From ac2cd3757b64b0e8a213c2f0ea4e6accc741f596 Mon Sep 17 00:00:00 2001
From: mgechev <mgechev@gmail.com>
Date: Mon, 4 May 2020 16:40:55 -0700
Subject: [PATCH] feat(devtools): introduce streamed visualization of the
 profiling data

---
 .../profiler/profiler.component.html          |   7 +-
 .../profiler/profiler.component.ts            |  47 ++++---
 .../devtools-tabs/profiler/profiler.module.ts |  15 +--
 .../frame-selector.component.html             |  15 +--
 .../frame-selector.component.scss             |   7 +-
 .../frame-selector.component.ts               |  60 +++++++--
 .../recording-dialog.component.html           |   2 +-
 .../recording-dialog.component.scss           |   0
 .../recording-dialog.component.ts             |   0
 .../recording-modal.component.html            |   2 +-
 .../recording-modal.component.scss            |   2 +-
 .../recording-modal.component.ts              |  12 +-
 .../timeline-controls.component.html          |  16 +--
 .../timeline-controls.component.scss          |   5 +
 .../timeline-controls.component.ts            |   3 +-
 .../timeline/timeline.component.html          |  56 +++++----
 .../timeline/timeline.component.scss          |  13 ++
 .../recording/timeline/timeline.component.ts  | 116 +++++++++++++-----
 .../recording/timeline/timeline.module.ts     |  16 ++-
 19 files changed, 256 insertions(+), 138 deletions(-)
 rename projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/{ => timeline}/recording-modal/recording-dialog/recording-dialog.component.html (62%)
 rename projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/{ => timeline}/recording-modal/recording-dialog/recording-dialog.component.scss (100%)
 rename projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/{ => timeline}/recording-modal/recording-dialog/recording-dialog.component.ts (100%)
 rename projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/{ => timeline}/recording-modal/recording-modal.component.html (54%)
 rename projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/{ => timeline}/recording-modal/recording-modal.component.scss (75%)
 rename projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/{ => timeline}/recording-modal/recording-modal.component.ts (55%)

diff --git a/projects/ng-devtools/src/lib/devtools-tabs/profiler/profiler.component.html b/projects/ng-devtools/src/lib/devtools-tabs/profiler/profiler.component.html
index 8e6a94fd6b4..bac99b97c05 100644
--- a/projects/ng-devtools/src/lib/devtools-tabs/profiler/profiler.component.html
+++ b/projects/ng-devtools/src/lib/devtools-tabs/profiler/profiler.component.html
@@ -15,11 +15,8 @@
         <input type="file" (change)="importProfilerResults($event)" placeholder="Upload file" accept=".json" />
       </span>
     </p>
-    <p class="recording" [class.hidden]="state !== 'recording'">
-      <ng-recording-modal></ng-recording-modal>
-    </p>
-    <p class="visualization" *ngIf="state === 'visualizing'">
-      <ng-recording-timeline [records]="stream" (exportProfile)="exportProfilerResults()"> </ng-recording-timeline>
+    <p class="visualization" *ngIf="state !== 'idle'">
+      <ng-recording-timeline [stream]="stream" (exportProfile)="exportProfilerResults()"> </ng-recording-timeline>
     </p>
   </div>
 </div>
diff --git a/projects/ng-devtools/src/lib/devtools-tabs/profiler/profiler.component.ts b/projects/ng-devtools/src/lib/devtools-tabs/profiler/profiler.component.ts
index 332310a2097..4127a02db79 100644
--- a/projects/ng-devtools/src/lib/devtools-tabs/profiler/profiler.component.ts
+++ b/projects/ng-devtools/src/lib/devtools-tabs/profiler/profiler.component.ts
@@ -1,9 +1,9 @@
-import { Component, ViewChildren, QueryList, OnInit, OnDestroy } from '@angular/core';
-import { RecordingModalComponent } from './recording/recording-modal/recording-modal.component';
+import { Component, OnInit, OnDestroy } from '@angular/core';
 import { MessageBus, Events, ProfilerFrame } from 'protocol';
 import { FileApiService } from '../../file-api-service';
 import { MatDialog } from '@angular/material/dialog';
 import { ProfilerImportDialogComponent } from './profiler-import-dialog/profiler-import-dialog.component';
+import { Subject } from 'rxjs';
 
 type State = 'idle' | 'recording' | 'visualizing';
 
