From 281c092d061f77b812e57f473e77cfd123016471 Mon Sep 17 00:00:00 2001
From: Zack Elliott <zell@google.com>
Date: Fri, 12 Jul 2024 12:43:55 -0700
Subject: [PATCH] feat(iconbutton): add `soft-disabled` attribute for focusable
 disabled icon buttons

PiperOrigin-RevId: 651858380
---
 iconbutton/demo/demo.ts                       |  1 +
 iconbutton/demo/stories.ts                    | 35 +++++++----
 iconbutton/icon-button_test.ts                | 60 +++++++++++++++++++
 iconbutton/internal/_filled-icon-button.scss  | 14 ++---
 .../internal/_filled-tonal-icon-button.scss   | 16 +++--
 iconbutton/internal/_icon-button.scss         |  6 +-
 .../internal/_outlined-icon-button.scss       | 14 ++---
 iconbutton/internal/_shared.scss              |  5 +-
 iconbutton/internal/icon-button.ts            | 55 ++++++++++++++---
 9 files changed, 160 insertions(+), 46 deletions(-)

diff --git a/iconbutton/demo/demo.ts b/iconbutton/demo/demo.ts
index 704b85c703..cb80be8198 100644
--- a/iconbutton/demo/demo.ts
+++ b/iconbutton/demo/demo.ts
@@ -23,6 +23,7 @@ const collection = new MaterialCollection<KnobTypesToKnobs<StoryKnobs>>(
     new Knob('disabled', {ui: boolInput(), defaultValue: false}),
     new Knob('icon', {ui: textInput(), defaultValue: ''}),
     new Knob('selectedIcon', {ui: textInput(), defaultValue: ''}),
+    new Knob('softDisabled', {ui: boolInput(), defaultValue: false}),
   ],
 );
 
diff --git a/iconbutton/demo/stories.ts b/iconbutton/demo/stories.ts
index 09ae67a06d..4a3e9b79ac 100644
--- a/iconbutton/demo/stories.ts
+++ b/iconbutton/demo/stories.ts
@@ -19,6 +19,7 @@ export interface StoryKnobs {
   icon: string;
   selectedIcon: string;
   disabled: boolean;
+  softDisabled: boolean;
 }
 
 const styles = [
@@ -44,26 +45,35 @@ const styles = [
 const buttons: MaterialStoryInit<StoryKnobs> = {
   name: 'Icon button variants',
   styles,
-  render({icon, disabled}) {
+  render({icon, disabled, softDisabled}) {
     return html`
       <div class="row md-typescale-body-medium">
         <div class="column">
           <p>Standard</p>
-          <md-icon-button aria-label="Open settings" ?disabled=${disabled}>
+          <md-icon-button
+            aria-label="Open settings"
+            ?disabled=${disabled}
+            ?soft-disabled=${softDisabled}>
             <md-icon>${icon || 'settings'}</md-icon>
           </md-icon-button>
         </div>
 
         <div class="column">
           <p>Outlined</p>
-          <md-outlined-icon-button aria-label="Search" ?disabled=${disabled}>
+          <md-outlined-icon-button
+            aria-label="Search"
+            ?disabled=${disabled}
+            ?soft-disabled=${softDisabled}>
             <md-icon>${icon || 'search'}</md-icon>
           </md-outlined-icon-button>
         </div>
 
