From 1f65c0892fad46b2855fd074e5a74dd2612f7742 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tu=C4=9F=C3=A7e=20K=C3=BC=C3=A7=C3=BCko=C4=9Flu?=
 <tugcekucukoglu.860@gmail.com>
Date: Thu, 1 Sep 2022 15:47:49 +0300
Subject: [PATCH] Fixed #2920 - Improve ScrollPanel implementation for
 Accessibility

---
 api-generator/components/scrollpanel.js     |  12 +-
 src/components/scrollpanel/ScrollPanel.d.ts |   5 +
 src/components/scrollpanel/ScrollPanel.vue  | 133 ++++++++++++++++++--
 src/views/scrollpanel/ScrollPanelDoc.vue    |  69 +++++++++-
 4 files changed, 208 insertions(+), 11 deletions(-)

diff --git a/api-generator/components/scrollpanel.js b/api-generator/components/scrollpanel.js
index f87bfca0d0..9ebb33e2e9 100644
--- a/api-generator/components/scrollpanel.js
+++ b/api-generator/components/scrollpanel.js
@@ -1,6 +1,16 @@
+const ScrollPanelProps = [
+    {
+        name: "step",
+        type: "number",
+        default: "5",
+        description: "Step factor to scroll the content while pressing the arrow keys."
+    }
+];
+
 module.exports = {
     scrollpanel: {
         name: "ScrollPanel",
-        description: "ScrollPanel is a cross browser, lightweight and themable alternative to native browser scrollbar."
+        description: "ScrollPanel is a cross browser, lightweight and themable alternative to native browser scrollbar.",
+        props: ScrollPanelProps
     }
 };
diff --git a/src/components/scrollpanel/ScrollPanel.d.ts b/src/components/scrollpanel/ScrollPanel.d.ts
index 8e532ca900..bb5c307528 100644
--- a/src/components/scrollpanel/ScrollPanel.d.ts
+++ b/src/components/scrollpanel/ScrollPanel.d.ts
@@ -2,6 +2,11 @@ import { VNode } from 'vue';
 import { ClassComponent, GlobalComponentConstructor } from '../ts-helpers';
 
 export interface ScrollPanelProps {
+    /**
+     * Step factor to scroll the content while pressing the arrow keys.
+     * Default value is 5.
+     */
+    step?: number | undefined;
 }
 
 export interface ScrollPanelSlots {
diff --git a/src/components/scrollpanel/ScrollPanel.vue b/src/components/scrollpanel/ScrollPanel.vue
index b59e0b14d8..acb32e4e49 100644
--- a/src/components/scrollpanel/ScrollPanel.vue
+++ b/src/components/scrollpanel/ScrollPanel.vue
@@ -1,20 +1,26 @@
 <template>
-    <div class="p-scrollpanel p-component">
-        <div class="p-scrollpanel-wrapper">
-            <div ref="content" class="p-scrollpanel-content" @scroll="moveBar" @mouseenter="moveBar">
+    <div class="p-scrollpanel p-component" role="scrollbar" :aria-orientation="orientation" :aria-valuenow="orientation === 'vertical' ? lastScrollTop : lastScrollLeft" :aria-controls="id + '_scrollpanel'">
+        <div class="p-scrollpanel-wrapper" :id="id + '_scrollpanel'">
+            <div ref="content" class="p-scrollpanel-content" @scroll="onScroll" @mouseenter="moveBar">
                 <slot></slot>
             </div>
         </div>
-        <div ref="xBar" class="p-scrollpanel-bar p-scrollpanel-bar-x" @mousedown="onXBarMouseDown"></div>
-        <div ref="yBar" class="p-scrollpanel-bar p-scrollpanel-bar-y" @mousedown="onYBarMouseDown"></div>
+        <div ref="xBar" class="p-scrollpanel-bar p-scrollpanel-bar-x" tabindex="0" @mousedown="onXBarMouseDown" @keydown="onKeyDown($event)" @keyup="onKeyUp" @focus="onFocus" @blur="onBlur"></div>
+        <div ref="yBar" class="p-scrollpanel-bar p-scrollpanel-bar-y" tabindex="0" @mousedown="onYBarMouseDown" @keydown="onKeyDown($event)" @keyup="onKeyUp" @focus="onFocus"></div>
     </div>
 </template>
 