@@ -17,10 +17,10 @@ const PROFILER_VERSION = 1;
 })
 export class ProfilerComponent implements OnInit, OnDestroy {
   state: State = 'idle';
-  stream: ProfilerFrame[] = [];
-  buffer: ProfilerFrame[] = [];
+  stream = new Subject<ProfilerFrame[]>();
 
-  @ViewChildren(RecordingModalComponent) recordingRef: QueryList<RecordingModalComponent>;
+  // We collect this buffer so we can have it available for export.
+  private _buffer: ProfilerFrame[] = [];
 
   constructor(
     private _fileApiService: FileApiService,
@@ -30,23 +30,26 @@ export class ProfilerComponent implements OnInit, OnDestroy {
 
   startRecording(): void {
     this.state = 'recording';
-    this.recordingRef.forEach((r) => r.start());
     this._messageBus.emit('startProfiling');
   }
 
   stopRecording(): void {
-    this.state = 'idle';
-    this.recordingRef.forEach((r) => r.stop());
+    this.state = 'visualizing';
     this._messageBus.emit('stopProfiling');
+    this.stream.complete();
   }
 
   ngOnInit(): void {
     this._messageBus.on('profilerResults', (remainingRecords) => {
-      this._profilerFinished(remainingRecords);
+      if (remainingRecords.duration > 0 && remainingRecords.source) {
+        this.stream.next([remainingRecords]);
+        this._buffer.push(remainingRecords);
+      }
     });
 
     this._messageBus.on('sendProfilerChunk', (chunkOfRecords: ProfilerFrame) => {
-      this.buffer.push(chunkOfRecords);
+      this.stream.next([chunkOfRecords]);
+      this._buffer.push(chunkOfRecords);
     });
 
     this._fileApiService.uploadedData.subscribe((importedFile) => {
@@ -69,34 +72,27 @@ export class ProfilerComponent implements OnInit, OnDestroy {
 
         processDataDialog.afterClosed().subscribe((result) => {
           if (result) {
-            this._viewProfilerData(importedFile.stream);
+            this.state = 'visualizing';
+            this._buffer = importedFile.buffer;
+            setTimeout(() => this.stream.next(importedFile.buffer));
           }
         });
       } else {
-        this._viewProfilerData(importedFile.stream);
+        this.state = 'visualizing';
+        this._buffer = importedFile.buffer;
+        setTimeout(() => this.stream.next(importedFile.buffer));
       }
     });
   }
 
-  private _profilerFinished(remainingRecords: ProfilerFrame): void {
-    const flattenedBuffer = [].concat.apply([], this.buffer);
-    this._viewProfilerData([...flattenedBuffer, remainingRecords]);
-    this.buffer = [];
-  }
-
   ngOnDestroy(): void {
     this._fileApiService.uploadedData.unsubscribe();
   }
 
-  private _viewProfilerData(stream: ProfilerFrame[]): void {
-    this.state = 'visualizing';
-    this.stream = stream;
-  }
-
   exportProfilerResults(): void {
     const fileToExport = {
       version: PROFILER_VERSION,
-      stream: this.stream,
+      buffer: this._buffer,
     };
     this._fileApiService.saveObjectAsJSON(fileToExport);
   }
@@ -106,7 +102,8 @@ export class ProfilerComponent implements OnInit, OnDestroy {
   }
 
   discardRecording(): void {
-    this.stream = [];
+    this.stream = new Subject<ProfilerFrame[]>();
     this.state = 'idle';
+    this._buffer = [];
   }
 }
diff --git a/projects/ng-devtools/src/lib/devtools-tabs/profiler/profiler.module.ts b/projects/ng-devtools/src/lib/devtools-tabs/profiler/profiler.module.ts
index 2042b334997..277648d71b9 100644
--- a/projects/ng-devtools/src/lib/devtools-tabs/profiler/profiler.module.ts
+++ b/projects/ng-devtools/src/lib/devtools-tabs/profiler/profiler.module.ts
@@ -1,28 +1,17 @@
 import { NgModule } from '@angular/core';
-import { MatProgressBarModule } from '@angular/material/progress-bar';
 import { CommonModule } from '@angular/common';
 import { MatSelectModule } from '@angular/material/select';
 import { MatDialogModule } from '@angular/material/dialog';
 import { FormsModule } from '@angular/forms';
 
