//
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// HXTagCollectionViewFlowLayout.m
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// 黄轩 https://github.com/huangxuan518
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//
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// Created by 黄轩 on 16/1/13.
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// Copyright © 2015年 IT小子. All rights reserved.
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//
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#import "HXTagCollectionViewFlowLayout.h"
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@interface HXTagCollectionViewFlowLayout()
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@property (nonatomic, weak) id<UICollectionViewDelegateFlowLayout> delegate;
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@property (nonatomic, strong) NSMutableArray *itemAttributes;
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@property (nonatomic, assign) CGFloat contentWidth;//滑动宽度 水平
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@property (nonatomic, assign) CGFloat contentHeight;//滑动高度 垂直
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@end
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@implementation HXTagCollectionViewFlowLayout
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- (instancetype)init
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{
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self = [super init];
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if (self) {
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self.scrollDirection = UICollectionViewScrollDirectionHorizontal;
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self.itemSize = CGSizeMake(100.0f, 34.0f);
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self.minimumInteritemSpacing = 10.0f;
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self.minimumLineSpacing = 10.0f;
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self.sectionInset = UIEdgeInsetsMake(10.0f, 10.0f, 10.0f, 10.0f);
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}
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return self;
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}
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#pragma mark -
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- (void)prepareLayout
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{
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[super prepareLayout];
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[self.itemAttributes removeAllObjects];
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//滑动的宽度 = 左边
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self.contentWidth = self.sectionInset.left;
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//cell的高度 = 顶部 + 高度
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self.contentHeight = self.sectionInset.top + self.itemSize.height;
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CGFloat originX = self.sectionInset.left;
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CGFloat originY = self.sectionInset.top;
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NSInteger itemCount = [self.collectionView numberOfItemsInSection:0];
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for (NSInteger i = 0; i < itemCount; i++) {
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NSIndexPath *indexPath = [NSIndexPath indexPathForItem:i inSection:0];
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CGSize itemSize = [self itemSizeForIndexPath:indexPath];
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if (self.scrollDirection == UICollectionViewScrollDirectionVertical) {
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//垂直滚动
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//当前CollectionViewCell的起点 + 当前CollectionViewCell的宽度 + 当前CollectionView距离右侧的间隔 > collectionView的宽度
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if ((originX + itemSize.width + self.sectionInset.right) > self.collectionView.frame.size.width) {
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originX = self.sectionInset.left;
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originY += itemSize.height + self.minimumLineSpacing;
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self.contentHeight += itemSize.height + self.minimumLineSpacing;
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}
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} else {
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self.contentWidth += itemSize.width + self.minimumInteritemSpacing;
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}
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UICollectionViewLayoutAttributes *attributes = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:indexPath];
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attributes.frame = CGRectMake(originX, originY, itemSize.width, itemSize.height);
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[self.itemAttributes addObject:attributes];
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originX += itemSize.width + self.minimumInteritemSpacing;
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}
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self.contentHeight += self.sectionInset.bottom;
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}
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- (CGSize)collectionViewContentSize
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{
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if (self.scrollDirection == UICollectionViewScrollDirectionVertical) {
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return CGSizeMake(self.collectionView.frame.size.width, self.contentHeight);
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} else {
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return CGSizeMake(self.contentWidth,self.collectionView.frame.size.height);
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}
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}
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- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect
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{
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return self.itemAttributes;
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}
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- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds
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{
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CGRect oldBounds = self.collectionView.bounds;
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if (CGRectGetWidth(newBounds) != CGRectGetWidth(oldBounds)) {
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return YES;
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}
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return NO;
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}
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#pragma mark -
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- (id<UICollectionViewDelegateFlowLayout>)delegate
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{
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if (_delegate == nil) {
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_delegate = (id<UICollectionViewDelegateFlowLayout>)self.collectionView.delegate;
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}
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return _delegate;
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}
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- (CGSize)itemSizeForIndexPath:(NSIndexPath *)indexPath
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{
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if ([self.delegate respondsToSelector:@selector(collectionView:layout:sizeForItemAtIndexPath:)]) {
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self.itemSize = [self.delegate collectionView:self.collectionView layout:self sizeForItemAtIndexPath:indexPath];
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}
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return self.itemSize;
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}
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#pragma mark - 懒加载
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//UICollectionViewLayoutAttributes数组
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- (NSMutableArray *)itemAttributes {
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if (!_itemAttributes) {
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_itemAttributes = [NSMutableArray array];
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}
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return _itemAttributes;
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}
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@end
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