Updates from Fri Feb 27

- [react-packager] transformModulePath option is not actually required | Amjad Masad
- Implement TextInput.clearButtonMode added by D1875684 on OSS fork + example | Tadeu Zagallo
- [ReactNative] Use local CocoaPod config for ReactNative modules | Spencer Ahrens
- [ReactNative] Pull out some OSS modules into separate libs | Spencer Ahrens
- Enqueue events at 60fps + profiling helpers | Tadeu Zagallo

Libraries/Image/RCTImageDownloader.m

@@ -0,0 +1,159 @@
+// Copyright 2004-present Facebook. All Rights Reserved.
+
+#import "RCTImageDownloader.h"
+
+#import "RCTCache.h"
+#import "RCTUtils.h"
+
+// TODO: something a bit more sophisticated
+
+typedef void (^RCTCachedDataDownloadBlock)(BOOL cached, NSData *data, NSError *error);
+
+@implementation RCTImageDownloader
+{
+  RCTCache *_cache;
+  NSMutableDictionary *_pendingBlocks;
+}
+
++ (instancetype)sharedInstance
+{
+  RCTAssertMainThread();
+  static RCTImageDownloader *sharedInstance;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    sharedInstance = [[self alloc] init];
+  });
+  return sharedInstance;
+}
+
+- (instancetype)init
+{
+  if ((self = [super init])) {
+    _cache = [[RCTCache alloc] initWithName:@"RCTImageDownloader"];
+    _pendingBlocks = [NSMutableDictionary dictionary];
+  }
+  return self;
+}
+
+- (NSString *)cacheKeyForURL:(NSURL *)url
+{
+  return url.absoluteString;
+}
+
+- (id)_downloadDataForURL:(NSURL *)url block:(RCTCachedDataDownloadBlock)block
+{
+  NSString *cacheKey = [self cacheKeyForURL:url];
+
+  __block BOOL cancelled = NO;
+  __block NSURLSessionDataTask *task = nil;
+  dispatch_block_t cancel = ^{
+    cancelled = YES;
+
+    NSMutableArray *pendingBlocks = _pendingBlocks[cacheKey];
+    [pendingBlocks removeObject:block];
+
+    if (task) {
+      [task cancel];
+      task = nil;
+    }
+  };
+
+  NSMutableArray *pendingBlocks = _pendingBlocks[cacheKey];
+  if (pendingBlocks) {
+    [pendingBlocks addObject:block];
+  } else {
+    _pendingBlocks[cacheKey] = [NSMutableArray arrayWithObject:block];
+
+    __weak RCTImageDownloader *weakSelf = self;
+    RCTCachedDataDownloadBlock runBlocks = ^(BOOL cached, NSData *data, NSError *error) {
+      RCTImageDownloader *strongSelf = weakSelf;
+      NSArray *blocks = strongSelf->_pendingBlocks[cacheKey];
+      [strongSelf->_pendingBlocks removeObjectForKey:cacheKey];
+
+      for (RCTCachedDataDownloadBlock block in blocks) {
+        block(cached, data, error);
+      }
+    };
+
+    if ([_cache hasDataForKey:cacheKey]) {
+      [_cache fetchDataForKey:cacheKey completionHandler:^(NSData *data) {
+        if (!cancelled) runBlocks(YES, data, nil);
+      }];
+    } else {
+      task = [[NSURLSession sharedSession] dataTaskWithURL:url completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
+        if (!cancelled) runBlocks(NO, data, error);
+      }];
+
+      [task resume];
+    }
+  }
+
+  return [cancel copy];
+}
+
+- (id)downloadDataForURL:(NSURL *)url block:(RCTDataDownloadBlock)block
+{
+  NSString *cacheKey = [self cacheKeyForURL:url];
+  __weak RCTImageDownloader *weakSelf = self;
+  return [self _downloadDataForURL:url block:^(BOOL cached, NSData *data, NSError *error) {
+    if (!cached) {
+      RCTImageDownloader *strongSelf = weakSelf;
+      [strongSelf->_cache setData:data forKey:cacheKey];
+    }
+
+    dispatch_async(dispatch_get_main_queue(), ^{
+      block(data, error);
+    });
+  }];
+}
+
+- (id)downloadImageForURL:(NSURL *)url size:(CGSize)size scale:(CGFloat)scale block:(RCTImageDownloadBlock)block
+{
+  NSString *cacheKey = [self cacheKeyForURL:url];
+  __weak RCTImageDownloader *weakSelf = self;
+  return [self _downloadDataForURL:url block:^(BOOL cached, NSData *data, NSError *error) {
+    if (!data) {
+      return dispatch_async(dispatch_get_main_queue(), ^{
+        block(nil, error);
+      });
+    }
+
+    UIImage *image = [UIImage imageWithData:data scale:scale];
+
+    if (image) {
+      CGSize imageSize = size;
+      if (CGSizeEqualToSize(imageSize, CGSizeZero)) {
+        imageSize = image.size;
+      }
+
+      CGFloat imageScale = scale;
+      if (imageScale == 0 || imageScale > image.scale) {
+        imageScale = image.scale;
+      }
+
+      UIGraphicsBeginImageContextWithOptions(imageSize, NO, imageScale);
+      [image drawInRect:(CGRect){{0, 0}, imageSize}];
+      image = UIGraphicsGetImageFromCurrentImageContext();
+      UIGraphicsEndImageContext();
+
+      if (!cached) {
+        RCTImageDownloader *strongSelf = weakSelf;
+        [strongSelf->_cache setData:UIImagePNGRepresentation(image) forKey:cacheKey];
+      }
+    }
+
+    dispatch_async(dispatch_get_main_queue(), ^{
+      block(image, nil);
+    });
+  }];
+}
+
+- (void)cancelDownload:(id)downloadToken
+{
+  if (downloadToken) {
+    dispatch_block_t block = (id)downloadToken;
+    block();
+  }
+}
+
+@end