 import { ProfilerComponent } from './profiler.component';
-import { RecordingModalComponent } from './recording/recording-modal/recording-modal.component';
 import { TimelineModule } from './recording/timeline/timeline.module';
-import { RecordingDialogComponent } from './recording/recording-modal/recording-dialog/recording-dialog.component';
 import { MatButtonModule } from '@angular/material/button';
 import { ProfilerImportDialogComponent } from './profiler-import-dialog/profiler-import-dialog.component';
 
 @NgModule({
-  declarations: [ProfilerComponent, RecordingModalComponent, RecordingDialogComponent, ProfilerImportDialogComponent],
-  imports: [
-    CommonModule,
-    MatDialogModule,
-    MatSelectModule,
-    FormsModule,
-    MatProgressBarModule,
-    TimelineModule,
-    MatButtonModule,
-  ],
+  declarations: [ProfilerComponent, ProfilerImportDialogComponent],
+  imports: [CommonModule, MatDialogModule, MatSelectModule, FormsModule, TimelineModule, MatButtonModule],
   exports: [ProfilerComponent],
   entryComponents: [ProfilerImportDialogComponent],
 })
diff --git a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/frame-selector/frame-selector.component.html b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/frame-selector/frame-selector.component.html
index dff65cf72dc..7634562cada 100644
--- a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/frame-selector/frame-selector.component.html
+++ b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/frame-selector/frame-selector.component.html
@@ -1,18 +1,19 @@
 <div class="bar-graph-container">
-  <p class="txt-frames">{{ currentFrameIndex + 1 }}/{{ graphData.length }}</p>
-  <button mat-icon-button (click)="move.emit(-1)" [disabled]="currentFrameIndex == 0">
+  <p class="txt-frames">{{ currentFrameIndex + 1 }}/{{ (graphData$ | async)?.length }}</p>
+  <button mat-icon-button (click)="move.emit(-1)" [disabled]="currentFrameIndex <= 0">
     <mat-icon>chevron_left</mat-icon>
   </button>
-  <div #barContainer class="bar-container">
+
+  <cdk-virtual-scroll-viewport #barContainer orientation="horizontal" [itemSize]="itemWidth" class="bar-container">
     <div
-      *ngFor="let d of graphData; let i = index"
-      [matTooltip]="d.toolTip"
+      *cdkVirtualFor="let d of graphData$ | async; let i = index"
       [ngStyle]="d.style"
       [class.selected]="i === currentFrameIndex"
       (click)="selectFrame.emit(i)"
     ></div>
-  </div>
-  <button mat-icon-button (click)="move.emit(1)" [disabled]="currentFrameIndex == graphData.length - 1">
+  </cdk-virtual-scroll-viewport>
+
+  <button mat-icon-button (click)="move.emit(1)" [disabled]="currentFrameIndex >= (graphData$ | async)?.length - 1">
     <mat-icon>chevron_right</mat-icon>
   </button>
 </div>
diff --git a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/frame-selector/frame-selector.component.scss b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/frame-selector/frame-selector.component.scss
index 7d858b6c01c..a891e62aa7e 100644
--- a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/frame-selector/frame-selector.component.scss
+++ b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/frame-selector/frame-selector.component.scss
@@ -19,9 +19,14 @@
 
   .bar-container {
     max-width: calc(100vw - 150px);
-    display: flex;
     align-items: baseline;
     overflow-x: auto;
+    width: 100%;
+    height: 100%;
+
+    ::ng-deep .cdk-virtual-scroll-content-wrapper {
+      display: flex;
+    }
 
