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// Copyright 2012 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 viewport size monitor that buffers RESIZE events until the
* window size has stopped changing, within a specified period of time. For
* every RESIZE event dispatched, this will dispatch up to two *additional*
* events:
* - {@link #EventType.RESIZE_WIDTH} if the viewport's width has changed since
* the last buffered dispatch.
* - {@link #EventType.RESIZE_HEIGHT} if the viewport's height has changed since
* the last buffered dispatch.
* You likely only need to listen to one of the three events. But if you need
* more, just be cautious of duplicating effort.
*
*/
goog.provide('goog.dom.BufferedViewportSizeMonitor');
goog.require('goog.async.Delay');
goog.require('goog.events');
goog.require('goog.events.EventTarget');
goog.require('goog.events.EventType');
goog.require('goog.math.Size');
/**
* Creates a new BufferedViewportSizeMonitor.
* @param {!goog.dom.ViewportSizeMonitor} viewportSizeMonitor The
* underlying viewport size monitor.
* @param {number=} opt_bufferMs The buffer time, in ms. If not specified, this
* value defaults to {@link #RESIZE_EVENT_DELAY_MS_}.
* @constructor
* @extends {goog.events.EventTarget}
*/
goog.dom.BufferedViewportSizeMonitor = function(
viewportSizeMonitor, opt_bufferMs) {
goog.base(this);
/**
* The underlying viewport size monitor.
* @type {goog.dom.ViewportSizeMonitor}
* @private
*/
this.viewportSizeMonitor_ = viewportSizeMonitor;
/**
* The current size of the viewport.
* @type {goog.math.Size}
* @private
*/
this.currentSize_ = this.viewportSizeMonitor_.getSize();
/**
* The previously recorded size of the viewport.
* @type {goog.math.Size}
* @private
*/
this.previousSize_ = this.currentSize_;
/**
* The resize buffer time in ms.
* @type {number}
* @private
*/
this.resizeBufferMs_ = opt_bufferMs ||
goog.dom.BufferedViewportSizeMonitor.RESIZE_EVENT_DELAY_MS_;
goog.events.listen(
this.viewportSizeMonitor_,
goog.events.EventType.RESIZE,
this.handleResize_,
false /* opt_capture */,
this);
};
goog.inherits(goog.dom.BufferedViewportSizeMonitor, goog.events.EventTarget);
/**
* Additional events to dispatch.
* @enum {string}
*/
goog.dom.BufferedViewportSizeMonitor.EventType = {
RESIZE_HEIGHT: goog.events.getUniqueId('rh'),
RESIZE_WIDTH: goog.events.getUniqueId('rw')
};
/**
* Delay for the resize event.
* @type {goog.async.Delay}
* @private
*/
goog.dom.BufferedViewportSizeMonitor.prototype.resizeDelay_;
/**
* Whether the monitoring has been paused.
* @type {boolean}
* @private
*/
goog.dom.BufferedViewportSizeMonitor.prototype.paused_;
/**
* Default number of milliseconds to wait after a resize event to relayout the
* page.
* @type {number}
* @const
* @private
*/
goog.dom.BufferedViewportSizeMonitor.RESIZE_EVENT_DELAY_MS_ = 100;
/** @override */
goog.dom.BufferedViewportSizeMonitor.prototype.disposeInternal =
function() {
goog.events.unlisten(
this.viewportSizeMonitor_,
goog.events.EventType.RESIZE,
this.handleResize_,
false /* opt_capture */,
this);
goog.base(this, 'disposeInternal');
};
/**
* Handles resize events on the underlying ViewportMonitor.
* @param {goog.events.Event} e The resize event.
* @private
*/
goog.dom.BufferedViewportSizeMonitor.prototype.handleResize_ =
function(e) {
if (!this.resizeDelay_) {
this.resizeDelay_ = new goog.async.Delay(
goog.bind(this.onWindowResize_, this, e), this.resizeBufferMs_);
this.registerDisposable(this.resizeDelay_);
}
this.resizeDelay_.start();
};
/**
* Window resize callback that determines whether to reflow the view contents.
* @param {goog.events.Event} e The resize event.
* @private
*/
goog.dom.BufferedViewportSizeMonitor.prototype.onWindowResize_ =
function(e) {
if (this.viewportSizeMonitor_.isDisposed()) {
return;
}
var viewportSize = this.viewportSizeMonitor_.getSize();
if (!this.paused_ &&
!goog.math.Size.equals(viewportSize, this.currentSize_)) {
if (!this.previousSize_ ||
viewportSize.width != this.previousSize_.width) {
this.dispatchEvent(
goog.dom.BufferedViewportSizeMonitor.EventType.RESIZE_WIDTH);
}
if (!this.previousSize_ ||
viewportSize.height != this.previousSize_.height) {
this.dispatchEvent(
goog.dom.BufferedViewportSizeMonitor.EventType.RESIZE_HEIGHT);
}
this.previousSize_ = this.currentSize_;
this.currentSize_ = viewportSize;
this.dispatchEvent(e);
}
};
/**
* Returns the current size of the viewport.
* @return {goog.math.Size?} The current viewport size.
*/
goog.dom.BufferedViewportSizeMonitor.prototype.getSize = function() {
return this.currentSize_ ? this.currentSize_.clone() : null;
};
/**
* Returns the previous size of the viewport.
* @return {goog.math.Size?} The previous size of the viewport on the last
* RESIZE event.
*/
goog.dom.BufferedViewportSizeMonitor.prototype.getPreviousSize = function() {
return this.previousSize_ ? this.previousSize_.clone() : null;
};
/**
* Pauses and unpauses viewport size monitoring.
* @param {boolean} paused True to pause.
*/
goog.dom.BufferedViewportSizeMonitor.prototype.setPaused = function(paused) {
this.paused_ = paused;
};
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