Oh No! Flutter Web App is Not Rendering if Not Visible? Let’s Fix It!

Solution 1: Use the `window Visibility API`

One way to tackle this issue is by using the `window Visibility API`. This API allows you to detect when the page is visible or hidden, enabling you to take action accordingly.

<script>
  let visibilityChange = () => {
    if (document.visibilityState === 'visible') {
      // The page is now visible, render the app
      runApp();
    } else {
      // The page is hidden, pause the app
      pauseApp();
    }
  };

  document.addEventListener('visibilitychange', visibilityChange);
</script>

In the code above, we’re using the `visibilityChange` event listener to detect when the page’s visibility changes. When the page becomes visible, we call the `runApp()` function to render the app. Conversely, when the page is hidden, we call the `pauseApp()` function to pause the app.

Solution 2: Utilize `IntersectionObserver`

Another approach is to use the `IntersectionObserver` API, which allows you to detect when an element becomes visible or invisible within the viewport.

<script>
  const observer = new IntersectionObserver((entries) => {
    if (entries[0].isIntersecting) {
      // The app is now visible, render the app
      runApp();
    } else {
      // The app is hidden, pause the app
      pauseApp();
    }
  }, { threshold: 1.0 });

  observer.observe(document.getElementById('app-container'));
</script>

In this example, we create an `IntersectionObserver` instance and pass it a callback function that’s triggered when the observed element (in this case, the app container) becomes visible or invisible. When the app becomes visible, we call the `runApp()` function, and when it’s hidden, we call the `pauseApp()` function.

Solution 3: Leverage `MutationObserver`

Yet another approach is to use the `MutationObserver` API, which allows you to detect changes to the DOM, including changes to an element’s visibility.

<script>
  const observer = new MutationObserver((mutations) => {
    for (const mutation of mutations) {
      if (mutation.type === 'attributes' && mutation.attributeName === 'hidden') {
        if (mutation.target.hidden) {
          // The app is now hidden, pause the app
          pauseApp();
        } else {
          // The app is now visible, render the app
          runApp();
        }
      }
    }
  });

  observer.observe(document.getElementById('app-container'), {
    attributes: true,
    attributeFilter: ['hidden']
  });
</script>

In this example, we create a `MutationObserver` instance and pass it a callback function that’s triggered when the observed element’s `hidden` attribute changes. When the app becomes hidden, we call the `pauseApp()` function, and when it becomes visible, we call the `runApp()` function.

Solution 4: Flutter-Specific Solutions

If the above solutions don’t work for you, there are some Flutter-specific solutions you can try:

• Use `WidgetsBinding.instance.addPostFrameCallback`**: This allows you to schedule a callback to run after the frame is built, ensuring that the app is rendered when it becomes visible.
• Override `WidgetsBinding.deferFirstFrame`**: By overriding this method, you can control when the first frame is rendered, allowing you to render the app when it becomes visible.
• Use `TickerProviderStateMixin`**: This mixin provides a way to schedule ticks on the widget tree, enabling you to control when the app is rendered.