//

// ASPagerNode.m

// AsyncDisplayKit

//

// Created by Levi McCallum on 12/7/15.

//

// 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 "ASPagerNode.h"

#import "ASDelegateProxy.h"

#import "ASDisplayNode+Subclasses.h"

#import "ASPagerFlowLayout.h"

@interface ASPagerNode () <ASCollectionDataSource, ASCollectionDelegate, ASCollectionViewDelegateFlowLayout, ASDelegateProxyInterceptor>

{

ASPagerFlowLayout *_flowLayout;

__weak id <ASPagerDataSource> _pagerDataSource;

ASPagerNodeProxy *_proxyDataSource;

BOOL _pagerDataSourceImplementsNodeBlockAtIndex;

__weak id <ASPagerDelegate> _pagerDelegate;

ASPagerNodeProxy *_proxyDelegate;

BOOL _pagerDelegateImplementsConstrainedSizeForNode;

}

@end

@implementation ASPagerNode

@dynamic view, delegate, dataSource;

#pragma mark - Lifecycle

- (instancetype)init

{

ASPagerFlowLayout *flowLayout = [[ASPagerFlowLayout alloc] init];

flowLayout.scrollDirection = UICollectionViewScrollDirectionHorizontal;

flowLayout.minimumInteritemSpacing = 0;

flowLayout.minimumLineSpacing = 0;

return [self initWithCollectionViewLayout:flowLayout];

}

- (instancetype)initWithCollectionViewLayout:(ASPagerFlowLayout *)flowLayout;

{

ASDisplayNodeAssert([flowLayout isKindOfClass:[ASPagerFlowLayout class]], @"ASPagerNode requires a flow layout.");

self = [super initWithCollectionViewLayout:flowLayout];

if (self != nil) {

_flowLayout = flowLayout;

}

return self;

}

#pragma mark - ASDisplayNode

- (void)didLoad

{

[super didLoad];

ASCollectionView *cv = self.view;

cv.asyncDataSource = (id<ASCollectionViewDataSource>)_proxyDataSource ?: self;

cv.asyncDelegate = (id<ASCollectionViewDelegate>)_proxyDelegate ?: self;

#if TARGET_OS_IOS

cv.pagingEnabled = YES;

cv.scrollsToTop = NO;

#endif

cv.allowsSelection = NO;

cv.showsVerticalScrollIndicator = NO;

cv.showsHorizontalScrollIndicator = NO;

// Zeroing contentInset is important, as UIKit will set the top inset for the navigation bar even though

// our view is only horizontally scrollable. This causes UICollectionViewFlowLayout to log a warning.

// From here we cannot disable this directly (UIViewController's automaticallyAdjustsScrollViewInsets).

cv.zeroContentInsets = YES;

ASRangeTuningParameters minimumRenderParams = { .leadingBufferScreenfuls = 0.0, .trailingBufferScreenfuls = 0.0 };

ASRangeTuningParameters minimumPreloadParams = { .leadingBufferScreenfuls = 1.0, .trailingBufferScreenfuls = 1.0 };

[self setTuningParameters:minimumRenderParams forRangeMode:ASLayoutRangeModeMinimum rangeType:ASLayoutRangeTypeDisplay];

[self setTuningParameters:minimumPreloadParams forRangeMode:ASLayoutRangeModeMinimum rangeType:ASLayoutRangeTypePreload];

ASRangeTuningParameters fullRenderParams = { .leadingBufferScreenfuls = 1.0, .trailingBufferScreenfuls = 1.0 };

ASRangeTuningParameters fullPreloadParams = { .leadingBufferScreenfuls = 2.0, .trailingBufferScreenfuls = 2.0 };

[self setTuningParameters:fullRenderParams forRangeMode:ASLayoutRangeModeFull rangeType:ASLayoutRangeTypeDisplay];

[self setTuningParameters:fullPreloadParams forRangeMode:ASLayoutRangeModeFull rangeType:ASLayoutRangeTypePreload];

}

#pragma mark - Getters / Setters

- (NSInteger)currentPageIndex

{

return (self.view.contentOffset.x / CGRectGetWidth(self.view.bounds));

}

#pragma mark - Helpers

- (void)scrollToPageAtIndex:(NSInteger)index animated:(BOOL)animated

{

NSIndexPath *indexPath = [NSIndexPath indexPathForItem:index inSection:0];

[self.view scrollToItemAtIndexPath:indexPath atScrollPosition:UICollectionViewScrollPositionLeft animated:animated];

}

- (ASCellNode *)nodeForPageAtIndex:(NSInteger)index

{

return [self.view nodeForItemAtIndexPath:[NSIndexPath indexPathForItem:index inSection:0]];

}

#pragma mark - ASCollectionViewDataSource

- (ASCellNodeBlock)collectionView:(ASCollectionView *)collectionView nodeBlockForItemAtIndexPath:(NSIndexPath *)indexPath

{

ASDisplayNodeAssert(_pagerDataSource != nil, @"ASPagerNode must have a data source to load nodes to display");

if (!_pagerDataSourceImplementsNodeBlockAtIndex) {

ASCellNode *node = [_pagerDataSource pagerNode:self nodeAtIndex:indexPath.item];

return ^{ return node; };

}

return [_pagerDataSource pagerNode:self nodeBlockAtIndex:indexPath.item];

}

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section

{

ASDisplayNodeAssert(_pagerDataSource != nil, @"ASPagerNode must have a data source to load nodes to display");

return [_pagerDataSource numberOfPagesInPagerNode:self];

}

- (ASSizeRange)collectionView:(ASCollectionView *)collectionView constrainedSizeForNodeAtIndexPath:(NSIndexPath *)indexPath

{

if (_pagerDelegateImplementsConstrainedSizeForNode) {

return [_pagerDelegate pagerNode:self constrainedSizeForNodeAtIndex:indexPath.item];

}

return ASSizeRangeMake(CGSizeZero, self.view.bounds.size);

}

#pragma mark - Data Source Proxy

- (id <ASPagerDataSource>)dataSource

{

return _pagerDataSource;

}

- (void)setDataSource:(id <ASPagerDataSource>)dataSource

{

if (dataSource != _pagerDataSource) {

_pagerDataSource = dataSource;

_pagerDataSourceImplementsNodeBlockAtIndex = [_pagerDataSource respondsToSelector:@selector(pagerNode:nodeBlockAtIndex:)];

// Data source must implement pagerNode:nodeBlockAtIndex: or pagerNode:nodeAtIndex:

ASDisplayNodeAssertTrue(_pagerDataSourceImplementsNodeBlockAtIndex || [_pagerDataSource respondsToSelector:@selector(pagerNode:nodeAtIndex:)]);

_proxyDataSource = dataSource ? [[ASPagerNodeProxy alloc] initWithTarget:dataSource interceptor:self] : nil;

super.dataSource = (id <ASCollectionDataSource>)_proxyDataSource;

}

}

- (void)setDelegate:(id<ASPagerDelegate>)delegate

{

if (delegate != _pagerDelegate) {

_pagerDelegate = delegate;

_pagerDelegateImplementsConstrainedSizeForNode = [_pagerDelegate respondsToSelector:@selector(pagerNode:constrainedSizeForNodeAtIndex:)];

_proxyDelegate = delegate ? [[ASPagerNodeProxy alloc] initWithTarget:delegate interceptor:self] : nil;

super.delegate = (id <ASCollectionDelegate>)_proxyDelegate;

}

}

- (void)proxyTargetHasDeallocated:(ASDelegateProxy *)proxy

{

[self setDataSource:nil];

[self setDelegate:nil];

}

@end