chrome-devtools-frontend/front_end/panels/timeline/TimelineFlameChartView.ts

Chrome DevTools UI

// Copyright 2016 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 * as Common from '../../core/common/common.js';
import * as i18n from '../../core/i18n/i18n.js';
import * as Platform from '../../core/platform/platform.js';
import * as Root from '../../core/root/root.js';
import * as SDK from '../../core/sdk/sdk.js';
import * as Bindings from '../../models/bindings/bindings.js';
import * as TimelineModel from '../../models/timeline_model/timeline_model.js';
import * as PerfUI from '../../ui/legacy/components/perf_ui/perf_ui.js';
import * as UI from '../../ui/legacy/legacy.js';

import {CountersGraph} from './CountersGraph.js';
import type {PerformanceModel, WindowChangedEvent} from './PerformanceModel.js';
import {Events as PerformanceModelEvents} from './PerformanceModel.js';
import {TimelineDetailsView} from './TimelineDetailsView.js';
import {TimelineRegExp} from './TimelineFilters.js';
import {
  Events as TimelineFlameChartDataProviderEvents,
  TimelineFlameChartDataProvider,
} from './TimelineFlameChartDataProvider.js';
import {TimelineFlameChartNetworkDataProvider} from './TimelineFlameChartNetworkDataProvider.js';
import type {TimelineModeViewDelegate} from './TimelinePanel.js';
import {TimelineSelection} from './TimelinePanel.js';
import {AggregatedTimelineTreeView} from './TimelineTreeView.js';
import type {TimelineMarkerStyle} from './TimelineUIUtils.js';
import {TimelineUIUtils} from './TimelineUIUtils.js';
import {WebVitalsIntegrator} from './WebVitalsTimelineUtils.js';

const UIStrings = {
  /**
  *@description Text in Timeline Flame Chart View of the Performance panel
  *@example {Frame} PH1
  *@example {10ms} PH2
  */
  sAtS: '{PH1} at {PH2}',
};
const str_ = i18n.i18n.registerUIStrings('panels/timeline/TimelineFlameChartView.ts', UIStrings);
const i18nString = i18n.i18n.getLocalizedString.bind(undefined, str_);
class MainSplitWidget extends UI.SplitWidget.SplitWidget {
  private webVitals!: WebVitalsIntegrator;
  private model!: PerformanceModel|null;
  constructor(
      isVertical: boolean, secondIsSidebar: boolean, settingName?: string, defaultSidebarWidth?: number,
      defaultSidebarHeight?: number, constraintsInDip?: boolean) {
    super(isVertical, secondIsSidebar, settingName, defaultSidebarWidth, defaultSidebarHeight, constraintsInDip);
  }

  setWebVitals(webVitals: WebVitalsIntegrator): void {
    this.webVitals = webVitals;
    this.webVitals.setMinimumSize(0, 120);
  }

  setWindowTimes(left: number, right: number, animate: boolean): void {
    if (!this.webVitals) {
      return;
    }

    const startTime = left - (this.model ? this.model.timelineModel().minimumRecordTime() : 0);
    this.webVitals.chartViewport.setWindowTimes(left, right, animate);
    this.webVitals.webVitalsTimeline.data = {
      startTime: startTime,
      duration: right - left,
      fcps: undefined,
      lcps: undefined,
      layoutShifts: undefined,
      longTasks: undefined,
      mainFrameNavigations: undefined,
      maxDuration: undefined,
    };
  }

  setModelAndUpdateBoundaries(model: PerformanceModel|null): void {
    this.model = model;
    if (!this.webVitals || !model) {
      return;
    }

    const left = model.window().left;
    const right = model.window().right;
    const timelineModel = model.timelineModel();

    const events: SDK.TracingModel.Event[] =
        timelineModel.tracks().reduce((prev, curr) => prev.concat(curr.events), ([] as SDK.TracingModel.Event[]));
    const minimumBoundary = model.timelineModel().minimumRecordTime();

    const prepareEvents = (filterFunction: (arg0: SDK.TracingModel.Event) => boolean): number[] =>
        events.filter(filterFunction).map(e => e.startTime - minimumBoundary);

    const lcpEvents = events.filter(e => timelineModel.isLCPCandidateEvent(e) || timelineModel.isLCPInvalidateEvent(e));
    const lcpEventsByNavigationId = new Map<string, SDK.TracingModel.Event>();
    for (const e of lcpEvents) {
      const navigationId = e.args['data']['navigationId'];
      const previousLastEvent = lcpEventsByNavigationId.get(navigationId);
      if (!previousLastEvent || previousLastEvent.args['data']['candidateIndex'] < e.args['data']['candidateIndex']) {
        lcpEventsByNavigationId.set(navigationId, e);
      }
    }

