[DevTools] Add screenshots to Scheduling Profiler

packages/react-devtools-scheduling-profiler/src/CanvasPage.js

@@ -46,6 +46,7 @@ import {
   NativeEventsView,
   ReactMeasuresView,
   SchedulingEventsView,
+  SnapshotsView,
   SuspenseEventsView,
   TimeAxisMarkersView,
   UserTimingMarksView,
@@ -157,6 +158,7 @@ function AutoSizedCanvas({
   const componentMeasuresViewRef = useRef(null);
   const reactMeasuresViewRef = useRef(null);
   const flamechartViewRef = useRef(null);
+  const snapshotsViewRef = useRef(null);
 
   const {hideMenu: hideContextMenu} = useContext(RegistryContext);
 
@@ -304,6 +306,18 @@ function AutoSizedCanvas({
       );
     }
 
+    let snapshotsViewWrapper = null;
+    if (data.snapshots.length > 0) {
+      const snapshotsView = new SnapshotsView(surface, defaultFrame, data);
+      snapshotsViewRef.current = snapshotsView;
+      snapshotsViewWrapper = createViewHelper(
+        snapshotsView,
+        'snapshots',
+        true,
+        true,
+      );
+    }
+
     const flamechartView = new FlamechartView(
       surface,
       defaultFrame,
@@ -340,6 +354,9 @@ function AutoSizedCanvas({
     if (componentMeasuresViewWrapper !== null) {
       rootView.addSubview(componentMeasuresViewWrapper);
     }
+    if (snapshotsViewWrapper !== null) {
+      rootView.addSubview(snapshotsViewWrapper);
+    }
     rootView.addSubview(flamechartViewWrapper);
 
     const verticalScrollOverflowView = new VerticalScrollOverflowView(
@@ -389,6 +406,7 @@ function AutoSizedCanvas({
               measure: null,
               nativeEvent: null,
               schedulingEvent: null,
+              snapshot: null,
               suspenseEvent: null,
               userTimingMark: null,
             };
@@ -447,6 +465,7 @@ function AutoSizedCanvas({
             measure: null,
             nativeEvent: null,
             schedulingEvent: null,
+            snapshot: null,
             suspenseEvent: null,
             userTimingMark,
           });
@@ -465,6 +484,7 @@ function AutoSizedCanvas({
             measure: null,
             nativeEvent,
             schedulingEvent: null,
+            snapshot: null,
             suspenseEvent: null,
             userTimingMark: null,
           });
@@ -483,6 +503,7 @@ function AutoSizedCanvas({
             measure: null,
             nativeEvent: null,
             schedulingEvent,
+            snapshot: null,
             suspenseEvent: null,
             userTimingMark: null,
           });
@@ -501,6 +522,7 @@ function AutoSizedCanvas({
             measure: null,
             nativeEvent: null,
             schedulingEvent: null,
+            snapshot: null,
             suspenseEvent,
             userTimingMark: null,
           });
@@ -519,6 +541,7 @@ function AutoSizedCanvas({
             measure,
             nativeEvent: null,
             schedulingEvent: null,
+            snapshot: null,
             suspenseEvent: null,
             userTimingMark: null,
           });
@@ -540,6 +563,26 @@ function AutoSizedCanvas({
             measure: null,
             nativeEvent: null,
             schedulingEvent: null,
+            snapshot: null,
+            suspenseEvent: null,
+            userTimingMark: null,
+          });
+        }
+      };
+    }
+
+    const {current: snapshotsView} = snapshotsViewRef;
+    if (snapshotsView) {
+      snapshotsView.onHover = snapshot => {
+        if (!hoveredEvent || hoveredEvent.snapshot !== snapshot) {
+          setHoveredEvent({
+            componentMeasure: null,
+            data,
+            flamechartStackFrame: null,
+            measure: null,
+            nativeEvent: null,
+            schedulingEvent: null,
+            snapshot,
             suspenseEvent: null,
             userTimingMark: null,
           });
@@ -561,6 +604,7 @@ function AutoSizedCanvas({
             measure: null,
             nativeEvent: null,
             schedulingEvent: null,
+            snapshot: null,
             suspenseEvent: null,
             userTimingMark: null,
           });

