Load local assets synchronously to prevent image flicker

Libraries/Image/RCTImage.xcodeproj/project.pbxproj

@@ -12,9 +12,7 @@
 		1304D5B21AA8C50D0002E2BE /* RCTGIFImageDecoder.m in Sources */ = {isa = PBXBuildFile; fileRef = 1304D5B11AA8C50D0002E2BE /* RCTGIFImageDecoder.m */; };
 		134B00A21B54232B00EC8DFB /* RCTImageUtils.m in Sources */ = {isa = PBXBuildFile; fileRef = 134B00A11B54232B00EC8DFB /* RCTImageUtils.m */; };
 		139A38841C4D587C00862840 /* RCTResizeMode.m in Sources */ = {isa = PBXBuildFile; fileRef = 139A38831C4D587C00862840 /* RCTResizeMode.m */; };
-		13EF7F0B1BC42D4E003F47DD /* RCTShadowVirtualImage.m in Sources */ = {isa = PBXBuildFile; fileRef = 13EF7F081BC42D4E003F47DD /* RCTShadowVirtualImage.m */; };
-		13EF7F0C1BC42D4E003F47DD /* RCTVirtualImageManager.m in Sources */ = {isa = PBXBuildFile; fileRef = 13EF7F0A1BC42D4E003F47DD /* RCTVirtualImageManager.m */; };
-		13EF7F7F1BC825B1003F47DD /* RCTXCAssetImageLoader.m in Sources */ = {isa = PBXBuildFile; fileRef = 13EF7F7E1BC825B1003F47DD /* RCTXCAssetImageLoader.m */; };
+		13EF7F7F1BC825B1003F47DD /* RCTLocalAssetImageLoader.m in Sources */ = {isa = PBXBuildFile; fileRef = 13EF7F7E1BC825B1003F47DD /* RCTLocalAssetImageLoader.m */; };
 		143879381AAD32A300F088A5 /* RCTImageLoader.m in Sources */ = {isa = PBXBuildFile; fileRef = 143879371AAD32A300F088A5 /* RCTImageLoader.m */; };
 		35123E6B1B59C99D00EBAD80 /* RCTImageStoreManager.m in Sources */ = {isa = PBXBuildFile; fileRef = 35123E6A1B59C99D00EBAD80 /* RCTImageStoreManager.m */; };
 		354631681B69857700AA0B86 /* RCTImageEditingManager.m in Sources */ = {isa = PBXBuildFile; fileRef = 354631671B69857700AA0B86 /* RCTImageEditingManager.m */; };
@@ -44,8 +42,8 @@
 		134B00A11B54232B00EC8DFB /* RCTImageUtils.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RCTImageUtils.m; sourceTree = "<group>"; };
 		139A38821C4D57AD00862840 /* RCTResizeMode.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RCTResizeMode.h; sourceTree = "<group>"; };
 		139A38831C4D587C00862840 /* RCTResizeMode.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RCTResizeMode.m; sourceTree = "<group>"; };
-		13EF7F7D1BC825B1003F47DD /* RCTXCAssetImageLoader.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RCTXCAssetImageLoader.h; sourceTree = "<group>"; };
-		13EF7F7E1BC825B1003F47DD /* RCTXCAssetImageLoader.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RCTXCAssetImageLoader.m; sourceTree = "<group>"; };
+		13EF7F7D1BC825B1003F47DD /* RCTLocalAssetImageLoader.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RCTLocalAssetImageLoader.h; sourceTree = "<group>"; };
+		13EF7F7E1BC825B1003F47DD /* RCTLocalAssetImageLoader.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RCTLocalAssetImageLoader.m; sourceTree = "<group>"; };
 		143879361AAD32A300F088A5 /* RCTImageLoader.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RCTImageLoader.h; sourceTree = "<group>"; };
 		143879371AAD32A300F088A5 /* RCTImageLoader.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = RCTImageLoader.m; sourceTree = "<group>"; };
 		35123E691B59C99D00EBAD80 /* RCTImageStoreManager.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = RCTImageStoreManager.h; sourceTree = "<group>"; };
@@ -75,8 +73,8 @@
 				EEF314711C9B0DD30049118E /* RCTImageBlurUtils.m */,
 				139A38821C4D57AD00862840 /* RCTResizeMode.h */,
 				139A38831C4D587C00862840 /* RCTResizeMode.m */,
-				13EF7F7D1BC825B1003F47DD /* RCTXCAssetImageLoader.h */,
-				13EF7F7E1BC825B1003F47DD /* RCTXCAssetImageLoader.m */,
+				13EF7F7D1BC825B1003F47DD /* RCTLocalAssetImageLoader.h */,
+				13EF7F7E1BC825B1003F47DD /* RCTLocalAssetImageLoader.m */,
 				1304D5B01AA8C50D0002E2BE /* RCTGIFImageDecoder.h */,
 				1304D5B11AA8C50D0002E2BE /* RCTGIFImageDecoder.m */,
 				354631661B69857700AA0B86 /* RCTImageEditingManager.h */,
@@ -169,7 +167,7 @@
 				139A38841C4D587C00862840 /* RCTResizeMode.m in Sources */,
 				1304D5AB1AA8C4A30002E2BE /* RCTImageView.m in Sources */,
 				EEF314721C9B0DD30049118E /* RCTImageBlurUtils.m in Sources */,
-				13EF7F7F1BC825B1003F47DD /* RCTXCAssetImageLoader.m in Sources */,
+				13EF7F7F1BC825B1003F47DD /* RCTLocalAssetImageLoader.m in Sources */,
 				134B00A21B54232B00EC8DFB /* RCTImageUtils.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;

