// Copyright 2006 The Closure Library Authors. All Rights Reserved. // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS-IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. /** * @fileoverview A timer class to which other classes and objects can * listen on. This is only an abstraction above setInterval. * * @see ../demos/timers.html */ goog.provide('goog.Timer'); goog.require('goog.events.EventTarget'); /** * Class for handling timing events. * * @param {number=} opt_interval Number of ms between ticks (Default: 1ms). * @param {Object=} opt_timerObject An object that has setTimeout, setInterval, * clearTimeout and clearInterval (eg Window). * @constructor * @extends {goog.events.EventTarget} */ goog.Timer = function(opt_interval, opt_timerObject) { goog.events.EventTarget.call(this); /** * Number of ms between ticks * @type {number} * @private */ this.interval_ = opt_interval || 1; /** * An object that implements setTimeout, setInterval, clearTimeout and * clearInterval. We default to the window object. Changing this on * goog.Timer.prototype changes the object for all timer instances which can * be useful if your environment has some other implementation of timers than * the window object. * @type {Object} * @private */ this.timerObject_ = opt_timerObject || goog.Timer.defaultTimerObject; /** * Cached tick_ bound to the object for later use in the timer. * @type {Function} * @private */ this.boundTick_ = goog.bind(this.tick_, this); /** * Firefox browser often fires the timer event sooner * (sometimes MUCH sooner) than the requested timeout. So we * compare the time to when the event was last fired, and * reschedule if appropriate. See also goog.Timer.intervalScale * @type {number} * @private */ this.last_ = goog.now(); }; goog.inherits(goog.Timer, goog.events.EventTarget); /** * Maximum timeout value. * * Timeout values too big to fit into a signed 32-bit integer may cause * overflow in FF, Safari, and Chrome, resulting in the timeout being * scheduled immediately. It makes more sense simply not to schedule these * timeouts, since 24.8 days is beyond a reasonable expectation for the * browser to stay open. * * @type {number} * @private */ goog.Timer.MAX_TIMEOUT_ = 2147483647; /** * Whether this timer is enabled * @type {boolean} */ goog.Timer.prototype.enabled = false; /** * An object that implements setTimout, setInterval, clearTimeout and * clearInterval. We default to the global object. Changing * goog.Timer.defaultTimerObject changes the object for all timer instances * which can be useful if your environment has some other implementation of * timers you'd like to use. * @type {Object} */ goog.Timer.defaultTimerObject = goog.global; /** * A variable that controls the timer error correction. If the * timer is called before the requested interval times * intervalScale, which often happens on mozilla, the timer is * rescheduled. See also this.last_ * @type {number} */ goog.Timer.intervalScale = 0.8; /** * Variable for storing the result of setInterval * @type {?number} * @private */ goog.Timer.prototype.timer_ = null; /** * Gets the interval of the timer. * @return {number} interval Number of ms between ticks. */ goog.Timer.prototype.getInterval = function() { return this.interval_; }; /** * Sets the interval of the timer. * @param {number} interval Number of ms between ticks. */ goog.Timer.prototype.setInterval = function(interval) { this.interval_ = interval; if (this.timer_ && this.enabled) { // Stop and then start the timer to reset the interval. this.stop(); this.start(); } else if (this.timer_) { this.stop(); } }; /** * Callback for the setTimeout used by the timer * @private */ goog.Timer.prototype.tick_ = function() { if (this.enabled) { var elapsed = goog.now() - this.last_; if (elapsed > 0 && elapsed < this.interval_ * goog.Timer.intervalScale) { this.timer_ = this.timerObject_.setTimeout(this.boundTick_, this.interval_ - elapsed); return; } // Prevents setInterval from registering a duplicate timeout when called // in the timer event handler. if (this.timer_) { this.timerObject_.clearTimeout(this.timer_); this.timer_ = null; } this.dispatchTick(); // The timer could be stopped in the timer event handler. if (this.enabled) { this.timer_ = this.timerObject_.setTimeout(this.boundTick_, this.interval_); this.last_ = goog.now(); } } }; /** * Dispatches the TICK event. This is its own method so subclasses can override. */ goog.Timer.prototype.dispatchTick = function() { this.dispatchEvent(goog.Timer.TICK); }; /** * Starts the timer. */ goog.Timer.prototype.start = function() { this.enabled = true; // If there is no interval already registered, start it now if (!this.timer_) { // IMPORTANT! // window.setInterval in FireFox has a bug - it fires based on // absolute time, rather than on relative time. What this means // is that if a computer is sleeping/hibernating for 24 hours // and the timer interval was configured to fire every 1000ms, // then after the PC wakes up the timer will fire, in rapid // succession, 3600*24 times. // This bug is described here and is already fixed, but it will // take time to propagate, so for now I am switching this over // to setTimeout logic. // https://bugzilla.mozilla.org/show_bug.cgi?id=376643 // this.timer_ = this.timerObject_.setTimeout(this.boundTick_, this.interval_); this.last_ = goog.now(); } }; /** * Stops the timer. */ goog.Timer.prototype.stop = function() { this.enabled = false; if (this.timer_) { this.timerObject_.clearTimeout(this.timer_); this.timer_ = null; } }; /** @override */ goog.Timer.prototype.disposeInternal = function() { goog.Timer.superClass_.disposeInternal.call(this); this.stop(); delete this.timerObject_; }; /** * Constant for the timer's event type * @type {string} */ goog.Timer.TICK = 'tick'; /** * Calls the given function once, after the optional pause. * * The function is always called asynchronously, even if the delay is 0. This * is a common trick to schedule a function to run after a batch of browser * event processing. * * @param {function(this:SCOPE)|{handleEvent:function()}|null} listener Function * or object that has a handleEvent method. * @param {number=} opt_delay Milliseconds to wait; default is 0. * @param {SCOPE=} opt_handler Object in whose scope to call the listener. * @return {number} A handle to the timer ID. * @template SCOPE */ goog.Timer.callOnce = function(listener, opt_delay, opt_handler) { if (goog.isFunction(listener)) { if (opt_handler) { listener = goog.bind(listener, opt_handler); } } else if (listener && typeof listener.handleEvent == 'function') { // using typeof to prevent strict js warning listener = goog.bind(listener.handleEvent, listener); } else { throw Error('Invalid listener argument'); } if (opt_delay > goog.Timer.MAX_TIMEOUT_) { // Timeouts greater than MAX_INT return immediately due to integer // overflow in many browsers. Since MAX_INT is 24.8 days, just don't // schedule anything at all. return -1; } else { return goog.Timer.defaultTimerObject.setTimeout( listener, opt_delay || 0); } }; /** * Clears a timeout initiated by callOnce * @param {?number} timerId a timer ID. */ goog.Timer.clear = function(timerId) { goog.Timer.defaultTimerObject.clearTimeout(timerId); };