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Initial Work for Range Controller to Support Supplementary Elements (#3140)

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* Initial work supporting supplementaries in range controller

* Rename indexPathForElementIfItem
This commit is contained in:
Adlai Holler
2017-03-06 10:11:00 -08:00
committed by GitHub
parent d0ad24808b
commit d59ea3902d
12 changed files with 172 additions and 69 deletions
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130
Source/Details/ASCollectionViewLayoutController.mm
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@@ -1,130 +0,0 @@
//
// ASCollectionViewLayoutController.mm
// 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/ASCollectionViewLayoutController.h>
#import <AsyncDisplayKit/ASAssert.h>
#import <AsyncDisplayKit/ASCollectionView.h>
#import <AsyncDisplayKit/CoreGraphics+ASConvenience.h>
#import <AsyncDisplayKit/UICollectionViewLayout+ASConvenience.h>
struct ASRangeGeometry {
CGRect rangeBounds;
CGRect updateBounds;
};
typedef struct ASRangeGeometry ASRangeGeometry;
#pragma mark -
#pragma mark ASCollectionViewLayoutController
@interface ASCollectionViewLayoutController ()
{
@package
ASCollectionView * __weak _collectionView;
UICollectionViewLayout * __strong _collectionViewLayout;
}
@end
@implementation ASCollectionViewLayoutController
- (instancetype)initWithCollectionView:(ASCollectionView *)collectionView
{
if (!(self = [super init])) {
return nil;
}
_collectionView = collectionView;
_collectionViewLayout = [collectionView collectionViewLayout];
return self;
}
- (NSSet *)indexPathsForScrolling:(ASScrollDirection)scrollDirection rangeMode:(ASLayoutRangeMode)rangeMode rangeType:(ASLayoutRangeType)rangeType
{
ASRangeTuningParameters tuningParameters = [self tuningParametersForRangeMode:rangeMode rangeType:rangeType];
CGRect rangeBounds = [self rangeBoundsWithScrollDirection:scrollDirection rangeTuningParameters:tuningParameters];
return [self indexPathsForItemsWithinRangeBounds:rangeBounds];
}
- (void)allIndexPathsForScrolling:(ASScrollDirection)scrollDirection rangeMode:(ASLayoutRangeMode)rangeMode displaySet:(NSSet **)displaySet preloadSet:(NSSet **)preloadSet
{
if (displaySet == NULL || preloadSet == NULL) {
return;
}
ASRangeTuningParameters displayParams = [self tuningParametersForRangeMode:rangeMode rangeType:ASLayoutRangeTypeDisplay];
ASRangeTuningParameters preloadParams = [self tuningParametersForRangeMode:rangeMode rangeType:ASLayoutRangeTypePreload];
CGRect displayBounds = [self rangeBoundsWithScrollDirection:scrollDirection rangeTuningParameters:displayParams];
CGRect preloadBounds = [self rangeBoundsWithScrollDirection:scrollDirection rangeTuningParameters:preloadParams];
CGRect unionBounds = CGRectUnion(displayBounds, preloadBounds);
NSArray *layoutAttributes = [_collectionViewLayout layoutAttributesForElementsInRect:unionBounds];
NSMutableSet *display = [NSMutableSet setWithCapacity:layoutAttributes.count];
NSMutableSet *preload = [NSMutableSet setWithCapacity:layoutAttributes.count];
for (UICollectionViewLayoutAttributes *la in layoutAttributes) {
// Manually filter out elements that don't intersect the range bounds.
// See comment in indexPathsForItemsWithinRangeBounds:
// This is re-implemented here so that the iteration over layoutAttributes can be done once to check both ranges.
CGRect frame = la.frame;
BOOL intersectsDisplay = CGRectIntersectsRect(displayBounds, frame);
BOOL intersectsPreload = CGRectIntersectsRect(preloadBounds, frame);
if (intersectsDisplay == NO && intersectsPreload == NO && CATransform3DIsIdentity(la.transform3D) == YES) {
// Questionable why the element would be included here, but it doesn't belong.
continue;
}
// Avoid excessive retains and releases, as well as property calls. We know the indexPath is kept alive by la.
__unsafe_unretained NSIndexPath *indexPath = la.indexPath;
if (intersectsDisplay) {
[display addObject:indexPath];
}
if (intersectsPreload) {
[preload addObject:indexPath];
}
}
*displaySet = display;
*preloadSet = preload;
return;
}
- (NSSet *)indexPathsForItemsWithinRangeBounds:(CGRect)rangeBounds
{
NSArray *layoutAttributes = [_collectionViewLayout layoutAttributesForElementsInRect:rangeBounds];
NSMutableSet *indexPathSet = [NSMutableSet setWithCapacity:layoutAttributes.count];
for (UICollectionViewLayoutAttributes *la in layoutAttributes) {
//ASDisplayNodeAssert(![indexPathSet containsObject:la.indexPath], @"Shouldn't already contain indexPath");
// Manually filter out elements that don't intersect the range bounds.
// If a layout returns elements outside the requested rect this can be a huge problem.
// For instance in a paging flow, you may only want to preload 3 pages (one center, one on each side)
// but if flow layout includes the 4th page (which it does! as of iOS 9&10), you will preload a 4th
// page as well.
if (CATransform3DIsIdentity(la.transform3D) && CGRectIntersectsRect(la.frame, rangeBounds) == NO) {
continue;
}
[indexPathSet addObject:la.indexPath];
}
return indexPathSet;
}
- (CGRect)rangeBoundsWithScrollDirection:(ASScrollDirection)scrollDirection
rangeTuningParameters:(ASRangeTuningParameters)tuningParameters
{
CGRect rect = _collectionView.bounds;
return CGRectExpandToRangeWithScrollableDirections(rect, tuningParameters, [_collectionView scrollableDirections], scrollDirection);
}
@end