Fix WebP animation blending and default support for animated WebP images

CHANGELOG.md

@@ -1,6 +1,8 @@
 ## master
 * Add your own contributions to the next release on the line below this with your name.
-- [new] Add PINRemoteImageManagerConfiguration configuration object [#492](https://github.com/pinterest/PINRemoteImage/pull/492) [rqueue](https://github.com/rqueue)
+- [new] Add PINRemoteImageManagerConfiguration configuration object. [#492](https://github.com/pinterest/PINRemoteImage/pull/492) [rqueue](https://github.com/rqueue)
+- [fixed] Fixes blending in animated WebP images. [#507](https://github.com/pinterest/PINRemoteImage/pull/507) [garrettmoon](https://github.com/garrettmoon)
+- [fixed] Fixes support in PINAnimatedImageView for WebP animated images. [#507](https://github.com/pinterest/PINRemoteImage/pull/507) [garrettmoon](https://github.com/garrettmoon)
 
 ## 3.0.0 Beta 14
 - [fixed] Re-enable warnings check [#506](https://github.com/pinterest/PINRemoteImage/pull/506) [garrettmoon](https://github.com/garrettmoon)

Source/Classes/AnimatedImages/PINWebPAnimatedImage.m

@@ -25,6 +25,7 @@ @interface PINWebPAnimatedImage ()
     BOOL _hasAlpha;
     size_t _frameCount;
     size_t _loopCount;
+    CGColorRef _backgroundColor;
     CFTimeInterval *_durations;
     NSError *_error;
 }
@@ -54,6 +55,16 @@ - (instancetype)initWithAnimatedImageData:(NSData *)animatedImageData
             uint32_t flags = WebPDemuxGetI(_demux, WEBP_FF_FORMAT_FLAGS);
             _hasAlpha = flags & ALPHA_FLAG;
             _durations = malloc(sizeof(CFTimeInterval) * _frameCount);
+
+            uint32_t backgroundColorInt = WebPDemuxGetI(_demux, WEBP_FF_BACKGROUND_COLOR);
+            CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
+            CGFloat components[4];
+            components[0] = (CGFloat)(((backgroundColorInt & 0xFF000000) >> 24)/255.0);
+            components[1] = (CGFloat)(((backgroundColorInt & 0x00FF0000) >> 16)/255.0);
+            components[2] = (CGFloat)(((backgroundColorInt & 0x0000FF00) >> 8)/255.0);
+            components[3] = (CGFloat)((backgroundColorInt & 0x000000FF)/255.0);
+            _backgroundColor = CGColorCreate(rgbColorSpace, components);
+            CGColorSpaceRelease(rgbColorSpace);
 
             // Iterate over the frames to gather duration
             WebPIterator iter;
@@ -85,6 +96,9 @@ - (void)dealloc
     if (_durations) {
         free(_durations);
     }
+    if (_backgroundColor) {
+        CGColorRelease(_backgroundColor);
+    }
 }
 
 - (NSData *)data
@@ -127,7 +141,13 @@ - (CFTimeInterval)durationAtIndex:(NSUInteger)index
     return _durations[index];
 }
 
-- (CGImageRef)canvasWithPreviousFrame:(CGImageRef)previousFrame image:(CGImageRef)image atRect:(CGRect)rect
+- (CGImageRef)canvasWithPreviousFrame:(CGImageRef)previousFrame
+                    previousFrameRect:(CGRect)previousFrameRect
+                   clearPreviousFrame:(BOOL)clearPreviousFrame
+                      backgroundColor:(CGColorRef)backgroundColor
+                                image:(CGImageRef)image
+                    clearCurrentFrame:(BOOL)clearCurrentFrame
+                               atRect:(CGRect)rect
 {
     CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
     CGContextRef context = CGBitmapContextCreate(NULL,
@@ -137,13 +157,23 @@ - (CGImageRef)canvasWithPreviousFrame:(CGImageRef)previousFrame image:(CGImageRe
                                                  0,
                                                  colorSpaceRef,
                                                  _hasAlpha ? kCGImageAlphaPremultipliedFirst : kCGImageAlphaNone);
+    if (backgroundColor) {
+        CGContextSetFillColorWithColor(context, backgroundColor);
+    }
 
     if (previousFrame) {
         CGContextDrawImage(context, CGRectMake(0, 0, _width, _height), previousFrame);
+        if (clearPreviousFrame) {
+            CGContextFillRect(context, previousFrameRect);
+        }
     }
 
     if (image) {
-        CGContextDrawImage(context, CGRectMake(rect.origin.x, _height - rect.size.height - rect.origin.y, rect.size.width, rect.size.height), image);
+        CGRect currentRect = CGRectMake(rect.origin.x, _height - rect.size.height - rect.origin.y, rect.size.width, rect.size.height);
+        if (clearCurrentFrame) {
+            CGContextFillRect(context, currentRect);
+        }
+        CGContextDrawImage(context, currentRect, image);
     }
 
