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Use a general approch to improve a11y for all checkboxes and dropdowns. (#23542) 

This PR follows #22599 and #23450

The major improvements:

1. The `aria-*.js` are totally transparent now, no need to call
`attachDropdownAria` explicitly anymore.
* It hooks the `$.fn.checkbox` and `$.fn.dropdown`, then our patch
works.
* It makes all dynamically generated checkbox/dropdown work with a11y
without any change
* eg: the `conversation.find('.dropdown').dropdown();` in `repo-diff.js`
2. Since it's totally transparent now, it could be easier to modify or
remove in the future.
3. It handles all selection labels as well (by onLabelCreate), so it
supports "multiple selection dropdown" now.
* It partially completes one of my TODOs: `TODO: multiple selection is
not supported yet.`
4. The code structure is clearer, code blocks are splitted into
different functions.
* The old `attachOneDropdownAria` was splitted into separate functions.
* It makes it easier to add more fine tunes in the future, and co-work
with contributors.
6. The code logic is similar as before, only two new parts: 
    1. the `ariaCheckboxFn` and `ariaDropdownFn` functions
    2. the `onLabelCreate` and `updateSelectionLabel` functions

In `aria-dropdown.js` I had to mix jQuery and Vanilla JS somewhat, I
think the code is still understandable, otherwise the code would be much
more complex to read.

Thanks to fsologureng for the idea about "improving the 'delete icon'
with aria attributes".

If there is anything unclear or incorrect, feel free to ask and discuss,
or propose new PRs for it.
This commit is contained in:
wxiaoguang 2023-03-22 10:52:01 +08:00 committed by GitHub
parent 43809e66ac
commit d4f35bd681
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GPG Key ID: 4AEE18F83AFDEB23
8 changed files with 198 additions and 94 deletions
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1
options/locale/locale_en-US.ini
View File

@ -84,6 +84,7 @@ add = Add
add_all = Add All
remove = Remove
remove_all = Remove All
remove_label_str = Remove item "%s"
edit = Edit
enabled = Enabled

1
templates/base/head_script.tmpl
View File

@ -41,6 +41,7 @@ If you introduce mistakes in it, Gitea JavaScript code wouldn't run correctly.
copy_error: '{{.locale.Tr "copy_error"}}',
error_occurred: '{{.locale.Tr "error.occurred"}}',
network_error: '{{.locale.Tr "error.network_error"}}',
remove_label_str: '{{.locale.Tr "remove_label_str"}}',
},
};
{{/* in case some pages don't render the pageData, we make sure it is an object to prevent null access */}}

5
web_src/js/features/common-global.js
View File

@ -4,7 +4,6 @@ import {mqBinarySearch} from '../utils.js';
import {createDropzone} from './dropzone.js';
import {initCompColorPicker} from './comp/ColorPicker.js';
import {showGlobalErrorMessage} from '../bootstrap.js';
import {attachCheckboxAria, attachDropdownAria} from './aria.js';
import {handleGlobalEnterQuickSubmit} from './comp/QuickSubmit.js';
import {initTooltip} from '../modules/tippy.js';
import {svg} from '../svg.js';
@ -123,9 +122,7 @@ export function initGlobalCommon() {
$uiDropdowns.filter('.slide.up').dropdown({transition: 'slide up'});
$uiDropdowns.filter('.upward').dropdown({direction: 'upward'});
attachDropdownAria($uiDropdowns);
attachCheckboxAria($('.ui.checkbox'));
$('.ui.checkbox').checkbox();
$('.tabular.menu .item').tab();
$('.tabable.menu .item').tab();

5
web_src/js/index.js
View File

@ -89,6 +89,8 @@ import {initFormattingReplacements} from './features/formatting.js';
import {initCopyContent} from './features/copycontent.js';
import {initCaptcha} from './features/captcha.js';
import {initRepositoryActionView} from './components/RepoActionView.vue';
import {initAriaCheckboxPatch} from './modules/aria/checkbox.js';
import {initAriaDropdownPatch} from './modules/aria/dropdown.js';
// Run time-critical code as soon as possible. This is safe to do because this
// script appears at the end of <body> and rendered HTML is accessible at that point.
@ -98,6 +100,9 @@ initFormattingReplacements();
$.fn.tab.settings.silent = true;
// Disable the behavior of fomantic to toggle the checkbox when you press enter on a checkbox element.
$.fn.checkbox.settings.enableEnterKey = false;
// Use the patches to improve accessibility, these patches are designed to be as independent as possible, make it easy to modify or remove in the future.
initAriaCheckboxPatch();
initAriaDropdownPatch();
$(document).ready(() => {
initGlobalCommon();

