Update to latest state

AsyncDisplayKit/ASPagerFlowLayout.h

@@ -8,17 +8,6 @@
 
 #import <UIKit/UIKit.h>
 
-@class ASPagerNode;
-
-@protocol ASPagerFlowLayoutPageProvider <NSObject>
-
-/// Provides the current page index to the ASPagerFlowLayout
-- (NSInteger)currentPageIndex;
-
-@end
-
 @interface ASPagerFlowLayout : UICollectionViewFlowLayout
 
-- (instancetype)initWithPageProvider:(id<ASPagerFlowLayoutPageProvider>)pageProvider;
-
 @end

AsyncDisplayKit/ASPagerFlowLayout.m

@@ -7,73 +7,78 @@
 //
 
 #import "ASPagerFlowLayout.h"
-#import "ASPagerNode.h"
 
 @interface ASPagerFlowLayout ()
 
 @property (strong, nonatomic) NSIndexPath *currentIndexPath;
-@property (weak, nonatomic) id<ASPagerFlowLayoutPageProvider> pageProvider;
 
 @end
 
-@implementation ASPagerFlowLayout
+@implementation ASPagerFlowLayout {
-
+    BOOL _didRotate;
-#pragma mark - Lifecycle
+    CGRect _cachedCollectionViewBounds;
-
-- (instancetype)initWithPageProvider:(id<ASPagerFlowLayoutPageProvider>)pageProvider
-{
-  self = [super init];
-  if (self == nil) { return self; }
-  _pageProvider = pageProvider;
-  return self;
 }
 
-#pragma mark - UICollectionViewFlowLayout
+- (CGPoint)targetContentOffsetForProposedContentOffset:(CGPoint)proposedContentOffset withScrollingVelocity:(CGPoint)velocity
-
-- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds
 {
-  CGRect oldBounds = self.collectionView.bounds;
+    NSInteger currentPage = ceil(proposedContentOffset.x / self.collectionView.bounds.size.width);
-  if (!CGSizeEqualToSize(oldBounds.size, newBounds.size)) {
+    self.currentIndexPath = [NSIndexPath indexPathForItem:currentPage inSection:0];
-    return YES;
-  }
     
-  return NO;
+    return [super targetContentOffsetForProposedContentOffset:proposedContentOffset withScrollingVelocity:velocity];
 }
 
+
+- (void)prepareForAnimatedBoundsChange:(CGRect)oldBounds
+{
+  // Cache the current page if a rotation did happen. This happens before the rotation animation
+  // is occuring and the bounds changed so we use this as an opportunity to cache the current index path
+  if (_cachedCollectionViewBounds.size.width != self.collectionView.bounds.size.width) {
+      _cachedCollectionViewBounds = self.collectionView.bounds;
+        
+    // Figurring out current page based on the old bounds visible space
+    CGRect visibleRect = oldBounds;
+           
+    CGFloat visibleXCenter = CGRectGetMidX(visibleRect);
+    NSArray<UICollectionViewLayoutAttributes *> *layoutAttributes = [self layoutAttributesForElementsInRect:visibleRect];
+    for (UICollectionViewLayoutAttributes *attributes in layoutAttributes) {
+      if ([attributes representedElementCategory] == UICollectionElementCategoryCell && attributes.center.x == visibleXCenter) {
+        self.currentIndexPath = attributes.indexPath;
+        break;
+      }
+    }
+      
+      _didRotate = YES;
+    }
+    
+    [super prepareForAnimatedBoundsChange:oldBounds];
+}
 - (CGPoint)targetContentOffsetForProposedContentOffset:(CGPoint)proposedContentOffset
+{
+    // Don't mess around if the user is interacting with the page node. Although if just a rotation happened we should
+    // try to use the current index path to not end up setting the target content offset to something in between pages
+    if (_didRotate || (!self.collectionView.isDecelerating && !self.collectionView.isTracking)) {
+        _didRotate = NO;
+        if (self.currentIndexPath) {
+            return [self _targetContentOffsetForItemAtIndexPath:self.currentIndexPath proposedContentOffset:proposedContentOffset];
+        }
+    }
+    
+    return [super targetContentOffsetForProposedContentOffset:proposedContentOffset];
+}
+
+- (CGPoint)_targetContentOffsetForItemAtIndexPath:(NSIndexPath *)indexPath proposedContentOffset:(CGPoint)proposedContentOffset
 {
   if ([self _dataSourceIsEmpty]) {
     return proposedContentOffset;
   }
   
