From 9482a3dcf44db9c0d39234f7b1aafcfebcc3d897 Mon Sep 17 00:00:00 2001
From: Jan <j.ackermann91@gmail.com>
Date: Mon, 12 Dec 2022 10:36:35 +0100
Subject: [PATCH] improve preloading

---
 packages/web-app-preview/src/App.vue | 30 ++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/packages/web-app-preview/src/App.vue b/packages/web-app-preview/src/App.vue
index 3631a420996..9b170361693 100644
--- a/packages/web-app-preview/src/App.vue
+++ b/packages/web-app-preview/src/App.vue
@@ -564,22 +564,36 @@ export default defineComponent({
           })
       }
 
-      console.log('active index: ', this.activeIndex)
+      const preloadUpcomingFile = (upcomingFileIndex) => {
+        let cycleIndex =
+          (((this.activeIndex + upcomingFileIndex) % this.filteredFiles.length) +
+            this.filteredFiles.length) %
+          this.filteredFiles.length
 
-      for (
-        let followingFileIndex = 1;
-        followingFileIndex <= PRELOAD_IMAGE_COUNT;
-        followingFileIndex++
-      ) {
-        let cycleIndex = (this.activeIndex + followingFileIndex) % this.activeFiles.length
         const file = this.filteredFiles[cycleIndex]
 
         if (!this.isFileTypeImage(file) || toPreloadFiles.includes(file.id)) {
-          continue
+          return
         }
 
         loadPreviewAsync(file)
       }
+
+      for (
+        let followingFileIndex = 1;
+        followingFileIndex <= PRELOAD_IMAGE_COUNT;
+        followingFileIndex++
+      ) {
+        preloadUpcomingFile(followingFileIndex)
+      }
+
+      for (
+        let previousFileIndex = -1;
+        previousFileIndex >= PRELOAD_IMAGE_COUNT * -1;
+        previousFileIndex--
+      ) {
+        preloadUpcomingFile(previousFileIndex)
+      }
     }
   }
 })