12
web_src/js/features/aria.md → web_src/js/modules/aria/aria.md
View File

@ -23,6 +23,14 @@ To test the aria/accessibility with screen readers, developers can use the follo
* Double-finger swipe means old single-finger swipe.
* TODO: on Windows, on Linux, on iOS
# Known Problems
* Tested with Apple VoiceOver: If a dropdown menu/combobox is opened by mouse click, then arrow keys don't work.
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.
The clue: when the dropdown is only opened by mouse click, VoiceOver doesn't send 'keydown' events of arrow keys to the DOM,
VoiceOver expects to use arrow keys to navigate between some elements, but it couldn't.
Users could use Option+ArrowKeys to navigate between menu/combobox items or selection labels if the menu/combobox is opened by mouse click.
# Checkbox
## Accessibility-friendly Checkbox
@ -52,9 +60,7 @@ There is still a problem: Fomantic UI checkbox is not friendly to screen readers
so we add IDs to all the Fomantic UI checkboxes automatically by JS.
If the `label` part is empty, then the checkbox needs to get the `aria-label` attribute manually.
# Dropdown
## Fomantic UI Dropdown
# Fomantic Dropdown
Fomantic Dropdown is designed to be used for many purposes:

5
web_src/js/modules/aria/base.js Normal file
View File

@ -0,0 +1,5 @@
let ariaIdCounter = 0;
export function generateAriaId() {
return `_aria_auto_id_${ariaIdCounter++}`;
}

38
web_src/js/modules/aria/checkbox.js Normal file
View File

@ -0,0 +1,38 @@
import $ from 'jquery';
import {generateAriaId} from './base.js';
const ariaPatchKey = '_giteaAriaPatchCheckbox';
const fomanticCheckboxFn = $.fn.checkbox;
// use our own `$.fn.checkbox` to patch Fomantic's checkbox module
export function initAriaCheckboxPatch() {
if ($.fn.checkbox === ariaCheckboxFn) throw new Error('initAriaCheckboxPatch could only be called once');
$.fn.checkbox = ariaCheckboxFn;
ariaCheckboxFn.settings = fomanticCheckboxFn.settings;
}
// the patched `$.fn.checkbox` checkbox function
// * it does the one-time attaching on the first call
function ariaCheckboxFn(...args) {
const ret = fomanticCheckboxFn.apply(this, args);
for (const el of this) {
if (el[ariaPatchKey]) continue;
attachInit(el);
}
return ret;
}
function attachInit(el) {
// Fomantic UI checkbox needs to be something like: <div class="ui checkbox"><label /><input /></div>
// It doesn't work well with <label><input />...</label>
// To make it work with aria, the "id"/"for" attributes are necessary, so add them automatically if missing.
// In the future, refactor to use native checkbox directly, then this patch could be removed.
el[ariaPatchKey] = {}; // record that this element has been patched
const label = el.querySelector('label');
const input = el.querySelector('input');
if (!label || !input || input.getAttribute('id')) return;
const id = generateAriaId();
input.setAttribute('id', id);
label.setAttribute('for', id);
}

