Define the Image Cache delegate to be used in the ImageLoader

Reviewed By: javache

Differential Revision: D3583472

fbshipit-source-id: d1f30f3f96aea7739b9f91093fbb6c92c8b9567e

Libraries/Image/RCTImageCache.h

@@ -0,0 +1,15 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#import <Foundation/Foundation.h>
+
+#import "RCTImageLoader.h"
+
+@interface RCTImageCache : NSObject <RCTImageCacheDelegate>
+@end

Libraries/Image/RCTImageCache.m

@@ -0,0 +1,100 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#import "RCTImageCache.h"
+
+#import <ImageIO/ImageIO.h>
+
+#import <libkern/OSAtomic.h>
+
+#import <objc/runtime.h>
+
+#import "RCTConvert.h"
+#import "RCTImageUtils.h"
+#import "RCTNetworking.h"
+#import "RCTUtils.h"
+
+static const NSUInteger RCTMaxCachableDecodedImageSizeInBytes = 1048576; // 1MB
+
+static NSString *RCTCacheKeyForImage(NSString *imageTag, CGSize size, CGFloat scale,
+                                     RCTResizeMode resizeMode, NSString *responseDate)
+{
+    return [NSString stringWithFormat:@"%@|%g|%g|%g|%zd|%@",
+            imageTag, size.width, size.height, scale, resizeMode, responseDate];
+}
+
+@implementation RCTImageCache
+{
+  NSOperationQueue *_imageDecodeQueue;
+  NSCache *_decodedImageCache;
+}
+
+- (instancetype)init
+{
+  _decodedImageCache = [NSCache new];
+  _decodedImageCache.totalCostLimit = 5 * 1024 * 1024; // 5MB
+
+  [[NSNotificationCenter defaultCenter] addObserver:self
+                                           selector:@selector(clearCache)
+                                               name:UIApplicationDidReceiveMemoryWarningNotification
+                                             object:nil];
+  [[NSNotificationCenter defaultCenter] addObserver:self
+                                           selector:@selector(clearCache)
+                                               name:UIApplicationWillResignActiveNotification
+                                             object:nil];
+
+  return self;
+}
+
+- (void)dealloc
+{
+  [[NSNotificationCenter defaultCenter] removeObserver:self];
+}
+
+- (void)clearCache
+{
+  [_decodedImageCache removeAllObjects];
+}
+
+- (void)addImageToCache:(UIImage *)image
+                 forKey:(NSString *)cacheKey
+{
+  if (!image) {
+    return;
+  }
+  CGFloat bytes = image.size.width * image.size.height * image.scale * image.scale * 4;
+  if (bytes <= RCTMaxCachableDecodedImageSizeInBytes) {
+    [self->_decodedImageCache setObject:image
+                                 forKey:cacheKey
+                                   cost:bytes];
+  }
+}
+
+- (UIImage *)imageForUrl:(NSString *)url
+                    size:(CGSize)size
+                   scale:(CGFloat)scale
+              resizeMode:(RCTResizeMode)resizeMode
+            responseDate:(NSString *)responseDate
+{
+  NSString *cacheKey = RCTCacheKeyForImage(url, size, scale, resizeMode, responseDate);
+  return [_decodedImageCache objectForKey:cacheKey];
+}
+
+- (void)addImageToCache:(UIImage *)image
+                    URL:(NSString *)url
+                   size:(CGSize)size
+                  scale:(CGFloat)scale
+             resizeMode:(RCTResizeMode)resizeMode
+           responseDate:(NSString *)responseDate
+{
+  NSString *cacheKey = RCTCacheKeyForImage(url, size, scale, resizeMode, responseDate);
+  return [self addImageToCache:image forKey:cacheKey];
+}
+
+@end