feat(UI builder): Add ability to compute screen reader narration of focused element in … …use mode

packages/fluentui/react-builder/src/components/Canvas.tsx

@@ -332,11 +332,12 @@ export const Canvas: React.FunctionComponent<CanvasProps> = ({
  )}
  {inUseMode && <EventListener capture type="focus" listener={handleFocus} target={document} />}
  {renderJSONTreeToJSXElement(jsonTree, renderJSONTreeElement)}
- {selectedComponent && (
- <div style={{ bottom: '0', position: 'absolute' }}>
- <ReaderNarration selector={`[data-builder-id="${selectedComponent.uuid}"]`} />
- </div>
- )}
+ <div style={{ bottom: '0', position: 'absolute' }}>
+ <ReaderNarration
+ selector={selectedComponent ? `[data-builder-id="${selectedComponent.uuid}"]` : null}
+ inUseMode={inUseMode}
+ />
+ </div>
  </Provider>
  </>
  )}

packages/fluentui/react-builder/src/components/ReaderNarration.tsx

@@ -3,73 +3,104 @@ import { Alert, Ref, Dropdown, DropdownProps } from '@fluentui/react-northstar';
 import { IAriaElement } from './../narration/NarrationComputer';
 import { DescendantsNarrationsComputer } from './../narration/DescendantsNarrationsComputer';
 
-const computer: DescendantsNarrationsComputer = new DescendantsNarrationsComputer();
-let narrationTexts: Record<string, string> = {};
+const computer = new DescendantsNarrationsComputer();
+let narrationPath = null;
+let narrationPaths = [];
+let narrationTexts = {};
 const aomMissing = !(window as any).getComputedAccessibleNode;
 
 export type ReaderNarrationProps = {
  selector: string;
+ inUseMode: boolean;
 };
 
-export const ReaderNarration: React.FunctionComponent<ReaderNarrationProps> = ({ selector }) => {
+export const ReaderNarration: React.FunctionComponent<ReaderNarrationProps> = ({ selector, inUseMode }) => {
  const ref = React.useRef<HTMLElement>();
+ const [selectedNarrationPath, setSelectedNarrationPath] = React.useState(null);
  const [narrationText, setNarrationText] = React.useState('');
- const [narrationPath, setNarrationPath] = React.useState('');
- const [narrationPaths, setNarrationPaths] = React.useState([]);
 
- React.useEffect(() => {
- if (!ref.current) {
- return;
- }
-
- if (aomMissing) {
- return;
- }
-
- const element = ref.current.ownerDocument.querySelector(selector) as IAriaElement;
-
- // Compute and store the narrations for the element and its focusable descendants
+ // Computes and saves the narration paths and texts for the given parent element and its focusable descendants
+ const computeAndSave = React.useCallback(element => {
  computer.compute(element, 'Win/JAWS').then(narrations => {
- const paths: string[] = [];
+ narrationPaths = [];
  narrationTexts = {};
  narrations.forEach(narration => {
  // Begin forEach 1
  const path = narration.path.join(' > ');
- paths.push(path);
+ narrationPaths.push(path);
  narrationTexts[path] = narration.text;
  }); // End forEach 1
 
- // Update the narration paths dropdown values
- setNarrationPaths(paths);
+ // If narration path has not been selected by user, preselect the first path and its associated narration as defaults
+ const text = narrationPath == null ? narrations[0]?.text || null : narrationTexts[narrationPath];
+ if (narrationPath == null && narrationPaths.length > 1) {
+ // Begin if 1
+ setSelectedNarrationPath(narrationPaths[0]);
+ } // End if 1
 
- // If some narration has been retrieved, choose the first one as the narration to be displayed
- const text = narrations[0]?.text || null;
  setCompleteText(text);
  }); // End compute
- });
+ }, []); // End computeAndSave
 
- // Composes and sets the complete screen reader narration text to be displayed
+ // Sets the complete screen reader narration text to be displayed.
  const setCompleteText = text => {
- setNarrationText(`Narration: ${text}`);
+ setNarrationText(text !== null ? `Narration: ${text}` : null);
  }; // End setCompleteText
 
+ // Handles the "focusin" event by computing and saving the narration paths and texts.
+ const handleFocusIn = React.useCallback(
+ event => {
+ computeAndSave(event.target as IAriaElement);
+ },
+ [computeAndSave],
+ ); // End handleFocusIn
+
+ // Handles the narration path dropdown change event by saving the narration path.
  const handleNarrationPathChange = (event: any, props: DropdownProps) => {
- setNarrationPath(props.value as string);
- const text = narrationTexts[props.value as string];
+ narrationPath = props.value as string;
+ setSelectedNarrationPath(narrationPath);
+ const text = narrationTexts[narrationPath];
  setCompleteText(text);
  }; // End handleNarrationPathChange
 
- if (!selector) {
+ // Recomputes the narration paths and texts upon every render.
+ React.useEffect(() => {
+ if (inUseMode || !ref.current || aomMissing) {
+ return;
+ }
+
+ // Compute and save the narration paths and texts for the selected component's parent element and its focusable descendants
+ const element = ref.current.ownerDocument.querySelector(selector) as IAriaElement;
+ computeAndSave(element);
+ }); // End useEffect
+
+ // Resets the narration path to its defaults if selector changes.
+ React.useEffect(() => {
+ narrationPath = null;
+ }, [selector]); // End useEffect
+
+ // If in the use mode, sets up the "focusin" event listener.
+ React.useEffect(() => {
+ const alert = ref.current;
+ if (!inUseMode || !alert) {
+ return null;
+ }
+ alert.ownerDocument.addEventListener('focusin', handleFocusIn);
+ return () => {
+ alert.ownerDocument.removeEventListener('focusin', handleFocusIn);
+ }; // End return
+ }, [inUseMode, handleFocusIn]); // End useEffect
+
+ if (selector == null && !inUseMode) {
  return null;
  }
-
  return (
  <>
  {narrationPaths.length > 1 && (
  <Dropdown
  items={narrationPaths}
- defaultValue={narrationPath}
- value={narrationPath}
+ defaultValue={selectedNarrationPath}
+ value={selectedNarrationPath}
  onChange={handleNarrationPathChange}
  getA11ySelectionMessage={{
  onAdd: item => `${item} has been selected.`,

packages/fluentui/react-builder/src/narration/DescendantsNarrationsComputer.tsx

@@ -28,9 +28,9 @@ export class DescendantsNarrationsComputer {
  // Begin if 1
  parents.push(element);
  } // End if 1
- Array.from(element.children).forEach((child: IAriaElement) => {
+ Array.from(element.children).forEach(child => {
  // Begin foreach 1
- this.findActiveDescendantsParents(child, parents);
+ this.findActiveDescendantsParents(child as IAriaElement, parents);
  }); // End foreach 1
  } // End findActiveDescendantsParents