2016-08-10 10:33:13 -07:00

102 lines
4.1 KiB
Objective-C

//
// ASLayoutSpec.h
// 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/ASLayoutable.h>
#import <AsyncDisplayKit/ASAsciiArtBoxCreator.h>
NS_ASSUME_NONNULL_BEGIN
/** A layout spec is an immutable object that describes a layout, loosely inspired by React. */
@interface ASLayoutSpec : NSObject <ASLayoutable>
/**
* Creation of a layout spec should only happen by a user in layoutSpecThatFits:. During that method, a
* layout spec can be created and mutated. Once it is passed back to ASDK, the isMutable flag will be
* set to NO and any further mutations will cause an assert.
*/
@property (nonatomic, assign) BOOL isMutable;
- (instancetype)init;
/**
* Parent of the layout spec
*/
@property (nullable, nonatomic, weak) id<ASLayoutable> parent;
/**
* Adds a child to this layout spec using a default identifier.
*
* @param child A child to be added.
*
* @discussion Every ASLayoutSpec must act on at least one child. The ASLayoutSpec base class takes the
* responsibility of holding on to the spec children. Some layout specs, like ASInsetLayoutSpec,
* only require a single child.
*
* For layout specs that require a known number of children (ASBackgroundLayoutSpec, for example)
* a subclass should use this method to set the "primary" child. It can then use setChild:forIdentifier:
* to set any other required children. Ideally a subclass would hide this from the user, and use the
* setChild:forIdentifier: internally. For example, ASBackgroundLayoutSpec exposes a backgroundChild
* property that behind the scenes is calling setChild:forIdentifier:.
*/
@property (nullable, strong, nonatomic) id<ASLayoutable> child;
/**
* Adds a child with the given identifier to this layout spec.
*
* @param child A child to be added.
*
* @param index An index associated with the child.
*
* @discussion Every ASLayoutSpec must act on at least one child. The ASLayoutSpec base class takes the
* responsibility of holding on to the spec children. Some layout specs, like ASInsetLayoutSpec,
* only require a single child.
*
* For layout specs that require a known number of children (ASBackgroundLayoutSpec, for example)
* a subclass can use the setChild method to set the "primary" child. It should then use this method
* to set any other required children. Ideally a subclass would hide this from the user, and use the
* setChild:forIndex: internally. For example, ASBackgroundLayoutSpec exposes a backgroundChild
* property that behind the scenes is calling setChild:forIndex:.
*/
- (void)setChild:(id<ASLayoutable>)child forIndex:(NSUInteger)index;
/**
* Adds childen to this layout spec.
*
* @param children An array of ASLayoutable children to be added.
*
* @discussion Every ASLayoutSpec must act on at least one child. The ASLayoutSpec base class takes the
* reponsibility of holding on to the spec children. Some layout specs, like ASStackLayoutSpec,
* can take an unknown number of children. In this case, the this method should be used.
* For good measure, in these layout specs it probably makes sense to define
* setChild: and setChild:forIdentifier: methods to do something appropriate or to assert.
*/
@property (nullable, strong, nonatomic) NSArray<id<ASLayoutable>> *children;
/**
* Returns the child added to this layout spec using the given index.
*
* @param index An identifier associated withe the child.
*/
- (nullable id<ASLayoutable>)childForIndex:(NSUInteger)index;
@end
@interface ASLayoutSpec (Debugging) <ASLayoutableAsciiArtProtocol>
/**
* Used by other layout specs to create ascii art debug strings
*/
+ (NSString *)asciiArtStringForChildren:(NSArray *)children parentName:(NSString *)parentName direction:(ASStackLayoutDirection)direction;
+ (NSString *)asciiArtStringForChildren:(NSArray *)children parentName:(NSString *)parentName;
@end
NS_ASSUME_NONNULL_END