// Copyright 2015 The Chromium Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. import 'package:flutter/rendering.dart'; import 'framework.dart'; /// Displays performance statistics. /// /// The overlay show two time series. The first shows how much time was required /// on this thread to produce each frame. The second shows how much time was /// required on the GPU thread to produce each frame. Ideally, both these values /// would be less than the total frame budget for the hardware on which the app /// is running. For example, if the hardware has a screen that updates at 60 Hz, /// each thread should ideally spend less than 16ms producing each frame. This /// ideal condition is indicated by a green vertical line for each thread. /// Otherwise, the performance overlay shows a red vertical line. /// /// The simplest way to show the performance overlay is to set /// [MaterialApp.showPerformanceOverlay] or [WidgetsApp.showPerformanceOverlay] /// to `true`. class PerformanceOverlay extends LeafRenderObjectWidget { // TODO(abarth): We should have a page on the web site with a screenshot and // an explanation of all the various readouts. /// Create a performance overlay that only displays specific statistics. The /// mask is created by shifting 1 by the index of the specific /// [StatisticOption] to enable. PerformanceOverlay({ Key key, this.optionsMask, this.rasterizerThreshold: 0 }) : super(key: key); /// Create a performance overlay that displays all available statistics PerformanceOverlay.allEnabled({ Key key, this.rasterizerThreshold: 0 }) : optionsMask = ( 1 << PerformanceOverlayOption.displayRasterizerStatistics.index | 1 << PerformanceOverlayOption.visualizeRasterizerStatistics.index | 1 << PerformanceOverlayOption.displayEngineStatistics.index | 1 << PerformanceOverlayOption.visualizeEngineStatistics.index ), super(key: key); /// The mask is created by shifting 1 by the index of the specific /// [PerformanceOverlayOption] to enable. final int optionsMask; /// The rasterizer threshold is an integer specifying the number of frame /// intervals that the rasterizer must miss before it decides that the frame /// is suitable for capturing an SkPicture trace for further analysis. /// /// For example, if you want a trace of all pictures that could not be /// renderered by the rasterizer within the frame boundary (and hence caused /// jank), specify 1. Specifying 2 will trace all pictures that took more /// more than 2 frame intervals to render. Adjust this value to only capture /// the particularly expensive pictures while skipping the others. Specifying /// 0 disables all capture. /// /// Captured traces are placed on your device in the application documents /// directory in this form "trace_<collection_time>.skp". These can /// be viewed in the Skia debugger. /// /// Notes: /// The rasterizer only takes into account the time it took to render /// the already constructed picture. This include the Skia calls (which is /// also why an SkPicture trace is generated) but not any of the time spent in /// dart to construct that picture. To profile that part of your code, use /// the instrumentation available in observatory. /// /// To decide what threshold interval to use, count the number of horizontal /// lines displayed in the performance overlay for the rasterizer (not the /// engine). That should give an idea of how often frames are skipped (and by /// how many frame intervals). final int rasterizerThreshold; @override RenderPerformanceOverlay createRenderObject(BuildContext context) => new RenderPerformanceOverlay( optionsMask: optionsMask, rasterizerThreshold: rasterizerThreshold ); @override void updateRenderObject(BuildContext context, RenderPerformanceOverlay renderObject) { renderObject ..optionsMask = optionsMask ..rasterizerThreshold = rasterizerThreshold; } }