Modifying and Testing Focus Management in TV Apps

In this section, we’ll modify our app to gain insights into how focus moves through our content grid. Then, we’ll test these changes to better understand focus management in TV apps.

Step 1: Modifying the SpatialNavigationFocusableView

Let’s start by locating the renderScrollableRow function in app/(drawer)/index.tsx. This function is responsible for rendering each row of content in our grid. Within this function, we’ll modify the SpatialNavigationFocusableView to log focus events.

const renderScrollableRow = useCallback((title: string, ref: React.RefObject<FlatList>) => {
  const renderItem = useCallback(({ item, index }: { item: CardData; index: number }) => (
    <SpatialNavigationFocusableView
      onSelect={() => { 
        router.push({
          pathname: '/details',
          params: { 
            title: item.title,
            description: item.description,
            headerImage: item.headerImage
          }         
        });
      }}
      onFocus={() => {
        setFocusedIndex(index);
        console.log(`Focused on ${item.title} (index: ${index})`);  // Modified this line
      }}
    >
      {({ isFocused }) => (
        <View style={[styles.highlightThumbnail, isFocused && styles.highlightThumbnailFocused]}>
          <Image source={item.headerImage} style={styles.headerImage} />
          <View style={styles.thumbnailTextContainer}>
            <Text style={styles.thumbnailText}>{item.title}</Text>   
          </View>
        </View>
      )}
    </SpatialNavigationFocusableView>
  ), [router, styles]);
 
  // ... rest of the function
}, [styles]);

Key changes:

• We’ve added a console.log statement in the onFocus callback.
• We’re logging both the title of the focused item and its index in the list.

Step 2: Implementing the Changes

Now, let’s implement these changes:

1. Open app/(drawer)/index.tsx in your code editor.
2. Locate the renderScrollableRow function.
3. Find the SpatialNavigationFocusableView component within this function.
4. Modify the onFocus callback as shown in the code above.
5. Save your changes.

Step 3: Testing Focus Management

With our changes in place, let’s test the focus management:

1. Ensure your app is running in development mode.
2. Open your browser’s developer tools (or the appropriate console for your development environment).
3. Navigate to the home screen of your app where the content grid is visible.

Now, let’s test the focus behavior:

1. Use the arrow keys on your keyboard to navigate through the content grid. This simulates using a TV remote control.

2. As you move the focus, observe the console logs. You should see messages like:

Focused on Wagon Train Warriors (index: 0)
Focused on Frontier Hearts (index: 1)
Focused on The Journey West (index: 2)

3. Pay attention to how focus moves:

   • Left and right navigation should move focus within a row.

4. Try navigating to the edges of the grid:

   • What happens when you try to move focus past the first or last item in a row?
   • What happens when you try to move focus above the first row or below the last row?

5. Observe how focus wraps or stops at the edges, depending on the implementation.

Step 4: Analyzing Focus Behavior

As you test, consider the following:

1. Predictability: Is the focus movement predictable? Can you anticipate where the focus will move with each key press?

2. Visual Feedback: Is it always clear which item is focused? How does the visual appearance change for focused items?

3. Edge Behavior: How does the app handle focus at the edges of the grid? Does it wrap around, stop, or behave in some other way?

4. Performance: Does focus movement remain smooth even when navigating quickly through the grid?

5. Default Focus: When you first land on this screen, which item is focused by default? Is this a logical starting point?

Step 5: Further Experimentation

Now that you understand how focus is currently managed, try making some modifications:

Modify how a focused card appears, for example change its scale or color.

Conclusion

Understanding and fine-tuning focus management is crucial for creating a great user experience in TV apps.