
-  },
-
-  /**
-   * @param {number} deltaTime
-   * @param {number} currentSpeed
-   * @param {boolean} updateObstacles Used as an override to prevent
-   *     the obstacles from being updated / added. This happens in the
-   *     ease in section.
-   * @param {boolean} showNightMode Night mode activated.
-   */
-  update: function(deltaTime, currentSpeed, updateObstacles, showNightMode) {
-    this.runningTime += deltaTime;
-    this.horizonLine.update(deltaTime, currentSpeed);
-    this.nightMode.update(showNightMode);
-    this.updateClouds(deltaTime, currentSpeed);
-
-    if (updateObstacles) {
-      this.updateObstacles(deltaTime, currentSpeed);
-    }
-  },
-
-  /**
-   * Update the cloud positions.
-   * @param {number} deltaTime
-   * @param {number} currentSpeed
-   */
-  updateClouds: function(deltaTime, speed) {
-    var cloudSpeed = this.cloudSpeed / 1000 * deltaTime * speed;
-    var numClouds = this.clouds.length;
-
-    if (numClouds) {
-      for (var i = numClouds - 1; i >= 0; i--) {
-        this.clouds[i].update(cloudSpeed);
-      }
-
-      var lastCloud = this.clouds[numClouds - 1];
-
-      // Check for adding a new cloud.
-      if (numClouds < this.config.MAX_CLOUDS &&
-          (this.dimensions.WIDTH - lastCloud.xPos) > lastCloud.cloudGap &&
-          this.cloudFrequency > Math.random()) {
-        this.addCloud();
-      }
-
-      // Remove expired clouds.
-      this.clouds = this.clouds.filter(function(obj) {
-        return !obj.remove;
-      });
-    } else {
-      this.addCloud();
-    }
-  },
-
-  /**
-   * Update the obstacle positions.
-   * @param {number} deltaTime
-   * @param {number} currentSpeed
-   */
-  updateObstacles: function(deltaTime, currentSpeed) {
-    // Obstacles, move to Horizon layer.
-    var updatedObstacles = this.obstacles.slice(0);
-
-    for (var i = 0; i < this.obstacles.length; i++) {
-      var obstacle = this.obstacles[i];
-      obstacle.update(deltaTime, currentSpeed);
-
-      // Clean up existing obstacles.
-      if (obstacle.remove) {
-        updatedObstacles.shift();
-      }
-    }
-    this.obstacles = updatedObstacles;
-
-    if (this.obstacles.length > 0) {
-      var lastObstacle = this.obstacles[this.obstacles.length - 1];
-
-      if (lastObstacle && !lastObstacle.followingObstacleCreated &&
-          lastObstacle.isVisible() &&
-          (lastObstacle.xPos + lastObstacle.width + lastObstacle.gap) <
-          this.dimensions.WIDTH) {
-        this.addNewObstacle(currentSpeed);
-        lastObstacle.followingObstacleCreated = true;
-      }
-    } else {
-      // Create new obstacles.
-      this.addNewObstacle(currentSpeed);
-    }
-  },
-
-  removeFirstObstacle: function() {
-    this.obstacles.shift();
-  },
-
-  /**
-   * Add a new obstacle.
-   * @param {number} currentSpeed
-   */
-  addNewObstacle: function(currentSpeed) {
-    var obstacleTypeIndex = getRandomNum(0, Obstacle.types.length - 1);
-    var obstacleType = Obstacle.types[obstacleTypeIndex];
-
-    // Check for multiples of the same type of obstacle.
-    // Also check obstacle is available at current speed.
-    if (this.duplicateObstacleCheck(obstacleType.type) ||
-        currentSpeed < obstacleType.minSpeed) {
-      this.addNewObstacle(currentSpeed);
-    } else {
-      var obstacleSpritePos = this.spritePos[obstacleType.type];
-
-      this.obstacles.push(new Obstacle(this.canvasCtx, obstacleType,
-          obstacleSpritePos, this.dimensions,
-          this.gapCoefficient, currentSpeed, obstacleType.width));
-
-      this.obstacleHistory.unshift(obstacleType.type);
-
-      if (this.obstacleHistory.length > 1) {
-        this.obstacleHistory.splice(Runner.config.MAX_OBSTACLE_DUPLICATION);
-      }
-    }
-  },
-
-  /**
-   * Returns whether the previous two obstacles are the same as the next one.
-   * Maximum duplication is set in config value MAX_OBSTACLE_DUPLICATION.
-   * @return {boolean}
-   */
-  duplicateObstacleCheck: function(nextObstacleType) {
-    var duplicateCount = 0;
-
-    for (var i = 0; i < this.obstacleHistory.length; i++) {
-      duplicateCount = this.obstacleHistory[i] == nextObstacleType ?
-          duplicateCount + 1 : 0;
-    }
-    return duplicateCount >= Runner.config.MAX_OBSTACLE_DUPLICATION;
-  },
-
-  /**
-   * Reset the horizon layer.
-   * Remove existing obstacles and reposition the horizon line.
-   */
-  reset: function() {
-    this.obstacles = [];
-    this.horizonLine.reset();
-    this.nightMode.reset();
-  },
-
-  /**
-   * Update the canvas width and scaling.
-   * @param {number} width Canvas width.
-   * @param {number} height Canvas height.
-   */
-  resize: function(width, height) {
-    this.canvas.width = width;
-    this.canvas.height = height;
-  },
-
-  /**
-   * Add a new cloud to the horizon.
-   */
-  addCloud: function() {
-    this.clouds.push(new Cloud(this.canvas, this.spritePos.CLOUD,
-        this.dimensions.WIDTH));
-  }
-};
-})();