Swiftgram/Source/Details/ASCollectionLayoutState.h
Huy Nguyen 7d365c7d07 Introduce ASCollectionLayout and friends (#3130)
* Introduce ASCollectionViewLayout
- `ASCollectionViewLayout` is an async `UICollectionViewLayout` that encapsulates its layout calculation logic into a separate thread-safe object which can be used ahead of time and/or on multiple threads.
- `ASDataController` now can prepare for a new layout resulted from a change set before `ASCollectionView` even knows about it. By the time the change set it ready to be consumed by `ASCollectionView`, its new layout is also ready.
- New `ASCollectionViewLayoutCalculating` protocol that is simple and generic enough that many types of calculators can be built on top. `ASCollectionViewLayoutSpecCalculator` conforms to `ASCollectionViewLayoutCalculating` protocol and can be backed by any layout spec (e.g `ASStackLayoutSpec`, `PIMasonryLayoutSpec`, etc). We can even build a `ASCollectionViewLayoutYogaCalculator` that uses Yoga internally.
- A built-in `ASCollectionViewFlowLayoutCalculator` that is a subclass of `ASCollectionViewLayoutSpecCalculator` and uses a multi-threaded multi-line `ASStackLayoutSpec` internally. The result is a performant and thread-safe flow layout calculator.
- Finally, `ASCollectionViewLayout` can be subclassed to handle a specific type of calculator with optimizations implemented based on the knowledge of such calculator. For example, `ASCollectionViewFlowLayout` can have a highly optimized implementation of `-layoutAttributesForElementsInRect:`.

Protocolize layout calculator providing and consuming

Add flex wrap documentation

Add a `multithreaded` flag to ASStackLayoutSpec that forces it to dispatch even if it's off main
- Update ASCollectionViewFlowLayoutSpecCalculator to use that flag.

Minor change in ASCollectionViewLayout

Implement Mosaic layout calculator

Minor change

Fix project file

Rename and fix project file

Skip fetching constrained size only if a layout calculator is available

Update examples/ASCollectionView

Remove unnecessary change in ASTableView

Address comments

Rename collection view calculator protocols

Minor changes after rebasing with master

Add ASLegacyCollectionLayoutCalculator for backward compatibility

Remove ASCollectionLayoutSpecCalculator

Remove ASLegacyCollectionLayoutCalculator

Introduce ASCollectionLayout
- A wrapper object that contains content size and an element to rect table.
- Collection layout calculators to return this new object instead of an ASLayout.

Before adding a content cache

Finishing hooking up ASCollectionLayoutDataSource to ASCollectionNode

Stash

Finish ASCollectionLayout

Rough impl of ASCollectionFlowLayout

Revert changes in CustomCollectionView example

Move ASRectTable back to Private

* Rename ASCollectionContentAttributes to ASCollectionLayoutState

* Address other comments

* Introduce ASCollectionLayoutDelegate and make ASCollectionLayout private

* Address comments

* API tweaks:
- Replace `-layoutContextWithElementMap:` in ASCollectionLayoutDelegate with `-additionalInfoForLayoutWithElements:`. The returned object is then stored in ASCollectionLayoutContext for later lookups.
- ASCollectionLayoutContext has no public initializer.
- ASDataControllerLayoutDelegate no longer requires a context of type ASCollectionLayoutContext but simply an `id`. This helps decouple ASDataController and ASCollectionLayout.
- Rename `elementMap` to `elements`.
- Rename `visibleMap` to `visibleElements`.
- Other minor changes.

* Rename ASCGSizeHash to ASHashFromCGSize

* Make sure to call super in -[ASCollectionLayout prepareLayout]

* Update example/ASCollectionView to use ASCollectionFlowLayoutDelegate

* Remove unnecessary change
2017-04-12 11:13:44 +01:00

56 lines
1.9 KiB
Objective-C

//
// ASCollectionLayoutState.h
// AsyncDisplayKit
//
// Created by Huy Nguyen on 9/3/17.
// Copyright © 2017 Facebook. All rights reserved.
//
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#import <AsyncDisplayKit/ASBaseDefines.h>
@class ASElementMap, ASCollectionElement, ASLayout;
NS_ASSUME_NONNULL_BEGIN
AS_SUBCLASSING_RESTRICTED
@interface ASCollectionLayoutState : NSObject
/// The elements used to calculate this object
@property (nonatomic, strong, readonly) ASElementMap *elements;
@property (nonatomic, assign, readonly) CGSize contentSize;
/// Element to layout attributes map. Should use weak pointers for elements.
@property (nonatomic, strong, readonly) NSMapTable<ASCollectionElement *, UICollectionViewLayoutAttributes *> *elementToLayoutArrtibutesMap;
- (instancetype)init __unavailable;
/**
* Designated initializer.
*
* @param elements The elements used to calculate this object
*
* @param contentSize The content size of the collection's layout
*
* @param elementToLayoutArrtibutesMap Map between elements to their layout attributes. The map may contain all elements, or a subset of them and will be updated later.
* Also, it should have NSMapTableObjectPointerPersonality and NSMapTableWeakMemory as key options.
*/
- (instancetype)initWithElements:(ASElementMap *)elements contentSize:(CGSize)contentSize elementToLayoutArrtibutesMap:(NSMapTable<ASCollectionElement *, UICollectionViewLayoutAttributes *> *)attrsMap NS_DESIGNATED_INITIALIZER;
/**
* Convenience initializer.
*
* @param elements The elements used to calculate this object
*
* @param layout The layout describes size and position of all elements, or a subset of them and will be updated later.
*
* @discussion The sublayouts that describe position of elements must be direct children of the root layout object parameter.
*/
- (instancetype)initWithElements:(ASElementMap *)elements layout:(ASLayout *)layout;
@end
NS_ASSUME_NONNULL_END