precache

lib/firebase_image.dart

@@ -2,3 +2,4 @@ library firebase_image;
 
 export 'src/firebase_image.dart';
 export 'src/cache_refresh_strategy.dart';
+export 'src/precache_firebase_image.dart';

lib/src/firebase_image.dart

@@ -49,9 +49,11 @@ class FirebaseImage extends ImageProvider<FirebaseImage> {
           reference: _getImageRef(location, firebaseApp),
         );
 
+  Uint8List _precachedBytes;
+
   /// Returns the image as bytes
-  Future<Uint8List> getBytes() {
-    return _fetchImage();
+  Future<Uint8List> getBytes() async {
+    return _precachedBytes ?? await _fetchImage();
   }
 
   static String _getBucket(String location) {
@@ -99,6 +101,17 @@ class FirebaseImage extends ImageProvider<FirebaseImage> {
     return bytes;
   }
 
+  /// Precache this image.
+  Future<void> precache() async {
+    assert(shouldCache == true);
+    FirebaseImageCacheManager cacheManager = FirebaseImageCacheManager(
+      cacheRefreshStrategy,
+    );
+    await cacheManager.open();
+    _precachedBytes ??= await cacheManager.upsertRemoteFileToCache(
+        _imageObject, this.maxSizeBytes);
+  }
+
   Future<Codec> _fetchImageCodec() async {
     return await PaintingBinding.instance
         .instantiateImageCodec(await _fetchImage());

lib/src/precache_firebase_image.dart

@@ -0,0 +1,21 @@
+import 'package:firebase_core/firebase_core.dart';
+
+import 'cache_refresh_strategy.dart';
+import 'firebase_image.dart';
+
+Future<void> precacheFirebaseImage(String location,
+    {FirebaseApp firebaseApp,
+    int maxSizeBytes = 2500 * 1000,
+    CacheRefreshStrategy cacheRefreshStrategy =
+        CacheRefreshStrategy.BY_METADATA_DATE}) async {
+  assert(location != null);
+
+  final image = FirebaseImage(
+    location,
+    firebaseApp: firebaseApp,
+    maxSizeBytes: maxSizeBytes,
+    cacheRefreshStrategy: cacheRefreshStrategy,
+  );
+
+  await image.precache();
+}