    const latestLcpCandidatesByNavigationId = Array.from(lcpEventsByNavigationId.values());
    const latestLcpEvents = latestLcpCandidatesByNavigationId.filter(e => timelineModel.isLCPCandidateEvent(e));

    const longTasks =
        events.filter(e => SDK.TracingModel.TracingModel.isCompletePhase(e.phase) && timelineModel.isLongRunningTask(e))
            .map(e => ({start: e.startTime - minimumBoundary, duration: e.duration || 0}));

    this.webVitals.chartViewport.setBoundaries(left, right - left);

    this.webVitals.chartViewport.setWindowTimes(left, right);

    const startTime = left - (this.model ? this.model.timelineModel().minimumRecordTime() : 0);
    this.webVitals.webVitalsTimeline.data = {
      startTime: startTime,
      duration: right - left,
      maxDuration: timelineModel.maximumRecordTime(),
      fcps: events.filter(e => timelineModel.isFCPEvent(e)).map(e => ({timestamp: e.startTime - minimumBoundary, e})),
      lcps: latestLcpEvents.map(e => e.startTime).map(t => ({timestamp: t - minimumBoundary})),
      layoutShifts: prepareEvents(e => timelineModel.isLayoutShiftEvent(e)).map(t => ({timestamp: t})),
      longTasks,
      mainFrameNavigations: prepareEvents(e => timelineModel.isMainFrameNavigationStartEvent(e)),
    };
  }
}

export class TimelineFlameChartView extends UI.Widget.VBox implements PerfUI.FlameChart.FlameChartDelegate,
                                                                      UI.SearchableView.Searchable {
  private readonly delegate: TimelineModeViewDelegate;
  private model: PerformanceModel|null;
  private searchResults!: number[]|undefined;
  private eventListeners: Common.EventTarget.EventDescriptor[];
  // TODO(crbug.com/1172300) Ignored during the jsdoc to ts migration
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  private readonly showMemoryGraphSetting: Common.Settings.Setting<any>;
  // TODO(crbug.com/1172300) Ignored during the jsdoc to ts migration
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  private readonly showWebVitalsSetting: Common.Settings.Setting<any>;
  private readonly networkSplitWidget: UI.SplitWidget.SplitWidget;
  private mainDataProvider: TimelineFlameChartDataProvider;
  private readonly mainFlameChart: PerfUI.FlameChart.FlameChart;
  // TODO(crbug.com/1172300) Ignored during the jsdoc to ts migration
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  private readonly networkFlameChartGroupExpansionSetting: Common.Settings.Setting<any>;
  private networkDataProvider: TimelineFlameChartNetworkDataProvider;
  private readonly networkFlameChart: PerfUI.FlameChart.FlameChart;
  private readonly networkPane: UI.Widget.VBox;
  private readonly splitResizer: HTMLElement;
  private readonly webVitals: WebVitalsIntegrator;
  private readonly mainSplitWidget: MainSplitWidget;
  private readonly chartSplitWidget: UI.SplitWidget.SplitWidget;
  private readonly countersView: CountersGraph;
  private readonly detailsSplitWidget: UI.SplitWidget.SplitWidget;
  private readonly detailsView: TimelineDetailsView;
  private readonly onMainEntrySelected: (event: Common.EventTarget.EventTargetEvent<number>) => void;
  private readonly onNetworkEntrySelected: (event: Common.EventTarget.EventTargetEvent<number>) => void;
  private nextExtensionIndex: number;
  private readonly boundRefresh: () => void;
  private selectedTrack: TimelineModel.TimelineModel.Track|null;
  // TODO(crbug.com/1172300) Ignored during the jsdoc to ts migration
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  private readonly groupBySetting: Common.Settings.Setting<any>;
  private searchableView!: UI.SearchableView.SearchableView;
  private urlToColorCache?: Map<Platform.DevToolsPath.UrlString, string>;
  private needsResizeToPreferredHeights?: boolean;
  private selectedSearchResult?: number;
  private searchRegex?: RegExp;
  constructor(delegate: TimelineModeViewDelegate) {
    super();
    this.element.classList.add('timeline-flamechart');
    this.delegate = delegate;
    this.model = null;
    this.eventListeners = [];

    this.showMemoryGraphSetting = Common.Settings.Settings.instance().createSetting('timelineShowMemory', false);
    this.showWebVitalsSetting = Common.Settings.Settings.instance().createSetting('timelineWebVitals', false);

