123 lines
5.3 KiB
Markdown
123 lines
5.3 KiB
Markdown
# Background
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This document is used as aria/accessibility(a11y) reference for future developers.
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There are a lot of a11y problems in the Fomantic UI library. Files in
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`web_src/js/modules/fomantic/` are used as a workaround to make the UI more accessible.
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The aria-related code is designed to avoid touching the official Fomantic UI library,
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and to be as independent as possible, so it can be easily modified/removed in the future.
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To test the aria/accessibility with screen readers, developers can use the following steps:
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* On macOS, you can use VoiceOver.
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* Press `Command + F5` to turn on VoiceOver.
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* Try to operate the UI with keyboard-only.
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* Use Tab/Shift+Tab to switch focus between elements.
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* Arrow keys (Option+Up/Down) to navigate between menu/combobox items (only aria-active, not really focused).
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* Press Enter to trigger the aria-active element.
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* On Android, you can use TalkBack.
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* Go to Settings -> Accessibility -> TalkBack, turn it on.
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* Long-press or press+swipe to switch the aria-active element (not really focused).
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* Double-tap means old single-tap on the aria-active element.
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* Double-finger swipe means old single-finger swipe.
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* TODO: on Windows, on Linux, on iOS
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# Known Problems
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* Tested with Apple VoiceOver: If a dropdown menu/combobox is opened by mouse click, then arrow keys don't work.
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But if the dropdown is opened by keyboard Tab, then arrow keys work, and from then on, the keys almost work with mouse click too.
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The clue: when the dropdown is only opened by mouse click, VoiceOver doesn't send 'keydown' events of arrow keys to the DOM,
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VoiceOver expects to use arrow keys to navigate between some elements, but it couldn't.
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Users could use Option+ArrowKeys to navigate between menu/combobox items or selection labels if the menu/combobox is opened by mouse click.
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# Checkbox
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## Accessibility-friendly Checkbox
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The ideal checkboxes should be:
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```html
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<label><input type="checkbox"> ... </label>
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```
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However, related CSS styles aren't supported (not implemented) yet, so at the moment,
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almost all the checkboxes are still using Fomantic UI checkbox.
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## Fomantic UI Checkbox
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```html
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<div class="ui checkbox">
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<input type="checkbox"> <!-- class "hidden" will be added by $.checkbox() -->
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<label>...</label>
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</div>
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```
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Then the JS `$.checkbox()` should be called to make it work with keyboard and label-clicking,
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then it works like the ideal checkboxes.
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There is still a problem: Fomantic UI checkbox is not friendly to screen readers,
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so we add IDs to all the Fomantic UI checkboxes automatically by JS.
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If the `label` part is empty, then the checkbox needs to get the `aria-label` attribute manually.
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# Fomantic Dropdown
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Fomantic Dropdown is designed to be used for many purposes:
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* Menu (the profile menu in navbar, the language menu in footer)
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* Popup (the branch/tag panel, the review box)
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* Simple `<select>` , used in many forms
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* Searchable option-list with static items (used in many forms)
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* Searchable option-list with dynamic items (ajax)
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* Searchable multiple selection option-list with dynamic items: the repo topic setting
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* More complex usages, like the Issue Label selector
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Fomantic Dropdown requires that the focus must be on its primary element.
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If the focus changes, it hides or panics.
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At the moment, the aria-related code only tries to partially resolve the a11y problems for dropdowns with items.
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There are different solutions:
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* combobox + listbox + option:
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* https://www.w3.org/WAI/ARIA/apg/patterns/combobox/
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* A combobox is an input widget with an associated popup that enables users to select a value for the combobox from
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a collection of possible values. In some implementations, the popup presents allowed values, while in other implementations,
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the popup presents suggested values, and users may either select one of the suggestions or type a value.
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* menu + menuitem:
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* https://www.w3.org/WAI/ARIA/apg/patterns/menubar/
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* A menu is a widget that offers a list of choices to the user, such as a set of actions or functions.
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The current approach is: detect if the dropdown has an input,
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if yes, it works like a combobox, otherwise it works like a menu.
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Multiple selection dropdown is not well-supported yet, it needs more work.
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Some important pages for dropdown testing:
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* Home(dashboard) page, the "Create Repo" / "Profile" / "Language" menu.
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* Create New Repo page, a lot of dropdowns as combobox.
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* Collaborators page, the "permission" dropdown (the old behavior was not quite good, it just works).
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```html
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<!-- read-only dropdown -->
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<div class="ui dropdown"> <!-- focused here, then it's not perfect to use aria-activedescendant to point to the menu item -->
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<input type="hidden" ...>
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<div class="text">Default</div>
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<div class="menu" tabindex="-1"> <!-- "transition hidden|visible" classes will be added by $.dropdown() and when the dropdown is working -->
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<div class="item active selected">Default</div>
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<div class="item">...</div>
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</div>
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</div>
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<!-- search input dropdown -->
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<div class="ui dropdown">
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<input type="hidden" ...>
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<input class="search" autocomplete="off" tabindex="0"> <!-- focused here -->
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<div class="text"></div>
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<div class="menu" tabindex="-1"> <!-- "transition hidden|visible" classes will be added by $.dropdown() and when the dropdown is working -->
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<div class="item selected">...</div>
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<div class="item">...</div>
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</div>
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</div>
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```
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