import defaultValue from '../Core/defaultValue.js';
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import defined from '../Core/defined.js';
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import destroyObject from '../Core/destroyObject.js';
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import DeveloperError from '../Core/DeveloperError.js';
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import Event from '../Core/Event.js';
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import getTimestamp from '../Core/getTimestamp.js';
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import TimeConstants from '../Core/TimeConstants.js';
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/**
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* Monitors the frame rate (frames per second) in a {@link Scene} and raises an event if the frame rate is
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* lower than a threshold. Later, if the frame rate returns to the required level, a separate event is raised.
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* To avoid creating multiple FrameRateMonitors for a single {@link Scene}, use {@link FrameRateMonitor.fromScene}
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* instead of constructing an instance explicitly.
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*
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* @alias FrameRateMonitor
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* @constructor
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*
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* @param {Object} [options] Object with the following properties:
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* @param {Scene} options.scene The Scene instance for which to monitor performance.
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* @param {Number} [options.samplingWindow=5.0] The length of the sliding window over which to compute the average frame rate, in seconds.
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* @param {Number} [options.quietPeriod=2.0] The length of time to wait at startup and each time the page becomes visible (i.e. when the user
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* switches back to the tab) before starting to measure performance, in seconds.
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* @param {Number} [options.warmupPeriod=5.0] The length of the warmup period, in seconds. During the warmup period, a separate
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* (usually lower) frame rate is required.
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* @param {Number} [options.minimumFrameRateDuringWarmup=4] The minimum frames-per-second that are required for acceptable performance during
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* the warmup period. If the frame rate averages less than this during any samplingWindow during the warmupPeriod, the
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* lowFrameRate event will be raised and the page will redirect to the redirectOnLowFrameRateUrl, if any.
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* @param {Number} [options.minimumFrameRateAfterWarmup=8] The minimum frames-per-second that are required for acceptable performance after
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* the end of the warmup period. If the frame rate averages less than this during any samplingWindow after the warmupPeriod, the
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* lowFrameRate event will be raised and the page will redirect to the redirectOnLowFrameRateUrl, if any.
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*/
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function FrameRateMonitor(options) {
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//>>includeStart('debug', pragmas.debug);
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if (!defined(options) || !defined(options.scene)) {
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throw new DeveloperError('options.scene is required.');
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}
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//>>includeEnd('debug');
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this._scene = options.scene;
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/**
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* Gets or sets the length of the sliding window over which to compute the average frame rate, in seconds.
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* @type {Number}
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*/
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this.samplingWindow = defaultValue(options.samplingWindow, FrameRateMonitor.defaultSettings.samplingWindow);
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/**
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* Gets or sets the length of time to wait at startup and each time the page becomes visible (i.e. when the user
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* switches back to the tab) before starting to measure performance, in seconds.
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* @type {Number}
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*/
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this.quietPeriod = defaultValue(options.quietPeriod, FrameRateMonitor.defaultSettings.quietPeriod);
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/**
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* Gets or sets the length of the warmup period, in seconds. During the warmup period, a separate
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* (usually lower) frame rate is required.
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* @type {Number}
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*/
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this.warmupPeriod = defaultValue(options.warmupPeriod, FrameRateMonitor.defaultSettings.warmupPeriod);
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/**
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* Gets or sets the minimum frames-per-second that are required for acceptable performance during
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* the warmup period. If the frame rate averages less than this during any <code>samplingWindow</code> during the <code>warmupPeriod</code>, the
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* <code>lowFrameRate</code> event will be raised and the page will redirect to the <code>redirectOnLowFrameRateUrl</code>, if any.
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* @type {Number}
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*/
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this.minimumFrameRateDuringWarmup = defaultValue(options.minimumFrameRateDuringWarmup, FrameRateMonitor.defaultSettings.minimumFrameRateDuringWarmup);
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/**
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* Gets or sets the minimum frames-per-second that are required for acceptable performance after
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* the end of the warmup period. If the frame rate averages less than this during any <code>samplingWindow</code> after the <code>warmupPeriod</code>, the
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* <code>lowFrameRate</code> event will be raised and the page will redirect to the <code>redirectOnLowFrameRateUrl</code>, if any.