     CGImageRef canvas = CGBitmapContextCreateImage(context);
@@ -234,13 +264,30 @@ - (CGImageRef)imageAtIndex:(NSUInteger)index cacheProvider:(nullable id<PINCache
                 // Output will be the same size as the canvas, just return it directly.
                 canvas = imageRef;
             } else {
-                canvas = [self canvasWithPreviousFrame:nil image:imageRef atRect:CGRectMake(iterator.x_offset, iterator.y_offset, iterator.width, iterator.height)];
+                canvas = [self canvasWithPreviousFrame:nil
+                                     previousFrameRect:CGRectZero
+                                    clearPreviousFrame:NO
+                                       backgroundColor:_backgroundColor
+                                                 image:imageRef
+                                     clearCurrentFrame:iterator.blend_method == WEBP_MUX_NO_BLEND
+                                                atRect:CGRectMake(iterator.x_offset, iterator.y_offset, iterator.width, iterator.height)];
             }
         } else {
             // If we have a cached image provider, try to get the last frame from them
             CGImageRef previousFrame = [cacheProvider cachedFrameImageAtIndex:index - 1];
             if (previousFrame) {
-                canvas = [self canvasWithPreviousFrame:previousFrame image:imageRef atRect:CGRectMake(iterator.x_offset, iterator.y_offset, iterator.width, iterator.height)];
+                // We need an iterator from the previous frame to dispose to background if
+                // necessary.
+                WebPDemuxReleaseIterator(&previousIterator);
+                WebPDemuxGetFrame(_demux, (int)index, &previousIterator);
+                CGRect previousFrameRect = CGRectMake(previousIterator.x_offset, _height - previousIterator.height - previousIterator.y_offset, previousIterator.width, previousIterator.height);
+                canvas = [self canvasWithPreviousFrame:previousFrame
+                                     previousFrameRect:previousFrameRect
+                                    clearPreviousFrame:previousIterator.dispose_method == WEBP_MUX_DISPOSE_BACKGROUND
+                                       backgroundColor:_backgroundColor
+                                                 image:imageRef
+                                     clearCurrentFrame:iterator.blend_method == WEBP_MUX_NO_BLEND
+                                                atRect:CGRectMake(iterator.x_offset, iterator.y_offset, iterator.width, iterator.height)];
             } else if (index > 0) {
                 // Sadly, we need to draw *all* the frames from the previous key frame previousIterator to the current one :(
                 CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
@@ -251,15 +298,32 @@ - (CGImageRef)imageAtIndex:(NSUInteger)index cacheProvider:(nullable id<PINCache
                                                              0,
                                                              colorSpaceRef,
                                                              _hasAlpha ? kCGImageAlphaPremultipliedFirst : kCGImageAlphaNone);
+                CGContextSetFillColorWithColor(context, _backgroundColor);
 
-                while (previousIterator.frame_num < iterator.frame_num) {
+                while (previousIterator.frame_num <= iterator.frame_num) {
                     CGImageRef previousFrame = [self rawImageWithIterator:previousIterator];
                     if (previousFrame) {
-                        CGContextDrawImage(context, CGRectMake(previousIterator.x_offset, _height - previousIterator.height - previousIterator.y_offset, previousIterator.width, iterator.height), previousFrame);
-                        WebPDemuxNextFrame(&previousIterator);
+                        CGRect previousFrameRect = CGRectMake(previousIterator.x_offset, _height - previousIterator.height - previousIterator.y_offset, previousIterator.width, previousIterator.height);
+                        if (previousIterator.blend_method == WEBP_MUX_NO_BLEND) {
+                            CGContextFillRect(context, previousFrameRect);
+                        }
+
+                        if (previousIterator.frame_num == iterator.frame_num) {
+                            CGContextDrawImage(context, previousFrameRect, previousFrame);
+                            // We have to break here because we're not getting the next frame! Basically
+                            // the while loop is a sham and only here to illustrate what we want to iterate.
+                            break;
+                        } else {
+                            if (previousIterator.dispose_method == WEBP_MUX_DISPOSE_BACKGROUND) {
+                                CGContextFillRect(context, previousFrameRect);
+                            } else {
+                                CGContextDrawImage(context, previousFrameRect, previousFrame);
+                            }
+                            WebPDemuxNextFrame(&previousIterator);
+                        }
                     }
                 }
-                
+
                 canvas = CGBitmapContextCreateImage(context);
                 if (canvas) {
                     CFAutorelease(canvas);

Source/Classes/PINAlternateRepresentationProvider.m

@@ -15,9 +15,15 @@ @implementation PINAlternateRepresentationProvider
 
 - (id)alternateRepresentationWithData:(NSData *)data options:(PINRemoteImageManagerDownloadOptions)options
 {
+#if PIN_WEBP
+    if ([data pin_isAnimatedGIF] || [data pin_isAnimatedWebP]) {
+        return [[PINCachedAnimatedImage alloc] initWithAnimatedImageData:data];
+    }
+#else
     if ([data pin_isAnimatedGIF]) {
         return [[PINCachedAnimatedImage alloc] initWithAnimatedImageData:data];
     }
+#endif
     return nil;
 }