     &::-webkit-scrollbar {
       display: none;
diff --git a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/frame-selector/frame-selector.component.ts b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/frame-selector/frame-selector.component.ts
index c714c686f47..6e134561644 100644
--- a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/frame-selector/frame-selector.component.ts
+++ b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/frame-selector/frame-selector.component.ts
@@ -1,25 +1,67 @@
-import { Component, ElementRef, EventEmitter, Input, Output, ViewChild } from '@angular/core';
+import { Component, ElementRef, EventEmitter, Input, Output, ViewChild, OnDestroy } from '@angular/core';
 import { GraphNode } from '../record-formatter/record-formatter';
+import { Observable, Subscription } from 'rxjs';
+import { CdkVirtualScrollViewport } from '@angular/cdk/scrolling';
+
+const ITEM_WIDTH = 29;
 
 @Component({
   selector: 'ng-frame-selector',
   templateUrl: './frame-selector.component.html',
   styleUrls: ['./frame-selector.component.scss'],
 })
-export class FrameSelectorComponent {
+export class FrameSelectorComponent implements OnDestroy {
   @ViewChild('barContainer') barContainer: ElementRef;
   @Input() set currentFrame(value: number) {
     this.currentFrameIndex = value;
-    this.barContainer?.nativeElement?.children?.[value]?.scrollIntoView({
-      behavior: 'auto',
-      block: 'end',
-      inline: 'nearest',
-    });
+    this._ensureVisible(value);
   }
-  @Input() graphData: GraphNode[];
-  @Input() profilerFramesLength: number;
+  @Input() set graphData$(graphData: Observable<GraphNode[]>) {
+    this._graphData$ = graphData;
+    this._graphDataSubscription = this._graphData$.subscribe((items) =>
+      setTimeout(() => {
+        this.viewPort.scrollToIndex(items.length);
+      })
+    );
+  }
+
+  get graphData$(): Observable<GraphNode[]> {
+    return this._graphData$;
+  }
+
   @Output() move = new EventEmitter<number>();
   @Output() selectFrame = new EventEmitter<number>();
+  @ViewChild(CdkVirtualScrollViewport) viewPort: CdkVirtualScrollViewport;
 
   currentFrameIndex: number;
+
+  get itemWidth(): number {
+    return ITEM_WIDTH;
+  }
+
+  private _graphData$: Observable<GraphNode[]>;
+  private _graphDataSubscription: Subscription;
+
+  ngOnDestroy(): void {
+    if (this._graphDataSubscription) {
+      this._graphDataSubscription.unsubscribe();
+    }
+  }
+
+  private _ensureVisible(index: number): void {
+    if (!this.viewPort) {
+      return;
+    }
+    const scrollParent = this.viewPort.elementRef.nativeElement;
+    // The left most point we see an element
+    const left = scrollParent.scrollLeft;
+    // That's the right most point we currently see an element.
+    const right = left + scrollParent.offsetWidth;
+    const itemLeft = index * this.itemWidth;
+    if (itemLeft < left) {
+      scrollParent.scrollTo({ left: itemLeft });
+    } else if (right < itemLeft + this.itemWidth) {
+      scrollParent.scrollTo({ left: itemLeft - scrollParent.offsetWidth + this.itemWidth });
+    }
+  }
 }
diff --git a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/recording-modal/recording-dialog/recording-dialog.component.html b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/recording-modal/recording-dialog/recording-dialog.component.html
similarity index 62%
rename from projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/recording-modal/recording-dialog/recording-dialog.component.html
rename to projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/recording-modal/recording-dialog/recording-dialog.component.html
index 98d26a8f56e..71b83fbc584 100644
--- a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/recording-modal/recording-dialog/recording-dialog.component.html
+++ b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/recording-modal/recording-dialog/recording-dialog.component.html
@@ -1,5 +1,5 @@
 <section class="main-wrapper">
-  <h2>Recording</h2>
+  <h2>Interact with your app to preview change detection</h2>
 
