Opt the macOS legacy animated encode, with the weak assigned frames to avoid re-decode again

It's still recommended to use the new API

SDWebImage/Core/SDAnimatedImageRep.m

@@ -16,6 +16,11 @@
 #import "SDImageHEICCoder.h"
 #import "SDImageAWebPCoder.h"
 
+@interface SDAnimatedImageRep ()
+/// This wrap the animated image frames for legacy animated image coder API (`encodedDataWithImage:`).
+@property (nonatomic, readwrite, weak) NSArray<SDImageFrame *> *frames;
+@end
+
 @implementation SDAnimatedImageRep {
     CGImageSourceRef _imageSource;
 }

SDWebImage/Core/SDImageCoderHelper.m

@@ -94,6 +94,13 @@ static CGFloat kDestImageLimitBytes = 30.f * kBytesPerMB;
 
 static const CGFloat kDestSeemOverlap = 2.0f;   // the numbers of pixels to overlap the seems where tiles meet.
 
+#if SD_MAC
+@interface SDAnimatedImageRep (Private)
+/// This wrap the animated image frames for legacy animated image coder API (`encodedDataWithImage:`).
+@property (nonatomic, readwrite, weak) NSArray<SDImageFrame *> *frames;
+@end
+#endif
+
 @implementation SDImageCoderHelper
 
 + (UIImage *)animatedImageWithFrames:(NSArray<SDImageFrame *> *)frames {
@@ -159,6 +166,7 @@ static const CGFloat kDestSeemOverlap = 2.0f;   // the numbers of pixels to over
     SDAnimatedImageRep *imageRep = [[SDAnimatedImageRep alloc] initWithData:imageData];
     NSSize size = NSMakeSize(imageRep.pixelsWide / scale, imageRep.pixelsHigh / scale);
     imageRep.size = size;
+    imageRep.frames = frames; // Weak assign to avoid effect lazy semantic of NSBitmapImageRep
     animatedImage = [[NSImage alloc] initWithSize:size];
     [animatedImage addRepresentation:imageRep];
 #endif
@@ -211,6 +219,14 @@ static const CGFloat kDestSeemOverlap = 2.0f;   // the numbers of pixels to over
     
     NSRect imageRect = NSMakeRect(0, 0, animatedImage.size.width, animatedImage.size.height);
     NSImageRep *imageRep = [animatedImage bestRepresentationForRect:imageRect context:nil hints:nil];
+    // Check weak assigned frames firstly
+    if ([imageRep isKindOfClass:[SDAnimatedImageRep class]]) {
+        SDAnimatedImageRep *animatedImageRep = (SDAnimatedImageRep *)imageRep;
+        if (animatedImageRep.frames) {
+            return animatedImageRep.frames;
+        }
+    }
+    
     NSBitmapImageRep *bitmapImageRep;
     if ([imageRep isKindOfClass:[NSBitmapImageRep class]]) {
         bitmapImageRep = (NSBitmapImageRep *)imageRep;

Tests/Tests/SDImageCoderTests.m

@@ -422,6 +422,32 @@
 #endif
 }
 
+- (void)test27ThatEncodeWithFramesWorks {
+    // Mock
+    NSMutableArray<SDImageFrame *> *frames = [NSMutableArray array];
+    NSUInteger frameCount = 5;
+    for (size_t i = 0; i < frameCount; i++) {
+        CGSize size = CGSizeMake(100, 100);
+        SDGraphicsImageRenderer *renderer = [[SDGraphicsImageRenderer alloc] initWithSize:size];
+        UIImage *image = [renderer imageWithActions:^(CGContextRef  _Nonnull context) {
+            CGContextSetRGBFillColor(context, 1.0 / i, 0.0, 0.0, 1.0);
+            CGContextSetRGBStrokeColor(context, 1.0 / i, 0.0, 0.0, 1.0);
+            CGContextFillRect(context, CGRectMake(0, 0, size.width, size.height));
+        }];
+        SDImageFrame *frame = [SDImageFrame frameWithImage:image duration:0.1];
+        [frames addObject:frame];
+    }
+    
+    // Test old API
+    UIImage *animatedImage = [SDImageCoderHelper animatedImageWithFrames:frames];
+    NSData *data = [SDImageGIFCoder.sharedCoder encodedDataWithImage:animatedImage format:SDImageFormatGIF options:nil];
+    expect(data).notTo.beNil();
+    
+    // Test new API
+    NSData *data2 = [SDImageGIFCoder.sharedCoder encodedDataWithFrames:frames loopCount:0 format:SDImageFormatGIF options:nil];
+    expect(data2).notTo.beNil();
+}
+
 #pragma mark - Utils
 
 - (void)verifyCoder:(id<SDImageCoder>)coder