refactor(material/core): granular animations disabled state

Adds a function that provides more granular information about why animations are disabled.

Author: crisbeto

goldens/material/core/index.api.md

@@ -132,6 +132,9 @@ export class _ErrorStateTracker {
     updateErrorState(): void;
 }
 
+// @public
+export function _getAnimationsState(): 'enabled' | 'di-disabled' | 'reduced-motion';
+
 // @public
 export function _getOptionScrollPosition(optionOffset: number, optionHeight: number, currentScrollPosition: number, panelHeight: number): number;
 

src/material/core/animation/animation.ts

@@ -41,18 +41,28 @@ export class AnimationDurations {
   static EXITING = '195ms';
 }
 
+let reducedMotion: boolean | null = null;
+
 /**
- * Returns whether animations have been disabled by DI. Must be called in a DI context.
+ * Gets the the configured animations state.
  * @docs-private
  */
-export function _animationsDisabled(): boolean {
+export function _getAnimationsState(): 'enabled' | 'di-disabled' | 'reduced-motion' {
   if (
     inject(MATERIAL_ANIMATIONS, {optional: true})?.animationsDisabled ||
     inject(ANIMATION_MODULE_TYPE, {optional: true}) === 'NoopAnimations'
   ) {
-    return true;
+    return 'di-disabled';
   }
 
-  const mediaMatcher = inject(MediaMatcher);
-  return mediaMatcher.matchMedia('(prefers-reduced-motion)').matches;
+  reducedMotion ??= inject(MediaMatcher).matchMedia('(prefers-reduced-motion)').matches;
+  return reducedMotion ? 'reduced-motion' : 'enabled';
+}
+
+/**
+ * Returns whether animations have been disabled by DI. Must be called in a DI context.
+ * @docs-private
+ */
+export function _animationsDisabled(): boolean {
+  return _getAnimationsState() !== 'enabled';
 }