react-native/Libraries/Network/RCTFileRequestHandler.m
Janic Duplessis 5903949ad6 Load local assets synchronously to prevent image flicker
Summary:
This uses `[UIImage imageNamed:]` to load local assets that are bundled using `require('../image/path.png')` and makes sure it is done synchronously on the main queue to prevent images from flickering. This improves user experience a lot when using large local images and prevents icon flickers to match the behaviour of most native apps.

This adds to methods to the ImageLoader protocol, one to tell if the image loader must be executed on the url cache queue and one to tell if the result of the image loader should be cached. I then use these to make the LocalImageLoader bypass the url cache queue and avoid caching images twice.

Note that this doesn't affect debug builds since images are loaded from the packager.

I'm not sure if we want to still support async loading of local images as I'm not sure how much of a perf difference this will make. Maybe someone at fb can benchmark this see how it affects your apps but there wasn't a noticeable one in mine. Also I only enabled this for loading png and jpg im
Closes https://github.com/facebook/react-native/pull/8102

Reviewed By: bnham

Differential Revision: D3433647

Pulled By: javache

fbshipit-source-id: 37bd6aff20c0465c163db3cdbcaeaedff55f7b1f
2016-07-21 07:58:51 -07:00

93 lines
2.7 KiB
Objective-C

/**
* Copyright (c) 2015-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 "RCTFileRequestHandler.h"
#import <MobileCoreServices/MobileCoreServices.h>
#import "RCTUtils.h"
@implementation RCTFileRequestHandler
{
NSOperationQueue *_fileQueue;
}
RCT_EXPORT_MODULE()
- (void)invalidate
{
[_fileQueue cancelAllOperations];
_fileQueue = nil;
}
- (BOOL)canHandleRequest:(NSURLRequest *)request
{
return
[request.URL.scheme caseInsensitiveCompare:@"file"] == NSOrderedSame
&& !RCTIsLocalAssetURL(request.URL);
}
- (NSOperation *)sendRequest:(NSURLRequest *)request
withDelegate:(id<RCTURLRequestDelegate>)delegate
{
// Lazy setup
if (!_fileQueue) {
_fileQueue = [NSOperationQueue new];
_fileQueue.maxConcurrentOperationCount = 4;
}
__weak __block NSBlockOperation *weakOp;
__block NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{
// Get content length
NSError *error = nil;
NSFileManager *fileManager = [NSFileManager new];
NSDictionary<NSString *, id> *fileAttributes = [fileManager attributesOfItemAtPath:request.URL.path error:&error];
if (!fileAttributes) {
[delegate URLRequest:weakOp didCompleteWithError:error];
return;
}
// Get mime type
NSString *fileExtension = [request.URL pathExtension];
NSString *UTI = (__bridge_transfer NSString *)UTTypeCreatePreferredIdentifierForTag(
kUTTagClassFilenameExtension, (__bridge CFStringRef)fileExtension, NULL);
NSString *contentType = (__bridge_transfer NSString *)UTTypeCopyPreferredTagWithClass(
(__bridge CFStringRef)UTI, kUTTagClassMIMEType);
// Send response
NSURLResponse *response = [[NSURLResponse alloc] initWithURL:request.URL
MIMEType:contentType
expectedContentLength:[fileAttributes[NSFileSize] ?: @-1 integerValue]
textEncodingName:nil];
[delegate URLRequest:weakOp didReceiveResponse:response];
// Load data
NSData *data = [NSData dataWithContentsOfURL:request.URL
options:NSDataReadingMappedIfSafe
error:&error];
if (data) {
[delegate URLRequest:weakOp didReceiveData:data];
}
[delegate URLRequest:weakOp didCompleteWithError:error];
}];
weakOp = op;
[_fileQueue addOperation:op];
return op;
}
- (void)cancelRequest:(NSOperation *)op
{
[op cancel];
}
@end