mirror of
https://github.com/Instagram/IGListKit
synced 2026-05-06 15:08:50 +00:00
edc38c77fe
Summary: Issue fixed: #655 - [x] All tests pass. Demo project builds and runs. - [ ] I added tests, an experiment, or detailed why my change isn't tested. - [ ] I added an entry to the `CHANGELOG.md` for any breaking changes, enhancements, or bug fixes. - [x] I have reviewed the [contributing guide](https://github.com/Instagram/IGListKit/blob/master/.github/CONTRIBUTING.md) I've also addressed a few cases where there was no empty line between the `param`s and `return`. Closes https://github.com/Instagram/IGListKit/pull/665 Differential Revision: D4906215 Pulled By: jessesquires fbshipit-source-id: 5693c85eb548644b0b0e2571eea8ff4d9f706b12
107 lines
4.4 KiB
Objective-C
107 lines
4.4 KiB
Objective-C
/**
|
|
* Copyright (c) 2016-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 <UIKit/UIKit.h>
|
|
|
|
#import <IGListKit/IGListMacros.h>
|
|
|
|
NS_ASSUME_NONNULL_BEGIN
|
|
|
|
/**
|
|
This UICollectionViewLayout subclass is for vertically-scrolling lists of data with variable widths and heights. It
|
|
supports an infinite number of sections and items. All work is done on the main thread, and while extremely efficient,
|
|
care must be taken not to stall the main thread in sizing delegate methods.
|
|
|
|
This layout piggybacks on the mechanics of UICollectionViewFlowLayout in that:
|
|
|
|
- Your UICollectionView data source must also conform to UICollectionViewDelegateFlowLayout
|
|
- Header support given via UICollectionElementKindSectionHeader
|
|
|
|
All UICollectionViewDelegateFlowLayout methods are required and used by this layout:
|
|
|
|
```
|
|
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath;
|
|
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section;
|
|
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section;
|
|
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section;
|
|
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section;
|
|
```
|
|
|
|
Sections and items are put into the same horizontal row until the max-x position of an item extends beyond the width
|
|
of the collection view. When that happens, the item is "newlined" to the next row. The y position of that row is
|
|
determined by the maximum height (including section insets) of the section/item of the previous row.
|
|
|
|
Ex. of a section (2,0) with a large width causing a newline.
|
|
```
|
|
|[ 0,0 ][ 1,0 ] |
|
|
|[ 2,0 ]|
|
|
```
|
|
|
|
A section with a non-zero height header will always cause that section to newline. Headers are always stretched to the
|
|
width of the collection view, pinched with the section insets.
|
|
|
|
Ex. of a section (2,0) with a header inset on the left/right.
|
|
```
|
|
|[ 0,0 ][ 1,0 ] |
|
|
| >======header=======< |
|
|
| [ 2,0 ] |
|
|
```
|
|
|
|
Section insets apply to items in the section no matter if they begin on a new row or are on the same row as a previous
|
|
section.
|
|
|
|
Ex. of a section (2) with multiple items and a left inset.
|
|
```
|
|
|[ 0,0 ][ 1,0 ] >[ 2,0 ]|
|
|
| >[ 2,1 ][ 2,2 ][ 2,3 ]|
|
|
```
|
|
|
|
Interitem spacing applies to items and sections within the same row. Line spacing only applies to items within the same
|
|
section.
|
|
|
|
Please see the unit tests for more configuration examples and expected output.
|
|
*/
|
|
|
|
@interface IGListCollectionViewLayout : UICollectionViewLayout
|
|
|
|
/**
|
|
Set this to adjust the offset of the sticky headers. Can be used to change the sticky header position as UI like the
|
|
navigation bar is scrolled offscreen. Changing this to the height of the navigation bar will give the effect of the
|
|
headers sticking to the nav as it is collapsed.
|
|
|
|
@discussion Changing the value on this method will invalidate the layout every time.
|
|
*/
|
|
@property (nonatomic, assign) CGFloat stickyHeaderOriginYAdjustment;
|
|
|
|
/**
|
|
Create and return a new collection view layout.
|
|
|
|
@param stickyHeaders Set to `YES` to stick section headers to the top of the bounds while scrolling.
|
|
@param topContentInset The top content inset used to offset the sticky headers. Ignored if stickyHeaders is `NO`.
|
|
@param stretchToEdge Specifies whether to stretch width of last item to right edge when distance from last item to right edge < epsilon(1)
|
|
|
|
@return A new collection view layout.
|
|
*/
|
|
- (instancetype)initWithStickyHeaders:(BOOL)stickyHeaders
|
|
topContentInset:(CGFloat)topContentInset
|
|
stretchToEdge:(BOOL)stretchToEdge NS_DESIGNATED_INITIALIZER;
|
|
|
|
/**
|
|
:nodoc:
|
|
*/
|
|
- (instancetype)init NS_UNAVAILABLE;
|
|
|
|
/**
|
|
:nodoc:
|
|
*/
|
|
+ (instancetype)new NS_UNAVAILABLE;
|
|
|
|
@end
|
|
|
|
NS_ASSUME_NONNULL_END
|