Add fiber summary tooltip to devtools profiling

packages/react-devtools-shared/src/devtools/views/Components/ProfilerWhatChanged.css

@@ -0,0 +1,30 @@
+.Component {
+  margin-bottom: 1rem;
+}
+
+.Item {
+  margin-top: 0.25rem;
+}
+
+.Key {
+  font-family: var(--font-family-monospace);
+  font-size: var(--font-size-monospace-small);
+  line-height: 1;
+}
+
+.Key:first-of-type::before {
+  content: ' (';
+}
+
+.Key::after {
+  content: ', ';
+}
+
+.Key:last-of-type::after {
+  content: ')';
+}
+
+.Label {
+  font-weight: bold;
+  margin-bottom: 0.5rem;
+}

packages/react-devtools-shared/src/devtools/views/Components/ProfilerWhatChanged.js

@@ -0,0 +1,138 @@
+/**
+ * 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 React, {useContext} from 'react';
+import {ProfilerContext} from '../Profiler/ProfilerContext';
+import {StoreContext} from '../context';
+
+import styles from './ProfilerWhatChanged.css';
+
+type ProfilerWhatChangedProps = {|
+  fiberID: number,
+|};
+
+export default function ProfilerWhatChanged({
+  fiberID,
+}: ProfilerWhatChangedProps) {
+  const {profilerStore} = useContext(StoreContext);
+  const {rootID, selectedCommitIndex} = useContext(ProfilerContext);
+
+  // TRICKY
+  // Handle edge case where no commit is selected because of a min-duration filter update.
+  // If the commit index is null, suspending for data below would throw an error.
+  // TODO (ProfilerContext) This check should not be necessary.
+  if (selectedCommitIndex === null) {
+    return null;
+  }
+
+  const {changeDescriptions} = profilerStore.getCommitData(
+    ((rootID: any): number),
+    selectedCommitIndex,
+  );
+
+  if (changeDescriptions === null) {
+    return null;
+  }
+
+  const changeDescription = changeDescriptions.get(fiberID);
+  if (changeDescription == null) {
+    return null;
+  }
+
+  if (changeDescription.isFirstMount) {
+    return (
+      <div className={styles.Component}>
+        <label className={styles.Label}>Why did this render?</label>
+        <div className={styles.Item}>
+          This is the first time the component rendered.
+        </div>
+      </div>
+    );
+  }
+
+  const changes = [];
+
+  if (changeDescription.context === true) {
+    changes.push(
+      <div key="context" className={styles.Item}>
+        • Context changed
+      </div>,
+    );
+  } else if (
+    typeof changeDescription.context === 'object' &&
+    changeDescription.context !== null &&
+    changeDescription.context.length !== 0
+  ) {
+    changes.push(
+      <div key="context" className={styles.Item}>
+        • Context changed:
+        {changeDescription.context.map(key => (
+          <span key={key} className={styles.Key}>
+            {key}
+          </span>
+        ))}
+      </div>,
+    );
+  }
+
+  if (changeDescription.didHooksChange) {
+    changes.push(
+      <div key="hooks" className={styles.Item}>
+        • Hooks changed
+      </div>,
+    );
+  }
+
+  if (
+    changeDescription.props !== null &&
+    changeDescription.props.length !== 0
+  ) {
+    changes.push(
+      <div key="props" className={styles.Item}>
+        • Props changed:
+        {changeDescription.props.map(key => (
+          <span key={key} className={styles.Key}>
+            {key}
+          </span>
+        ))}
+      </div>,
+    );
+  }
+
+  if (
+    changeDescription.state !== null &&
+    changeDescription.state.length !== 0
+  ) {
+    changes.push(
+      <div key="state" className={styles.Item}>
+        • State changed:
+        {changeDescription.state.map(key => (
+          <span key={key} className={styles.Key}>
+            {key}
+          </span>
+        ))}
+      </div>,
+    );
+  }
+
+  if (changes.length === 0) {
+    changes.push(
+      <div key="nothing" className={styles.Item}>
+        The parent component rendered.
+      </div>,
+    );
+  }
+
+  return (
+    <div className={styles.Component}>
+      <label className={styles.Label}>Why did this render?</label>
+      {changes}
+    </div>
+  );
+}

packages/react-devtools-shared/src/devtools/views/Components/Tooltip.css

@@ -0,0 +1,24 @@
+.Tooltip {
+  position: absolute;
+  pointer-events: none;
+  border: none;
+  border-radius: 0.25rem;
+  padding: 0.25rem 0.5rem;
+  font-family: var(--font-family-sans);
+  font-size: 12px;
+  background-color: var(--color-tooltip-background);
+  color: var(--color-tooltip-text);
+  opacity: 1;
+  /* Make sure this is above the DevTools, which are above the Overlay */
+  z-index: 10000002;
+}
+
+.Tooltip.hidden {
+  opacity: 0;
+}
+
+
+.Container {
+  width: -moz-max-content;
+  width: -webkit-max-content;
+}