 <script>
-import {DomHandler} from 'primevue/utils';
+import {DomHandler,UniqueComponentId} from 'primevue/utils';
 
 export default {
     name: 'ScrollPanel',
+    props: {
+        step: {
+            type: Number,
+            default: 5
+        }
+    },
     initialized: false,
     documentResizeListener: null,
     documentMouseMoveListener: null,
@@ -26,6 +32,16 @@ export default {
     isYBarClicked: false,
     lastPageX: null,
     lastPageY: null,
+    timer: null,
+    outsideClickListener: null,
+    data() {
+        return {
+            id: UniqueComponentId(),
+            orientation: 'vertical',
+            lastScrollTop: 0,
+            lastScrollLeft: 0
+        }
+    },
     mounted() {
         if (this.$el.offsetParent) {
             this.initialize();
@@ -55,7 +71,7 @@ export default {
             pureContainerHeight = DomHandler.getHeight(this.$el) - parseInt(xBarStyles['height'], 10);
 
             if (containerStyles['max-height'] !== "none" && pureContainerHeight === 0) {
-                if(this.$refs.content.offsetHeight + parseInt(xBarStyles['height'], 10) > parseInt(containerStyles['max-height'], 10)) {
+                if (this.$refs.content.offsetHeight + parseInt(xBarStyles['height'], 10) > parseInt(containerStyles['max-height'], 10)) {
                     this.$el.style.height = containerStyles['max-height'];
                 }
                 else {
@@ -98,6 +114,7 @@ export default {
         },
         onYBarMouseDown(e) {
             this.isYBarClicked = true;
+            this.$refs.yBar.focus();
             this.lastPageY = e.pageY;
             DomHandler.addClass(this.$refs.yBar, 'p-scrollpanel-grabbed');
             DomHandler.addClass(document.body, 'p-scrollpanel-grabbed');
@@ -107,6 +124,7 @@ export default {
         },
         onXBarMouseDown(e) {
             this.isXBarClicked = true;
+            this.$refs.xBar.focus();
             this.lastPageX = e.pageX;
             DomHandler.addClass(this.$refs.xBar, 'p-scrollpanel-grabbed');
             DomHandler.addClass(document.body, 'p-scrollpanel-grabbed');
@@ -114,6 +132,89 @@ export default {
             this.bindDocumentMouseListeners();
             e.preventDefault();
         },
+        onScroll(event) {
+            if (this.lastScrollLeft !== event.target.scrollLeft) {
+                this.lastScrollLeft = event.target.scrollLeft;
+                this.orientation = 'horizontal';
+            }
+            else if (this.lastScrollTop !== event.target.scrollTop) {
+                this.lastScrollTop = event.target.scrollTop;
+                this.orientation = 'vertical';
+            }
+
+            this.moveBar();
+        },
+        onKeyDown(event) {
+            if (this.orientation === 'vertical') {
+                switch(event.code) {
+                    case 'ArrowDown': {
+                        this.setTimer('scrollTop', this.step);
+                        event.preventDefault();
+                        break;
+                    }
+
+                    case 'ArrowUp': {
+                        this.setTimer('scrollTop', this.step * -1);
+                        event.preventDefault();
+                        break;
+                    }
+
+                    case 'ArrowLeft':
+                    case 'ArrowRight': {
+                        event.preventDefault();
+                        break;
+                    }
+
+                    default:
+                        //no op
+                    break;
+                }
+            }
+
+            else if (this.orientation === 'horizontal') {
+                switch(event.code) {
+                    case 'ArrowRight': {
+                        this.setTimer('scrollLeft', this.step);
+                        event.preventDefault();
+                        break;
+                    }
+
+                    case 'ArrowLeft': {
+                        this.setTimer('scrollLeft', this.step * -1);
+                        event.preventDefault();
+                        break;
+                    }
+
+                    case 'ArrowDown':
+                    case 'ArrowUp': {
+                        event.preventDefault();
+                        break;
+                    }
+
+                    default:
+                        //no op
+                    break;
+                }
+            }
+        },
+        onKeyUp() {
+            this.clearTimer();
+        },
+        repeat(bar, step) {
+            this.$refs.content[bar] += step;
+            this.moveBar();
+        },
+        setTimer(bar, step) {
+            this.clearTimer();
+            this.timer = setTimeout(() => {
+                this.repeat(bar, step);
+            }, 40);
+        },
+        clearTimer() {
+            if (this.timer) {
+                clearTimeout(this.timer);
+            }
+        },
         onDocumentMouseMove(e) {
             if (this.isXBarClicked) {
                 this.onMouseMoveForXBar(e);
@@ -142,6 +243,19 @@ export default {
                 this.$refs.content.scrollTop += deltaY / this.scrollYRatio;
             });
         },
+        onFocus(event) {
+            if (this.$refs.xBar.isSameNode(event.target)) {
+                this.orientation = 'horizontal';
+            }
+            else if (this.$refs.yBar.isSameNode(event.target)) {
+                this.orientation = 'vertical';
+            }
+        },
+        onBlur() {
+            if (this.orientation === 'horizontal') {
+                this.orientation = 'vertical';
+            }
+        },
         onDocumentMouseUp() {
             DomHandler.removeClass(this.$refs.yBar, 'p-scrollpanel-grabbed');
             DomHandler.removeClass(this.$refs.xBar, 'p-scrollpanel-grabbed');
@@ -161,7 +275,10 @@ export default {
         scrollTop(scrollTop) {
             let scrollableHeight = this.$refs.content.scrollHeight - this.$refs.content.clientHeight;
             scrollTop = scrollTop > scrollableHeight ? scrollableHeight : scrollTop > 0 ? scrollTop : 0;
-            this.$refs.contentscrollTop = scrollTop;
+            this.$refs.content.scrollTop = scrollTop;
+        },
+        timeoutFrame(fn) {
+            setTimeout(fn, 0);
         },
         bindDocumentMouseListeners() {
 			if (!this.documentMouseMoveListener) {
diff --git a/src/views/scrollpanel/ScrollPanelDoc.vue b/src/views/scrollpanel/ScrollPanelDoc.vue
index aec0433ce4..6ff7646fb6 100644
--- a/src/views/scrollpanel/ScrollPanelDoc.vue
+++ b/src/views/scrollpanel/ScrollPanelDoc.vue
@@ -46,10 +46,39 @@ import ScrollPanel from 'primevue/scrollpanel';
     background-color: #135ba1;
 }
 