   <mat-progress-bar mode="indeterminate"></mat-progress-bar>
 </section>
diff --git a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/recording-modal/recording-dialog/recording-dialog.component.scss b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/recording-modal/recording-dialog/recording-dialog.component.scss
similarity index 100%
rename from projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/recording-modal/recording-dialog/recording-dialog.component.scss
rename to projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/recording-modal/recording-dialog/recording-dialog.component.scss
diff --git a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/recording-modal/recording-dialog/recording-dialog.component.ts b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/recording-modal/recording-dialog/recording-dialog.component.ts
similarity index 100%
rename from projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/recording-modal/recording-dialog/recording-dialog.component.ts
rename to projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/recording-modal/recording-dialog/recording-dialog.component.ts
diff --git a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/recording-modal/recording-modal.component.html b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/recording-modal/recording-modal.component.html
similarity index 54%
rename from projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/recording-modal/recording-modal.component.html
rename to projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/recording-modal/recording-modal.component.html
index d95cbc94059..a16311c881c 100644
--- a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/recording-modal/recording-modal.component.html
+++ b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/recording-modal/recording-modal.component.html
@@ -1,3 +1,3 @@
-<section *ngIf="visible" id="recorder-wrapper">
+<section id="recorder-wrapper">
   <ng-recording-dialog></ng-recording-dialog>
 </section>
diff --git a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/recording-modal/recording-modal.component.scss b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/recording-modal/recording-modal.component.scss
similarity index 75%
rename from projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/recording-modal/recording-modal.component.scss
rename to projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/recording-modal/recording-modal.component.scss
index c19bcc65235..f42bc8573d5 100644
--- a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/recording-modal/recording-modal.component.scss
+++ b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/recording-modal/recording-modal.component.scss
@@ -1,4 +1,4 @@
-@import '../../../../../../../../node_modules/@angular/cdk/overlay-prebuilt.css';
+@import '../../../../../../../../../node_modules/@angular/cdk/overlay-prebuilt.css';
 
 :host {
   overflow: hidden;
diff --git a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/recording-modal/recording-modal.component.ts b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/recording-modal/recording-modal.component.ts
similarity index 55%
rename from projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/recording-modal/recording-modal.component.ts
rename to projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/recording-modal/recording-modal.component.ts
index c1ba2a832e7..285f10a261f 100644
--- a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/recording-modal/recording-modal.component.ts
+++ b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/recording-modal/recording-modal.component.ts
@@ -5,14 +5,4 @@ import { Component } from '@angular/core';
   templateUrl: './recording-modal.component.html',
   styleUrls: ['./recording-modal.component.scss'],
 })
-export class RecordingModalComponent {
-  visible = false;
-
-  stop(): void {
-    this.visible = false;
-  }
-
-  start(): void {
-    this.visible = true;
-  }
-}
+export class RecordingModalComponent {}
diff --git a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline-controls/timeline-controls.component.html b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline-controls/timeline-controls.component.html
index ac7c47d8c42..3a4e1f62382 100644
--- a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline-controls/timeline-controls.component.html
+++ b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline-controls/timeline-controls.component.html
@@ -1,6 +1,6 @@
 <div class="controls">
-  <button mat-stroked-button (click)="exportProfile.emit()">Export to JSON</button>
-  <mat-form-field>
+  <button *ngIf="!empty" mat-stroked-button (click)="exportProfile.emit()">Export to JSON</button>
+  <mat-form-field *ngIf="record">
     <mat-select [value]="visualizationMode" (selectionChange)="this.changeVisualizationMode.emit($event.value)">
       <mat-option [value]="flameGraphMode">
         Flame graph
@@ -14,12 +14,14 @@
     </mat-select>
   </mat-form-field>
 
-  <label *ngIf="estimatedFrameRate >= 60"> Time spent: {{ record.duration | number }} ms </label>
+  <label *ngIf="estimatedFrameRate >= 60 && record"> Time spent: {{ record?.duration | number }} ms </label>
 
-  <label [style.color]="frameColor" *ngIf="estimatedFrameRate < 60">
-    Time spent: {{ record.duration | number }} ms
+  <label [style.color]="frameColor" *ngIf="estimatedFrameRate < 60 && record">
+    Time spent: {{ record?.duration | number }} ms
   </label>
 