225
web_src/js/features/aria.js → web_src/js/modules/aria/dropdown.js
View File

@ -1,14 +1,116 @@
import $ from 'jquery';
import {generateAriaId} from './base.js';
let ariaIdCounter = 0;
const ariaPatchKey = '_giteaAriaPatchDropdown';
const fomanticDropdownFn = $.fn.dropdown;
function generateAriaId() {
return `_aria_auto_id_${ariaIdCounter++}`;
// use our own `$().dropdown` function to patch Fomantic's dropdown module
export function initAriaDropdownPatch() {
if ($.fn.dropdown === ariaDropdownFn) throw new Error('initAriaDropdownPatch could only be called once');
$.fn.dropdown = ariaDropdownFn;
ariaDropdownFn.settings = fomanticDropdownFn.settings;
}
function attachOneDropdownAria($dropdown) {
if ($dropdown.attr('data-aria-attached') || $dropdown.hasClass('custom')) return;
$dropdown.attr('data-aria-attached', 1);
// the patched `$.fn.dropdown` function, it passes the arguments to Fomantic's `$.fn.dropdown` function, and:
// * it does the one-time attaching on the first call
// * it delegates the `onLabelCreate` to the patched `onLabelCreate` to add necessary aria attributes
function ariaDropdownFn(...args) {
const ret = fomanticDropdownFn.apply(this, args);
// if the `$().dropdown()` call is without arguments, or it has non-string (object) argument,
// it means that this call will reset the dropdown internal settings, then we need to re-delegate the callbacks.
const needDelegate = (!args.length || typeof args[0] !== 'string');
for (const el of this) {
const $dropdown = $(el);
if (!el[ariaPatchKey]) {
attachInit($dropdown);
}
if (needDelegate) {
delegateOne($dropdown);
}
}
return ret;
}
// make the item has role=option/menuitem, add an id if there wasn't one yet, make items as non-focusable
// the elements inside the dropdown menu item should not be focusable, the focus should always be on the dropdown primary element.
function updateMenuItem(dropdown, item) {
if (!item.id) item.id = generateAriaId();
item.setAttribute('role', dropdown[ariaPatchKey].listItemRole);
item.setAttribute('tabindex', '-1');
for (const a of item.querySelectorAll('a')) a.setAttribute('tabindex', '-1');
}
// make the label item and its "delete icon" has correct aria attributes
function updateSelectionLabel($label) {
// the "label" is like this: "<a|div class="ui label" data-value="1">the-label-name <i|svg class="delete icon"/></a>"
if (!$label.attr('id')) $label.attr('id', generateAriaId());
$label.attr('tabindex', '-1');
$label.find('.delete.icon').attr({
'aria-hidden': 'false',
'aria-label': window.config.i18n.remove_label_str.replace('%s', $label.attr('data-value')),
'role': 'button',
});
}
// delegate the dropdown's template functions and callback functions to add aria attributes.
function delegateOne($dropdown) {
const dropdownCall = fomanticDropdownFn.bind($dropdown);
// the "template" functions are used for dynamic creation (eg: AJAX)
const dropdownTemplates = {...dropdownCall('setting', 'templates'), t: performance.now()};
const dropdownTemplatesMenuOld = dropdownTemplates.menu;
dropdownTemplates.menu = function(response, fields, preserveHTML, className) {
// when the dropdown menu items are loaded from AJAX requests, the items are created dynamically
const menuItems = dropdownTemplatesMenuOld(response, fields, preserveHTML, className);
const $wrapper = $('<div>').append(menuItems);
const $items = $wrapper.find('> .item');
$items.each((_, item) => updateMenuItem($dropdown[0], item));
$dropdown[0][ariaPatchKey].deferredRefreshAriaActiveItem();
return $wrapper.html();
};
dropdownCall('setting', 'templates', dropdownTemplates);
// the `onLabelCreate` is used to add necessary aria attributes for dynamically created selection labels
const dropdownOnLabelCreateOld = dropdownCall('setting', 'onLabelCreate');
dropdownCall('setting', 'onLabelCreate', function(value, text) {
const $label = dropdownOnLabelCreateOld.call(this, value, text);
updateSelectionLabel($label);
return $label;
});
}
// for static dropdown elements (generated by server-side template), prepare them with necessary aria attributes
function attachStaticElements($dropdown, $focusable, $menu) {
const dropdown = $dropdown[0];
// prepare static dropdown menu list popup
if (!$menu.attr('id')) $menu.attr('id', generateAriaId());
$menu.find('> .item').each((_, item) => updateMenuItem(dropdown, item));
// this role could only be changed after its content is ready, otherwise some browsers+readers (like Chrome+AppleVoice) crash
$menu.attr('role', dropdown[ariaPatchKey].listPopupRole);
// prepare selection label items
$dropdown.find('.ui.label').each((_, label) => updateSelectionLabel($(label)));
// make the primary element (focusable) aria-friendly
$focusable.attr({
'role': $focusable.attr('role') ?? dropdown[ariaPatchKey].focusableRole,
