Swiftgram/Source/Details/ASCollectionLayoutContext.mm
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

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//
// ASCollectionLayoutContext.mm
// AsyncDisplayKit
//
// Created by Huy Nguyen on 21/3/17.
// Copyright © 2017 Facebook. All rights reserved.
//
#import <AsyncDisplayKit/ASCollectionLayoutContext.h>
#import <AsyncDisplayKit/ASCollectionLayoutContext+Private.h>
#import <AsyncDisplayKit/ASAssert.h>
#import <AsyncDisplayKit/ASElementMap.h>
#import <AsyncDisplayKit/ASEqualityHelpers.h>
#import <AsyncDisplayKit/ASEqualityHashHelpers.h>
@implementation ASCollectionLayoutContext
- (instancetype)initWithViewportSize:(CGSize)viewportSize elements:(ASElementMap *)elements additionalInfo:(id)additionalInfo
{
self = [super init];
if (self) {
_viewportSize = viewportSize;
_elements = elements;
_additionalInfo = additionalInfo;
}
return self;
}
- (BOOL)isEqualToContext:(ASCollectionLayoutContext *)context
{
if (context == nil) {
return NO;
}
return CGSizeEqualToSize(_viewportSize, context.viewportSize) && ASObjectIsEqual(_elements, context.elements) && ASObjectIsEqual(_additionalInfo, context.additionalInfo);
}
- (BOOL)isEqual:(id)other
{
if (self == other) {
return YES;
}
if (! [other isKindOfClass:[ASCollectionLayoutContext class]]) {
return NO;
}
return [self isEqualToContext:other];
}
- (NSUInteger)hash
{
NSUInteger subhashes[] = {
ASHashFromCGSize(_viewportSize),
[_elements hash],
[_additionalInfo hash]
};
return ASIntegerArrayHash(subhashes, sizeof(subhashes) / sizeof(subhashes[0]));
}
@end