From 2bb3e152f8329b07e0abd2c879da6d748ae62366 Mon Sep 17 00:00:00 2001
From: Manav Rathi <manav@mrmr.io>
Date: Tue, 16 Apr 2024 19:54:00 +0530
Subject: [PATCH] Precache

---
 web/apps/cast/src/pages/slideshow.tsx | 28 ++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/web/apps/cast/src/pages/slideshow.tsx b/web/apps/cast/src/pages/slideshow.tsx
index 60aded0336..8d8b61c703 100644
--- a/web/apps/cast/src/pages/slideshow.tsx
+++ b/web/apps/cast/src/pages/slideshow.tsx
@@ -162,12 +162,34 @@ export default function Slideshow() {
         }
     };
 
-    useEffect(() => {
-        if (currentFile) {
-            getRenderableFileURL();
+    const precacheNextRenderableFileURL = async () => {
+        if (!nextFile) return;
+
+        const cacheValue = renderableFileURLCache.get(nextFile.id);
+        if (cacheValue) return;
+
+        try {
+            const blob = await getPreviewableImage(
+                nextFile as EnteFile,
+                castToken,
+            );
+
+            const url = URL.createObjectURL(blob);
+
+            renderableFileURLCache.set(nextFile?.id, url);
+        } catch (e) {
+            return;
         }
+    };
+
+    useEffect(() => {
+        getRenderableFileURL();
     }, [currentFile]);
 
+    useEffect(() => {
+        precacheNextRenderableFileURL();
+    }, [nextFile]);
+
     return (
         <>
             <SlideshowContext.Provider value={{ showNextSlide }}>