From 621ab48e409769a44b08e81c593de6ef1001b7c5 Mon Sep 17 00:00:00 2001
From: GU Yiling <justice360@gmail.com>
Date: Tue, 6 Mar 2018 11:33:30 +0800
Subject: [PATCH] * add `.veui-sr-only` (#249)

* fix backward tabbing by adding focus ward on both directions
* add aria support for DatePicker
---
 packages/veui-theme-one/common.less           |  4 ++
 .../veui-theme-one/components/calendar.less   |  6 +--
 .../components/date-picker.less               | 11 ++++-
 packages/veui-theme-one/mixins.less           | 11 +++++
 packages/veui/src/components/Calendar.vue     |  5 ++-
 packages/veui/src/components/DatePicker.vue   | 33 +++++++++++---
 packages/veui/src/managers/focus.js           | 44 ++++++++++++-------
 packages/veui/src/utils/dom.js                | 24 +++++++---
 8 files changed, 104 insertions(+), 34 deletions(-)

diff --git a/packages/veui-theme-one/common.less b/packages/veui-theme-one/common.less
index 0d84e66d6..cb21b878f 100644
--- a/packages/veui-theme-one/common.less
+++ b/packages/veui-theme-one/common.less
@@ -53,6 +53,10 @@ button {
   cursor: not-allowed !important;
 }
 
+.veui-sr-only {
+  .veui-invisible();
+}
+
 a {
   text-decoration: none;
 }
diff --git a/packages/veui-theme-one/components/calendar.less b/packages/veui-theme-one/components/calendar.less
index 0f8b9f2cd..195cdc783 100644
--- a/packages/veui-theme-one/components/calendar.less
+++ b/packages/veui-theme-one/components/calendar.less
@@ -5,11 +5,7 @@
   overflow: hidden;
   border: 1px solid @veui-gray-color-6;
   background-color: #fff;
-
-  &-invisible {
-    .size(0);
-    opacity: 0;
-  }
+  outline: none;
 
   button {
     .veui-button-transition();
diff --git a/packages/veui-theme-one/components/date-picker.less b/packages/veui-theme-one/components/date-picker.less
index 70d3e3dae..37abf8348 100644
--- a/packages/veui-theme-one/components/date-picker.less
+++ b/packages/veui-theme-one/components/date-picker.less
@@ -33,7 +33,6 @@
   }
 
   &-clear {
-    display: none;
     .absolute(10px, 10px, _, _);
     .size(16px);
     background: #fff;
@@ -44,10 +43,20 @@
     cursor: pointer;
     .veui-button-transition();
 
+    .veui-date-picker:hover &,
+    &.focus-visible {
+      .size(16px);
+      clip: auto;
+    }
+
     &:hover {
       color: @veui-text-color-normal;
     }
 
+    &.focus-visible {
+      color: @veui-brand-color;
+    }
+
     .veui-icon {
       display: block;
     }
diff --git a/packages/veui-theme-one/mixins.less b/packages/veui-theme-one/mixins.less
index 5ef24f772..170b7c772 100644
--- a/packages/veui-theme-one/mixins.less
+++ b/packages/veui-theme-one/mixins.less
@@ -1,6 +1,17 @@
 @import "~less-plugin-est/src/all.less";
 @import "./variables.less";
 