         <div class="column">
           <p>Filled</p>
-          <md-filled-icon-button aria-label="Complete" ?disabled=${disabled}>
+          <md-filled-icon-button
+            aria-label="Complete"
+            ?disabled=${disabled}
+            ?soft-disabled=${softDisabled}>
             <md-icon>${icon || 'done'}</md-icon>
           </md-filled-icon-button>
         </div>
@@ -72,7 +82,8 @@ const buttons: MaterialStoryInit<StoryKnobs> = {
           <p>Filled tonal</p>
           <md-filled-tonal-icon-button
             aria-label="Add new"
-            ?disabled=${disabled}>
+            ?disabled=${disabled}
+            ?soft-disabled=${softDisabled}>
             <md-icon>${icon || 'add'}</md-icon>
           </md-filled-tonal-icon-button>
         </div>
@@ -84,7 +95,7 @@ const buttons: MaterialStoryInit<StoryKnobs> = {
 const toggles: MaterialStoryInit<StoryKnobs> = {
   name: 'Toggle icon buttons',
   styles,
-  render({icon, selectedIcon, disabled}) {
+  render({icon, selectedIcon, disabled, softDisabled}) {
     return html`
       <div class="row">
         <div class="column">
@@ -93,7 +104,8 @@ const toggles: MaterialStoryInit<StoryKnobs> = {
             aria-label="Show password"
             aria-label-selected="Hide password"
             toggle
-            ?disabled=${disabled}>
+            ?disabled=${disabled}
+            ?soft-disabled=${softDisabled}>
             <md-icon>${icon || 'visibility'}</md-icon>
             <md-icon slot="selected">
               ${selectedIcon || 'visibility_off'}
@@ -107,7 +119,8 @@ const toggles: MaterialStoryInit<StoryKnobs> = {
             aria-label="Play"
             aria-label-selected="Pause"
             toggle
-            ?disabled=${disabled}>
+            ?disabled=${disabled}
+            ?soft-disabled=${softDisabled}>
             <md-icon>${icon || 'play_arrow'}</md-icon>
             <md-icon slot="selected">${selectedIcon || 'pause'}</md-icon>
           </md-outlined-icon-button>
@@ -119,7 +132,8 @@ const toggles: MaterialStoryInit<StoryKnobs> = {
             aria-label="Show more"
             aria-label-selected="Show less"
             toggle
-            ?disabled=${disabled}>
+            ?disabled=${disabled}
+            ?soft-disabled=${softDisabled}>
             <md-icon>${icon || 'expand_more'}</md-icon>
             <md-icon slot="selected">${selectedIcon || 'expand_less'}</md-icon>
           </md-filled-icon-button>
@@ -131,7 +145,8 @@ const toggles: MaterialStoryInit<StoryKnobs> = {
             aria-label="Open menu"
             aria-label-selected="Close menu"
             toggle
-            ?disabled=${disabled}>
+            ?disabled=${disabled}
+            ?soft-disabled=${softDisabled}>
             <md-icon>${icon || 'menu'}</md-icon>
             <md-icon slot="selected">${selectedIcon || 'close'}</md-icon>
           </md-filled-tonal-icon-button>
diff --git a/iconbutton/icon-button_test.ts b/iconbutton/icon-button_test.ts
index ffd4a81e87..64281926b8 100644
--- a/iconbutton/icon-button_test.ts
+++ b/iconbutton/icon-button_test.ts
@@ -61,6 +61,66 @@ describe('icon button tests', () => {
       },
     );
 
+    it('should not be focusable when disabled', async () => {
+      // Arrange
+      const {element} = await setUpTest('button');
+      element.disabled = true;
+      await element.updateComplete;
+
+      // Act
+      element.focus();
+
+      // Assert
+      expect(document.activeElement)
+        .withContext('disabled button should not be focused')
+        .not.toBe(element);
+    });
+
+    it('should be focusable when soft-disabled', async () => {
+      // Arrange
+      const {element} = await setUpTest('button');
+      element.softDisabled = true;
+      await element.updateComplete;
+
+      // Act
+      element.focus();
+
+      // Assert
+      expect(document.activeElement)
+        .withContext('soft-disabled button should be focused')
+        .toBe(element);
+    });
+
+    it('should not be clickable when disabled', async () => {
+      // Arrange
+      const clickListener = jasmine.createSpy('clickListener');
+      const {element} = await setUpTest('button');
+      element.disabled = true;
+      element.addEventListener('click', clickListener);
+      await element.updateComplete;
+
+      // Act
+      element.click();
+
+      // Assert
+      expect(clickListener).not.toHaveBeenCalled();
+    });
+
+    it('should not be clickable when soft-disabled', async () => {
+      // Arrange
+      const clickListener = jasmine.createSpy('clickListener');
+      const {element} = await setUpTest('button');
+      element.softDisabled = true;
+      element.addEventListener('click', clickListener);
+      await element.updateComplete;
+
+      // Act
+      element.click();
+
+      // Assert
+      expect(clickListener).not.toHaveBeenCalled();
+    });
+
     it(
       'setting `ariaLabel` updates the aria-label attribute on the native ' +
         'button element',
diff --git a/iconbutton/internal/_filled-icon-button.scss b/iconbutton/internal/_filled-icon-button.scss
index 7293798c27..3332e3f84b 100644
--- a/iconbutton/internal/_filled-icon-button.scss
+++ b/iconbutton/internal/_filled-icon-button.scss
@@ -53,7 +53,7 @@
       color: var(--_pressed-icon-color);
     }
 
