131 lines
4.3 KiB
Objective-C
131 lines
4.3 KiB
Objective-C
/*
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* This file is part of the SDWebImage package.
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* (c) Olivier Poitrey <rs@dailymotion.com>
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*
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* For the full copyright and license information, please view the LICENSE
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* file that was distributed with this source code.
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*/
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#import "SDWebImagePrefetcher.h"
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@interface SDWebImagePrefetcher ()
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@property (strong, nonatomic) SDWebImageManager *manager;
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@property (strong, nonatomic) NSArray *prefetchURLs;
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@property (assign, nonatomic) NSUInteger requestedCount;
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@property (assign, nonatomic) NSUInteger skippedCount;
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@property (assign, nonatomic) NSUInteger finishedCount;
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@property (assign, nonatomic) NSTimeInterval startedTime;
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@property (copy, nonatomic) void (^completionBlock)(NSUInteger, NSUInteger);
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@end
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@implementation SDWebImagePrefetcher
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+ (SDWebImagePrefetcher *)sharedImagePrefetcher {
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static dispatch_once_t once;
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static id instance;
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dispatch_once(&once, ^{
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instance = [self new];
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});
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return instance;
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}
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- (id)init {
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if ((self = [super init])) {
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_manager = [SDWebImageManager new];
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_options = SDWebImageLowPriority;
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self.maxConcurrentDownloads = 3;
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}
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return self;
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}
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- (void)setMaxConcurrentDownloads:(NSUInteger)maxConcurrentDownloads {
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self.manager.imageDownloader.maxConcurrentDownloads = maxConcurrentDownloads;
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}
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- (NSUInteger)maxConcurrentDownloads {
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return self.manager.imageDownloader.maxConcurrentDownloads;
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}
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- (void)startPrefetchingAtIndex:(NSUInteger)index {
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if (index >= self.prefetchURLs.count) return;
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self.requestedCount++;
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[self.manager downloadWithURL:self.prefetchURLs[index] options:self.options progress:nil completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, BOOL finished) {
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if (!finished) return;
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self.finishedCount++;
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if (image) {
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#ifdef SD_VERBOSE
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NSLog(@"Prefetched %d out of %d", self.finishedCount, self.prefetchURLs.count);
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#endif
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}
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else {
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#ifdef SD_VERBOSE
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NSLog(@"Prefetched %d out of %d (Failed)", self.finishedCount, [self.prefetchURLs count]);
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#endif
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// Add last failed
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self.skippedCount++;
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}
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if ([self.delegate respondsToSelector:@selector(imagePrefetcher:didPrefetchURL:finishedCount:totalCount:)]) {
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[self.delegate imagePrefetcher:self
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didPrefetchURL:self.prefetchURLs[index]
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finishedCount:self.finishedCount
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totalCount:self.prefetchURLs.count
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];
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}
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if (self.prefetchURLs.count > self.requestedCount) {
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[self startPrefetchingAtIndex:self.requestedCount];
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}
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else if (self.finishedCount == self.requestedCount) {
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[self reportStatus];
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if (self.completionBlock) {
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self.completionBlock(self.finishedCount, self.skippedCount);
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self.completionBlock = nil;
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}
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}
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}];
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}
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- (void)reportStatus {
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NSUInteger total = [self.prefetchURLs count];
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#ifdef SD_VERBOSE
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NSLog(@"Finished prefetching (%d successful, %d skipped, timeElasped %.2f)", total - self.skippedCount, self.skippedCount, CFAbsoluteTimeGetCurrent() - self.startedTime);
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#endif
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if ([self.delegate respondsToSelector:@selector(imagePrefetcher:didFinishWithTotalCount:skippedCount:)]) {
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[self.delegate imagePrefetcher:self
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didFinishWithTotalCount:(total - self.skippedCount)
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skippedCount:self.skippedCount
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];
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}
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}
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- (void)prefetchURLs:(NSArray *)urls {
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[self prefetchURLs:urls completed:nil];
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}
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- (void)prefetchURLs:(NSArray *)urls completed:(void (^)(NSUInteger, NSUInteger))completionBlock {
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[self cancelPrefetching]; // Prevent duplicate prefetch request
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self.startedTime = CFAbsoluteTimeGetCurrent();
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self.prefetchURLs = urls;
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self.completionBlock = completionBlock;
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// Starts prefetching from the very first image on the list with the max allowed concurrency
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NSUInteger listCount = self.prefetchURLs.count;
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for (NSUInteger i = 0; i < self.maxConcurrentDownloads && self.requestedCount < listCount; i++) {
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[self startPrefetchingAtIndex:i];
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}
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}
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- (void)cancelPrefetching {
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self.prefetchURLs = nil;
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self.skippedCount = 0;
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self.requestedCount = 0;
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self.finishedCount = 0;
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[self.manager cancelAll];
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}
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@end
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