Add ability to automatically hide tab-group scroll control

docs/pages/components/tab-group.md

@@ -411,6 +411,148 @@ const App = () => (
 );
 ```
 
+### Fixed scroll controls
+
+When tabs are scrolled all the way to one side, the scroll button on that side can't be clicked. Set the `fixed-scroll-controls` attribute to keep the effected button visible in that case.
+
+```html:preview
+<sl-tab-group fixed-scroll-controls>
+  <sl-tab slot="nav" panel="tab-1">Tab 1</sl-tab>
+  <sl-tab slot="nav" panel="tab-2">Tab 2</sl-tab>
+  <sl-tab slot="nav" panel="tab-3">Tab 3</sl-tab>
+  <sl-tab slot="nav" panel="tab-4">Tab 4</sl-tab>
+  <sl-tab slot="nav" panel="tab-5">Tab 5</sl-tab>
+  <sl-tab slot="nav" panel="tab-6">Tab 6</sl-tab>
+  <sl-tab slot="nav" panel="tab-7">Tab 7</sl-tab>
+  <sl-tab slot="nav" panel="tab-8">Tab 8</sl-tab>
+  <sl-tab slot="nav" panel="tab-9">Tab 9</sl-tab>
+  <sl-tab slot="nav" panel="tab-10">Tab 10</sl-tab>
+  <sl-tab slot="nav" panel="tab-11">Tab 11</sl-tab>
+  <sl-tab slot="nav" panel="tab-12">Tab 12</sl-tab>
+  <sl-tab slot="nav" panel="tab-13">Tab 13</sl-tab>
+  <sl-tab slot="nav" panel="tab-14">Tab 14</sl-tab>
+  <sl-tab slot="nav" panel="tab-15">Tab 15</sl-tab>
+  <sl-tab slot="nav" panel="tab-16">Tab 16</sl-tab>
+  <sl-tab slot="nav" panel="tab-17">Tab 17</sl-tab>
+  <sl-tab slot="nav" panel="tab-18">Tab 18</sl-tab>
+  <sl-tab slot="nav" panel="tab-19">Tab 19</sl-tab>
+  <sl-tab slot="nav" panel="tab-20">Tab 20</sl-tab>
+
+  <sl-tab-panel name="tab-1">Tab panel 1</sl-tab-panel>
+  <sl-tab-panel name="tab-2">Tab panel 2</sl-tab-panel>
+  <sl-tab-panel name="tab-3">Tab panel 3</sl-tab-panel>
+  <sl-tab-panel name="tab-4">Tab panel 4</sl-tab-panel>
+  <sl-tab-panel name="tab-5">Tab panel 5</sl-tab-panel>
+  <sl-tab-panel name="tab-6">Tab panel 6</sl-tab-panel>
+  <sl-tab-panel name="tab-7">Tab panel 7</sl-tab-panel>
+  <sl-tab-panel name="tab-8">Tab panel 8</sl-tab-panel>
+  <sl-tab-panel name="tab-9">Tab panel 9</sl-tab-panel>
+  <sl-tab-panel name="tab-10">Tab panel 10</sl-tab-panel>
+  <sl-tab-panel name="tab-11">Tab panel 11</sl-tab-panel>
+  <sl-tab-panel name="tab-12">Tab panel 12</sl-tab-panel>
+  <sl-tab-panel name="tab-13">Tab panel 13</sl-tab-panel>
+  <sl-tab-panel name="tab-14">Tab panel 14</sl-tab-panel>
+  <sl-tab-panel name="tab-15">Tab panel 15</sl-tab-panel>
+  <sl-tab-panel name="tab-16">Tab panel 16</sl-tab-panel>
+  <sl-tab-panel name="tab-17">Tab panel 17</sl-tab-panel>
+  <sl-tab-panel name="tab-18">Tab panel 18</sl-tab-panel>
+  <sl-tab-panel name="tab-19">Tab panel 19</sl-tab-panel>
+  <sl-tab-panel name="tab-20">Tab panel 20</sl-tab-panel>
+</sl-tab-group>
+```
+
+```jsx:react
+import SlTab from '@shoelace-style/shoelace/dist/react/tab';
+import SlTabGroup from '@shoelace-style/shoelace/dist/react/tab-group';
+import SlTabPanel from '@shoelace-style/shoelace/dist/react/tab-panel';
+
+const App = () => (
+  <SlTabGroup auto-hide-scroll-buttons>
+    <SlTab slot="nav" panel="tab-1">
+      Tab 1
+    </SlTab>
+    <SlTab slot="nav" panel="tab-2">
+      Tab 2
+    </SlTab>
+    <SlTab slot="nav" panel="tab-3">
+      Tab 3
+    </SlTab>
+    <SlTab slot="nav" panel="tab-4">
+      Tab 4
+    </SlTab>
+    <SlTab slot="nav" panel="tab-5">
+      Tab 5
+    </SlTab>
+    <SlTab slot="nav" panel="tab-6">
+      Tab 6
+    </SlTab>
+    <SlTab slot="nav" panel="tab-7">
+      Tab 7
+    </SlTab>
+    <SlTab slot="nav" panel="tab-8">
+      Tab 8
+    </SlTab>
+    <SlTab slot="nav" panel="tab-9">
+      Tab 9
+    </SlTab>
+    <SlTab slot="nav" panel="tab-10">
+      Tab 10
+    </SlTab>
+    <SlTab slot="nav" panel="tab-11">
+      Tab 11
+    </SlTab>
+    <SlTab slot="nav" panel="tab-12">
+      Tab 12
+    </SlTab>
+    <SlTab slot="nav" panel="tab-13">
+      Tab 13
+    </SlTab>
+    <SlTab slot="nav" panel="tab-14">
+      Tab 14
+    </SlTab>
+    <SlTab slot="nav" panel="tab-15">
+      Tab 15
+    </SlTab>
+    <SlTab slot="nav" panel="tab-16">
+      Tab 16
+    </SlTab>
+    <SlTab slot="nav" panel="tab-17">