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* @type {Number}
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*/
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this.minimumFrameRateAfterWarmup = defaultValue(options.minimumFrameRateAfterWarmup, FrameRateMonitor.defaultSettings.minimumFrameRateAfterWarmup);
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this._lowFrameRate = new Event();
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this._nominalFrameRate = new Event();
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this._frameTimes = [];
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this._needsQuietPeriod = true;
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this._quietPeriodEndTime = 0.0;
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this._warmupPeriodEndTime = 0.0;
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this._frameRateIsLow = false;
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this._lastFramesPerSecond = undefined;
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this._pauseCount = 0;
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var that = this;
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this._preUpdateRemoveListener = this._scene.preUpdate.addEventListener(function(scene, time) {
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update(that, time);
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});
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this._hiddenPropertyName = (document.hidden !== undefined) ? 'hidden' :
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(document.mozHidden !== undefined) ? 'mozHidden' :
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(document.msHidden !== undefined) ? 'msHidden' :
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(document.webkitHidden !== undefined) ? 'webkitHidden' : undefined;
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var visibilityChangeEventName = (document.hidden !== undefined) ? 'visibilitychange' :
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(document.mozHidden !== undefined) ? 'mozvisibilitychange' :
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(document.msHidden !== undefined) ? 'msvisibilitychange' :
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(document.webkitHidden !== undefined) ? 'webkitvisibilitychange' : undefined;
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function visibilityChangeListener() {
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visibilityChanged(that);
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}
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this._visibilityChangeRemoveListener = undefined;
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if (defined(visibilityChangeEventName)) {
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document.addEventListener(visibilityChangeEventName, visibilityChangeListener, false);
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this._visibilityChangeRemoveListener = function() {
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document.removeEventListener(visibilityChangeEventName, visibilityChangeListener, false);
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};
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}
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}
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/**
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* The default frame rate monitoring settings. These settings are used when {@link FrameRateMonitor.fromScene}
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* needs to create a new frame rate monitor, and for any settings that are not passed to the
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* {@link FrameRateMonitor} constructor.
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*
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* @memberof FrameRateMonitor
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* @type {Object}
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*/
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FrameRateMonitor.defaultSettings = {
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samplingWindow : 5.0,
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quietPeriod : 2.0,
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warmupPeriod : 5.0,
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minimumFrameRateDuringWarmup : 4,
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minimumFrameRateAfterWarmup : 8
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};
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/**
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* Gets the {@link FrameRateMonitor} for a given scene. If the scene does not yet have
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* a {@link FrameRateMonitor}, one is created with the {@link FrameRateMonitor.defaultSettings}.
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*
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* @param {Scene} scene The scene for which to get the {@link FrameRateMonitor}.
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* @returns {FrameRateMonitor} The scene's {@link FrameRateMonitor}.
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*/
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FrameRateMonitor.fromScene = function(scene) {
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//>>includeStart('debug', pragmas.debug);
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if (!defined(scene)) {
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throw new DeveloperError('scene is required.');
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}
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//>>includeEnd('debug');
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if (!defined(scene._frameRateMonitor) || scene._frameRateMonitor.isDestroyed()) {
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scene._frameRateMonitor = new FrameRateMonitor({
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scene : scene
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});
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}
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return scene._frameRateMonitor;
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};
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Object.defineProperties(FrameRateMonitor.prototype, {
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/**
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* Gets the {@link Scene} instance for which to monitor performance.
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* @memberof FrameRateMonitor.prototype
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* @type {Scene}
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*/
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scene : {
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get : function() {
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return this._scene;
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}
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},
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/**
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* Gets the event that is raised when a low frame rate is detected. The function will be passed
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* the {@link Scene} instance as its first parameter and the average number of frames per second
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* over the sampling window as its second parameter.
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* @memberof FrameRateMonitor.prototype
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* @type {Event}
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*/
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lowFrameRate : {
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get : function() {
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return this._lowFrameRate;
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}
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},
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/**
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* Gets the event that is raised when the frame rate returns to a normal level after having been low.
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* The function will be passed the {@link Scene} instance as its first parameter and the average
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* number of frames per second over the sampling window as its second parameter.
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* @memberof FrameRateMonitor.prototype
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* @type {Event}
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*/
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nominalFrameRate : {
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get : function() {
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return this._nominalFrameRate;
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}
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},
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/**
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* Gets the most recently computed average frames-per-second over the last <code>samplingWindow</code>.
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* This property may be undefined if the frame rate has not been computed.
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* @memberof FrameRateMonitor.prototype
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* @type {Number}
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*/
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lastFramesPerSecond : {
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get : function() {
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return this._lastFramesPerSecond;
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}
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}
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});
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/**
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* Pauses monitoring of the frame rate. To resume monitoring, {@link FrameRateMonitor#unpause}
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* must be called once for each time this function is called.