    // Create main and network flamecharts.
    this.networkSplitWidget = new UI.SplitWidget.SplitWidget(false, false, 'timelineFlamechartMainView', 150);

    // Ensure that the network panel & resizer appears above the web vitals / main thread.
    this.networkSplitWidget.sidebarElement().style.zIndex = '120';

    const mainViewGroupExpansionSetting =
        Common.Settings.Settings.instance().createSetting('timelineFlamechartMainViewGroupExpansion', {});
    this.mainDataProvider = new TimelineFlameChartDataProvider();
    this.mainDataProvider.addEventListener(
        TimelineFlameChartDataProviderEvents.DataChanged, () => this.mainFlameChart.scheduleUpdate());
    this.mainFlameChart = new PerfUI.FlameChart.FlameChart(this.mainDataProvider, this, mainViewGroupExpansionSetting);
    this.mainFlameChart.alwaysShowVerticalScroll();
    this.mainFlameChart.enableRuler(false);

    this.networkFlameChartGroupExpansionSetting =
        Common.Settings.Settings.instance().createSetting('timelineFlamechartNetworkViewGroupExpansion', {});
    this.networkDataProvider = new TimelineFlameChartNetworkDataProvider();
    this.networkFlameChart =
        new PerfUI.FlameChart.FlameChart(this.networkDataProvider, this, this.networkFlameChartGroupExpansionSetting);
    this.networkFlameChart.alwaysShowVerticalScroll();
    this.networkFlameChart.disableRangeSelection();

    this.networkPane = new UI.Widget.VBox();
    this.networkPane.setMinimumSize(23, 23);
    this.networkFlameChart.show(this.networkPane.element);
    this.splitResizer = this.networkPane.element.createChild('div', 'timeline-flamechart-resizer');
    this.networkSplitWidget.hideDefaultResizer(true);
    this.networkSplitWidget.installResizer(this.splitResizer);

    this.webVitals = new WebVitalsIntegrator(this);

    this.mainSplitWidget = new MainSplitWidget(false, false, 'timelineFlamechartMainAndVitalsView', undefined, 120);
    this.mainSplitWidget.setWebVitals(this.webVitals);
    this.mainSplitWidget.setMainWidget(this.mainFlameChart);
    this.mainSplitWidget.setSidebarWidget(this.webVitals);
    this.toggleWebVitalsLane();

    this.networkSplitWidget.setMainWidget(this.mainSplitWidget);
    this.networkSplitWidget.setSidebarWidget(this.networkPane);

    // Create counters chart splitter.
    this.chartSplitWidget = new UI.SplitWidget.SplitWidget(false, true, 'timelineCountersSplitViewState');
    this.countersView = new CountersGraph(this.delegate);
    this.chartSplitWidget.setMainWidget(this.networkSplitWidget);
    this.chartSplitWidget.setSidebarWidget(this.countersView);
    this.chartSplitWidget.hideDefaultResizer();
    this.chartSplitWidget.installResizer((this.countersView.resizerElement() as Element));
    this.updateCountersGraphToggle();

    // Create top level properties splitter.
    this.detailsSplitWidget = new UI.SplitWidget.SplitWidget(false, true, 'timelinePanelDetailsSplitViewState');
    this.detailsSplitWidget.element.classList.add('timeline-details-split');
    this.detailsView = new TimelineDetailsView(delegate);
    this.detailsSplitWidget.installResizer(this.detailsView.headerElement());
    this.detailsSplitWidget.setMainWidget(this.chartSplitWidget);
    this.detailsSplitWidget.setSidebarWidget(this.detailsView);
    this.detailsSplitWidget.show(this.element);

    this.onMainEntrySelected = this.onEntrySelected.bind(this, this.mainDataProvider);
    this.onNetworkEntrySelected = this.onEntrySelected.bind(this, this.networkDataProvider);
    this.mainFlameChart.addEventListener(PerfUI.FlameChart.Events.EntrySelected, this.onMainEntrySelected, this);
    this.mainFlameChart.addEventListener(PerfUI.FlameChart.Events.EntryInvoked, this.onMainEntrySelected, this);
    this.networkFlameChart.addEventListener(PerfUI.FlameChart.Events.EntrySelected, this.onNetworkEntrySelected, this);
    this.networkFlameChart.addEventListener(PerfUI.FlameChart.Events.EntryInvoked, this.onNetworkEntrySelected, this);
    this.mainFlameChart.addEventListener(PerfUI.FlameChart.Events.EntryHighlighted, this.onEntryHighlighted, this);
    this.nextExtensionIndex = 0;

