Swiftgram/AsyncDisplayKit/Private/ASInternalHelpers.mm
Huy Nguyen f8531f467d Add Layout nodes.
- The code is forked from LayoutComponents in ComponentKit.
- Public interfaces are modified to be strictly Objective-C. As a result, users are not forced to switch to Objective-C++, the linker can happily compile and Swift fans can continue using the mighty ASDK.
2015-06-25 11:32:30 +07:00

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/*
* 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 "ASInternalHelpers.h"
#import <functional>
#import <objc/runtime.h>
#import "ASLayout.h"
BOOL ASSubclassOverridesSelector(Class superclass, Class subclass, SEL selector)
{
Method superclassMethod = class_getInstanceMethod(superclass, selector);
Method subclassMethod = class_getInstanceMethod(subclass, selector);
IMP superclassIMP = superclassMethod ? method_getImplementation(superclassMethod) : NULL;
IMP subclassIMP = subclassMethod ? method_getImplementation(subclassMethod) : NULL;
return (superclassIMP != subclassIMP);
}
static void ASDispatchOnceOnMainThread(dispatch_once_t *predicate, dispatch_block_t block)
{
if ([NSThread isMainThread]) {
dispatch_once(predicate, block);
} else {
if (DISPATCH_EXPECT(*predicate == 0L, NO)) {
dispatch_sync(dispatch_get_main_queue(), ^{
dispatch_once(predicate, block);
});
}
}
}
CGFloat ASScreenScale()
{
static CGFloat _scale;
static dispatch_once_t onceToken;
ASDispatchOnceOnMainThread(&onceToken, ^{
_scale = [UIScreen mainScreen].scale;
});
return _scale;
}
CGFloat ASFloorPixelValue(CGFloat f)
{
return floorf(f * ASScreenScale()) / ASScreenScale();
}
CGFloat ASCeilPixelValue(CGFloat f)
{
return ceilf(f * ASScreenScale()) / ASScreenScale();
}
CGFloat ASRoundPixelValue(CGFloat f)
{
return roundf(f * ASScreenScale()) / ASScreenScale();
}