-  if (_pageProvider == nil || [self _visibleRectIsInvalid]) {
+  CGFloat currentPageXOffset = self.currentIndexPath.item * CGRectGetWidth(self.collectionView.bounds);
-    return [super targetContentOffsetForProposedContentOffset:proposedContentOffset];
+    return CGPointMake(currentPageXOffset, proposedContentOffset.y);
-  }
-
-  NSIndexPath *indexPath = [NSIndexPath indexPathForItem:_pageProvider.currentPageIndex inSection:0];
-  UICollectionViewLayoutAttributes *attributes = [self layoutAttributesForItemAtIndexPath:indexPath];
-  CGFloat xOffset = (CGRectGetWidth(self.collectionView.bounds) - CGRectGetWidth(attributes.frame)) / 2;
-  return CGPointMake(attributes.frame.origin.x - xOffset, proposedContentOffset.y);
 }
 
-#pragma mark - Helper
-
 - (BOOL)_dataSourceIsEmpty
 {
-  return ([self.collectionView numberOfSections] == 0 || [self.collectionView numberOfItemsInSection:0] == 0);
+    return ([self.collectionView numberOfSections] == 0 || [self.collectionView numberOfItemsInSection:0] == 0);
-}
-
-- (CGRect)_visibleRect
-{
-  CGRect visibleRect;
-  visibleRect.origin = self.collectionView.contentOffset;
-  visibleRect.size = self.collectionView.bounds.size;
-  return visibleRect;
-}
-
-- (BOOL)_visibleRectIsInvalid
-{
-  return CGRectEqualToRect([self _visibleRect], CGRectZero);
 }
 
 @end

AsyncDisplayKit/ASPagerNode.h

@@ -96,4 +96,3 @@
 - (void)scrollToPageAtIndex:(NSInteger)index animated:(BOOL)animated;
 
 @end
-

AsyncDisplayKit/ASPagerNode.m

@@ -12,26 +12,25 @@
 #import "ASPagerFlowLayout.h"
 #import "UICollectionViewLayout+ASConvenience.h"
 
-@interface ASPagerNode () <ASCollectionDataSource, ASCollectionViewDelegateFlowLayout, ASDelegateProxyInterceptor, ASPagerFlowLayoutPageProvider>
+@interface ASPagerNode () <ASCollectionDataSource, ASCollectionViewDelegateFlowLayout, ASDelegateProxyInterceptor>
 {
   ASPagerFlowLayout *_flowLayout;
-  ASPagerNodeProxy *_dataSourceProxy;
+  ASPagerNodeProxy *_proxy;
-  ASPagerNodeProxy *_delegateProxy;
   __weak id <ASPagerNodeDataSource> _pagerDataSource;
   BOOL _pagerDataSourceImplementsNodeBlockAtIndex;
   BOOL _pagerDataSourceImplementsConstrainedSizeForNode;
 }
 
-@property (nonatomic, assign, readonly) NSInteger numberOfPages;
-
 @end
 
 @implementation ASPagerNode
 @dynamic view, delegate, dataSource;
 
+#pragma mark - Lifecycle
+
 - (instancetype)init
 {
-  ASPagerFlowLayout *flowLayout = [[ASPagerFlowLayout alloc] initWithPageProvider:self];
+  ASPagerFlowLayout *flowLayout = [[ASPagerFlowLayout alloc] init];
   flowLayout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
   flowLayout.minimumInteritemSpacing = 0;
   flowLayout.minimumLineSpacing = 0;
@@ -45,11 +44,12 @@
   self = [super initWithCollectionViewLayout:flowLayout];
   if (self != nil) {
     _flowLayout = flowLayout;
-    _currentPageIndex = 0;
   }
   return self;
 }
 
+#pragma mark - ASDisplayNode
+
 - (void)didLoad
 {
   [super didLoad];
@@ -67,10 +67,6 @@
   // 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;
-  
-  // Set the super delegate to the pager for now to inject the scroll delegate calls. If the API consumer
-  // set's the delegate on the ASPagerNode we add an ASPagerNodeProxy in between in setDelegate:
-  super.delegate = self;
 
   ASRangeTuningParameters minimumRenderParams = { .leadingBufferScreenfuls = 0.0, .trailingBufferScreenfuls = 0.0 };
   ASRangeTuningParameters minimumPreloadParams = { .leadingBufferScreenfuls = 1.0, .trailingBufferScreenfuls = 1.0 };
@@ -83,34 +79,23 @@
   [self setTuningParameters:fullPreloadParams forRangeMode:ASLayoutRangeModeFull rangeType:ASLayoutRangeTypeFetchData];
 }
 
-#pragma mark - Getter / Setter
+#pragma mark - Getters / Setters
 
-- (NSInteger)numberOfPages
+- (NSInteger)currentPageIndex
 {
-  return [_pagerDataSource numberOfPagesInPagerNode:self];
+  return (self.view.contentOffset.x / CGRectGetWidth(self.view.bounds));
 }
 