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* @memberof FrameRateMonitor
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*/
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FrameRateMonitor.prototype.pause = function() {
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++this._pauseCount;
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if (this._pauseCount === 1) {
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this._frameTimes.length = 0;
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this._lastFramesPerSecond = undefined;
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}
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};
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/**
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* Resumes monitoring of the frame rate. If {@link FrameRateMonitor#pause} was called
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* multiple times, this function must be called the same number of times in order to
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* actually resume monitoring.
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* @memberof FrameRateMonitor
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*/
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FrameRateMonitor.prototype.unpause = function() {
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--this._pauseCount;
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if (this._pauseCount <= 0) {
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this._pauseCount = 0;
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this._needsQuietPeriod = true;
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}
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};
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/**
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* Returns true if this object was destroyed; otherwise, false.
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* <br /><br />
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* If this object was destroyed, it should not be used; calling any function other than
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* <code>isDestroyed</code> will result in a {@link DeveloperError} exception.
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*
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* @memberof FrameRateMonitor
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*
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* @returns {Boolean} True if this object was destroyed; otherwise, false.
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*
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* @see FrameRateMonitor#destroy
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*/
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FrameRateMonitor.prototype.isDestroyed = function() {
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return false;
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};
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/**
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* Unsubscribes this instance from all events it is listening to.
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* Once an object is destroyed, it should not be used; calling any function other than
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* <code>isDestroyed</code> will result in a {@link DeveloperError} exception. Therefore,
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* assign the return value (<code>undefined</code>) to the object as done in the example.
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*
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* @memberof FrameRateMonitor
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*
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* @exception {DeveloperError} This object was destroyed, i.e., destroy() was called.
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*
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* @see FrameRateMonitor#isDestroyed
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*/
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FrameRateMonitor.prototype.destroy = function() {
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this._preUpdateRemoveListener();
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if (defined(this._visibilityChangeRemoveListener)) {
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this._visibilityChangeRemoveListener();
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}
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return destroyObject(this);
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};
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function update(monitor, time) {
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if (monitor._pauseCount > 0) {
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return;
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}
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var timeStamp = getTimestamp();
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if (monitor._needsQuietPeriod) {
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monitor._needsQuietPeriod = false;
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monitor._frameTimes.length = 0;
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monitor._quietPeriodEndTime = timeStamp + (monitor.quietPeriod / TimeConstants.SECONDS_PER_MILLISECOND);
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monitor._warmupPeriodEndTime = monitor._quietPeriodEndTime + ((monitor.warmupPeriod + monitor.samplingWindow) / TimeConstants.SECONDS_PER_MILLISECOND);
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} else if (timeStamp >= monitor._quietPeriodEndTime) {
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monitor._frameTimes.push(timeStamp);
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var beginningOfWindow = timeStamp - (monitor.samplingWindow / TimeConstants.SECONDS_PER_MILLISECOND);
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if (monitor._frameTimes.length >= 2 && monitor._frameTimes[0] <= beginningOfWindow) {
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while (monitor._frameTimes.length >= 2 && monitor._frameTimes[1] < beginningOfWindow) {
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monitor._frameTimes.shift();
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}
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var averageTimeBetweenFrames = (timeStamp - monitor._frameTimes[0]) / (monitor._frameTimes.length - 1);
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monitor._lastFramesPerSecond = 1000.0 / averageTimeBetweenFrames;
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var maximumFrameTime = 1000.0 / (timeStamp > monitor._warmupPeriodEndTime ? monitor.minimumFrameRateAfterWarmup : monitor.minimumFrameRateDuringWarmup);
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if (averageTimeBetweenFrames > maximumFrameTime) {
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if (!monitor._frameRateIsLow) {
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monitor._frameRateIsLow = true;
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monitor._needsQuietPeriod = true;
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monitor.lowFrameRate.raiseEvent(monitor.scene, monitor._lastFramesPerSecond);
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}
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} else if (monitor._frameRateIsLow) {
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monitor._frameRateIsLow = false;
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monitor._needsQuietPeriod = true;
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monitor.nominalFrameRate.raiseEvent(monitor.scene, monitor._lastFramesPerSecond);
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}
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}
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}
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}
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function visibilityChanged(monitor) {
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if (document[monitor._hiddenPropertyName]) {
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monitor.pause();
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} else {
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monitor.unpause();
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}
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}
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export default FrameRateMonitor;
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