Accesibility on Flutter

Talk presented in Flutter Mumbai https://www.meetup.com/Mumbai-Flutter/events/272334519/

Transcript

1. Accessibility on Flutter Apps for Everyone Lara Martín @Lariki Flutter/Dart GDE - Android Miguel Beltran @MiBLT Freelance Consultant Updated:
 August 2020
2. What’s accessibility? Design of products to be used by people with disabilities. Universal design Products that can be used by the widest majority of people. https://unsplash.com/@yomex4life
3. TECH ASSISTIVE ADAPTIVE Two ways of helping Blue2 by Ablenet
4. https://github.com/janoodleFTW/timy-messenger
5. Types of disability (some of them) Motor Disability Vision Neurodiversity
6. Accessibility Scanner
8. iOS Simulator: Fewer accessibility options! Simulator Real device
9. Motor Disability Vision Neurodiversity
10. Motor disability Challenges • Require large click areas • Require special hardware • Require voice activated software https://webaim.org/articles/motor/motordisabilities
11. Motor disability Challenges • Require large click areas • Require special hardware • Require voice activated software How to help • Games: Difficulty settings, turns • Keyboard navigation • Voice navigation • Adaptive UI components • Autocompletion https://webaim.org/articles/motor/motordisabilities
13. Keyboard Navigation - We try to open the user profile and navigate through the app but it doesn’t work well - “Selected” color hard to see most of the time
14. https://support.google.com/accessibility/android/answer/6122836?hl=en
15. Switch Access 1. Open user profile 2. Navigate back to chat window 3. Start creating a message
16. Found Issues Small touch targets Switch navigation worked well on start, but keyboard navigation was bad.
17. Motor Disability Vision Neurodiversity
18. Vision 4 levels of visual function • Blindness • Severe visual impairment • Moderate visual impairment • Mild vision https://www.who.int/news-room/fact-sheets/detail/blindness-and-visual-impairment
19. Vision 4 levels of visual function • Blindness • Severe visual impairment • Moderate visual impairment • Mild vision How to help • Large font sizes • Screen readers • High contrast content https://www.who.int/news-room/fact-sheets/detail/blindness-and-visual-impairment
20. Font Scaling • Make text larger • Supported by the Text widget • But not with RichText
21. Default Largest Font Scaling (Android)
22. Font Scaling (iOS)
23. Display Size (Android) • Make items larger • Not text, but UI components
24. Display Size (Android) Default Largest
25. Bold Text (iOS)
26. Magnify • Both on Android and iOS • Tab X times to zoom • Drag with X fingers
27. iOS: Unsupported Options? • Button Shapes (underline) • On/Off Labels • Reduce Transparency • Increase Contrast These show no difference.
28. Colorblindness Challenges • Not being able to see or differentiate certain colours • Affects 8% of male population, 0.5% women
29. Colorblindness Challenges • Not being able to see or differentiate certain colours • Affects 8% of male population, 0.5% women How to help • Use color AND icons to convey messages • Options to change color
30. Simulate Color Space (Android)
33. Android: TalkBack - Tap on screen reads Scaffold title. - Menu buttons are unlabelled - Attach button is unlabelled - Tap on message item reads the time + message but not the username - “Dogs are the best” - “Unlabelled button” - “16:18 - Good morning everyone! smiley face”
34. Android: TalkBack + Gestures - Swipe to navigate to next item. - TalkBar reads the item. - “Dogs are the best” - “Unlabelled button” - “16:18 - Good morning everyone! smiley face”
35. iOS: VoiceOver + Gestures - Swipe to navigate to next item. - VoiceOver reads the item. - Different reads than Android - “Dogs are the best” - “Image - Puzzles” - “Image - Possibly Menu” - “16:18 - Good morning everyone! smiley face”
36. Found Issues TalkBack: Missing labels TalkBack: Missing text descriptions like author of a message Low text contrast Display size not supported Unsupported iOS features
37. Motor Disability Vision Neurodiversity
38. Neurodiversity Challenges • Focusing problems • Learning difficulties • Autism • Dyslexia • ADHD
39. Neurodiversity Challenges • Focusing problems • Learning difficulties • Autism • Dyslexia • ADHD How to help • Minimal design • Voice narration and subtitles • Spell checking • Remember settings and passwords • Guide the user (without overwhelm)
40. Helping neurodiverse users: • Autocorrection is enabled • Capitalization by sentences not! We can help users write better by enabling Text Capitalization by sentences.
