Swiftgram/Source/TextKit/ASTextKitContext.mm
2017-02-26 18:14:13 -08:00

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//
// ASTextKitContext.mm
// 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 <AsyncDisplayKit/ASTextKitContext.h>
#import <AsyncDisplayKit/ASLayoutManager.h>
#import <AsyncDisplayKit/ASThread.h>
#include <memory>
@implementation ASTextKitContext
{
// All TextKit operations (even non-mutative ones) must be executed serially.
std::shared_ptr<ASDN::Mutex> __instanceLock__;
NSLayoutManager *_layoutManager;
NSTextStorage *_textStorage;
NSTextContainer *_textContainer;
}
- (instancetype)initWithAttributedString:(NSAttributedString *)attributedString
lineBreakMode:(NSLineBreakMode)lineBreakMode
maximumNumberOfLines:(NSUInteger)maximumNumberOfLines
exclusionPaths:(NSArray *)exclusionPaths
constrainedSize:(CGSize)constrainedSize
{
if (self = [super init]) {
// Concurrently initialising TextKit components crashes (rdar://18448377) so we use a global lock.
static ASDN::Mutex __staticMutex;
ASDN::MutexLocker l(__staticMutex);
__instanceLock__ = std::make_shared<ASDN::Mutex>();
// Create the TextKit component stack with our default configuration.
_textStorage = [[NSTextStorage alloc] init];
_layoutManager = [[ASLayoutManager alloc] init];
_layoutManager.usesFontLeading = NO;
[_textStorage addLayoutManager:_layoutManager];
// Instead of calling [NSTextStorage initWithAttributedString:], setting attributedString just after calling addlayoutManager can fix CJK language layout issues.
// See https://github.com/facebook/AsyncDisplayKit/issues/2894
if (attributedString) {
[_textStorage setAttributedString:attributedString];
}
_textContainer = [[NSTextContainer alloc] initWithSize:constrainedSize];
// We want the text laid out up to the very edges of the container.
_textContainer.lineFragmentPadding = 0;
_textContainer.lineBreakMode = lineBreakMode;
_textContainer.maximumNumberOfLines = maximumNumberOfLines;
_textContainer.exclusionPaths = exclusionPaths;
[_layoutManager addTextContainer:_textContainer];
}
return self;
}
- (void)performBlockWithLockedTextKitComponents:(void (^)(NSLayoutManager *,
NSTextStorage *,
NSTextContainer *))block
{
ASDN::MutexSharedLocker l(__instanceLock__);
if (block) {
block(_layoutManager, _textStorage, _textContainer);
}
}
@end