Swiftgram/AsyncDisplayKit/Layout/ASOverlayLayoutSpec.mm
rcancro 7446578f6f Added method to ASLayoutable to allow a layoutable to override how it will be added to the layoutSpec.
Also moved ASStaticLayoutSpec to act more like the other layouts.
2015-09-08 09:49:40 -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 "ASOverlayLayoutSpec.h"
#import "ASAssert.h"
#import "ASBaseDefines.h"
#import "ASLayout.h"
static NSString * const kOverlayChildKey = @"kOverlayChildKey";
@implementation ASOverlayLayoutSpec
- (instancetype)initWithChild:(id<ASLayoutable>)child overlay:(id<ASLayoutable>)overlay
{
if (!(self = [super init])) {
return nil;
}
ASDisplayNodeAssertNotNil(child, @"Child that will be overlayed on shouldn't be nil");
self.overlay = overlay;
[self setChild:child];
return self;
}
+ (instancetype)overlayLayoutSpecWithChild:(id<ASLayoutable>)child overlay:(id<ASLayoutable>)overlay
{
return [[self alloc] initWithChild:child overlay:overlay];
}
- (void)setOverlay:(id<ASLayoutable>)overlay
{
[super setChild:overlay forIdentifier:kOverlayChildKey];
}
- (id<ASLayoutable>)overlay
{
return [super childForIdentifier:kOverlayChildKey];
}
/**
First layout the contents, then fit the overlay on top of it.
*/
- (ASLayout *)measureWithSizeRange:(ASSizeRange)constrainedSize
{
ASLayout *contentsLayout = [_child measureWithSizeRange:constrainedSize];
contentsLayout.position = CGPointZero;
NSMutableArray *sublayouts = [NSMutableArray arrayWithObject:contentsLayout];
if (self.overlay) {
ASLayout *overlayLayout = [self.overlay measureWithSizeRange:{contentsLayout.size, contentsLayout.size}];
overlayLayout.position = CGPointZero;
[sublayouts addObject:overlayLayout];
}
return [ASLayout layoutWithLayoutableObject:self size:contentsLayout.size sublayouts:sublayouts];
}
@end