-  <label [style.color]="frameColor" *ngIf="estimatedFrameRate < 60"> Frame rate: {{ estimatedFrameRate }} fps </label>
-  <label *ngIf="record.source">Source: {{ record.source }}</label>
+  <label [style.color]="frameColor" *ngIf="estimatedFrameRate < 60 && record">
+    Frame rate: {{ estimatedFrameRate }} fps
+  </label>
+  <label *ngIf="record?.source && record">Source: {{ record?.source }}</label>
 </div>
diff --git a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline-controls/timeline-controls.component.scss b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline-controls/timeline-controls.component.scss
index 77cd3c98daa..4779ca773a0 100644
--- a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline-controls/timeline-controls.component.scss
+++ b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline-controls/timeline-controls.component.scss
@@ -1,3 +1,8 @@
+:host {
+  height: 60px;
+  display: block;
+}
+
 .controls {
   top: 0;
   left: 300px;
diff --git a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline-controls/timeline-controls.component.ts b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline-controls/timeline-controls.component.ts
index f9a7f2d6a3a..171e9750e6f 100644
--- a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline-controls/timeline-controls.component.ts
+++ b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline-controls/timeline-controls.component.ts
@@ -8,10 +8,11 @@ import { ProfilerFrame } from 'protocol';
   styleUrls: ['./timeline-controls.component.scss'],
 })
 export class TimelineControlsComponent {
-  @Input() record: ProfilerFrame;
+  @Input() record: ProfilerFrame | undefined;
   @Input() estimatedFrameRate: number;
   @Input() frameColor: string;
   @Input() visualizationMode: VisualizationMode;
+  @Input() empty: boolean;
   @Output() changeVisualizationMode = new EventEmitter<VisualizationMode>();
   @Output() exportProfile = new EventEmitter<void>();
 
diff --git a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline.component.html b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline.component.html
index ea9bee87825..d50666695e4 100644
--- a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline.component.html
+++ b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline.component.html
@@ -1,26 +1,34 @@
-<ng-container *ngIf="profilerFrames.length > 0; else noRecords">
-  <ng-container *ngTemplateOutlet="recordView; context: { record: frame }"></ng-container>
-</ng-container>
+<ng-recording-modal *ngIf="!hasFrames && !visualizing"></ng-recording-modal>
 
-<ng-template #noRecords>
-  Nothing was profiled
-</ng-template>
+<p class="info" *ngIf="!hasFrames && visualizing">
+  There's no information to show.
+</p>
 
-<ng-template let-record="record" #recordView>
-  <ng-timeline-controls
-    [frameColor]="getColorByFrameRate(estimateFrameRate(record.duration))"
-    [record]="record"
-    [estimatedFrameRate]="estimateFrameRate(record.duration)"
-    [visualizationMode]="visualizationMode"
-    (changeVisualizationMode)="visualizationMode = $event"
-    (exportProfile)="exportProfile.emit($event)"
-  ></ng-timeline-controls>
-  <ng-frame-selector
-    (move)="move($event)"
-    (selectFrame)="selectFrame($event)"
-    [profilerFramesLength]="profilerFrames.length"
-    [graphData]="graphData"
-    [currentFrame]="currentFrameIndex"
-  ></ng-frame-selector>
-  <ng-timeline-visualizer [visualizationMode]="visualizationMode" [frame]="record"></ng-timeline-visualizer>
-</ng-template>
+<ng-timeline-controls
+  [class.hidden]="!hasFrames"
+  [record]="frame"
+  [empty]="!hasFrames"
+  [frameColor]="getColorByFrameRate(estimateFrameRate(frame?.duration))"
+  [estimatedFrameRate]="estimateFrameRate(frame?.duration)"
+  [visualizationMode]="visualizationMode"
+  (changeVisualizationMode)="visualizationMode = $event"
+  (exportProfile)="exportProfile.emit($event)"
+></ng-timeline-controls>
+
+<ng-frame-selector
+  [class.hidden]="!hasFrames"
+  (move)="move($event)"
+  (selectFrame)="selectFrame($event)"
+  [graphData$]="graphData$"
+  [currentFrame]="currentFrameIndex"
+></ng-frame-selector>
+
+<p class="info" *ngIf="hasFrames && currentFrameIndex < 0">
+  Select a bar to preview a particular change detection cycle.
+</p>
+
+<ng-timeline-visualizer
+  *ngIf="hasFrames && currentFrameIndex >= 0"
+  [visualizationMode]="visualizationMode"
+  [frame]="frame"
+></ng-timeline-visualizer>
diff --git a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline.component.scss b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline.component.scss
index d3bf526af5d..f32c655a37d 100644
--- a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline.component.scss
+++ b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline.component.scss
@@ -4,3 +4,16 @@
   height: 100%;
   display: block;
 }
+
+.info {
+  font-size: 1.2em;
+  text-align: center;
+}
+
+.hidden {
+  /*
+    intentionally using visibility: hidden
+    display: none breaks the virtual scroll
+  */
+  visibility: hidden;
+}
diff --git a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline.component.ts b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline.component.ts
index c19344c2296..c1fc43950dd 100644
--- a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline.component.ts
+++ b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline.component.ts
@@ -1,6 +1,8 @@
-import { ChangeDetectionStrategy, Component, EventEmitter, Input, Output } from '@angular/core';
+import { Component, EventEmitter, Input, Output, OnDestroy } from '@angular/core';
 import { ProfilerFrame } from 'protocol';
 import { GraphNode } from './record-formatter/record-formatter';
+import { Observable, Subscription, BehaviorSubject } from 'rxjs';
+import { share } from 'rxjs/operators';
 
