refactor(material-experimental/mdc-button): switch to new theming API (#24201)

* refactor(material-experimental/mdc-button): switch to new theming API

Switches the MDC-based buttons to the new token-based theming API.

* refactor(material-experimental/mdc-button): reduce bundle size

Reworks the MDC buttons to reduce their bundle size.

(cherry picked from commit 4ee7159)

Author: crisbeto

src/material-experimental/mdc-button/_button-base.scss

@@ -1,3 +1,4 @@
+@use 'sass:map';
 @use '@material/touch-target' as mdc-touch-target;
 @use '../mdc-helpers/mdc-helpers';
 @use '../../material/core/style/layout-common';
@@ -8,22 +9,10 @@
 // ripple and state container so that they fill the button, match the border radius, and avoid
 // pointer events.
 @mixin mat-private-button-interactive() {
-  .mdc-button__ripple::before, .mdc-button__ripple::after,
-  .mdc-fab__ripple::before, .mdc-fab__ripple::after {
-    content: '';
-    pointer-events: none;
-    position: absolute;
-    top: 0;
-    right: 0;
-    bottom: 0;
-    left: 0;
-    opacity: 0;
-    border-radius: inherit;
-    @content;
-  }
-
   // The ripple container should match the bounds of the entire button.
-  .mat-mdc-button-ripple, .mdc-button__ripple, .mdc-fab__ripple {
+  .mat-mdc-button-ripple,
+  .mat-mdc-button-persistent-ripple,
+  .mat-mdc-button-persistent-ripple::before {
     @include layout-common.fill;
 
     // Disable pointer events for the ripple container and state overlay because the container
@@ -38,6 +27,17 @@
     border-radius: inherit;
   }
 
+  // We use ::before so that we can reuse some of MDC's theming.
+  .mat-mdc-button-persistent-ripple::before {
+    content: '';
+    opacity: 0;
+    background-color: var(--mat-mdc-button-persistent-ripple-color);
+  }
+
+  .mat-ripple-element {
+    background-color: var(--mat-mdc-button-ripple-color);
+  }
+
   // The content should appear over the state and ripple layers, otherwise they may adversely affect
   // the accessibility of the text content.
   .mdc-button__label {
@@ -59,6 +59,7 @@
   &[disabled] {
     cursor: default;
     pointer-events: none;
+    @content;
   }
 }
 
@@ -75,3 +76,15 @@
       $query: mdc-helpers.$mat-base-styles-query);
   }
 }
+
+// Changes a button theme to exclude the ripple styles.
+@function mat-private-button-remove-ripple($theme) {
+  @return map.merge($theme, (
+    focus-state-layer-color: null,
+    focus-state-layer-opacity: null,
+    hover-state-layer-color: null,
+    hover-state-layer-opacity: null,
+    pressed-state-layer-color: null,
+    pressed-state-layer-opacity: null,
+  ));
+}

src/material-experimental/mdc-button/_button-theme-private.scss

@@ -1,28 +1,43 @@
+@use 'sass:map';
+@use '@material/ripple/ripple-theme' as mdc-ripple-theme;
 @use '@material/theme/theme-color' as mdc-theme-color;
-@use '@material/theme/theme' as mdc-theme;
 @use '../../material/core/ripple/ripple-theme';
 
-// Selector for the element that has a background color and opacity applied to its ::before and
-// ::after for state interactions (hover, active, focus). Their API calls this their
-// "ripple target", but we do not use it as our ripple, just state color.
-$button-state-target: '.mdc-button__ripple';
-$fab-state-target: '.mdc-fab__ripple';
-
-// The MDC button's ripple ink color is based on the theme color, not on the foreground base
-// which is what the ripple mixin uses. This creates a new theme that sets the color to the
-// foreground base to appropriately color the ink.
-@mixin ripple-ink-color($mdc-color) {
-  @include ripple-theme.color((
-    foreground: (
-      base: mdc-theme-color.prop-value($mdc-color)
-    ),
-  ));
+@mixin _ripple-color($color) {
+  --mat-mdc-button-persistent-ripple-color: #{$color};
+  --mat-mdc-button-ripple-color: #{rgba($color, 0.1)};
 }
 
-// Applies the disabled theme color to the text color.
-@mixin apply-disabled-color() {
-  @include mdc-theme.prop(color,
-      mdc-theme-color.ink-color-for-fill_(disabled, mdc-theme-color.$background));
+@mixin ripple-theme-styles($config, $is-filled) {
+  $opacities: if(map.get($config, is-dark),
+    mdc-ripple-theme.$light-ink-opacities, mdc-ripple-theme.$dark-ink-opacities);
+
+  // Ideally these styles would be structural, but MDC bases some of the opacities on the theme.
+  &:hover .mat-mdc-button-persistent-ripple::before {
+    opacity: map.get($opacities, hover);
+  }
+
+  &:focus .mat-mdc-button-persistent-ripple::before {
+    opacity: map.get($opacities, focus);
+  }
+
+  &:active .mat-mdc-button-persistent-ripple::before {
+    opacity: map.get($opacities, press);
+  }
+
+  @include _ripple-color(mdc-theme-color.prop-value(on-surface));
+
+  &.mat-primary {
+    @include _ripple-color(mdc-theme-color.prop-value(if($is-filled, on-primary, primary)));
+  }
+
+  &.mat-accent {
+    @include _ripple-color(mdc-theme-color.prop-value(if($is-filled, on-secondary, secondary)));
+  }
+
+  &.mat-warn {
+    @include _ripple-color(mdc-theme-color.prop-value(if($is-filled, on-error, error)));
+  }
 }
 
 // Wraps the content style in a selector for the disabled state.
@@ -37,14 +52,6 @@ $fab-state-target: '.mdc-fab__ripple';
   }
 }
 
-// Applies the disabled theme background color for raised buttons. Value is taken from
-// mixin `mdc-button--filled`.
-// TODO(andrewseguin): Discuss with the MDC team about providing a variable for the 0.12 value
-// or otherwise have a mixin we can call to apply this style for both button and anchors.
-@mixin apply-disabled-background() {
-  @include mdc-theme.prop(background-color, rgba(mdc-theme-color.prop-value(on-surface), 0.12));
-}
-
 // Hides the touch target on lower densities.
 @mixin touch-target-density($scale) {
   @if ($scale == -2 or $scale == 'minimum') {