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// Copyright 2007 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 Defines a class useful for handling functions that must be
* invoked after a delay, especially when that delay is frequently restarted.
* Examples include delaying before displaying a tooltip, menu hysteresis,
* idle timers, etc.
* @author brenneman@google.com (Shawn Brenneman)
* @see ../demos/timers.html
*/
goog.provide('goog.Delay');
goog.provide('goog.async.Delay');
goog.require('goog.Disposable');
goog.require('goog.Timer');
/**
* A Delay object invokes the associated function after a specified delay. The
* interval duration can be specified once in the constructor, or can be defined
* each time the delay is started. Calling start on an active delay will reset
* the timer.
*
* @param {Function} listener Function to call when the delay completes.
* @param {number=} opt_interval The default length of the invocation delay (in
* milliseconds).
* @param {Object=} opt_handler The object scope to invoke the function in.
* @constructor
* @extends {goog.Disposable}
*/
goog.async.Delay = function(listener, opt_interval, opt_handler) {
goog.Disposable.call(this);
/**
* The function that will be invoked after a delay.
* @type {Function}
* @private
*/
this.listener_ = listener;
/**
* The default amount of time to delay before invoking the callback.
* @type {number}
* @private
*/
this.interval_ = opt_interval || 0;
/**
* The object context to invoke the callback in.
* @type {Object|undefined}
* @private
*/
this.handler_ = opt_handler;
/**
* Cached callback function invoked when the delay finishes.
* @type {Function}
* @private
*/
this.callback_ = goog.bind(this.doAction_, this);
};
goog.inherits(goog.async.Delay, goog.Disposable);
/**
* A deprecated alias.
* @deprecated Use goog.async.Delay instead.
* @constructor
*/
goog.Delay = goog.async.Delay;
/**
* Identifier of the active delay timeout, or 0 when inactive.
* @type {number}
* @private
*/
goog.async.Delay.prototype.id_ = 0;
/**
* Disposes of the object, cancelling the timeout if it is still outstanding and
* removing all object references.
* @override
* @protected
*/
goog.async.Delay.prototype.disposeInternal = function() {
goog.async.Delay.superClass_.disposeInternal.call(this);
this.stop();
delete this.listener_;
delete this.handler_;
};
/**
* Starts the delay timer. The provided listener function will be called after
* the specified interval. Calling start on an active timer will reset the
* delay interval.
* @param {number=} opt_interval If specified, overrides the object's default
* interval with this one (in milliseconds).
*/
goog.async.Delay.prototype.start = function(opt_interval) {
this.stop();
this.id_ = goog.Timer.callOnce(
this.callback_,
goog.isDef(opt_interval) ? opt_interval : this.interval_);
};
/**
* Stops the delay timer if it is active. No action is taken if the timer is not
* in use.
*/
goog.async.Delay.prototype.stop = function() {
if (this.isActive()) {
goog.Timer.clear(this.id_);
}
this.id_ = 0;
};
/**
* Fires delay's action even if timer has already gone off or has not been
* started yet; guarantees action firing. Stops the delay timer.
*/
goog.async.Delay.prototype.fire = function() {
this.stop();
this.doAction_();
};
/**
* Fires delay's action only if timer is currently active. Stops the delay
* timer.
*/
goog.async.Delay.prototype.fireIfActive = function() {
if (this.isActive()) {
this.fire();
}
};
/**
* @return {boolean} True if the delay is currently active, false otherwise.
*/
goog.async.Delay.prototype.isActive = function() {
return this.id_ != 0;
};
/**
* Invokes the callback function after the delay successfully completes.
* @private
*/
goog.async.Delay.prototype.doAction_ = function() {
this.id_ = 0;
if (this.listener_) {
this.listener_.call(this.handler_);
}
};
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