'aria-haspopup': dropdown[ariaPatchKey].listPopupRole,
'aria-controls': $menu.attr('id'),
'aria-expanded': 'false',
});
// use tooltip's content as aria-label if there is no aria-label
if ($dropdown.hasClass('tooltip') && $dropdown.attr('data-content') && !$dropdown.attr('aria-label')) {
$dropdown.attr('aria-label', $dropdown.attr('data-content'));
}
}
function attachInit($dropdown) {
const dropdown = $dropdown[0];
dropdown[ariaPatchKey] = {};
if ($dropdown.hasClass('custom')) return;
// Dropdown has 2 different focusing behaviors
// * with search input: the input is focused, and it works with aria-activedescendant pointing another sibling element.
@ -23,71 +125,39 @@ function attachOneDropdownAria($dropdown) {
// - if the menu item is clickable (eg: <a>), then trigger the click event
// - otherwise, the dropdown control (low-level code) handles the Enter event, hides the dropdown menu
// TODO: multiple selection is not supported yet.
// TODO: multiple selection is only partially supported. Check and test them one by one in the future.
const $textSearch = $dropdown.find('input.search').eq(0);
const $focusable = $textSearch.length ? $textSearch : $dropdown; // the primary element for focus, see comment above
if (!$focusable.length) return;
let $menu = $dropdown.find('> .menu');
if (!$menu.length) {
// some "multiple selection" dropdowns don't have a static menu element in HTML, we need to pre-create it to make it have correct aria attributes
$menu = $('<div class="menu"></div>').appendTo($dropdown);
}
// There are 2 possible solutions about the role: combobox or menu.
// The idea is that if there is an input, then it's a combobox, otherwise it's a menu.
// Since #19861 we have prepared the "combobox" solution, but didn't get enough time to put it into practice and test before.
const isComboBox = $dropdown.find('input').length > 0;
const focusableRole = isComboBox ? 'combobox' : 'button';
const listPopupRole = isComboBox ? 'listbox' : 'menu';
const listItemRole = isComboBox ? 'option' : 'menuitem';
dropdown[ariaPatchKey].focusableRole = isComboBox ? 'combobox' : 'button';
dropdown[ariaPatchKey].listPopupRole = isComboBox ? 'listbox' : 'menu';
dropdown[ariaPatchKey].listItemRole = isComboBox ? 'option' : 'menuitem';
// make the item has role=option/menuitem, add an id if there wasn't one yet, make items as non-focusable
// the elements inside the dropdown menu item should not be focusable, the focus should always be on the dropdown primary element.
function prepareMenuItem($item) {
if (!$item.attr('id')) $item.attr('id', generateAriaId());
$item.attr({'role': listItemRole, 'tabindex': '-1'});
$item.find('a').attr('tabindex', '-1');
}
// delegate the dropdown's template function to add aria attributes.
// the "template" functions are used for dynamic creation (eg: AJAX)
const dropdownTemplates = {...$dropdown.dropdown('setting', 'templates')};
const dropdownTemplatesMenuOld = dropdownTemplates.menu;
dropdownTemplates.menu = function(response, fields, preserveHTML, className) {
// when the dropdown menu items are loaded from AJAX requests, the items are created dynamically
const menuItems = dropdownTemplatesMenuOld(response, fields, preserveHTML, className);
const $wrapper = $('<div>').append(menuItems);
const $items = $wrapper.find('> .item');
$items.each((_, item) => prepareMenuItem($(item)));
return $wrapper.html();
};
$dropdown.dropdown('setting', 'templates', dropdownTemplates);
// use tooltip's content as aria-label if there is no aria-label
if ($dropdown.hasClass('tooltip') && $dropdown.attr('data-content') && !$dropdown.attr('aria-label')) {
$dropdown.attr('aria-label', $dropdown.attr('data-content'));
}
// prepare dropdown menu list popup
const $menu = $dropdown.find('> .menu');
if (!$menu.attr('id')) $menu.attr('id', generateAriaId());
$menu.find('> .item').each((_, item) => {
prepareMenuItem($(item));
});
// this role could only be changed after its content is ready, otherwise some browsers+readers (like Chrome+AppleVoice) crash
$menu.attr('role', listPopupRole);
// make the primary element (focusable) aria-friendly
$focusable.attr({
'role': $focusable.attr('role') ?? focusableRole,
'aria-haspopup': listPopupRole,
'aria-controls': $menu.attr('id'),
'aria-expanded': 'false',
});
attachDomEvents($dropdown, $focusable, $menu);
attachStaticElements($dropdown, $focusable, $menu);
}
function attachDomEvents($dropdown, $focusable, $menu) {
const dropdown = $dropdown[0];
// when showing, it has class: ".animating.in"
// when hiding, it has class: ".visible.animating.out"
const isMenuVisible = () => ($menu.hasClass('visible') && !$menu.hasClass('out')) || $menu.hasClass('in');
// update aria attributes according to current active/selected item
const refreshAria = () => {
const refreshAriaActiveItem = () => {