+// https://github.com/twbs/bootstrap/blob/e43f97304eac2b276c755267e29de70ae2ac7afd/scss/mixins/_screen-reader.scss#L6-L15
+.veui-invisible() {
+  position: absolute;
+  .size(1px);
+  padding: 0;
+  overflow: hidden;
+  clip: rect(0, 0, 0, 0);
+  white-space: nowrap;
+  border: 0;
+}
+
 .veui-button-transition() {
   transition-property: border-color, background-color, color, opacity;
   transition-duration: .2s;
diff --git a/packages/veui/src/components/Calendar.vue b/packages/veui/src/components/Calendar.vue
index fa21a2fc0..db0a00060 100644
--- a/packages/veui/src/components/Calendar.vue
+++ b/packages/veui/src/components/Calendar.vue
@@ -15,7 +15,7 @@
         ref="prev"
         :class="{
           'veui-calendar-prev': true,
-          'veui-calendar-invisible': pIndex !== 0 && p.view === 'days'
+          'veui-sr-only': pIndex !== 0 && p.view === 'days'
         }"
         :disabled="disabled || readonly"
         @click="step(false, p.view)"
@@ -64,7 +64,7 @@
         ref="next"
         :class="{
           'veui-calendar-next': true,
-          'veui-calendar-invisible': pIndex !== panels.length - 1 && p.view === 'days'
+          'veui-sr-only': pIndex !== panels.length - 1 && p.view === 'days'
         }"
         :disabled="disabled || readonly"
         @click="step(true, p.view)"
@@ -96,6 +96,7 @@
                   @keydown.right.prevent="moveFocus(p.view, 1)"
                   @keydown.down.prevent="moveFocus(p.view, 7)"
                   @keydown.left.prevent="moveFocus(p.view, -1)"
+                  :autofocus="day.isFocus"
                   :aria-label="getLocaleString(day)"
                   :tabindex="day.isFocus ? null : '-1'">
                   <slot name="date" v-bind="{
diff --git a/packages/veui/src/components/DatePicker.vue b/packages/veui/src/components/DatePicker.vue
index 1fe3a87d3..4af793cbb 100644
--- a/packages/veui/src/components/DatePicker.vue
+++ b/packages/veui/src/components/DatePicker.vue
@@ -5,7 +5,13 @@
     'veui-date-picker-range': range,
     'veui-date-picker-expanded': expanded
   }">
-  <veui-button ref="button" class="veui-date-picker-button" :ui="ui" :disabled="realDisabled || realReadonly" @click="expanded = !expanded">
+  <veui-button
+    ref="button"
+    class="veui-date-picker-button"
+    :ui="ui"
+    :disabled="realDisabled || realReadonly"
+    @click="expanded = !expanded"
+    @keydown.down.up.prevent="expanded = true">
     <template v-if="range">
       <span class="veui-date-picker-label">
         <slot v-if="formatted" name="date" :formatted="formatted ? formatted[0] : null" :date="selected ? selected[0] : null">{{ formatted[0] }}</slot>
@@ -25,12 +31,29 @@
     </template>
     <veui-icon class="veui-date-picker-icon" :name="icons.calendar"></veui-icon>
   </veui-button>
-  <button type="button" v-if="clearable" v-show="!!selected" class="veui-date-picker-clear" @click="clear">
+  <button v-if="clearable && !!selected" type="button" class="veui-date-picker-clear veui-sr-only" @click="clear">
     <veui-icon :name="icons.clear"></veui-icon>
   </button>
-  <veui-overlay v-if="expanded" target="button" :open="expanded" :options="realOverlayOptions" :overlay-class="overlayClass">
-    <veui-calendar class="veui-date-picker-overlay" v-model="localSelected" v-bind="calendarProps" ref="cal"
-      v-outside:button="close" @select="handleSelect" @selectstart="handleProgress" @selectprogress="handleProgress" :panel="realPanel">
+  <veui-overlay
+    v-if="expanded"
+    target="button"
+    :open="expanded"
+    :options="realOverlayOptions"
+    :overlay-class="overlayClass"
+    autofocus
+    modal>
+    <veui-calendar
+      class="veui-date-picker-overlay"
+      v-model="localSelected"
+      v-bind="calendarProps"
+      ref="cal"
+      v-outside:button="close"
+      @select="handleSelect"
+      @selectstart="handleProgress"
+      @selectprogress="handleProgress"
+      :panel="realPanel"
+      tabindex="-1"
+      @keydown.esc.native="close">
       <template :slot="shortcutsPosition" v-if="range && realShortcuts && realShortcuts.length">
         <div class="veui-date-picker-shortcuts">
           <button v-for="({from, to, label}, index) in realShortcuts" type="button" :key="index"
diff --git a/packages/veui/src/managers/focus.js b/packages/veui/src/managers/focus.js
index 11084f7af..96a577c4f 100644
--- a/packages/veui/src/managers/focus.js
+++ b/packages/veui/src/managers/focus.js
@@ -11,13 +11,20 @@ class FocusContext {
    * @param {=Element} preferred Where we should start searching for focusable elements
    */
   constructor (root, { source, trap = false, preferred }) {
+    if (!root) {
+      throw new Error('Root must be specified to create a FocusContext instance.')
+    }
+
     this.root = root
     this.source = source
     this.trap = trap
     this.preferred = preferred
 
