Merge pull request SDWebImage#941 from mishagray/cost_compute_fix

Cost compute fix

Author: bpoplauschi

SDWebImage/SDImageCache.m

@@ -147,7 +147,7 @@ - (void)storeImage:(UIImage *)image recalculateFromImage:(BOOL)recalculate image
         return;
     }
 
-    [self.memCache setObject:image forKey:key cost:image.size.height * image.size.width * image.scale];
+    [self.memCache setObject:image forKey:key cost:image.size.height * image.size.width * image.scale * image.scale];
 
     if (toDisk) {
         dispatch_async(self.ioQueue, ^{
@@ -234,7 +234,7 @@ - (UIImage *)imageFromDiskCacheForKey:(NSString *)key {
     // Second check the disk cache...
     UIImage *diskImage = [self diskImageForKey:key];
     if (diskImage) {
-        CGFloat cost = diskImage.size.height * diskImage.size.width * diskImage.scale;
+        CGFloat cost = diskImage.size.height * diskImage.size.width * diskImage.scale * diskImage.scale;
         [self.memCache setObject:diskImage forKey:key cost:cost];
     }
 
@@ -302,7 +302,7 @@ - (NSOperation *)queryDiskCacheForKey:(NSString *)key done:(SDWebImageQueryCompl
         @autoreleasepool {
             UIImage *diskImage = [self diskImageForKey:key];
             if (diskImage) {
-                CGFloat cost = diskImage.size.height * diskImage.size.width * diskImage.scale;
+                CGFloat cost = diskImage.size.height * diskImage.size.width * diskImage.scale * diskImage.scale;
                 [self.memCache setObject:diskImage forKey:key cost:cost];
             }