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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.asserts');
goog.require('goog.async.Delay');
goog.require('goog.events');
goog.require('goog.events.EventTarget');
goog.require('goog.events.EventType');
/**
* 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}
* @final
*/
goog.dom.BufferedViewportSizeMonitor = function(
viewportSizeMonitor, opt_bufferMs) {
goog.dom.BufferedViewportSizeMonitor.base(this, 'constructor');
/**
* Delay for the resize event.
* @private {goog.async.Delay}
*/
this.resizeDelay_;
/**
* 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 resize buffer time in ms.
* @type {number}
* @private
*/
this.resizeBufferMs_ = opt_bufferMs ||
goog.dom.BufferedViewportSizeMonitor.RESIZE_EVENT_DELAY_MS_;
/**
* Listener key for the viewport size monitor.
* @type {goog.events.Key}
* @private
*/
this.listenerKey_ = goog.events.listen(
viewportSizeMonitor, goog.events.EventType.RESIZE, this.handleResize_,
false, this);
};
goog.inherits(goog.dom.BufferedViewportSizeMonitor, goog.events.EventTarget);
/**
* Additional events to dispatch.
* @enum {string}
*/
goog.dom.BufferedViewportSizeMonitor.EventType = {
RESIZE_HEIGHT: goog.events.getUniqueId('resizeheight'),
RESIZE_WIDTH: goog.events.getUniqueId('resizewidth')
};
/**
* 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.unlistenByKey(this.listenerKey_);
goog.dom.BufferedViewportSizeMonitor.base(this, 'disposeInternal');
};
/**
* Handles resize events on the underlying ViewportMonitor.
* @private
*/
goog.dom.BufferedViewportSizeMonitor.prototype.handleResize_ = function() {
// Lazily create when needed.
if (!this.resizeDelay_) {
this.resizeDelay_ =
new goog.async.Delay(this.onWindowResize_, this.resizeBufferMs_, this);
this.registerDisposable(this.resizeDelay_);
}
this.resizeDelay_.start();
};
/**
* Window resize callback that determines whether to reflow the view contents.
* @private
*/
goog.dom.BufferedViewportSizeMonitor.prototype.onWindowResize_ = function() {
if (this.viewportSizeMonitor_.isDisposed()) {
return;
}
var previousSize = this.currentSize_;
var currentSize = this.viewportSizeMonitor_.getSize();
goog.asserts.assert(currentSize, 'Viewport size should be set at this point');
this.currentSize_ = currentSize;
if (previousSize) {
var resized = false;
// Width has changed
if (previousSize.width != currentSize.width) {
this.dispatchEvent(
goog.dom.BufferedViewportSizeMonitor.EventType.RESIZE_WIDTH);
resized = true;
}
// Height has changed
if (previousSize.height != currentSize.height) {
this.dispatchEvent(
goog.dom.BufferedViewportSizeMonitor.EventType.RESIZE_HEIGHT);
resized = true;
}
// If either has changed, this is a resize event.
if (resized) {
this.dispatchEvent(goog.events.EventType.RESIZE);
}
} else {
// If we didn't have a previous size, we consider all events to have
// changed.
this.dispatchEvent(
goog.dom.BufferedViewportSizeMonitor.EventType.RESIZE_HEIGHT);
this.dispatchEvent(
goog.dom.BufferedViewportSizeMonitor.EventType.RESIZE_WIDTH);
this.dispatchEvent(goog.events.EventType.RESIZE);
}
};
/**
* 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;
};
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