    this.boundRefresh = this.refresh.bind(this);
    this.selectedTrack = null;

    this.mainDataProvider.setEventColorMapping(TimelineUIUtils.eventColor);
    this.groupBySetting = Common.Settings.Settings.instance().createSetting(
        'timelineTreeGroupBy', AggregatedTimelineTreeView.GroupBy.None);
    this.groupBySetting.addChangeListener(this.updateColorMapper, this);
    this.updateColorMapper();
  }

  toggleWebVitalsLane(): void {
    if (this.showWebVitalsSetting.get()) {
      this.mainSplitWidget.showBoth();
      this.mainSplitWidget.setSidebarSize(120);
      this.mainSplitWidget.setResizable(false);
      this.mainSplitWidget.hideDefaultResizer(true);
    } else {
      this.mainSplitWidget.hideSidebar();
    }
  }

  private updateColorMapper(): void {
    this.urlToColorCache = new Map();
    if (!this.model) {
      return;
    }
    this.mainDataProvider.setEventColorMapping(TimelineUIUtils.eventColor);
    this.mainFlameChart.update();
  }

  private onWindowChanged(event: Common.EventTarget.EventTargetEvent<WindowChangedEvent>): void {
    const {window, animate} = event.data;
    this.mainFlameChart.setWindowTimes(window.left, window.right, animate);
    this.networkFlameChart.setWindowTimes(window.left, window.right, animate);
    this.networkDataProvider.setWindowTimes(window.left, window.right);
    this.mainSplitWidget.setWindowTimes(window.left, window.right, Boolean(animate));
    this.updateSearchResults(false, false);
  }

  windowChanged(windowStartTime: number, windowEndTime: number, animate: boolean): void {
    if (this.model) {
      this.model.setWindow({left: windowStartTime, right: windowEndTime}, animate);
    }
  }

  updateRangeSelection(startTime: number, endTime: number): void {
    this.delegate.select(TimelineSelection.fromRange(startTime, endTime));
  }

  updateSelectedGroup(flameChart: PerfUI.FlameChart.FlameChart, group: PerfUI.FlameChart.Group|null): void {
    if (flameChart !== this.mainFlameChart) {
      return;
    }
    const track = group ? this.mainDataProvider.groupTrack(group) : null;
    this.selectedTrack = track;
    this.updateTrack();
  }

  setModel(model: PerformanceModel|null): void {
    if (model === this.model) {
      return;
    }
    Common.EventTarget.removeEventListeners(this.eventListeners);
    this.model = model;
    this.selectedTrack = null;
    this.mainDataProvider.setModel(this.model);
    this.networkDataProvider.setModel(this.model);
    if (this.model) {
      this.eventListeners = [
        this.model.addEventListener(PerformanceModelEvents.WindowChanged, this.onWindowChanged, this),
        this.model.addEventListener(PerformanceModelEvents.ExtensionDataAdded, this.appendExtensionData, this),
      ];
      const window = this.model.window();
      this.mainFlameChart.setWindowTimes(window.left, window.right);
      this.networkFlameChart.setWindowTimes(window.left, window.right);
      this.networkDataProvider.setWindowTimes(window.left, window.right);
      this.mainSplitWidget.setModelAndUpdateBoundaries(model);
      this.updateSearchResults(false, false);
    }
    this.updateColorMapper();
    this.updateTrack();
    this.nextExtensionIndex = 0;
    this.appendExtensionData();
    this.refresh();
  }

  private updateTrack(): void {
    this.countersView.setModel(this.model, this.selectedTrack);
    this.detailsView.setModel(this.model, this.selectedTrack);
  }

  private refresh(): void {
    if (this.networkDataProvider.isEmpty()) {
      this.mainFlameChart.enableRuler(true);
      this.networkSplitWidget.hideSidebar();
    } else {
      this.mainFlameChart.enableRuler(false);
      this.networkSplitWidget.showBoth();
      this.resizeToPreferredHeights();
    }
    this.mainFlameChart.reset();
    this.networkFlameChart.reset();
    this.updateSearchResults(false, false);
  }