41. Helping neurodiverse users: • Offer text narration • Users can read and listen at the same time • Helps distracted minds We can help users with learning difficulties.
42. Found Issues Sentence Capitalization
43. Let’s Fix It
44. TODO LIST Fix touch targets for names and user avatars Fix sentence capitalisation Fix low text contrast Check dynamic font scaling with textScaleFactor Fix missing semantic labels on buttons Fix missing semantic text descriptions like author of a message
45. Touch Targets
46. Touch Target User Name InkWell( //... child: Text(author.name) ) InkWell is constrained to the child region. Not satisfying the “Minimum Interactive Dimension”
47. kMinInteractiveDimension “The minimum dimension of any interactive region according to Material guidelines.” 48.0 Android 44.0 iOS (kMinInteractiveDimensionCupertino) https://api.flutter.dev/flutter/material/kMinInteractiveDimension-constant.html
48. Touch Target with ConstrainedBox InkWell( //... child: ConstrainedBox( constraints: const BoxConstraints( minWidth: kMinInteractiveDimension, minHeight: kMinInteractiveDimension, ), child: Text(author.name) ) )
49. Fix Alignment in ConstrainedBox InkWell( //... child: ConstrainedBox( constraints: .. child: Align( alignment: Alignment.centerLeft, child: Text(author.name) ) ) )
50. Capitalization and Auto-Correct
51. TextField( textCapitalization: TextCapitalization.sentences, ) Fix text capitalisation: • Disabled by default (none) • Quick win! • Think of the use case.
52. TextField( enableSuggestions: true, autocorrect: true, ) More improvements for Neurodiverse users: • Autocorrection • Enable Suggestions Both are enabled by default.
53. Low Contrast
54. Low Contrast InputDecoration( hintStyle: AppTheme.inputHintTextStyle, ), Color.fromRGBO(153, 153, 153, 1.0);
55. MediaQuery HighContrast “Whether the user requested a high contrast between foreground and background content on iOS, via Settings -> Accessibility -> Increase Contrast.” MediaQuery.of(context).highContrast
56. MediaQuery HighContrast TextStyle( fontSize: 16 * pixelMultiplier, fontFamily: fontFamilyEdmondsansRegular, color: MediaQuery.of(context).highContrast ? Colors.black : colorTextDisabled, );
57. MediaQuery HighContrast
58. Text Scaling
59. RichText and textScaleFactor RichText allows you to have text spans to do things like (highlight URLs). Does not support text scaling by default! RichText( textScaleFactor: MediaQuery.of(context).textScaleFactor, text: … )
60. Semantic Labels
61. Missing Labels We need to add descriptions to Widgets! Semantics Widget • Explains what a piece of UI means. • It is enabled? • It is a button? • It is read only?
62. SemanticsDebugger • Draws each Semantics region • Displays the TalkBack text • Will help us fix the app! Add to the top of your Widget tree SemanticsDebugger( child: …Scaffold or similar… )
63. Fixing the Menu Button • Wrap with a Semantic Widget • Add a label “Menu” • Set Button to True Semantics( label: “Menu", button: true, child: MenuWidget(…) )
64. Fixing the Send Button • Add “enabled” status to Semantics Semantics( label: “Send", button: true, enabled: _enabled, child: SendWidget(…) ) Disabled Enabled • TalkBack says “Send button disabled”
65. Scaffold Semantics • Tap on the center reads AppBar title “Dogs are the best” • Wrap Scaffold with Semantics Semantics( label: "Chat Screen", child: Scaffold( … ) ) • Now reads “Chat Screen - Dogs are the best”
66. Fixing Messages Semantics( label: "Message from ${_author.name} ${_message.body} " "at ${DateFormat.Hm().format(_message.timestamp)}", child: MessageWidget(…) )
67. Fixing Messages ExcludeSemantics( child: RichText( … ) ) ExcludeSemantics to remove Text Widgets from Semantics tree
68. testWidgets(… { await tester.pumpWidget(CirclesApp()); expect(find.bySemanticsLabel("Menu"), findsOneWidget); }); Testing Semantics • Use bySemanticsLabel to find Widgets when testing • Easier to use than other Matchers! • And you help others!
69. We are done!
70. TODO DONE LIST Fix touch targets for names and user avatars Fix sentence capitalisation Fix low text contrast (iOS) Check dynamic font scaling with textScaleFactor Fix missing semantic labels on buttons Fix missing semantic text descriptions like author of a message
72. Summary Perform analysis with Accessibility Scanner on Android Test large scale fonts on iOS (larger setting) Use Semantics as alternative for Widget Tests for a win-win Embrace TextField features like capitalization
73. Thank You! L a r a M a r t í n F l u t t e r G D E A n d r o i d D e v e l o p e r @ L a r i k i M i g u e l B e l t r a n F r e e l a n c e C o n s u l t a n t @ M i B LT