Improve timeline scroll, media layout, avatars, and emoji coverage.

Remember room scroll position across switches, reserve image/video heights from Matrix dimensions, cache authenticated media blobs for avatars, restore jumbo emoji-only messages, and extend emoji font unicode-range for Unicode 15 glyphs.

src/app/components/message/content/style.css.ts

@@ -1,11 +1,13 @@
-import { style } from '@vanilla-extract/css';
-import { DefaultReset, config } from 'folds';
+import { keyframes, style } from '@vanilla-extract/css';
+import { DefaultReset, color, config } from 'folds';
 
 export const RelativeBase = style([
   DefaultReset,
   {
     position: 'relative',
     display: 'flex',
+    width: '100%',
+    height: '100%',
     maxWidth: '100%',
     maxHeight: '100%',
     borderRadius: '7px',
@@ -16,9 +18,13 @@ export const RelativeBase = style([
 export const AbsoluteContainer = style([
   DefaultReset,
   {
+    position: 'absolute',
+    inset: 0,
     display: 'flex',
     alignItems: 'center',
     justifyContent: 'center',
+    width: '100%',
+    height: '100%',
     maxWidth: '100%',
     maxHeight: '100%',
     borderRadius: 'inherit',
@@ -34,6 +40,7 @@ export const AbsoluteFooter = style([
     bottom: config.space.S100,
     left: config.space.S100,
     right: config.space.S100,
+    zIndex: 1,
   },
 ]);
 
@@ -43,3 +50,67 @@ export const Blur = style([
     filter: 'blur(44px)',
   },
 ]);
+
+const shimmer = keyframes({
+  '0%': {
+    backgroundPosition: '200% 0',
+  },
+  '100%': {
+    backgroundPosition: '-200% 0',
+  },
+});
+
+/** Soft fallback when no blurhash is available. */
+export const MediaSkeleton = style([
+  DefaultReset,
+  {
+    position: 'absolute',
+    inset: 0,
+    borderRadius: 'inherit',
+    backgroundImage: `linear-gradient(
+      90deg,
+      ${color.SurfaceVariant.Container} 0%,
+      ${color.SurfaceVariant.ContainerHover} 40%,
+      ${color.SurfaceVariant.Container} 80%
+    )`,
+    backgroundSize: '200% 100%',
+    animation: `${shimmer} 1.4s ease-in-out infinite`,
+  },
+]);
+
+const blurhashFadeIn = keyframes({
+  from: {
+    opacity: 0,
+  },
+  to: {
+    opacity: 1,
+  },
+});
+
+/** Soft blurhash layer that fills the reserved media box. */
+export const BlurhashPlaceholder = style([
+  DefaultReset,
+  {
+    position: 'absolute',
+    inset: 0,
+    overflow: 'hidden',
+    borderRadius: 'inherit',
+    zIndex: 0,
+    // Soften the decode so it reads as color blobs; slight scale hides blur edges.
+    filter: 'blur(14px)',
+    transform: 'scale(1.06)',
+    opacity: 0,
+    animation: `${blurhashFadeIn} 560ms cubic-bezier(0.22, 1, 0.36, 1) forwards`,
+  },
+]);
+
+/** Media starts invisible and fades in once loaded over the placeholder. */
+export const MediaFadeIn = style({
+  zIndex: 1,
+  opacity: 0,
+  transition: 'opacity 520ms cubic-bezier(0.22, 1, 0.36, 1)',
+});
+
+export const MediaFadeInLoaded = style({
+  opacity: 1,
+});