  private appendExtensionData(): void {
    if (!this.model) {
      return;
    }
    const extensions = this.model.extensionInfo();
    while (this.nextExtensionIndex < extensions.length) {
      this.mainDataProvider.appendExtensionEvents(extensions[this.nextExtensionIndex++]);
    }
    this.mainFlameChart.scheduleUpdate();
  }

  private onEntryHighlighted(commonEvent: Common.EventTarget.EventTargetEvent<number>): void {
    SDK.OverlayModel.OverlayModel.hideDOMNodeHighlight();
    const entryIndex = commonEvent.data;
    const event = this.mainDataProvider.eventByIndex(entryIndex);
    if (!event) {
      return;
    }
    const target = this.model && this.model.timelineModel().targetByEvent(event);
    if (!target) {
      return;
    }
    const timelineData = TimelineModel.TimelineModel.TimelineData.forEvent(event);
    const backendNodeIds = timelineData.backendNodeIds;
    if (!backendNodeIds) {
      return;
    }
    for (let i = 0; i < backendNodeIds.length; ++i) {
      new SDK.DOMModel.DeferredDOMNode(target, backendNodeIds[i]).highlight();
    }
  }

  highlightEvent(event: SDK.TracingModel.Event|null): void {
    const entryIndex =
        event ? this.mainDataProvider.entryIndexForSelection(TimelineSelection.fromTraceEvent(event)) : -1;
    if (entryIndex >= 0) {
      this.mainFlameChart.highlightEntry(entryIndex);
    } else {
      this.mainFlameChart.hideHighlight();
    }
  }

  willHide(): void {
    this.networkFlameChartGroupExpansionSetting.removeChangeListener(this.resizeToPreferredHeights, this);
    this.showMemoryGraphSetting.removeChangeListener(this.updateCountersGraphToggle, this);
    Bindings.IgnoreListManager.IgnoreListManager.instance().removeChangeListener(this.boundRefresh);
  }

  wasShown(): void {
    this.networkFlameChartGroupExpansionSetting.addChangeListener(this.resizeToPreferredHeights, this);
    this.showMemoryGraphSetting.addChangeListener(this.updateCountersGraphToggle, this);
    Bindings.IgnoreListManager.IgnoreListManager.instance().addChangeListener(this.boundRefresh);
    if (this.needsResizeToPreferredHeights) {
      this.resizeToPreferredHeights();
    }
    this.mainFlameChart.scheduleUpdate();
    this.networkFlameChart.scheduleUpdate();
  }

  private updateCountersGraphToggle(): void {
    if (this.showMemoryGraphSetting.get()) {
      this.chartSplitWidget.showBoth();
    } else {
      this.chartSplitWidget.hideSidebar();
    }
  }

  setSelection(selection: TimelineSelection|null): void {
    let index = this.mainDataProvider.entryIndexForSelection(selection);
    this.mainFlameChart.setSelectedEntry(index);
    index = this.networkDataProvider.entryIndexForSelection(selection);
    this.networkFlameChart.setSelectedEntry(index);
    if (this.detailsView) {
      this.detailsView.setSelection(selection);
    }
  }

  private onEntrySelected(
      dataProvider: PerfUI.FlameChart.FlameChartDataProvider,
      event: Common.EventTarget.EventTargetEvent<number>): void {
    const entryIndex = event.data;
    if (Root.Runtime.experiments.isEnabled('timelineEventInitiators') && dataProvider === this.mainDataProvider) {
      if (this.mainDataProvider.buildFlowForInitiator(entryIndex)) {
        this.mainFlameChart.scheduleUpdate();
      }
    }
    this.delegate.select((dataProvider as TimelineFlameChartNetworkDataProvider).createSelection(entryIndex));
  }

  resizeToPreferredHeights(): void {
    if (!this.isShowing()) {
      this.needsResizeToPreferredHeights = true;
      return;
    }
    this.needsResizeToPreferredHeights = false;
    this.networkPane.element.classList.toggle(
        'timeline-network-resizer-disabled', !this.networkDataProvider.isExpanded());
    this.networkSplitWidget.setSidebarSize(
        this.networkDataProvider.preferredHeight() + this.splitResizer.clientHeight + PerfUI.FlameChart.HeaderHeight +
        2);
  }

  setSearchableView(searchableView: UI.SearchableView.SearchableView): void {
    this.searchableView = searchableView;
  }