packages/react-devtools-scheduling-profiler/src/EventTooltip.js

@@ -17,6 +17,7 @@ import type {
   ReactProfilerData,
   Return,
   SchedulingEvent,
+  Snapshot,
   SuspenseEvent,
   UserTimingMark,
 } from './types';
@@ -87,6 +88,7 @@ export default function EventTooltip({
     measure,
     nativeEvent,
     schedulingEvent,
+    snapshot,
     suspenseEvent,
     userTimingMark,
   } = hoveredEvent;
@@ -110,6 +112,8 @@ export default function EventTooltip({
         tooltipRef={tooltipRef}
       />
     );
+  } else if (snapshot !== null) {
+    return <TooltipSnapshot snapshot={snapshot} tooltipRef={tooltipRef} />;
   } else if (suspenseEvent !== null) {
     return (
       <TooltipSuspenseEvent
@@ -301,6 +305,23 @@ const TooltipSchedulingEvent = ({
   );
 };
 
+const TooltipSnapshot = ({
+  snapshot,
+  tooltipRef,
+}: {
+  snapshot: Snapshot,
+  tooltipRef: Return<typeof useRef>,
+}) => {
+  return (
+    <div className={styles.Tooltip} ref={tooltipRef}>
+      <img
+        src={snapshot.imageSource}
+        style={{width: snapshot.width / 2, height: snapshot.height / 2}}
+      />
+    </div>
+  );
+};
+
 const TooltipSuspenseEvent = ({
   suspenseEvent,
   tooltipRef,

