47 lines
1.7 KiB
Objective-C

/*
* 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/ASDimension.h>
#import <AsyncDisplayKit/ASStackLayoutDefines.h>
#import <AsyncDisplayKit/ASLayoutOptions.h>
@class ASLayout;
@class ASLayoutSpec;
/**
* The ASLayoutable protocol declares a method for measuring the layout of an object. A class must implement the method
* so that instances of that class can be used to build layout trees. The protocol also provides information
* about how an object should be laid out within an ASStackLayoutSpec.
*/
@protocol ASLayoutable <NSObject>
/**
* @abstract Calculate a layout based on given size range.
*
* @param constrainedSize The minimum and maximum sizes the receiver should fit in.
*
* @return An ASLayout instance defining the layout of the receiver and its children.
*/
- (ASLayout *)measureWithSizeRange:(ASSizeRange)constrainedSize;
/**
@abstract Give this object a last chance to add itself to a container ASLayoutable (most likely an ASLayoutSpec) before
being added to a ASLayoutSpec.
For example, consider a node whose superclass is laid out via calculateLayoutThatFits:. The subclass cannot implement
layoutSpecThatFits: since its ASLayout is already being created by calculateLayoutThatFits:. By implementing this method
a subclass can wrap itself in an ASLayoutSpec right before it is added to a layout spec.
It is rare that a class will need to implement this method.
*/
- (id<ASLayoutable>)finalLayoutable;
@end