mirror of https://github.com/perkeep/perkeep.git
129 lines
3.0 KiB
JavaScript
129 lines
3.0 KiB
JavaScript
/*
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Copyright 2013 The Camlistore Authors
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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goog.provide('camlistore.AnimationLoop');
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goog.require('goog.events.EventTarget');
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/**
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* Provides an easier-to-use interface around
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* window.requestAnimationFrame(), and abstracts away browser differences.
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* @param {Window} win
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*/
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camlistore.AnimationLoop = function(win) {
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/**
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* @type {Window}
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* @private
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*/
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this.win_ = win;
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/**
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* @type {Function}
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* @private
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*/
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this.requestAnimationFrame_ = win.requestAnimationFrame ||
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win.mozRequestAnimationFrame || win.webkitRequestAnimationFrame ||
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win.msRequestAnimationFrame;
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/**
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* @type {Function}
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* @private
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*/
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this.handleFrame_ = this.handleFrame_.bind(this);
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/**
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* @type {number}
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* @private
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*/
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this.lastTimestamp_ = 0;
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if (this.requestAnimationFrame_) {
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this.requestAnimationFrame_ = this.requestAnimationFrame_.bind(win);
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} else {
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this.requestAnimationFrame_ = this.simulateAnimationFrame_.bind(this);
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}
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};
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goog.inherits(camlistore.AnimationLoop, goog.events.EventTarget);
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/**
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* @type {string}
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*/
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camlistore.AnimationLoop.FRAME_EVENT_TYPE = 'frame';
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/**
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* @returns {boolean}
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*/
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camlistore.AnimationLoop.prototype.isRunning = function() {
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return Boolean(this.lastTimestamp_);
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};
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camlistore.AnimationLoop.prototype.start = function() {
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if (this.isRunning()) {
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return;
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}
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this.lastTimestamp_ = -1;
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this.schedule_();
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};
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camlistore.AnimationLoop.prototype.stop = function() {
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this.lastTimestamp_ = 0;
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};
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/**
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* @private
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*/
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camlistore.AnimationLoop.prototype.schedule_ = function() {
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this.requestAnimationFrame_(this.handleFrame_);
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};
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/**
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* @param {number=} opt_timestamp A timestamp in milliseconds that is used to
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* measure progress through the animation.
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* @private
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*/
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camlistore.AnimationLoop.prototype.handleFrame_ = function(opt_timestamp) {
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if (this.lastTimestamp_ == 0) {
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return;
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}
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var timestamp = opt_timestamp || new Date().getTime();
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if (this.lastTimestamp_ == -1) {
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this.lastTimestamp_ = timestamp;
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} else {
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this.dispatchEvent({
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type: this.constructor.FRAME_EVENT_TYPE,
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delay: timestamp - this.lastTimestamp_
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});
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this.lastTimestamp_ = timestamp;
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}
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this.schedule_();
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};
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/**
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* Simulates requestAnimationFrame as best as possible for browsers that don't
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* have it.
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* @param {Function} fn
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* @private
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*/
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camlistore.AnimationLoop.prototype.simulateAnimationFrame_ = function(fn) {
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this.win_.setTimeout(function() {
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fn(new Date().getTime());
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}, 0);
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};
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