Libraries/Image/RCTImageLoader.h

@@ -185,6 +185,18 @@ __deprecated_msg("Use getImageSizeWithURLRequest:block: instead");
  */
 - (float)loaderPriority;
 
+/**
+ * If the loader must be called on the serial url cache queue. If this is NO,
+ * the loader will be called from the main queue. Defaults to YES.
+ */
+- (BOOL)requiresScheduling;
+
+/**
+ * If images loaded by the loader should be cached in the decoded image cache.
+ * Defaults to YES.
+ */
+- (BOOL)shouldCacheLoadedImages;
+
 @end
 
 /**

Libraries/Image/RCTImageLoader.m

@@ -290,27 +290,44 @@ - (RCTImageLoaderCancellationBlock)loadImageOrDataWithURLRequest:(NSURLRequest *
                                                            scale:(CGFloat)scale
                                                       resizeMode:(RCTResizeMode)resizeMode
                                                    progressBlock:(RCTImageLoaderProgressBlock)progressHandler
-                                                 completionBlock:(void (^)(NSError *error, id imageOrData))completionBlock
+                                                 completionBlock:(void (^)(NSError *error, id imageOrData, BOOL cacheResult))completionBlock
 {
   __block volatile uint32_t cancelled = 0;
   __block void(^cancelLoad)(void) = nil;
   __weak RCTImageLoader *weakSelf = self;
+  // Find suitable image URL loader
+  __block id<RCTImageURLLoader> loadHandler = [self imageURLLoaderForURL:imageURLRequest.URL];
+  __block BOOL cacheResult = [loadHandler respondsToSelector:@selector(shouldCacheLoadedImages)] ?
+      [loadHandler shouldCacheLoadedImages] : YES;
+  BOOL requiresScheduling = [loadHandler respondsToSelector:@selector(requiresScheduling)] ?
+      [loadHandler requiresScheduling] : YES;
 
   void (^completionHandler)(NSError *error, id imageOrData) = ^(NSError *error, id imageOrData) {
-    if (RCTIsMainQueue()) {
+    if (RCTIsMainQueue() && requiresScheduling) {
 
       // Most loaders do not return on the main thread, so caller is probably not
       // expecting it, and may do expensive post-processing in the callback
       dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
         if (!cancelled) {
-          completionBlock(error, imageOrData);
+          completionBlock(error, imageOrData, cacheResult);
         }
       });
     } else if (!cancelled) {
-      completionBlock(error, imageOrData);
+      completionBlock(error, imageOrData, cacheResult);
     }
   };
 
