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// Copyright 2011 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 Displays frames per second (FPS) for the current window.
* Only supported in browsers that support requestAnimationFrame.
* See: https://developer.mozilla.org/en/DOM/window.requestAnimationFrame.
*
* @see ../demos/fpsdisplay.html
*/
goog.provide('goog.debug.FpsDisplay');
goog.require('goog.asserts');
goog.require('goog.async.AnimationDelay');
goog.require('goog.dom');
goog.require('goog.dom.TagName');
goog.require('goog.ui.Component');
/**
* Displays frames per seconds that the window this component is
* rendered in is animating at.
*
* @param {goog.dom.DomHelper=} opt_domHelper An optional dom helper.
* @constructor
* @extends {goog.ui.Component}
* @final
*/
goog.debug.FpsDisplay = function(opt_domHelper) {
goog.debug.FpsDisplay.base(this, 'constructor', opt_domHelper);
};
goog.inherits(goog.debug.FpsDisplay, goog.ui.Component);
/**
* CSS class for the FPS display.
*/
goog.debug.FpsDisplay.CSS = goog.getCssName('goog-fps-display');
/**
* The number of samples per FPS report.
*/
goog.debug.FpsDisplay.SAMPLES = 10;
/**
* The current animation.
* @type {goog.debug.FpsDisplay.FpsAnimation_}
* @private
*/
goog.debug.FpsDisplay.prototype.animation_ = null;
/** @override */
goog.debug.FpsDisplay.prototype.createDom = function() {
this.setElementInternal(
this.getDomHelper().createDom(
goog.dom.TagName.DIV, goog.debug.FpsDisplay.CSS));
};
/** @override */
goog.debug.FpsDisplay.prototype.enterDocument = function() {
goog.debug.FpsDisplay.base(this, 'enterDocument');
this.animation_ = new goog.debug.FpsDisplay.FpsAnimation_(this.getElement());
this.delay_ = new goog.async.AnimationDelay(
this.handleDelay_, this.getDomHelper().getWindow(), this);
this.delay_.start();
};
/**
* @param {number} now The current time.
* @private
*/
goog.debug.FpsDisplay.prototype.handleDelay_ = function(now) {
if (this.isInDocument()) {
this.animation_.onAnimationFrame(now);
this.delay_.start();
}
};
/** @override */
goog.debug.FpsDisplay.prototype.exitDocument = function() {
goog.debug.FpsDisplay.base(this, 'exitDocument');
this.animation_ = null;
goog.dispose(this.delay_);
};
/**
* @return {number} The average frames per second.
*/
goog.debug.FpsDisplay.prototype.getFps = function() {
goog.asserts.assert(
this.isInDocument(), 'Render the FPS display before querying FPS');
return this.animation_.lastFps_;
};
/**
* @param {Element} elem An element to hold the FPS count.
* @constructor
* @private
*/
goog.debug.FpsDisplay.FpsAnimation_ = function(elem) {
/**
* An element to hold the current FPS rate.
* @type {Element}
* @private
*/
this.element_ = elem;
/**
* The number of frames observed so far.
* @type {number}
* @private
*/
this.frameNumber_ = 0;
};
/**
* The last time which we reported FPS at.
* @type {number}
* @private
*/
goog.debug.FpsDisplay.FpsAnimation_.prototype.lastTime_ = 0;
/**
* The last average FPS.
* @type {number}
* @private
*/
goog.debug.FpsDisplay.FpsAnimation_.prototype.lastFps_ = -1;
/**
* @param {number} now The current time.
*/
goog.debug.FpsDisplay.FpsAnimation_.prototype.onAnimationFrame = function(now) {
var SAMPLES = goog.debug.FpsDisplay.SAMPLES;
if (this.frameNumber_ % SAMPLES == 0) {
this.lastFps_ = Math.round((1000 * SAMPLES) / (now - this.lastTime_));
goog.dom.setTextContent(this.element_, this.lastFps_);
this.lastTime_ = now;
}
this.frameNumber_++;
};
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