+      Tab 17
+    </SlTab>
+    <SlTab slot="nav" panel="tab-18">
+      Tab 18
+    </SlTab>
+    <SlTab slot="nav" panel="tab-19">
+      Tab 19
+    </SlTab>
+    <SlTab slot="nav" panel="tab-20">
+      Tab 20
+    </SlTab>
+
+    <SlTabPanel name="tab-1">Tab panel 1</SlTabPanel>
+    <SlTabPanel name="tab-2">Tab panel 2</SlTabPanel>
+    <SlTabPanel name="tab-3">Tab panel 3</SlTabPanel>
+    <SlTabPanel name="tab-4">Tab panel 4</SlTabPanel>
+    <SlTabPanel name="tab-5">Tab panel 5</SlTabPanel>
+    <SlTabPanel name="tab-6">Tab panel 6</SlTabPanel>
+    <SlTabPanel name="tab-7">Tab panel 7</SlTabPanel>
+    <SlTabPanel name="tab-8">Tab panel 8</SlTabPanel>
+    <SlTabPanel name="tab-9">Tab panel 9</SlTabPanel>
+    <SlTabPanel name="tab-10">Tab panel 10</SlTabPanel>
+    <SlTabPanel name="tab-11">Tab panel 11</SlTabPanel>
+    <SlTabPanel name="tab-12">Tab panel 12</SlTabPanel>
+    <SlTabPanel name="tab-13">Tab panel 13</SlTabPanel>
+    <SlTabPanel name="tab-14">Tab panel 14</SlTabPanel>
+    <SlTabPanel name="tab-15">Tab panel 15</SlTabPanel>
+    <SlTabPanel name="tab-16">Tab panel 16</SlTabPanel>
+    <SlTabPanel name="tab-17">Tab panel 17</SlTabPanel>
+    <SlTabPanel name="tab-18">Tab panel 18</SlTabPanel>
+    <SlTabPanel name="tab-19">Tab panel 19</SlTabPanel>
+    <SlTabPanel name="tab-20">Tab panel 20</SlTabPanel>
+  </SlTabGroup>
+);
+```
+
 ### Manual Activation
 
 When focused, keyboard users can press [[Left]] or [[Right]] to select the desired tab. By default, the corresponding tab panel will be shown immediately (automatic activation). You can change this behavior by setting `activation="manual"` which will require the user to press [[Space]] or [[Enter]] before showing the tab panel (manual activation).

docs/pages/resources/changelog.md

@@ -14,6 +14,7 @@ New versions of Shoelace are released as-needed and generally occur when a criti
 
 ## Next
 
+- Scroll buttons for `<sl-tab-group>` auto hide when they are not clickable. The `fixed-scroll-controls` attribute can be included to prevent this behavior. [#2128]
 - Added support for using `<sl-dropdown>` in `<sl-breadcrumb-item>` default slot [#2015]
 - Fixed a bug that caused errors to show in the console when components disconnect before before `firstUpdated()` executes [#2127]
 

src/components/tab-group/tab-group.component.ts

@@ -1,7 +1,8 @@
+import '../../internal/scrollend-polyfill.js';
 import { classMap } from 'lit/directives/class-map.js';
+import { eventOptions, property, query, state } from 'lit/decorators.js';
 import { html } from 'lit';
 import { LocalizeController } from '../../utilities/localize.js';
-import { property, query, state } from 'lit/decorators.js';
 import { scrollIntoView } from '../../internal/scroll.js';
 import { watch } from '../../internal/watch.js';
 import componentStyles from '../../styles/component.styles.js';
@@ -60,6 +61,9 @@ export default class SlTabGroup extends ShoelaceElement {
 
   @state() private hasScrollControls = false;
 
+  @state() private shouldHideScrollStartButton = false;
+  @state() private shouldHideScrollEndButton = false;
+
   /** The placement of the tabs. */
   @property() placement: 'top' | 'bottom' | 'start' | 'end' = 'top';
 
@@ -72,6 +76,9 @@ export default class SlTabGroup extends ShoelaceElement {
   /** Disables the scroll arrows that appear when tabs overflow. */
   @property({ attribute: 'no-scroll-controls', type: Boolean }) noScrollControls = false;
 
+  /** Prevent scroll buttons from being hidden when inactive. */
+  @property({ attribute: 'fixed-scroll-controls', type: Boolean }) fixedScrollControls = false;
+
   connectedCallback() {
     const whenAllDefined = Promise.all([
       customElements.whenDefined('sl-tab'),
@@ -365,6 +372,28 @@ export default class SlTabGroup extends ShoelaceElement {
     return nextTab;
   }
 
+  /**
+   * The reality of the browser means that we can't expect the scroll position to be exactly what we want it to be, so
+   * we add one pixel of wiggle room to our calculations.