 export enum VisualizationMode {
   FlameGraph,
@@ -14,22 +16,41 @@ const MAX_HEIGHT = 50;
   selector: 'ng-recording-timeline',
   templateUrl: './timeline.component.html',
   styleUrls: ['./timeline.component.scss'],
-  changeDetection: ChangeDetectionStrategy.OnPush,
 })
-export class TimelineComponent {
-  @Input() set records(data: ProfilerFrame[]) {
-    this.profilerFrames = data.filter((frame) => frame.duration > 0);
-    this.renderBarChart(this.profilerFrames);
+export class TimelineComponent implements OnDestroy {
+  @Input() set stream(data: Observable<ProfilerFrame[]>) {
+    if (this._subscription) {
+      this._subscription.unsubscribe();
+    }
+    this._allRecords = [];
+    this._maxDuration = -Infinity;
+    this._subscription = data.subscribe({
+      next: (frames: ProfilerFrame[]): void => {
+        this._processFrames(frames);
+      },
+      complete: (): void => {
+        this.visualizing = true;
+      },
+    });
   }
-  @Input() profilerFrames: ProfilerFrame[] = [];
   @Output() exportProfile = new EventEmitter<void>();
 
   visualizationMode = VisualizationMode.BarGraph;
-  graphData: GraphNode[] = [];
-  currentFrameIndex = 0;
+  currentFrameIndex = -1;
+
+  private _maxDuration = -Infinity;
+  private _subscription: Subscription;
+  private _allRecords: ProfilerFrame[] = [];
+  private _graphDataSubject = new BehaviorSubject<GraphNode[]>([]);
+  visualizing = false;
+  graphData$ = this._graphDataSubject.asObservable().pipe(share());
+
+  get hasFrames(): boolean {
+    return this._allRecords.length > 0;
+  }
 
   get frame(): ProfilerFrame {
-    return this.profilerFrames[this.currentFrameIndex];
+    return this._allRecords[this.currentFrameIndex];
   }
 
   estimateFrameRate(timeSpent: number): number {
@@ -39,7 +60,7 @@ export class TimelineComponent {
 
   move(value: number): void {
     const newVal = this.currentFrameIndex + value;
-    if (newVal > -1 && newVal < this.profilerFrames.length) {
+    if (newVal > -1 && newVal < this._allRecords.length) {
       this.currentFrameIndex = newVal;
     }
   }
@@ -59,26 +80,59 @@ export class TimelineComponent {
     return 'red';
   }
 
-  renderBarChart(records: ProfilerFrame[]): void {
-    const maxValue = records.reduce((acc: number, frame: ProfilerFrame) => Math.max(acc, frame.duration), 0);
-    const multiplicationFactor = parseFloat((MAX_HEIGHT / maxValue).toFixed(2));
-    this.graphData = records.map((r) => {
-      const height = r.duration * multiplicationFactor;
-      const colorPercentage = Math.round((height / MAX_HEIGHT) * 100);
-      const backgroundColor = this.getColorByFrameRate(this.estimateFrameRate(r.duration));
+  ngOnDestroy(): void {
+    if (this._subscription) {
+      this._subscription.unsubscribe();
+    }
+  }
 
