From b1a896ba612a90320168541c2c289dc73aa6edbb Mon Sep 17 00:00:00 2001
From: martyfuhry <martyfuhry@gmail.com>
Date: Wed, 28 Feb 2024 17:13:15 -0500
Subject: [PATCH] feat(mobile): Adds better precaching for assets in gallery
 view and memory lane (#7486)

Adds better precaching for assets in gallery view and memory lane
---
 .../asset_viewer/views/gallery_viewer.dart    | 30 +++++++++++++++----
 .../modules/memories/views/memory_page.dart   |  7 +++--
 2 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/mobile/lib/modules/asset_viewer/views/gallery_viewer.dart b/mobile/lib/modules/asset_viewer/views/gallery_viewer.dart
index e296483cc2..dfdfb32844 100644
--- a/mobile/lib/modules/asset_viewer/views/gallery_viewer.dart
+++ b/mobile/lib/modules/asset_viewer/views/gallery_viewer.dart
@@ -1,3 +1,4 @@
+import 'dart:async';
 import 'dart:io';
 import 'dart:math';
 import 'dart:ui' as ui;
@@ -132,7 +133,7 @@ class GalleryViewerPage extends HookConsumerWidget {
     void toggleFavorite(Asset asset) =>
         ref.read(assetProvider.notifier).toggleFavorite([asset]);
 
-    void precacheNextImage(int index) {
+    Future<void> precacheNextImage(int index) async {
       void onError(Object exception, StackTrace? stackTrace) {
         // swallow error silently
         debugPrint('Error precaching next image: $exception, $stackTrace');
@@ -140,7 +141,7 @@ class GalleryViewerPage extends HookConsumerWidget {
 
       if (index < totalAssets && index >= 0) {
         final asset = loadAsset(index);
-        precacheImage(
+        await precacheImage(
           ImmichImage.imageProvider(asset: asset),
           context,
           onError: onError,
@@ -711,6 +712,21 @@ class GalleryViewerPage extends HookConsumerWidget {
       [],
     );
 
+    useEffect(
+      () {
+        // No need to await this
+        unawaited(
+          // Delay this a bit so we can finish loading the page
+          Future.delayed(const Duration(milliseconds: 400)).then(
+            // Precache the next image
+            (_) => precacheNextImage(currentIndex.value + 1),
+          ),
+        );
+        return null;
+      },
+      [],
+    );
+
     ref.listen(showControlsProvider, (_, show) {
       if (show) {
         SystemChrome.setEnabledSystemUIMode(SystemUiMode.edgeToEdge);
@@ -761,12 +777,16 @@ class GalleryViewerPage extends HookConsumerWidget {
                   ),
               itemCount: totalAssets,
               scrollDirection: Axis.horizontal,
-              onPageChanged: (value) {
+              onPageChanged: (value) async {
                 final next = currentIndex.value < value ? value + 1 : value - 1;
-                precacheNextImage(next);
+                HapticFeedback.selectionClick();
                 currentIndex.value = value;
                 stackIndex.value = -1;
-                HapticFeedback.selectionClick();
+
+                // Wait for page change animation to finish
+                await Future.delayed(const Duration(milliseconds: 400));
+                // Then precache the next image
+                unawaited(precacheNextImage(next));
               },
               builder: (context, index) {
                 final a =
diff --git a/mobile/lib/modules/memories/views/memory_page.dart b/mobile/lib/modules/memories/views/memory_page.dart
index 9308e812dc..d06bb959ee 100644
--- a/mobile/lib/modules/memories/views/memory_page.dart
+++ b/mobile/lib/modules/memories/views/memory_page.dart
@@ -124,11 +124,14 @@ class MemoryPage extends HookConsumerWidget {
           .then((_) => precacheAsset(1));
     }
 
-    onAssetChanged(int otherIndex) {
+    Future<void> onAssetChanged(int otherIndex) async {
       HapticFeedback.selectionClick();
       currentAssetPage.value = otherIndex;
-      precacheAsset(otherIndex + 1);
       updateProgressText();
+      // Wait for page change animation to finish
+      await Future.delayed(const Duration(milliseconds: 400));
+      // And then precache the next asset
+      await precacheAsset(otherIndex + 1);
     }
 
     /* Notification listener is used instead of OnPageChanged callback since OnPageChanged is called