+   */
+  private scrollOffset = 1;
+
+  @eventOptions({ passive: true })
+  private updateScrollButtons() {
+    if (this.hasScrollControls && !this.fixedScrollControls) {
+      this.shouldHideScrollStartButton = this.scrollFromStart() <= this.scrollOffset;
+      this.shouldHideScrollEndButton = this.isScrolledToEnd();
+    }
+  }
+
+  private isScrolledToEnd() {
+    return this.scrollFromStart() + this.nav.clientWidth >= this.nav.scrollWidth - this.scrollOffset;
+  }
+
+  private scrollFromStart() {
+    return this.localize.dir() === 'rtl' ? -this.nav.scrollLeft : this.nav.scrollLeft;
+  }
+
   @watch('noScrollControls', { waitUntilFirstUpdate: true })
   updateScrollControls() {
     if (this.noScrollControls) {
@@ -378,6 +407,8 @@ export default class SlTabGroup extends ShoelaceElement {
       this.hasScrollControls =
         ['top', 'bottom'].includes(this.placement) && this.nav.scrollWidth > this.nav.clientWidth + 1;
     }
+
+    this.updateScrollButtons();
   }
 
   @watch('placement', { waitUntilFirstUpdate: true })
@@ -425,16 +456,22 @@ export default class SlTabGroup extends ShoelaceElement {
                 <sl-icon-button
                   part="scroll-button scroll-button--start"
                   exportparts="base:scroll-button__base"
-                  class="tab-group__scroll-button tab-group__scroll-button--start"
+                  class=${classMap({
+                    'tab-group__scroll-button': true,
+                    'tab-group__scroll-button--start': true,
+                    'tab-group__scroll-button--start--hidden': this.shouldHideScrollStartButton
+                  })}
                   name=${isRtl ? 'chevron-right' : 'chevron-left'}
                   library="system"
+                  tabindex="-1"
+                  aria-hidden="true"
                   label=${this.localize.term('scrollToStart')}
                   @click=${this.handleScrollToStart}
                 ></sl-icon-button>
               `
             : ''}
 
-          <div class="tab-group__nav">
+          <div class="tab-group__nav" @scrollend=${this.updateScrollButtons}>
             <div part="tabs" class="tab-group__tabs" role="tablist">
               <div part="active-tab-indicator" class="tab-group__indicator"></div>
               <slot name="nav" @slotchange=${this.syncTabsAndPanels}></slot>
@@ -446,9 +483,15 @@ export default class SlTabGroup extends ShoelaceElement {
                 <sl-icon-button
                   part="scroll-button scroll-button--end"
                   exportparts="base:scroll-button__base"
-                  class="tab-group__scroll-button tab-group__scroll-button--end"
+                  class=${classMap({
+                    'tab-group__scroll-button': true,
+                    'tab-group__scroll-button--end': true,
+                    'tab-group__scroll-button--end--hidden': this.shouldHideScrollEndButton
+                  })}
                   name=${isRtl ? 'chevron-left' : 'chevron-right'}
                   library="system"
+                  tabindex="-1"
+                  aria-hidden="true"
                   label=${this.localize.term('scrollToEnd')}
                   @click=${this.handleScrollToEnd}
                 ></sl-icon-button>

src/components/tab-group/tab-group.styles.ts

@@ -31,6 +31,11 @@ export default css`
     padding: 0 var(--sl-spacing-x-large);
   }
 
+  .tab-group--has-scroll-controls .tab-group__scroll-button--start--hidden,
+  .tab-group--has-scroll-controls .tab-group__scroll-button--end--hidden {
+    visibility: hidden;
+  }
+
   .tab-group__body {
     display: block;
     overflow: auto;