Michael Sheldon's Stuff

While developing Pied, I discovered that Flutter’s AlertDialog widget isn’t accessible to screen reader users (there’s been a bug report filed against this for over a year). Text within the AlertDialog doesn’t get sent to the screen reader when the dialog is focused. The user has no indication that the dialog is present, let alone what its contents are.

Example

The following video demonstrates a typical Flutter AlertDialog with the Orca screen reader enabled. When the ‘Launch inaccessible alert’ button is pressed an alert dialog appears, but the screen reader is unable to read its contents. The ‘Launch accessible alert’ button is then pressed and an accessible alert dialog is demonstrated, with the screen reader successfully reading the contents of the dialog.

The example application used in the video can be found in the accessible_alert_example GitHub repository.

Creating a standard alert dialog

The following code will create a normal Flutter AlertDialog as recommended in the official Flutter documentation. Unfortunately this doesn’t work correctly for screen reader users:

showDialog(
  context: context,
  builder: (context) => AlertDialog(
    actions: [
      TextButton(
        onPressed: () {
          Navigator.pop(context);
        },
      child: const Text('Close Alert'),
      )
    ],
    content: Text(
      'This text is invisible to screen readers. There is no indication that this dialog has even appeared.'
    ),
  )
);

Creating an accessible alert dialog

By making a few small changes to the above code we can make it work correctly with screen readers. First we wrap the AlertDialog in a Semantics widget. This allows us to attach a screen reader friendly label to the AlertDialog. The Semantics label text should be the same as the text displayed in the AlertDialog. Finally, to have this text read as soon as the alert is triggered, we enable autofocus on the TextButton:

showDialog(
  context: context,
  builder: (context) => Semantics(
    label: 'This text will be read by a screen reader. It is clear to the user that something has happened.',
    enabled: true,
    container: true,
    child: AlertDialog(
      actions: [
        TextButton(
          autofocus: true,
          onPressed: () {
            Navigator.pop(context);
          },
          child: const Text('Close Alert'),
        )
      ],
      content: Text(
        'This text will be read by a screen reader. It is clear to the user that something has happened.'
      ),
    )
  )
);