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gestures on mobile and keyboard shortcuts on desktop.
turn on VoiceOver or TalkBack on your mobile device and
navigate around your app.
to turn on the screen reader on your device, complete the following steps:
to learn how to find and customize android’s
accessibility features, view the following video.
to learn how to find and customize iOS
accessibility features, view the following video.
for web, the following screen readers are currently supported:
mobile browsers:
desktop browsers:
screen readers users on web must toggle the
“enable accessibility” button to build the semantics tree.
users can skip this step if you programmatically auto-enable
accessibility for your app using this API:
windows comes with a screen reader called narrator
but some developers recommend using the more popular
NVDA screen reader. to learn about using NVDA to test
windows apps, check out
screen readers 101 for Front-End developers (windows).
on a mac, you can use the desktop version of VoiceOver,
which is included in macOS.
on linux, a popular screen reader is called orca.
it comes pre-installed with some distributions
and is available on package repositories such as apt.
to learn about using orca, check out
getting started with orca screen reader on gnome desktop.
check out the following video demo to see victor tsaran,
using VoiceOver with the now-archived flutter gallery web app.
flutter’s standard widgets generate an accessibility tree automatically.
however, if your app needs something different,
it can be customized using the semantics widget.
when there is text in your app that should be voiced
with a specific voice, inform the screen reader
which voice to use by calling TextSpan.locale.
note that MaterialApp.locale and localizations.override
don’t affect which voice the screen reader uses.
usually, the screen reader uses the system voice
except where you explicitly set it with TextSpan.locale.
<topic_end>
<topic_start>
sufficient contrast
sufficient color contrast makes text and images easier to read.
along with benefitting users with various visual impairments,
sufficient color contrast helps all users when viewing an interface
on devices in extreme lighting conditions,
such as when exposed to direct sunlight or on a display with low
brightness.
the W3C recommends:
<topic_end>
<topic_start>
building with accessibility in mind
ensuring your app can be used by everyone means building accessibility
into it from the start. for some apps, that’s easier said than done.
in the video below, two of our engineers take a mobile app from a dire
accessibility state to one that takes advantage of flutter’s built-in
widgets to offer a dramatically more accessible experience.
<topic_end>
<topic_start>
testing accessibility on mobile
test your app using flutter’s accessibility guideline API.
this API checks if your app’s UI meets flutter’s accessibility recommendations.
these cover recommendations for text contrast, target size, and target labels.
the following example shows how to use the guideline API on name generator.
you created this app as part of the
write your first flutter app codelab.
each button on the app’s main screen serves as a tappable target
with text represented in 18 point.
<code_start>
final SemanticsHandle handle = tester.ensureSemantics();
await tester.pumpWidget(MyApp());
// checks that tappable nodes have a minimum size of 48 by 48 pixels
// for android.
await expectLater(tester, meetsGuideline(androidTapTargetGuideline));
// checks that tappable nodes have a minimum size of 44 by 44 pixels
// for iOS.
await expectLater(tester, meetsGuideline(iOSTapTargetGuideline));
// checks that touch targets with a tap or long press action are labeled.
await expectLater(tester, meetsGuideline(labeledTapTargetGuideline));
// checks whether semantic nodes meet the minimum text contrast levels.
// the recommended text contrast is 3:1 for larger text
// (18 point and above regular).
await expectLater(tester, meetsGuideline(textContrastGuideline));
handle.dispose();
<code_end>
you can add guideline API tests
in test/widget_test.dart of your app directory, or as a separate test
file (such as test/a11y_test.dart in the case of the name generator).
<topic_end>
<topic_start>
testing accessibility on web
you can debug accessibility by visualizing the semantic nodes created for your web app
using the following command line flag in profile and release modes:
with the flag activated, the semantic nodes appear on top of the widgets;
you can verify that the semantic elements are placed where they should be.
if the semantic nodes are incorrectly placed, please file a bug report.
<topic_end>
<topic_start>
accessibility release checklist
here is a non-exhaustive list of things to consider as you prepare your