Unify dimensions cache between lightbox and feed (#6047)

* Remove useless memo

* Use explicit values when useImageAspectRatio doesn't know

It's not very good that you can't distingiush when we haven't loaded vs when we're certain. This shifts the burden of dealing with missing values to the caller.

* Check cache early

* Handle src change

* Rewrite image-sizes.fetch to avoid mixing async styles

* Make image-sizes LRU

Code is copy paste from useImageDimensions.ts

* Rm unused fields

* Derive aspect on the fly

* Factor useImageDimensions out of useImageAspectRatio

* Move useImageDimensions into image-sizes

* Make lightbox use the same cache

* Wire up known dimensions to the lightbox

* Handle division by zero in the hook

* Use safe aspect for lightbox calculations

src/view/com/util/images/AutoSizedImage.tsx

@@ -5,7 +5,7 @@ import {AppBskyEmbedImages} from '@atproto/api'
 import {msg} from '@lingui/macro'
 import {useLingui} from '@lingui/react'
 
-import * as imageSizes from '#/lib/media/image-sizes'
+import {useImageDimensions} from '#/lib/media/image-sizes'
 import {Dimensions} from '#/lib/media/types'
 import {isNative} from '#/platform/detection'
 import {useLargeAltBadgeEnabled} from '#/state/preferences/large-alt-badge'
@@ -14,44 +14,24 @@ import {ArrowsDiagonalOut_Stroke2_Corner0_Rounded as Fullscreen} from '#/compone
 import {MediaInsetBorder} from '#/components/MediaInsetBorder'
 import {Text} from '#/components/Typography'
 
-export function useImageAspectRatio({
+function useImageAspectRatio({
   src,
-  dimensions,
+  knownDimensions,
 }: {
   src: string
-  dimensions: Dimensions | undefined
+  knownDimensions: Dimensions | null
 }) {
-  const [raw, setAspectRatio] = React.useState<number>(
-    dimensions ? calc(dimensions) : 1,
-  )
-  // this basically controls the width of the image
-  const {isCropped, constrained, max} = React.useMemo(() => {
+  const [raw] = useImageDimensions({src, knownDimensions})
+  let constrained: number | undefined
+  let max: number | undefined
+  let isCropped: boolean | undefined
+  if (raw !== undefined) {
     const ratio = 1 / 2 // max of 1:2 ratio in feeds
-    const constrained = Math.max(raw, ratio)
-    const max = Math.max(raw, 0.25) // max of 1:4 in thread
-    const isCropped = raw < constrained
-    return {
-      isCropped,
-      constrained,
-      max,
-    }
-  }, [raw])
-
-  React.useEffect(() => {
-    let aborted = false
-    if (dimensions) return
-    imageSizes.fetch(src).then(newDim => {
-      if (aborted) return
-      setAspectRatio(calc(newDim))
-    })
-    return () => {
-      aborted = true
-    }
-  }, [dimensions, setAspectRatio, src])
-
+    constrained = Math.max(raw, ratio)
+    max = Math.max(raw, 0.25) // max of 1:4 in thread
+    isCropped = raw < constrained
+  }
   return {
-    dimensions,
-    raw,
     constrained,
     max,
     isCropped,
@@ -125,7 +105,7 @@ export function AutoSizedImage({
     isCropped: rawIsCropped,
   } = useImageAspectRatio({
     src: image.thumb,
-    dimensions: image.aspectRatio,
+    knownDimensions: image.aspectRatio ?? null,
   })
   const cropDisabled = crop === 'none'
   const isCropped = rawIsCropped && !cropDisabled
@@ -222,14 +202,16 @@ export function AutoSizedImage({
           a.rounded_md,
           a.overflow_hidden,
           t.atoms.bg_contrast_25,
-          {aspectRatio: max},
+          {aspectRatio: max ?? 1},
         ]}>
         {contents}
       </Pressable>
     )
   } else {
     return (
-      <ConstrainedImage fullBleed={crop === 'square'} aspectRatio={constrained}>
+      <ConstrainedImage
+        fullBleed={crop === 'square'}
+        aspectRatio={constrained ?? 1}>
         <Pressable
           onPress={onPress}
           onLongPress={onLongPress}
@@ -244,10 +226,3 @@ export function AutoSizedImage({
     )
   }
 }
-
-function calc(dim: Dimensions) {
-  if (dim.width === 0 || dim.height === 0) {
-    return 1
-  }
-  return dim.width / dim.height
-}

src/view/com/util/post-embeds/index.tsx

@@ -145,7 +145,7 @@ export function PostEmbeds({
         uri: img.fullsize,
         thumbUri: img.thumb,
         alt: img.alt,
-        aspectRatio: img.aspectRatio,
+        dimensions: img.aspectRatio ?? null,
       }))
       const _openLightbox = (
         index: number,