-    &:disabled {
+    &:is(:disabled, [aria-disabled='true']) {
       color: var(--_disabled-icon-color);
     }
 
@@ -77,17 +77,17 @@
     z-index: -1; // place behind content
   }
 
-  .icon-button:disabled::before {
+  .icon-button:is(:disabled, [aria-disabled='true'])::before {
     background-color: var(--_disabled-container-color);
     opacity: var(--_disabled-container-opacity);
   }
 
-  .icon-button:disabled .icon {
+  .icon-button:is(:disabled, [aria-disabled='true']) .icon {
     opacity: var(--_disabled-icon-opacity);
   }
 
   .toggle-filled {
-    &:not(:disabled) {
+    &:not(:disabled, [aria-disabled='true']) {
       color: var(--_toggle-icon-color);
 
       &:hover {
@@ -111,14 +111,14 @@
     );
   }
 
-  .toggle-filled:not(:disabled)::before {
+  .toggle-filled:not(:disabled, [aria-disabled='true'])::before {
     // Note: filled icon buttons have three container colors,
     // "container-color" for regular, then selected/unselected for toggle.
     background-color: var(--_unselected-container-color);
   }
 
   .selected {
-    &:not(:disabled) {
+    &:not(:disabled, [aria-disabled='true']) {
       color: var(--_toggle-selected-icon-color);
 
       &:hover {
@@ -142,7 +142,7 @@
     );
   }
 
-  .selected:not(:disabled)::before {
+  .selected:not(:disabled, [aria-disabled='true'])::before {
     background-color: var(--_selected-container-color);
   }
 }
diff --git a/iconbutton/internal/_filled-tonal-icon-button.scss b/iconbutton/internal/_filled-tonal-icon-button.scss
index e50c65b065..8de926a1ad 100644
--- a/iconbutton/internal/_filled-tonal-icon-button.scss
+++ b/iconbutton/internal/_filled-tonal-icon-button.scss
@@ -12,8 +12,6 @@
 @use '../../tokens';
 // go/keep-sorted end
 
-$_custom-property-prefix: 'filled-tonal-icon-button';
-
 @mixin theme($tokens) {
   $supported-tokens: tokens.$md-comp-filled-tonal-icon-button-supported-tokens;
   @each $token, $value in $tokens {
@@ -55,7 +53,7 @@ $_custom-property-prefix: 'filled-tonal-icon-button';
       color: var(--_pressed-icon-color);
     }
 
-    &:disabled {
+    &:is(:disabled, [aria-disabled='true']) {
       color: var(--_disabled-icon-color);
     }
 
@@ -79,17 +77,17 @@ $_custom-property-prefix: 'filled-tonal-icon-button';
     z-index: -1; // place behind content
   }
 
-  .icon-button:disabled::before {
+  .icon-button:is(:disabled, [aria-disabled='true'])::before {
     background-color: var(--_disabled-container-color);
     opacity: var(--_disabled-container-opacity);
   }
 
-  .icon-button:disabled .icon {
+  .icon-button:is(:disabled, [aria-disabled='true']) .icon {
     opacity: var(--_disabled-icon-opacity);
   }
 
   .toggle-filled-tonal {
-    &:not(:disabled) {
+    &:not(:disabled, [aria-disabled='true']) {
       color: var(--_toggle-icon-color);
 
       &:hover {
@@ -113,14 +111,14 @@ $_custom-property-prefix: 'filled-tonal-icon-button';
     );
   }
 
-  .toggle-filled-tonal:not(:disabled)::before {
+  .toggle-filled-tonal:not(:disabled, [aria-disabled='true'])::before {
     // Note: filled tonal icon buttons have three container colors,
     // "container-color" for regular, then selected/unselected for toggle.
     background-color: var(--_unselected-container-color);
   }
 
