Merge pull request #2181 from dreampiggy/trick_code_fix_FLAnimatedImageView_fade

Use the associate object to store the FLAnimatedImage into memory cache, avoid blinking or UIView transaction. Tricky but may work

@@ -15,6 +15,24 @@
 #import "NSData+ImageContentType.h"
 #import "UIImageView+WebCache.h"
 
+@interface UIImage (FLAnimatedImage)
+
+@property (nonatomic, strong) FLAnimatedImage *sd_FLAnimatedImage;
+
+@end
+
+@implementation UIImage (FLAnimatedImage)
+
+- (FLAnimatedImage *)sd_FLAnimatedImage {
+    return objc_getAssociatedObject(self, @selector(sd_FLAnimatedImage));
+}
+
+- (void)setSd_FLAnimatedImage:(FLAnimatedImage *)sd_FLAnimatedImage {
+    objc_setAssociatedObject(self, @selector(sd_FLAnimatedImage), sd_FLAnimatedImage, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+}
+
+@end
+
 @implementation FLAnimatedImageView (WebCache)
 
 - (void)sd_setImageWithURL:(nullable NSURL *)url {
@@ -46,8 +64,6 @@
                    options:(SDWebImageOptions)options
                   progress:(nullable SDWebImageDownloaderProgressBlock)progressBlock
                  completed:(nullable SDExternalCompletionBlock)completedBlock {
-    options |= SDWebImageQueryDataWhenInMemory;
-    options |= SDWebImageQueryDiskSync;
     dispatch_group_t group = dispatch_group_create();
     __weak typeof(self)weakSelf = self;
     [self sd_internalSetImageWithURL:url
@@ -56,20 +72,31 @@
                         operationKey:nil
                        setImageBlock:^(UIImage *image, NSData *imageData) {
                            SDImageFormat imageFormat = [NSData sd_imageFormatForImageData:imageData];
-                           if (imageFormat == SDImageFormatGIF) {
-                               // Firstly set the static poster image to avoid flashing
-                               UIImage *posterImage = image.images ? image.images.firstObject : image;
-                               weakSelf.image = posterImage;
-                               dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
-                                   // Secondly create FLAnimatedImage in global queue because it's time consuming, then set it back
-                                   FLAnimatedImage *animatedImage = [FLAnimatedImage animatedImageWithGIFData:imageData];
-                                   dispatch_main_async_safe(^{
-                                       weakSelf.animatedImage = animatedImage;
-                                       if (group) {
-                                           dispatch_group_leave(group);
-                                       }
+                           __block FLAnimatedImage *animatedImage = image.sd_FLAnimatedImage;
+                           // We could not directlly create the animated image on bacakground queue because it's time consuming, by the time we set it back, the current runloop has passed and the placeholder has been rendered and then replaced with animated image, this cause a flashing.
+                           // Previously we use a trick to firstly set the static poster image, then set animated image back to avoid flashing, but this trick fail when using with UIView transition because it's based on the Core Animation. Core Animation will capture the current layer state to do rendering, so even we later set it back, the transition will not update
+                           // So we have no choice to force store the FLAnimatedImage into memory cache using a associated object binding to UIImage instance. This consumed memory is adoptable and much smaller than `_UIAnimatedImage` for big GIF
+                           if (animatedImage || imageFormat == SDImageFormatGIF) {
+                               if (animatedImage) {
+                                   weakSelf.animatedImage = animatedImage;
+                                   weakSelf.image = nil;
+                                   if (group) {
+                                       dispatch_group_leave(group);
+                                   }
+                               } else {
+                                   // The imageData should not be nil, create FLAnimatedImage in global queue because it's time consuming, then set it back
+                                   dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
+                                       animatedImage = [FLAnimatedImage animatedImageWithGIFData:imageData];
+                                       image.sd_FLAnimatedImage = animatedImage;
+                                       dispatch_async(dispatch_get_main_queue(), ^{
+                                           weakSelf.animatedImage = animatedImage;
+                                           weakSelf.image = nil;
+                                           if (group) {
+                                               dispatch_group_leave(group);
+                                           }
+                                       });
                                    });
-                               });
+                               }
                            } else {
                                weakSelf.image = image;
                                weakSelf.animatedImage = nil;