packages/react-devtools-shared/src/devtools/views/Components/Tooltip.js

@@ -0,0 +1,106 @@
+/** @flow */
+
+import React, {useRef} from 'react';
+
+import styles from './Tooltip.css';
+
+const initialTooltipState = {height: 0, mouseX: 0, mouseY: 0, width: 0};
+
+export default function Tooltip({children, label}: any) {
+  const containerRef = useRef(null);
+  const tooltipRef = useRef(null);
+
+  // update the position of the tooltip based on current mouse position
+  const updateTooltipPosition = (event: SyntheticMouseEvent<*>) => {
+    const element = tooltipRef.current;
+    if (element != null) {
+      // first find the mouse position
+      const mousePosition = getMousePosition(containerRef.current, event);
+      // use the mouse position to find the position of tooltip
+      const {left, top} = getTooltipPosition(element, mousePosition);
+      // update tooltip position
+      element.style.left = left;
+      element.style.top = top;
+    }
+  };
+
+  const onMouseMove = (event: SyntheticMouseEvent<*>) => {
+    updateTooltipPosition(event);
+  };
+
+  const tooltipClassName = label === null ? styles.hidden : '';
+
+  return (
+    <div
+      className={styles.Container}
+      onMouseMove={onMouseMove}
+      ref={containerRef}>
+      <div ref={tooltipRef} className={`${styles.Tooltip} ${tooltipClassName}`}>
+        {label}
+      </div>
+      {children}
+    </div>
+  );
+}
+
+// Method used to find the position of the tooltip based on current mouse position
+function getTooltipPosition(element, mousePosition) {
+  const {height, mouseX, mouseY, width} = mousePosition;
+  const TOOLTIP_OFFSET_X = 5;
+  const TOOLTIP_OFFSET_Y = 15;
+  let top = 0;
+  let left = 0;
+
+  // Let's check the vertical position.
+  if (mouseY + TOOLTIP_OFFSET_Y + element.offsetHeight >= height) {
+    // The tooltip doesn't fit below the mouse cursor (which is our
+    // default strategy). Therefore we try to position it either above the
+    // mouse cursor or finally aligned with the window's top edge.
+    if (mouseY - TOOLTIP_OFFSET_Y - element.offsetHeight > 0) {
+      // We position the tooltip above the mouse cursor if it fits there.
+      top = `${mouseY - element.offsetHeight - TOOLTIP_OFFSET_Y}px`;
+    } else {
+      // Otherwise we align the tooltip with the window's top edge.
+      top = '0px';
+    }
+  } else {
+    top = `${mouseY + TOOLTIP_OFFSET_Y}px`;
+  }
+
+  // Now let's check the horizontal position.
+  if (mouseX + TOOLTIP_OFFSET_X + element.offsetWidth >= width) {
+    // The tooltip doesn't fit at the right of the mouse cursor (which is
+    // our default strategy). Therefore we try to position it either at the
+    // left of the mouse cursor or finally aligned with the window's left
+    // edge.
+    if (mouseX - TOOLTIP_OFFSET_X - element.offsetWidth > 0) {
+      // We position the tooltip at the left of the mouse cursor if it fits
+      // there.
+      left = `${mouseX - element.offsetWidth - TOOLTIP_OFFSET_X}px`;
+    } else {
+      // Otherwise, align the tooltip with the window's left edge.
+      left = '0px';
+    }
+  } else {
+    left = `${mouseX + TOOLTIP_OFFSET_X * 2}px`;
+  }
+
+  return {left, top};
+}
+
+// method used to find the current mouse position inside the container
+function getMousePosition(
+  relativeContainer,
+  mouseEvent: SyntheticMouseEvent<*>,
+) {
+  if (relativeContainer !== null) {
+    const {height, top, width} = relativeContainer.getBoundingClientRect();
+
+    const mouseX = mouseEvent.clientX;
+    const mouseY = mouseEvent.clientY - top;
+
+    return {height, mouseX, mouseY, width};
+  } else {
+    return initialTooltipState;
+  }
+}

packages/react-devtools-shared/src/devtools/views/Profiler/ChartNode.js

@@ -18,6 +18,8 @@ type Props = {|
   label: string,
   onClick: (event: SyntheticMouseEvent<*>) => mixed,
   onDoubleClick?: (event: SyntheticMouseEvent<*>) => mixed,
+  onMouseEnter: (event: SyntheticMouseEvent<*>) => mixed,
+  onMouseLeave: (event: SyntheticMouseEvent<*>) => mixed,
   placeLabelAboveNode?: boolean,
   textStyle?: Object,
   width: number,
@@ -33,6 +35,8 @@ export default function ChartNode({
   isDimmed = false,
   label,
   onClick,
+  onMouseEnter,
+  onMouseLeave,
   onDoubleClick,
   textStyle,
   width,
@@ -41,12 +45,13 @@ export default function ChartNode({
 }: Props) {
   return (
     <g className={styles.Group} transform={`translate(${x},${y})`}>
-      <title>{label}</title>
       <rect
         width={width}
         height={height}
         fill={color}
         onClick={onClick}
+        onMouseEnter={onMouseEnter}
+        onMouseLeave={onMouseLeave}
         onDoubleClick={onDoubleClick}
         className={styles.Rect}
         style={{