1 <!DOCTYPE html> 2 <!-- 3 Copyright (c) 2015 The Chromium Authors. All rights reserved. 4 Use of this source code is governed by a BSD-style license that can be 5 found in the LICENSE file. 6 --> 7 8 <link rel="import" href="/tracing/base/statistics.html"> 9 <link rel="import" href="/tracing/metrics/system_health/utils.html"> 10 <link rel="import" href="/tracing/model/user_model/animation_expectation.html"> 11 12 <script> 13 'use strict'; 14 15 tr.exportTo('tr.metrics.sh', function() { 16 // The smoothness score is maximized when frame timestamp discrepancy is 17 // less than or equal to this: 18 var MIN_DISCREPANCY = 0.05; 19 20 // The smoothness score is minimized when frame timestamp discrepancy is 21 // greater than or equal to this: 22 var MAX_DISCREPANCY = 0.3; 23 24 var UNIT = tr.v.Unit.byName.normalizedPercentage_biggerIsBetter; 25 26 var DESCRIPTION = 'Mean Opinion Score for Animation smoothness'; 27 28 function AnimationSmoothnessMetric(valueList, model) { 29 model.userModel.expectations.forEach(function(ue) { 30 if (!(ue instanceof tr.model.um.AnimationExpectation)) 31 return; 32 33 if (ue.frameEvents === undefined || 34 ue.frameEvents.length === 0) 35 throw new Error('Animation missing frameEvents ' + ue.stableId); 36 37 var options = {}; 38 options.description = DESCRIPTION; 39 40 var groupingKeys = {}; 41 groupingKeys.userExpectationStableId = ue.stableId; 42 groupingKeys.userExpectationStageTitle = ue.stageTitle; 43 groupingKeys.userExpectationInitiatorTitle = ue.initiatorTitle; 44 45 var frameTimestamps = ue.frameEvents.toArray().map(function(event) { 46 return event.start; 47 }); 48 49 var absolute = false; 50 var discrepancy = tr.b.Statistics.timestampsDiscrepancy( 51 frameTimestamps, absolute); 52 var smoothness = 1 - tr.b.normalize( 53 discrepancy, MIN_DISCREPANCY, MAX_DISCREPANCY); 54 var score = tr.b.clamp(smoothness, 0, 1); 55 56 valueList.addValue(new tr.v.NumericValue( 57 model.canonicalUrlThatCreatedThisTrace, 'smoothness', 58 new tr.v.ScalarNumeric(UNIT, score), 59 options, groupingKeys)); 60 }); 61 } 62 63 AnimationSmoothnessMetric.prototype = { 64 __proto__: Function.prototype 65 }; 66 67 tr.metrics.MetricRegistry.register(AnimationSmoothnessMetric); 68 69 return { 70 AnimationSmoothnessMetric: AnimationSmoothnessMetric 71 }; 72 }); 73 </script> 74