-    this.outsideHandler = () => {
-      this.focusFirst(true)
+    this.outsideStartHandler = () => {
+      this.focusAt(-2, true)
+    }
+    this.outsideEndHandler = () => {
+      this.focusAt(1, true)
     }
 
     this.init()
@@ -29,29 +36,37 @@ class FocusContext {
    * 2. focus `root` by default
    */
   init () {
-    this.focusFirst()
+    this.focusAt()
 
     if (this.trap) {
-      let ward = document.createElement('div')
-      ward.tabIndex = 0
-      ward.addEventListener('focus', this.outsideHandler, true)
-      this.root.appendChild(ward)
-      this.ward = ward
+      let before = document.createElement('div')
+      before.tabIndex = 0
+      let after = before.cloneNode()
+
+      before.addEventListener('focus', this.outsideStartHandler, true)
+      after.addEventListener('focus', this.outsideEndHandler, true)
+
+      this.root.insertBefore(before, this.root.firstChild)
+      this.root.appendChild(after)
+
+      this.wardBefore = before
+      this.wardAfter = after
     }
   }
 
-  focusFirst (ignoreFocus) {
+  focusAt (index = 0, ignoreAutofocus) {
     Vue.nextTick(() => {
-      if (!focusIn(this.preferred || this.root, ignoreFocus)) {
+      if (!focusIn(this.preferred || this.root, index, ignoreAutofocus)) {
         this.root.focus()
       }
     })
   }
 
   destroy () {
-    let { trap, source, ward } = this
+    let { trap, source, wardBefore, wardAfter } = this
     if (trap) {
-      ward.removeEventListener('focus', this.outsideHandler, true)
+      wardBefore.removeEventListener('focus', this.outsideStartHandler, true)
+      wardAfter.removeEventListener('focus', this.outsideEndHandler, true)
     }
     if (source && typeof source.focus === 'function') {
       this.source = null
@@ -62,9 +77,8 @@ class FocusContext {
         source.focus()
       }, 0)
     }
-    if (ward) {
-      ward.parentElement.removeChild(ward)
-    }
+    this.root.removeChild(wardBefore)
+    this.root.removeChild(wardAfter)
     this.preferred = null
     this.root = null
   }
diff --git a/packages/veui/src/utils/dom.js b/packages/veui/src/utils/dom.js
index 7b5efe353..0d53a6ba5 100644
--- a/packages/veui/src/utils/dom.js
+++ b/packages/veui/src/utils/dom.js
@@ -129,10 +129,11 @@ export function getFocusable (elem) {
  * 将焦点移入指定元素内的第一个可聚焦的元素
  *
  * @param {Element} elem 需要查找的指定元素
+ * @param {number=} index 聚焦元素在可聚焦元素的位置
  * @param {Boolean=} ignoreAutofocus 是否忽略 autofocus
  * @returns {Boolean} 是否找到可聚焦的元素
  */
-export function focusIn (elem, ignoreAutofocus) {
+export function focusIn (elem, index = 0, ignoreAutofocus) {
   if (!ignoreAutofocus) {
     let auto = elem.querySelector('[autofocus]')
     if (auto) {
@@ -140,10 +141,21 @@ export function focusIn (elem, ignoreAutofocus) {
       return true
     }
   }
-  let first = elem.querySelector(FOCUSABLE_SELECTOR)
-  if (first) {
-    first.focus()
-    return true
+
+  if (index === 0) {
+    let first = elem.querySelector(FOCUSABLE_SELECTOR)
+    if (first) {
+      first.focus()
+      return true
+    }
   }
-  return false
+
+  let focusable = [...elem.querySelectorAll(FOCUSABLE_SELECTOR)]
+  let count = focusable.length
+  if (!count) {
+    return false
+  }
+
+  focusable[(index + count) % count].focus()
+  return true
 }