const menuVisible = isMenuVisible();
$focusable.attr('aria-expanded', menuVisible ? 'true' : 'false');
@ -97,7 +167,7 @@ function attachOneDropdownAria($dropdown) {
// if the popup is visible and has an active/selected item, use its id as aria-activedescendant
if (menuVisible) {
$focusable.attr('aria-activedescendant', $active.attr('id'));
} else if (!isComboBox) {
} else if (dropdown[ariaPatchKey].listPopupRole === 'menu') {
// for menu, when the popup is hidden, no need to keep the aria-activedescendant, and clear the active/selected item
$focusable.removeAttr('aria-activedescendant');
$active.removeClass('active').removeClass('selected');
@ -107,7 +177,8 @@ function attachOneDropdownAria($dropdown) {
$dropdown.on('keydown', (e) => {
// here it must use keydown event before dropdown's keyup handler, otherwise there is no Enter event in our keyup handler
if (e.key === 'Enter') {
let $item = $dropdown.dropdown('get item', $dropdown.dropdown('get value'));
const dropdownCall = fomanticDropdownFn.bind($dropdown);
let $item = dropdownCall('get item', dropdownCall('get value'));
if (!$item) $item = $menu.find('> .item.selected'); // when dropdown filters items by input, there is no "value", so query the "selected" item
// if the selected item is clickable, then trigger the click event.
// we can not click any item without check, because Fomantic code might also handle the Enter event. that would result in double click.
@ -119,8 +190,9 @@ function attachOneDropdownAria($dropdown) {
// do not return any value, jQuery has return-value related behaviors.
// when the popup is hiding, it's better to have a small "delay", because there is a Fomantic UI animation
// without the delay for hiding, the UI will be somewhat laggy and sometimes may get stuck in the animation.
const deferredRefreshAria = (delay = 0) => { setTimeout(refreshAria, delay) };
$dropdown.on('keyup', (e) => { if (e.key.startsWith('Arrow')) deferredRefreshAria(); });
const deferredRefreshAriaActiveItem = (delay = 0) => { setTimeout(refreshAriaActiveItem, delay) };
dropdown[ariaPatchKey].deferredRefreshAriaActiveItem = deferredRefreshAriaActiveItem;
$dropdown.on('keyup', (e) => { if (e.key.startsWith('Arrow')) deferredRefreshAriaActiveItem(); });
// if the dropdown has been opened by focus, do not trigger the next click event again.
// otherwise the dropdown will be closed immediately, especially on Android with TalkBack
@ -128,26 +200,26 @@ function attachOneDropdownAria($dropdown) {
// * mobile event sequence: focus -> mousedown -> mouseup -> click
// Fomantic may stop propagation of blur event, use capture to make sure we can still get the event
let ignoreClickPreEvents = 0, ignoreClickPreVisible = 0;
$dropdown[0].addEventListener('mousedown', () => {
dropdown.addEventListener('mousedown', () => {
ignoreClickPreVisible += isMenuVisible() ? 1 : 0;
ignoreClickPreEvents++;
}, true);
$dropdown[0].addEventListener('focus', () => {
dropdown.addEventListener('focus', () => {
ignoreClickPreVisible += isMenuVisible() ? 1 : 0;
ignoreClickPreEvents++;
deferredRefreshAria();
deferredRefreshAriaActiveItem();
}, true);
$dropdown[0].addEventListener('blur', () => {
dropdown.addEventListener('blur', () => {
ignoreClickPreVisible = ignoreClickPreEvents = 0;
deferredRefreshAria(100);
deferredRefreshAriaActiveItem(100);
}, true);
$dropdown[0].addEventListener('mouseup', () => {
dropdown.addEventListener('mouseup', () => {
setTimeout(() => {
ignoreClickPreVisible = ignoreClickPreEvents = 0;
deferredRefreshAria(100);
deferredRefreshAriaActiveItem(100);
}, 0);
}, true);
$dropdown[0].addEventListener('click', (e) => {
dropdown.addEventListener('click', (e) => {
if (isMenuVisible() &&
ignoreClickPreVisible !== 2 && // dropdown is switch from invisible to visible
ignoreClickPreEvents === 2 // the click event is related to mousedown+focus
@ -157,24 +229,3 @@ function attachOneDropdownAria($dropdown) {
ignoreClickPreEvents = ignoreClickPreVisible = 0;
}, true);
}
export function attachDropdownAria($dropdowns) {
$dropdowns.each((_, e) => attachOneDropdownAria($(e)));
}
export function attachCheckboxAria($checkboxes) {
$checkboxes.checkbox();
// Fomantic UI checkbox needs to be something like: <div class="ui checkbox"><label /><input /></div>
// It doesn't work well with <label><input />...</label>
// To make it work with aria, the "id"/"for" attributes are necessary, so add them automatically if missing.
// In the future, refactor to use native checkbox directly, then this patch could be removed.
for (const el of $checkboxes) {
const label = el.querySelector('label');
const input = el.querySelector('input');
if (!label || !input || input.getAttribute('id')) continue;
const id = generateAriaId();
input.setAttribute('id', id);
label.setAttribute('for', id);
}
}