+  // If the loader doesn't require scheduling we call it directly on
+  // the main queue.
+  if (loadHandler && !requiresScheduling) {
+    return [loadHandler loadImageForURL:imageURLRequest.URL
+                                   size:size
+                                  scale:scale
+                             resizeMode:resizeMode
+                        progressHandler:progressHandler
+                      completionHandler:completionHandler] ?: ^{};
+  }
+
   // All access to URL cache must be serialized
   if (!_URLCacheQueue) {
     [self setUp];
@@ -328,16 +345,15 @@ - (RCTImageLoaderCancellationBlock)loadImageOrDataWithURLRequest:(NSURLRequest *
       return;
     }
 
-    // Find suitable image URL loader
     NSURLRequest *request = imageURLRequest; // Use a local variable so we can reassign it in this block
-    id<RCTImageURLLoader> loadHandler = [strongSelf imageURLLoaderForURL:request.URL];
-    if (loadHandler) {
-      cancelLoad = [loadHandler loadImageForURL:request.URL
-                                           size:size
-                                          scale:scale
-                                     resizeMode:resizeMode
-                                progressHandler:progressHandler
-                              completionHandler:completionHandler] ?: ^{};
+
+    if (loadHandler && requiresScheduling) {
+      cancelLoad = [loadHandler loadImageForURL:imageURLRequest.URL
+                                     size:size
+                                    scale:scale
+                               resizeMode:resizeMode
+                          progressHandler:progressHandler
+                        completionHandler:completionHandler] ?: ^{};
       return;
     }
 
@@ -504,17 +520,18 @@ - (RCTImageLoaderCancellationBlock)loadImageWithURLRequest:(NSURLRequest *)image
     completionBlock(error, image);
   };
 
-  void (^completionHandler)(NSError *, id) = ^(NSError *error, id imageOrData) {
+  void (^completionHandler)(NSError *, id, BOOL) = ^(NSError *error, id imageOrData, BOOL cacheResult) {
     if (!cancelled) {
+      RCTImageLoaderCompletionBlock resultHandler = cacheResult ? cacheResultHandler : completionBlock;
       if (!imageOrData || [imageOrData isKindOfClass:[UIImage class]]) {
-        cacheResultHandler(error, imageOrData);
+        resultHandler(error, imageOrData);
       } else {
         cancelLoad = [weakSelf decodeImageData:imageOrData
                                           size:size
                                          scale:scale
                                        clipped:clipped
                                     resizeMode:resizeMode
-                               completionBlock:cacheResultHandler];
+                               completionBlock:resultHandler];
       }
     }
   };
@@ -652,7 +669,7 @@ - (RCTImageLoaderCancellationBlock)getImageSizeForURLRequest:(NSURLRequest *)ima
                                 scale:1
                            resizeMode:RCTResizeModeStretch
                         progressBlock:nil
-                      completionBlock:^(NSError *error, id imageOrData) {
+                      completionBlock:^(NSError *error, id imageOrData, __unused BOOL cacheResult) {
                         CGSize size;
                         if ([imageOrData isKindOfClass:[NSData class]]) {
                           NSDictionary *meta = RCTGetImageMetadata(imageOrData);

Libraries/Image/RCTXCAssetImageLoader.h → Libraries/Image/RCTLocalAssetImageLoader.h

@@ -9,6 +9,6 @@
 
 #import "RCTImageLoader.h"
 
-@interface RCTXCAssetImageLoader : NSObject <RCTImageURLLoader>
+@interface RCTLocalAssetImageLoader : NSObject <RCTImageURLLoader>
 
 @end

Libraries/Image/RCTXCAssetImageLoader.m → Libraries/Image/RCTLocalAssetImageLoader.m

@@ -7,19 +7,33 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  */
 
-#import "RCTXCAssetImageLoader.h"
+#import "RCTLocalAssetImageLoader.h"
 
