| /* |
| * This file is part of the SDWebImage package. |
| * (c) Olivier Poitrey <rs@dailymotion.com> |
| * |
| * For the full copyright and license information, please view the LICENSE |
| * file that was distributed with this source code. |
| */ |
| |
| #import "SDWebImagePrefetcher.h" |
| |
| @interface SDWebImagePrefetcher () |
| |
| @property (strong, nonatomic) SDWebImageManager *manager; |
| @property (strong, nonatomic) NSArray *prefetchURLs; |
| @property (assign, nonatomic) NSUInteger requestedCount; |
| @property (assign, nonatomic) NSUInteger skippedCount; |
| @property (assign, nonatomic) NSUInteger finishedCount; |
| @property (assign, nonatomic) NSTimeInterval startedTime; |
| @property (copy, nonatomic) SDWebImagePrefetcherCompletionBlock completionBlock; |
| @property (copy, nonatomic) SDWebImagePrefetcherProgressBlock progressBlock; |
| |
| @end |
| |
| @implementation SDWebImagePrefetcher |
| |
| + (SDWebImagePrefetcher *)sharedImagePrefetcher { |
| static dispatch_once_t once; |
| static id instance; |
| dispatch_once(&once, ^{ |
| instance = [self new]; |
| }); |
| return instance; |
| } |
| |
| - (id)init { |
| return [self initWithImageManager:[SDWebImageManager new]]; |
| } |
| |
| - (id)initWithImageManager:(SDWebImageManager *)manager { |
| if ((self = [super init])) { |
| _manager = manager; |
| _options = SDWebImageLowPriority; |
| _prefetcherQueue = dispatch_get_main_queue(); |
| self.maxConcurrentDownloads = 3; |
| } |
| return self; |
| } |
| |
| - (void)setMaxConcurrentDownloads:(NSUInteger)maxConcurrentDownloads { |
| self.manager.imageDownloader.maxConcurrentDownloads = maxConcurrentDownloads; |
| } |
| |
| - (NSUInteger)maxConcurrentDownloads { |
| return self.manager.imageDownloader.maxConcurrentDownloads; |
| } |
| |
| - (void)startPrefetchingAtIndex:(NSUInteger)index { |
| if (index >= self.prefetchURLs.count) return; |
| self.requestedCount++; |
| [self.manager downloadImageWithURL:self.prefetchURLs[index] options:self.options progress:nil completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, BOOL finished, NSURL *imageURL) { |
| if (!finished) return; |
| self.finishedCount++; |
| |
| if (image) { |
| if (self.progressBlock) { |
| self.progressBlock(self.finishedCount,[self.prefetchURLs count]); |
| } |
| } |
| else { |
| if (self.progressBlock) { |
| self.progressBlock(self.finishedCount,[self.prefetchURLs count]); |
| } |
| // Add last failed |
| self.skippedCount++; |
| } |
| if ([self.delegate respondsToSelector:@selector(imagePrefetcher:didPrefetchURL:finishedCount:totalCount:)]) { |
| [self.delegate imagePrefetcher:self |
| didPrefetchURL:self.prefetchURLs[index] |
| finishedCount:self.finishedCount |
| totalCount:self.prefetchURLs.count |
| ]; |
| } |
| if (self.prefetchURLs.count > self.requestedCount) { |
| dispatch_async(self.prefetcherQueue, ^{ |
| [self startPrefetchingAtIndex:self.requestedCount]; |
| }); |
| } else if (self.finishedCount == self.requestedCount) { |
| [self reportStatus]; |
| if (self.completionBlock) { |
| self.completionBlock(self.finishedCount, self.skippedCount); |
| self.completionBlock = nil; |
| } |
| self.progressBlock = nil; |
| } |
| }]; |
| } |
| |
| - (void)reportStatus { |
| NSUInteger total = [self.prefetchURLs count]; |
| if ([self.delegate respondsToSelector:@selector(imagePrefetcher:didFinishWithTotalCount:skippedCount:)]) { |
| [self.delegate imagePrefetcher:self |
| didFinishWithTotalCount:(total - self.skippedCount) |
| skippedCount:self.skippedCount |
| ]; |
| } |
| } |
| |
| - (void)prefetchURLs:(NSArray *)urls { |
| [self prefetchURLs:urls progress:nil completed:nil]; |
| } |
| |
| - (void)prefetchURLs:(NSArray *)urls progress:(SDWebImagePrefetcherProgressBlock)progressBlock completed:(SDWebImagePrefetcherCompletionBlock)completionBlock { |
| [self cancelPrefetching]; // Prevent duplicate prefetch request |
| self.startedTime = CFAbsoluteTimeGetCurrent(); |
| self.prefetchURLs = urls; |
| self.completionBlock = completionBlock; |
| self.progressBlock = progressBlock; |
| |
| if (urls.count == 0) { |
| if (completionBlock) { |
| completionBlock(0,0); |
| } |
| } else { |
| // Starts prefetching from the very first image on the list with the max allowed concurrency |
| NSUInteger listCount = self.prefetchURLs.count; |
| for (NSUInteger i = 0; i < self.maxConcurrentDownloads && self.requestedCount < listCount; i++) { |
| [self startPrefetchingAtIndex:i]; |
| } |
| } |
| } |
| |
| - (void)cancelPrefetching { |
| self.prefetchURLs = nil; |
| self.skippedCount = 0; |
| self.requestedCount = 0; |
| self.finishedCount = 0; |
| [self.manager cancelAll]; |
| } |
| |
| @end |