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Do not add layout attributes for header or footer if size is zero #24

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Do not add layout attributes for header or footer if size is zero #24

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0ccc0d5
Do not add layout attributes for header or footer if size is zero
haitaoli Apr 8, 2014
6c5300c
Get number of sections/items directly from datasource. UICollectionVi…
haitaoli Apr 9, 2014
7f643da
Fix layout with empty sections
haitaoli Apr 9, 2014
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28 changes: 19 additions & 9 deletions NHBalancedFlowLayout/NHBalancedFlowLayout.m
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Original file line number Diff line number Diff line change
Expand Up @@ -104,10 +104,10 @@ - (void)prepareLayout
[self clearItemFrames];

// create new item frame sections
_numberOfItemFrameSections = [self.collectionView numberOfSections];
_numberOfItemFrameSections = [self.collectionView.dataSource numberOfSectionsInCollectionView:self.collectionView];
_itemFrameSections = (CGRect **)malloc(sizeof(CGRect *) * _numberOfItemFrameSections);
for (int section = 0; section < [self.collectionView numberOfSections]; section++) {

for (int section = 0; section < _numberOfItemFrameSections; section++) {
// add new item frames array to sections array
NSInteger numberOfItemsInSections = [self.collectionView numberOfItemsInSection:section];
CGRect *itemFrames = (CGRect *)malloc(sizeof(CGRect) * numberOfItemsInSections);
Expand Down Expand Up @@ -167,14 +167,16 @@ - (CGSize)collectionViewContentSize
- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect
{
NSMutableArray *layoutAttributes = [NSMutableArray array];

for (NSInteger section = 0, n = [self.collectionView numberOfSections]; section < n; section++) {
NSInteger n = [self.collectionView.dataSource numberOfSectionsInCollectionView:self.collectionView];

for (NSInteger section = 0; section < n; section++) {
NSIndexPath *sectionIndexPath = [NSIndexPath indexPathForItem:0 inSection:section];

UICollectionViewLayoutAttributes *headerAttributes = [self layoutAttributesForSupplementaryViewOfKind:UICollectionElementKindSectionHeader
atIndexPath:sectionIndexPath];

if (! CGSizeEqualToSize(headerAttributes.frame.size, CGSizeZero) && CGRectIntersectsRect(headerAttributes.frame, rect)) {
CGSize size = headerAttributes.frame.size;
if (size.height != 0 && size.width != 0 && CGRectIntersectsRect(headerAttributes.frame, rect)) {
[layoutAttributes addObject:headerAttributes];
}

Expand All @@ -188,8 +190,8 @@ - (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect

UICollectionViewLayoutAttributes *footerAttributes = [self layoutAttributesForSupplementaryViewOfKind:UICollectionElementKindSectionFooter
atIndexPath:sectionIndexPath];

if (! CGSizeEqualToSize(footerAttributes.frame.size, CGSizeZero) && CGRectIntersectsRect(footerAttributes.frame, rect)) {
size = footerAttributes.frame.size;
if (size.width != 0 && size.height != 0 && CGRectIntersectsRect(footerAttributes.frame, rect)) {
[layoutAttributes addObject:footerAttributes];
}
}
Expand Down Expand Up @@ -253,7 +255,9 @@ - (CGRect)footerFrameForSection:(NSInteger)section
- (CGFloat)totalItemSizeForSection:(NSInteger)section preferredRowSize:(CGFloat)preferredRowSize
{
CGFloat totalItemSize = 0;
for (NSInteger i = 0, n = [self.collectionView numberOfItemsInSection:section]; i < n; i++) {
NSUInteger n = [self.collectionView.dataSource collectionView:self.collectionView numberOfItemsInSection:section];

for (NSInteger i = 0; i < n; i++) {
CGSize preferredSize = [self.delegate collectionView:self.collectionView layout:self preferredSizeForItemAtIndexPath:[NSIndexPath indexPathForItem:i inSection:section]];

if (self.scrollDirection == UICollectionViewScrollDirectionVertical) {
Expand Down Expand Up @@ -282,6 +286,12 @@ - (NSArray *)weightsForItemsInSection:(NSInteger)section
- (void)setFrames:(CGRect *)frames forItemsInSection:(NSInteger)section numberOfRows:(NSUInteger)numberOfRows sectionOffset:(CGPoint)sectionOffset sectionSize:(CGSize *)sectionSize
{
NSArray *weights = [self weightsForItemsInSection:section];

if (weights.count == 0) {
*sectionSize = CGSizeZero;
return;
}

NSArray *partition = [NHLinearPartition linearPartitionForSequence:weights numberOfPartitions:numberOfRows];

int i = 0;
Expand Down