 #import <libkern/OSAtomic.h>
 
 #import "RCTUtils.h"
 
-@implementation RCTXCAssetImageLoader
+@implementation RCTLocalAssetImageLoader
 
 RCT_EXPORT_MODULE()
 
 - (BOOL)canLoadImageURL:(NSURL *)requestURL
 {
-  return RCTIsXCAssetURL(requestURL);
+  return RCTIsLocalAssetURL(requestURL);
+}
+
+- (BOOL)requiresScheduling
+{
+  // Don't schedule this loader on the URL queue so we can load the
+  // local assets synchronously to avoid flickers.
+  return NO;
+}
+
+- (BOOL)shouldCacheLoadedImages
+{
+  // UIImage imageNamed handles the caching automatically so we don't want
+  // to add it to the image cache.
+  return NO;
 }
 
  - (RCTImageLoaderCancellationBlock)loadImageForURL:(NSURL *)imageURL
@@ -30,11 +44,12 @@ - (RCTImageLoaderCancellationBlock)loadImageForURL:(NSURL *)imageURL
                                   completionHandler:(RCTImageLoaderCompletionBlock)completionHandler
 {
   __block volatile uint32_t cancelled = 0;
-  dispatch_async(dispatch_get_main_queue(), ^{
 
+  RCTExecuteOnMainQueue(^{
     if (cancelled) {
       return;
     }
+
     NSString *imageName = RCTBundlePathForURL(imageURL);
     UIImage *image = [UIImage imageNamed:imageName];
     if (image) {

Libraries/Network/RCTFileRequestHandler.m

@@ -30,7 +30,7 @@ - (BOOL)canHandleRequest:(NSURLRequest *)request
 {
   return
   [request.URL.scheme caseInsensitiveCompare:@"file"] == NSOrderedSame
-  && !RCTIsXCAssetURL(request.URL);
+  && !RCTIsLocalAssetURL(request.URL);
 }
 
 - (NSOperation *)sendRequest:(NSURLRequest *)request

React/Base/RCTUtils.h

@@ -120,8 +120,8 @@ RCT_EXTERN NSData *__nullable RCTGzipData(NSData *__nullable data, float level);
 // (or nil, if the URL does not specify a path within the main bundle)
 RCT_EXTERN NSString *__nullable RCTBundlePathForURL(NSURL *__nullable URL);
 
-// Determines if a given image URL actually refers to an XCAsset
-RCT_EXTERN BOOL RCTIsXCAssetURL(NSURL *__nullable imageURL);
+// Determines if a given image URL refers to a local image
+RCT_EXTERN BOOL RCTIsLocalAssetURL(NSURL *__nullable imageURL);
 
 // Creates a new, unique temporary file path with the specified extension
 RCT_EXTERN NSString *__nullable RCTTempFilePath(NSString *__nullable extension, NSError **error);

React/Base/RCTUtils.m

@@ -612,21 +612,17 @@ BOOL RCTIsGzippedData(NSData *__nullable data)
   return path;
 }
 
-BOOL RCTIsXCAssetURL(NSURL *__nullable imageURL)
+BOOL RCTIsLocalAssetURL(NSURL *__nullable imageURL)
 {
   NSString *name = RCTBundlePathForURL(imageURL);
-  if (name.pathComponents.count != 1) {
-    // URL is invalid, or is a file path, not an XCAsset identifier
+  if (name == nil) {
     return NO;
   }
   NSString *extension = [name pathExtension];
-  if (extension.length && ![extension isEqualToString:@"png"]) {
-    // Not a png
-    return NO;
-  }
-  extension = extension.length ? nil : @"png";
-  if ([[NSBundle mainBundle] pathForResource:name ofType:extension]) {
-    // File actually exists in bundle, so is not an XCAsset
+  if (extension.length &&
+      ![extension isEqualToString:@"png"] &&
+      ![extension isEqualToString:@"jpg"]) {
+    // Not a supported image.
     return NO;
   }
   return YES;