 #pragma mark - Helpers
 
 - (void)scrollToPageAtIndex:(NSInteger)index animated:(BOOL)animated
 {
-  // Prevent an exception to scroll to an index path that is invalid
+  NSIndexPath *indexPath = [NSIndexPath indexPathForItem:index inSection:0];
-  if (index >= 0 && index < self.numberOfPages) {
+  [self.view scrollToItemAtIndexPath:indexPath atScrollPosition:UICollectionViewScrollPositionLeft animated:animated];
-    NSIndexPath *indexPath = [NSIndexPath indexPathForItem:index inSection:0];
-    [self.view scrollToItemAtIndexPath:indexPath atScrollPosition:UICollectionViewScrollPositionLeft animated:animated];
-  
-    _currentPageIndex = index;
-  }
 }
 
 #pragma mark - ASCollectionViewDataSource
 
-- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
-{
-  ASDisplayNodeAssert(_pagerDataSource != nil, @"ASPagerNode must have a data source to load nodes to display");
-  return self.numberOfPages;
-}
-
 - (ASCellNodeBlock)collectionView:(ASCollectionView *)collectionView nodeBlockForItemAtIndexPath:(NSIndexPath *)indexPath
 {
   ASDisplayNodeAssert(_pagerDataSource != nil, @"ASPagerNode must have a data source to load nodes to display");
@@ -121,6 +106,12 @@
   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 (_pagerDataSourceImplementsConstrainedSizeForNode) {
@@ -129,7 +120,7 @@
   return ASSizeRangeMake(CGSizeZero, self.view.bounds.size);
 }
 
-#pragma mark - Proxies
+#pragma mark - Data Source Proxy
 
 - (id <ASPagerDataSource>)dataSource
 {
@@ -142,59 +133,20 @@
     _pagerDataSource = pagerDataSource;
     
     _pagerDataSourceImplementsNodeBlockAtIndex = [_pagerDataSource respondsToSelector:@selector(pagerNode:nodeBlockAtIndex:)];
-    _pagerDataSourceImplementsConstrainedSizeForNode = [_pagerDataSource respondsToSelector:@selector(pagerNode:constrainedSizeForNodeAtIndexPath:)];
-    
     // Data source must implement pagerNode:nodeBlockAtIndex: or pagerNode:nodeAtIndex:
     ASDisplayNodeAssertTrue(_pagerDataSourceImplementsNodeBlockAtIndex || [_pagerDataSource respondsToSelector:@selector(pagerNode:nodeAtIndex:)]);
     
-    _dataSourceProxy = pagerDataSource ? [[ASPagerNodeProxy alloc] initWithTarget:pagerDataSource interceptor:self] : nil;
+    _pagerDataSourceImplementsConstrainedSizeForNode = [_pagerDataSource respondsToSelector:@selector(pagerNode:constrainedSizeForNodeAtIndexPath:)];
     
-    super.dataSource = (id <ASCollectionDataSource>)_dataSourceProxy;
+    _proxy = pagerDataSource ? [[ASPagerNodeProxy alloc] initWithTarget:pagerDataSource interceptor:self] : nil;
+    
+    super.dataSource = (id <ASCollectionDataSource>)_proxy;
   }
 }
 
-- (void)setDelegate:(id<ASCollectionDelegate>)delegate
-{
-  _delegateProxy = delegate ? [[ASPagerNodeProxy alloc] initWithTarget:delegate interceptor:self] : nil;
-  
-  super.delegate = (id <ASCollectionDelegate>)_delegateProxy;
-}
-
 - (void)proxyTargetHasDeallocated:(ASDelegateProxy *)proxy
 {
   [self setDataSource:nil];
-  [self setDelegate:nil];
-}
-
-#pragma mark - <ASCollectionDelegate>
-
-- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
-{
-  CGFloat pageWidth = CGRectGetWidth(self.view.frame);
-  _currentPageIndex = floor((self.view.contentOffset.x - pageWidth / 2) / pageWidth) + 1;
-}
-
-- (void)scrollViewWillEndDragging:(UIScrollView*)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint*)targetContentOffset
-{
-  CGFloat pageWidth = CGRectGetWidth(self.view.frame);
-  NSInteger newPageIndex = _currentPageIndex;
-
-  if (velocity.x == 0) {
-    // Handle slow dragging not lifting finger
-    newPageIndex = floor((targetContentOffset->x - pageWidth / 2) / pageWidth) + 1;
-  } else {
-    newPageIndex = velocity.x > 0 ? _currentPageIndex + 1 : _currentPageIndex - 1;
-
-    if (newPageIndex < 0) {
-        newPageIndex = 0;
-    }
-    if (newPageIndex > self.view.contentSize.width / pageWidth) {
-        newPageIndex = ceil(self.view.contentSize.width / pageWidth) - 1.0;
-    }
-  }
-  _currentPageIndex = newPageIndex;
-
-  *targetContentOffset = CGPointMake(newPageIndex * pageWidth, targetContentOffset->y);
 }
 
 @end