   .selected {
-    &:not(:disabled) {
+    &:not(:disabled, [aria-disabled='true']) {
       color: var(--_toggle-selected-icon-color);
 
       &:hover {
@@ -144,7 +142,7 @@ $_custom-property-prefix: 'filled-tonal-icon-button';
     );
   }
 
-  .selected:not(:disabled)::before {
+  .selected:not(:disabled, [aria-disabled='true'])::before {
     background-color: var(--_selected-container-color);
   }
 }
diff --git a/iconbutton/internal/_icon-button.scss b/iconbutton/internal/_icon-button.scss
index 433a11de27..96b3eaba76 100644
--- a/iconbutton/internal/_icon-button.scss
+++ b/iconbutton/internal/_icon-button.scss
@@ -91,7 +91,7 @@
       color: var(--_pressed-icon-color);
     }
 
-    &:disabled {
+    &:is(:disabled, [aria-disabled='true']) {
       color: var(--_disabled-icon-color);
     }
   }
@@ -100,12 +100,12 @@
     border-radius: var(--_state-layer-shape);
   }
 
-  .standard:disabled .icon {
+  .standard:is(:disabled, [aria-disabled='true']) {
     opacity: var(--_disabled-icon-opacity);
   }
 
   .selected {
-    &:not(:disabled) {
+    &:not(:disabled, [aria-disabled='true']) {
       color: var(--_selected-icon-color);
 
       &:hover {
diff --git a/iconbutton/internal/_outlined-icon-button.scss b/iconbutton/internal/_outlined-icon-button.scss
index 0ecc5f4c59..819521eb1f 100644
--- a/iconbutton/internal/_outlined-icon-button.scss
+++ b/iconbutton/internal/_outlined-icon-button.scss
@@ -69,7 +69,7 @@
       color: var(--_pressed-icon-color);
     }
 
-    &:disabled {
+    &:is(:disabled, [aria-disabled='true']) {
       color: var(--_disabled-icon-color);
 
       &::before {
@@ -79,7 +79,7 @@
     }
   }
 
-  .outlined:disabled .icon {
+  .outlined:is(:disabled, [aria-disabled='true']) .icon {
     opacity: var(--_disabled-icon-opacity);
   }
 
@@ -103,7 +103,7 @@
 
   // Selected icon button toggle.
   .selected {
-    &:not(:disabled) {
+    &:not(:disabled, [aria-disabled='true']) {
       color: var(--_selected-icon-color);
 
       &:hover {
@@ -129,17 +129,17 @@
     );
   }
 
-  .selected:not(:disabled)::before {
+  .selected:not(:disabled, [aria-disabled='true'])::before {
     background-color: var(--_selected-container-color);
   }
 
-  .selected:disabled::before {
+  .selected:is(:disabled, [aria-disabled='true'])::before {
     background-color: var(--_disabled-selected-container-color);
     opacity: var(--_disabled-selected-container-opacity);
   }
 
   @media (forced-colors: active) {
-    :host([disabled]) {
+    :host(:is([disabled], [soft-disabled])) {
       --_disabled-outline-opacity: 1;
     }
 
@@ -150,7 +150,7 @@
         border-width: var(--_outline-width);
       }
 
-      &:disabled::before {
+      &:is(:disabled, [aria-disabled='true'])::before {
         border-color: GrayText;
         opacity: 1;
       }
diff --git a/iconbutton/internal/_shared.scss b/iconbutton/internal/_shared.scss
index eea1b05aae..b1275f5ba5 100644
--- a/iconbutton/internal/_shared.scss
+++ b/iconbutton/internal/_shared.scss
@@ -41,7 +41,7 @@
     );
   }
 
-  :host([disabled]) {
+  :host(:is([disabled], [soft-disabled])) {
     pointer-events: none;
   }
 