+</code></pre>
+
+        <h5>Steps</h5>
+        <p>Step factor is 5px by default and can be customized with <i>step</i> option.</p>
+<pre v-code><code>
+&lt;ScrollPanel style="width: 100%; height: 200px" :step="10"3&gt;
+    content
+&lt;/ScrollPanel&gt;
+
 </code></pre>
 
 		<h5>Properties</h5>
-        <p>Any property such as style and class are passed to the main container element. There are no component specific properties.</p>
+        <p>Any property such as style and class are passed to the main container element. Following are the additional properties to configure the component.</p>
+        <div class="doc-tablewrapper">
+			<table class="doc-table">
+				<thead>
+                    <tr>
+                        <th>Name</th>
+                        <th>Type</th>
+                        <th>Default</th>
+                        <th>Description</th>
+                    </tr>
+				</thead>
+				<tbody>
+                    <tr>
+                        <td>step</td>
+                        <td>number</td>
+                        <td>1</td>
+                        <td>Step factor to scroll the content while pressing the arrow keys.</td>
+                    </tr>
+				</tbody>
+			</table>
+		</div>
 
 		<h5>Styling</h5>
 		<p>Following is the list of structural style classes, for theming classes visit <router-link to="/theming">theming</router-link> page.</p>
@@ -90,6 +119,42 @@ import ScrollPanel from 'primevue/scrollpanel';
 			</table>
 		</div>
 
+        <h5>Accessibility</h5>
+    <DevelopmentSection>
+        <h6>Screen Reader</h6>
+        <p>Scrollbars of the ScrollPanel has a <i>scrollbar</i> role along with the <i>aria-controls</i> attribute that refers to the id of the scrollable content container and the <i>aria-orientation</i> to indicate the orientation of scrolling.</p>
+
+        <h6>Header Keyboard Support</h6>
+        <div class="doc-tablewrapper">
+            <table class="doc-table">
+                <thead>
+                    <tr>
+                        <th>Key</th>
+                        <th>Function</th>
+                    </tr>
+                </thead>
+                <tbody>
+                    <tr>
+                        <td><i>down arrow</i></td>
+                        <td>Scrolls content down when vertical scrolling is available.</td>
+                    </tr>
+                    <tr>
+                        <td><i>up arrow</i></td>
+                        <td>Scrolls content up when vertical scrolling is available.</td>
+                    </tr>
+                    <tr>
+                        <td><i>left</i></td>
+                        <td>Scrolls content left when horizontal scrolling is available.</td>
+                    </tr>
+                    <tr>
+                        <td><i>right</i></td>
+                        <td>Scrolls content right when horizontal scrolling is available.</td>
+                    </tr>
+                </tbody>
+            </table>
+        </div>
+    </DevelopmentSection>
+
 		<h5>Dependencies</h5>
 		<p>None.</p>
     </AppDoc>
@@ -99,7 +164,7 @@ import ScrollPanel from 'primevue/scrollpanel';
 export default {
     data() {
         return {
-           sources: {
+            sources: {
                 'options-api': {
                     tabName: 'Options API Source',
                     content: `