158 lines
4.1 KiB
Objective-C
158 lines
4.1 KiB
Objective-C
// Copyright 2004-present Facebook. All Rights Reserved.
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#import "RCTImageDownloader.h"
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#import "RCTCache.h"
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#import "RCTUtils.h"
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// TODO: something a bit more sophisticated
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typedef void (^RCTCachedDataDownloadBlock)(BOOL cached, NSData *data, NSError *error);
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@implementation RCTImageDownloader
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{
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RCTCache *_cache;
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NSMutableDictionary *_pendingBlocks;
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}
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+ (instancetype)sharedInstance
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{
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RCTAssertMainThread();
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static RCTImageDownloader *sharedInstance;
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static dispatch_once_t onceToken;
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dispatch_once(&onceToken, ^{
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sharedInstance = [[self alloc] init];
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});
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return sharedInstance;
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}
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- (instancetype)init
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{
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if ((self = [super init])) {
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_cache = [[RCTCache alloc] initWithName:@"RCTImageDownloader"];
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_pendingBlocks = [NSMutableDictionary dictionary];
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}
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return self;
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}
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- (NSString *)cacheKeyForURL:(NSURL *)url
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{
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return url.absoluteString;
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}
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- (id)_downloadDataForURL:(NSURL *)url block:(RCTCachedDataDownloadBlock)block
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{
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NSString *cacheKey = [self cacheKeyForURL:url];
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__block BOOL cancelled = NO;
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__block NSURLSessionDataTask *task = nil;
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dispatch_block_t cancel = ^{
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cancelled = YES;
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NSMutableArray *pendingBlocks = _pendingBlocks[cacheKey];
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[pendingBlocks removeObject:block];
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if (task) {
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[task cancel];
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task = nil;
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}
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};
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NSMutableArray *pendingBlocks = _pendingBlocks[cacheKey];
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if (pendingBlocks) {
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[pendingBlocks addObject:block];
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} else {
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_pendingBlocks[cacheKey] = [NSMutableArray arrayWithObject:block];
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__weak RCTImageDownloader *weakSelf = self;
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RCTCachedDataDownloadBlock runBlocks = ^(BOOL cached, NSData *data, NSError *error) {
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RCTImageDownloader *strongSelf = weakSelf;
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NSArray *blocks = strongSelf->_pendingBlocks[cacheKey];
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[strongSelf->_pendingBlocks removeObjectForKey:cacheKey];
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for (RCTCachedDataDownloadBlock block in blocks) {
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block(cached, data, error);
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}
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};
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if ([_cache hasDataForKey:cacheKey]) {
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[_cache fetchDataForKey:cacheKey completionHandler:^(NSData *data) {
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if (!cancelled) runBlocks(YES, data, nil);
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}];
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} else {
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task = [[NSURLSession sharedSession] dataTaskWithURL:url completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
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if (!cancelled) runBlocks(NO, data, error);
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}];
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[task resume];
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}
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}
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return [cancel copy];
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}
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- (id)downloadDataForURL:(NSURL *)url block:(RCTDataDownloadBlock)block
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{
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NSString *cacheKey = [self cacheKeyForURL:url];
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__weak RCTImageDownloader *weakSelf = self;
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return [self _downloadDataForURL:url block:^(BOOL cached, NSData *data, NSError *error) {
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if (!cached) {
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RCTImageDownloader *strongSelf = weakSelf;
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[strongSelf->_cache setData:data forKey:cacheKey];
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}
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dispatch_async(dispatch_get_main_queue(), ^{
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block(data, error);
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});
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}];
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}
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- (id)downloadImageForURL:(NSURL *)url size:(CGSize)size scale:(CGFloat)scale block:(RCTImageDownloadBlock)block
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{
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return [self downloadDataForURL:url block:^(NSData *data, NSError *error) {
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UIImage *image = [UIImage imageWithData:data scale:scale];
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if (image) {
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// Resize (TODO: should we take aspect ratio into account?)
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CGSize imageSize = size;
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if (CGSizeEqualToSize(imageSize, CGSizeZero)) {
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imageSize = image.size;
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} else {
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imageSize = (CGSize){
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MIN(size.width, image.size.width),
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MIN(size.height, image.size.height)
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};
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}
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// Rescale image if required size is smaller
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CGFloat imageScale = scale;
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if (imageScale == 0 || imageScale < image.scale) {
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imageScale = image.scale;
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}
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// Decompress image at required size
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UIGraphicsBeginImageContextWithOptions(imageSize, NO, imageScale);
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[image drawInRect:(CGRect){{0, 0}, imageSize}];
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image = UIGraphicsGetImageFromCurrentImageContext();
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UIGraphicsEndImageContext();
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}
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// TODO: should we cache the decompressed image?
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dispatch_async(dispatch_get_main_queue(), ^{
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block(image, nil);
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});
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}];
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}
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- (void)cancelDownload:(id)downloadToken
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{
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if (downloadToken) {
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dispatch_block_t block = (id)downloadToken;
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block();
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}
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}
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@end
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