  // UI.SearchableView.Searchable implementation

  jumpToNextSearchResult(): void {
    if (!this.searchResults || !this.searchResults.length) {
      return;
    }
    const index =
        typeof this.selectedSearchResult !== 'undefined' ? this.searchResults.indexOf(this.selectedSearchResult) : -1;
    this.selectSearchResult(Platform.NumberUtilities.mod(index + 1, this.searchResults.length));
  }

  jumpToPreviousSearchResult(): void {
    if (!this.searchResults || !this.searchResults.length) {
      return;
    }
    const index =
        typeof this.selectedSearchResult !== 'undefined' ? this.searchResults.indexOf(this.selectedSearchResult) : 0;
    this.selectSearchResult(Platform.NumberUtilities.mod(index - 1, this.searchResults.length));
  }

  supportsCaseSensitiveSearch(): boolean {
    return true;
  }

  supportsRegexSearch(): boolean {
    return true;
  }

  private selectSearchResult(index: number): void {
    this.searchableView.updateCurrentMatchIndex(index);
    if (this.searchResults) {
      this.selectedSearchResult = this.searchResults[index];
      this.delegate.select(this.mainDataProvider.createSelection(this.selectedSearchResult));
    }
  }

  private updateSearchResults(shouldJump: boolean, jumpBackwards?: boolean): void {
    const oldSelectedSearchResult = (this.selectedSearchResult as number);
    delete this.selectedSearchResult;
    this.searchResults = [];
    if (!this.searchRegex || !this.model) {
      return;
    }
    const regExpFilter = new TimelineRegExp(this.searchRegex);
    const window = this.model.window();
    this.searchResults = this.mainDataProvider.search(window.left, window.right, regExpFilter);
    this.searchableView.updateSearchMatchesCount(this.searchResults.length);
    if (!shouldJump || !this.searchResults.length) {
      return;
    }
    let selectedIndex = this.searchResults.indexOf(oldSelectedSearchResult);
    if (selectedIndex === -1) {
      selectedIndex = jumpBackwards ? this.searchResults.length - 1 : 0;
    }
    this.selectSearchResult(selectedIndex);
  }

  searchCanceled(): void {
    if (typeof this.selectedSearchResult !== 'undefined') {
      this.delegate.select(null);
    }
    delete this.searchResults;
    delete this.selectedSearchResult;
    delete this.searchRegex;
  }

  performSearch(searchConfig: UI.SearchableView.SearchConfig, shouldJump: boolean, jumpBackwards?: boolean): void {
    this.searchRegex = searchConfig.toSearchRegex().regex;
    this.updateSearchResults(shouldJump, jumpBackwards);
  }
}

export class Selection {
  timelineSelection: TimelineSelection;
  entryIndex: number;
  constructor(selection: TimelineSelection, entryIndex: number) {
    this.timelineSelection = selection;
    this.entryIndex = entryIndex;
  }
}

export const FlameChartStyle = {
  textColor: '#333',
};

export class TimelineFlameChartMarker implements PerfUI.FlameChart.FlameChartMarker {
  private readonly startTimeInternal: number;
  private readonly startOffset: number;
  private style: TimelineMarkerStyle;
  constructor(startTime: number, startOffset: number, style: TimelineMarkerStyle) {
    this.startTimeInternal = startTime;
    this.startOffset = startOffset;
    this.style = style;
  }

  startTime(): number {
    return this.startTimeInternal;
  }

  color(): string {
    return this.style.color;
  }

  title(): string|null {
    if (this.style.lowPriority) {
      return null;
    }
    const startTime = i18n.TimeUtilities.millisToString(this.startOffset);
    return i18nString(UIStrings.sAtS, {PH1: this.style.title, PH2: startTime});
  }

  draw(context: CanvasRenderingContext2D, x: number, height: number, pixelsPerMillisecond: number): void {
    const lowPriorityVisibilityThresholdInPixelsPerMs = 4;

    if (this.style.lowPriority && pixelsPerMillisecond < lowPriorityVisibilityThresholdInPixelsPerMs) {
      return;
    }

    context.save();
    if (this.style.tall) {
      context.strokeStyle = this.style.color;
      context.lineWidth = this.style.lineWidth;
      context.translate(this.style.lineWidth < 1 || (this.style.lineWidth & 1) ? 0.5 : 0, 0.5);
      context.beginPath();
      context.moveTo(x, 0);
      context.setLineDash(this.style.dashStyle);
      context.lineTo(x, context.canvas.height);
      context.stroke();
    }
    context.restore();
  }
}

// TODO(crbug.com/1167717): Make this a const enum again
// eslint-disable-next-line rulesdir/const_enum
export enum ColorBy {
  URL = 'URL',
}