// // ASNetworkImageNode.h // AsyncDisplayKit // // Copyright (c) 2014-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 NS_ASSUME_NONNULL_BEGIN @protocol ASNetworkImageNodeDelegate, ASImageCacheProtocol, ASImageDownloaderProtocol; /** * ASNetworkImageNode is a simple image node that can download and display an image from the network, with support for a * placeholder image (). The currently-displayed image is always available in the inherited ASImageNode * property. * * @see ASMultiplexImageNode for a more powerful counterpart to this class. */ @interface ASNetworkImageNode : ASImageNode /** * The designated initializer. Cache and Downloader are WEAK references. * * @param cache The object that implements a cache of images for the image node. Weak reference. * @param downloader The object that implements image downloading for the image node. Must not be nil. Weak reference. * * @discussion If `cache` is nil, the receiver will not attempt to retrieve images from a cache before downloading them. * * @return An initialized ASNetworkImageNode. */ - (instancetype)initWithCache:(nullable id)cache downloader:(id)downloader NS_DESIGNATED_INITIALIZER; /** * Convenience initializer. * * @return An ASNetworkImageNode configured to use the NSURLSession-powered ASBasicImageDownloader, and no extra cache. */ - (instancetype)init; /** * The delegate, which must conform to the protocol. */ @property (nullable, nonatomic, weak, readwrite) id delegate; /** * The image to display. * * @discussion By setting an image to the image property the ASNetworkImageNode will act like a plain ASImageNode. * As soon as the URL is set the ASNetworkImageNode will act like an ASNetworkImageNode and the image property * will be managed internally. This means the image property will be cleared out and replaced by the placeholder * () image while loading and the final image after the new image data was downloaded and processed. * If you want to use a placholder image functionality use the defaultImage property instead. */ @property (nullable, nonatomic, strong) UIImage *image; /** * A placeholder image to display while the URL is loading. This is slightly different than placeholderImage in the * ASDisplayNode superclass as defaultImage will *not* be displayed synchronously. If you wish to have the image * displayed synchronously, use @c placeholderImage. */ @property (nullable, nonatomic, strong, readwrite) UIImage *defaultImage; /** * The URL of a new image to download and display. * * @discussion By setting an URL, the image property of this node will be managed internally. This means previously * directly set images to the image property will be cleared out and replaced by the placeholder () image * while loading and the final image after the new image data was downloaded and processed. */ @property (nullable, nonatomic, strong, readwrite) NSURL *URL; /** * Download and display a new image. * * @param URL The URL of a new image to download and display. * @param reset Whether to display a placeholder () while loading the new image. * * @discussion By setting an URL, the image property of this node will be managed internally. This means previously * directly set images to the image property will be cleared out and replaced by the placeholder () image * while loading and the final image after the new image data was downloaded and processed. */ - (void)setURL:(nullable NSURL *)URL resetToDefault:(BOOL)reset; /** * If is a local file, set this property to YES to take advantage of UIKit's image caching. Defaults to YES. */ @property (nonatomic, assign, readwrite) BOOL shouldCacheImage; /** * If the downloader implements progressive image rendering and this value is YES progressive renders of the * image will be displayed as the image downloads. Regardless of this properties value, progress renders will * only occur when the node is visible. Defaults to YES. */ @property (nonatomic, assign, readwrite) BOOL shouldRenderProgressImages; /** * The image quality of the current image. This is a number between 0 and 1 and can be used to track * progressive progress. Calculated by dividing number of bytes / expected number of total bytes. */ @property (nonatomic, assign, readonly) CGFloat currentImageQuality; /** * The image quality (value between 0 and 1) of the last image that completed displaying. */ @property (nonatomic, assign, readonly) CGFloat renderedImageQuality; @end #pragma mark - /** * The methods declared by the ASNetworkImageNodeDelegate protocol allow the adopting delegate to respond to * notifications such as finished decoding and downloading an image. */ @protocol ASNetworkImageNodeDelegate @optional /** * Notification that the image node finished downloading an image. * * @param imageNode The sender. * @param image The newly-loaded image. * * @discussion Called on a background queue. */ - (void)imageNode:(ASNetworkImageNode *)imageNode didLoadImage:(UIImage *)image; /** * Notification that the image node started to load * * @param imageNode The sender. * * @discussion Called on a background queue. */ - (void)imageNodeDidStartFetchingData:(ASNetworkImageNode *)imageNode; /** * Notification that the image node failed to download the image. * * @param imageNode The sender. * @param error The error with details. * * @discussion Called on a background queue. */ - (void)imageNode:(ASNetworkImageNode *)imageNode didFailWithError:(NSError *)error; /** * Notification that the image node finished decoding an image. * * @param imageNode The sender. */ - (void)imageNodeDidFinishDecoding:(ASNetworkImageNode *)imageNode; @end NS_ASSUME_NONNULL_END