-      const style = {
-        'margin-left': '1px',
-        'margin-right': '1px',
-        background: `-webkit-linear-gradient(bottom, ${backgroundColor} ${colorPercentage}%, #f3f3f3 ${colorPercentage}%)`,
-        border: '1px solid #d0d0d0',
-        cursor: 'pointer',
-        'min-width': '25px',
-        width: '25px',
-        height: '50px',
-      };
-      const toolTip = `${r.source} TimeSpent: ${r.duration.toFixed(3)}ms`;
-      return { style, toolTip };
-    });
+  private _processFrames(frames: ProfilerFrame[]): void {
+    let regenerate = false;
+    for (const frame of frames) {
+      if (frame.duration >= this._maxDuration) {
+        regenerate = true;
+      }
+      this._allRecords.push(frame);
+    }
+    if (regenerate) {
+      this._graphDataSubject.next(this._generateBars());
+      return;
+    }
+    const multiplicationFactor = parseFloat((MAX_HEIGHT / this._maxDuration).toFixed(2));
+    frames.forEach((frame) => this._graphDataSubject.value.push(this._getBarStyles(frame, multiplicationFactor)));
+
+    // We need to pass a new reference, because the CDK virtual scroll
+    // has OnPush strategy, so it doesn't update the UI otherwise.
+    // If this turns out ot be a bottleneck, we can easily create an immutable reference.
+    this._graphDataSubject.next(this._graphDataSubject.value.slice());
+  }
+
+  private _generateBars(): GraphNode[] {
+    const maxValue = this._allRecords.reduce((acc: number, frame: ProfilerFrame) => Math.max(acc, frame.duration), 0);
+    const multiplicationFactor = parseFloat((MAX_HEIGHT / maxValue).toFixed(2));
+    this._maxDuration = Math.max(this._maxDuration, maxValue);
+    return this._allRecords.map((r) => this._getBarStyles(r, multiplicationFactor));
+  }
+
+  private _getBarStyles(
+    record: ProfilerFrame,
+    multiplicationFactor: number
+  ): { style: { [key: string]: string }; toolTip: string } {
+    const height = record.duration * multiplicationFactor;
+    const colorPercentage = Math.round((height / MAX_HEIGHT) * 100);
+    const backgroundColor = this.getColorByFrameRate(this.estimateFrameRate(record.duration));
+
+    const style = {
+      'margin-left': '1px',
+      'margin-right': '1px',
+      background: `-webkit-linear-gradient(bottom, ${backgroundColor} ${colorPercentage}%, #f3f3f3 ${colorPercentage}%)`,
+      border: '1px solid #d0d0d0',
+      cursor: 'pointer',
+      'min-width': '25px',
+      width: '25px',
+      height: '50px',
+    };
+    const toolTip = `${record.source} TimeSpent: ${record.duration.toFixed(3)}ms`;
+    return { style, toolTip };
   }
 }
diff --git a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline.module.ts b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline.module.ts
index 1221cd91251..b0f65ed9d14 100644
--- a/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline.module.ts
+++ b/projects/ng-devtools/src/lib/devtools-tabs/profiler/recording/timeline/timeline.module.ts
@@ -10,13 +10,27 @@ import { MatTooltipModule } from '@angular/material/tooltip';
 import { MatIconModule } from '@angular/material/icon';
 import { FrameSelectorComponent } from './frame-selector/frame-selector.component';
 import { TimelineControlsComponent } from './timeline-controls/timeline-controls.component';
+import { ScrollingModule } from '@angular/cdk/scrolling';
+import { RecordingDialogComponent } from './recording-modal/recording-dialog/recording-dialog.component';
+import { RecordingModalComponent } from './recording-modal/recording-modal.component';
+import { MatProgressBarModule } from '@angular/material/progress-bar';
+import { MatDialogModule } from '@angular/material/dialog';
 
 @NgModule({
-  declarations: [TimelineComponent, FrameSelectorComponent, TimelineControlsComponent],
+  declarations: [
+    TimelineComponent,
+    RecordingDialogComponent,
+    RecordingModalComponent,
+    FrameSelectorComponent,
+    TimelineControlsComponent,
+  ],
   imports: [
+    ScrollingModule,
     CommonModule,
     FormsModule,
     RecordingVisualizerModule,
+    MatDialogModule,
+    MatProgressBarModule,
     MatButtonModule,
     MatTooltipModule,
     MatIconModule,