packages/react-devtools-scheduling-profiler/src/content-views/SnapshotsView.js

@@ -0,0 +1,208 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ */
+
+import type {Snapshot, ReactProfilerData} from '../types';
+import type {
+  Interaction,
+  MouseMoveInteraction,
+  Rect,
+  Size,
+  Surface,
+  ViewRefs,
+} from '../view-base';
+
+import {positioningScaleFactor, timestampToPosition} from './utils/positioning';
+import {
+  intersectionOfRects,
+  rectContainsPoint,
+  rectEqualToRect,
+  View,
+} from '../view-base';
+import {BORDER_SIZE, COLORS, SNAPSHOT_HEIGHT} from './constants';
+
+type OnHover = (node: Snapshot | null) => void;
+
+export class SnapshotsView extends View {
+  _intrinsicSize: Size;
+  _profilerData: ReactProfilerData;
+
+  onHover: OnHover | null = null;
+
+  constructor(surface: Surface, frame: Rect, profilerData: ReactProfilerData) {
+    super(surface, frame);
+
+    this._intrinsicSize = {
+      width: profilerData.duration,
+      height: SNAPSHOT_HEIGHT,
+    };
+    this._profilerData = profilerData;
+  }
+
+  desiredSize() {
+    return this._intrinsicSize;
+  }
+
+  draw(context: CanvasRenderingContext2D) {
+    const {visibleArea} = this;
+
+    context.fillStyle = COLORS.BACKGROUND;
+    context.fillRect(
+      visibleArea.origin.x,
+      visibleArea.origin.y,
+      visibleArea.size.width,
+      visibleArea.size.height,
+    );
+
+    const y = visibleArea.origin.y;
+
+    let x = visibleArea.origin.x;
+
+    // Rather than drawing each snapshot where it occured,
+    // draw them at fixed intervals and just show the nearest one.
+    while (x < visibleArea.origin.x + visibleArea.size.width) {
+      const snapshot = this._findClosestSnapshot(x);
+
+      const scaledHeight = SNAPSHOT_HEIGHT;
+      const scaledWidth = (snapshot.width * SNAPSHOT_HEIGHT) / snapshot.height;
+
+      const imageRect: Rect = {
+        origin: {
+          x,
+          y,
+        },
+        size: {width: scaledWidth, height: scaledHeight},
+      };
+
+      // Lazily create and cache Image objects as we render a snapsho for the first time.
+      if (snapshot.image === null) {
+        const img = (snapshot.image = new Image());
+        img.onload = () => {
+          this._drawSnapshotImage(context, snapshot, imageRect);
+        };
+        img.src = snapshot.imageSource;
+      } else {
+        this._drawSnapshotImage(context, snapshot, imageRect);
+      }
+
+      x += scaledWidth + BORDER_SIZE;
+    }
+  }
+
+  handleInteraction(interaction: Interaction, viewRefs: ViewRefs) {
+    switch (interaction.type) {
+      case 'mousemove':
+        this._handleMouseMove(interaction, viewRefs);
+        break;
+    }
+  }
+
+  _drawSnapshotImage(
+    context: CanvasRenderingContext2D,
+    snapshot: Snapshot,
+    imageRect: Rect,
+  ) {
+    const visibleArea = this.visibleArea;
+
+    // Prevent snapshot from visibly overflowing its container when clipped.
+    const shouldClip = !rectEqualToRect(imageRect, visibleArea);
+    if (shouldClip) {
+      const clippedRect = intersectionOfRects(imageRect, visibleArea);
+      context.save();
+      context.beginPath();
+      context.rect(
+        clippedRect.origin.x,
+        clippedRect.origin.y,
+        clippedRect.size.width,
+        clippedRect.size.height,
+      );
+      context.closePath();
+      context.clip();
+    }
+
+    // $FlowFixMe Flow doesn't know about the 9 argument variant of drawImage()
+    context.drawImage(
+      snapshot.image,
+
+      // Image coordinates
+      0,
+      0,
+
+      // Native image size
+      snapshot.width,
+      snapshot.height,
+
+      // Canvas coordinates
+      imageRect.origin.x,
+      imageRect.origin.y,
+
+      // Scaled image size
+      imageRect.size.width,
+      imageRect.size.height,
+    );
+
+    if (shouldClip) {
+      context.restore();
+    }
+  }
+
+  _findClosestSnapshot(x: number): Snapshot {
+    const frame = this.frame;
+    const scaleFactor = positioningScaleFactor(
+      this._intrinsicSize.width,
+      frame,
+    );
+
+    const snapshots = this._profilerData.snapshots;
+
+    let startIndex = 0;
+    let stopIndex = snapshots.length - 1;
+    while (startIndex <= stopIndex) {
+      const currentIndex = Math.floor((startIndex + stopIndex) / 2);
+      const snapshot = snapshots[currentIndex];
+      const {timestamp} = snapshot;
+
+      const snapshotX = Math.floor(
+        timestampToPosition(timestamp, scaleFactor, frame),
+      );
+
+      if (x < snapshotX) {
+        stopIndex = currentIndex - 1;
+      } else {
+        startIndex = currentIndex + 1;
+      }
+    }
+
+    return snapshots[stopIndex];
+  }
+
+  /**
+   * @private
+   */
+  _handleMouseMove(interaction: MouseMoveInteraction, viewRefs: ViewRefs) {
+    const {onHover, visibleArea} = this;
+    if (!onHover) {
+      return;
+    }
+
+    const {location} = interaction.payload;
+    if (!rectContainsPoint(location, visibleArea)) {
+      onHover(null);
+      return;
+    }
+
+    const snapshot = this._findClosestSnapshot(location.x);
+    if (snapshot) {
+      this.currentCursor = 'context-menu';
+      viewRefs.hoveredView = this;
+      onHover(snapshot);
+    } else {
+      onHover(null);
+    }
+  }
+}

packages/react-devtools-scheduling-profiler/src/content-views/constants.js

@@ -23,6 +23,7 @@ export const REACT_MEASURE_HEIGHT = 14;
 export const BORDER_SIZE = 1;
 export const FLAMECHART_FRAME_HEIGHT = 14;
 export const TEXT_PADDING = 3;
+export const SNAPSHOT_HEIGHT = 50;
 
 export const INTERVAL_TIMES = [
   1,