@@ -109,7 +109,8 @@
   }
 
   @media (forced-colors: active) {
-    :host([disabled]) {
+    :host(:is([disabled], [soft-disabled])) {
+      --_disabled-icon-color: GrayText;
       --_disabled-icon-opacity: 1;
     }
   }
diff --git a/iconbutton/internal/icon-button.ts b/iconbutton/internal/icon-button.ts
index 9a23674922..a74f70c3c2 100644
--- a/iconbutton/internal/icon-button.ts
+++ b/iconbutton/internal/icon-button.ts
@@ -7,7 +7,7 @@
 import '../../focus/md-focus-ring.js';
 import '../../ripple/ripple.js';
 
-import {html, LitElement, nothing} from 'lit';
+import {html, isServer, LitElement, nothing} from 'lit';
 import {property, state} from 'lit/decorators.js';
 import {classMap} from 'lit/directives/class-map.js';
 import {literal, html as staticHtml} from 'lit/static-html.js';
@@ -58,6 +58,16 @@ export class IconButton extends iconButtonBaseClass implements FormSubmitter {
    */
   @property({type: Boolean, reflect: true}) disabled = false;
 
+  /**
+   * "Soft-disables" the icon button (disabled but still focusable).
+   *
+   * Use this when an icon button needs increased visibility when disabled. See
+   * https://www.w3.org/WAI/ARIA/apg/practices/keyboard-interface/#kbd_disabled_controls
+   * for more guidance on when this is needed.
+   */
+  @property({type: Boolean, attribute: 'soft-disabled', reflect: true})
+  softDisabled = false;
+
   /**
    * Flips the icon if it is in an RTL context at startup.
    */
@@ -127,12 +137,18 @@ export class IconButton extends iconButtonBaseClass implements FormSubmitter {
 
   @state() private flipIcon = isRtl(this, this.flipIconInRtl);
 
-  /**
-   * Link buttons cannot be disabled.
-   */
+  constructor() {
+    super();
+    if (!isServer) {
+      this.addEventListener('click', this.handleClick.bind(this));
+    }
+  }
+
   protected override willUpdate() {
+    // Link buttons cannot be disabled or soft-disabled.
     if (this.href) {
       this.disabled = false;
+      this.softDisabled = false;
     }
   }
 
@@ -156,8 +172,9 @@ export class IconButton extends iconButtonBaseClass implements FormSubmitter {
         aria-haspopup="${(!this.href && ariaHasPopup) || nothing}"
         aria-expanded="${(!this.href && ariaExpanded) || nothing}"
         aria-pressed="${ariaPressedValue}"
+        aria-disabled=${(!this.href && this.softDisabled) || nothing}
         ?disabled="${!this.href && this.disabled}"
-        @click="${this.handleClick}">
+        @click="${this.handleClickOnChild}">
         ${this.renderFocusRing()}
         ${this.renderRipple()}
         ${!this.selected ? this.renderIcon() : nothing}
@@ -210,10 +227,11 @@ export class IconButton extends iconButtonBaseClass implements FormSubmitter {
   }
 
   private renderRipple() {
+    const isRippleDisabled = !this.href && (this.disabled || this.softDisabled);
     // TODO(b/310046938): use the same id for both elements
     return html`<md-ripple
       for=${this.href ? 'link' : nothing}
-      ?disabled="${!this.href && this.disabled}"></md-ripple>`;
+      ?disabled="${isRippleDisabled}"></md-ripple>`;
   }
 
   override connectedCallback() {
@@ -221,10 +239,31 @@ export class IconButton extends iconButtonBaseClass implements FormSubmitter {
     super.connectedCallback();
   }
 
-  private async handleClick(event: Event) {
+  /** Handles a click on this element. */
+  private handleClick(event: MouseEvent) {
+    // If the icon button is soft-disabled, we need to explicitly prevent the
+    // click from propagating to other event listeners as well as prevent the
+    // default action.
+    if (!this.href && this.softDisabled) {
+      event.stopImmediatePropagation();
+      event.preventDefault();
+      return;
+    }
+  }
+
+  /**
+   * Handles a click on the child <div> or <button> element within this
+   * element's shadow DOM.
+   */
+  private async handleClickOnChild(event: Event) {
     // Allow the event to propagate
     await 0;
-    if (!this.toggle || this.disabled || event.defaultPrevented) {
+    if (
+      !this.toggle ||
+      this.disabled ||
+      this.softDisabled ||
+      event.defaultPrevented
+    ) {
       return;
     }