//
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// CWFlowLayout.m
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// CWCarousel
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//
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// Created by WangChen on 2018/4/3.
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// Copyright © 2018年 ChenWang. All rights reserved.
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//
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#import "CWFlowLayout.h"
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@interface CWFlowLayout () {
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}
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/**
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默认轮播图宽度
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*/
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@property (nonatomic, assign) CGFloat defaultItemWidth;
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@property (nonatomic, assign) CGFloat factItemSpace;
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@end
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@implementation CWFlowLayout
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- (instancetype)initWithStyle:(CWCarouselStyle)style {
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if(self = [super init]) {
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self.style = style;
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[self initial];
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}
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return self;
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}
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- (void)dealloc {
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NSLog(@"%s", __func__);
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}
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- (void)initial {
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self.itemSpace_H = 1;
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self.itemSpace_V = 1;
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self.minScale = 0.8;
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self.maxScale = 1.2;
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}
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- (void)prepareLayout {
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switch (self.style) {
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case CWCarouselStyle_Normal:
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{
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CGFloat width = CGRectGetWidth(self.collectionView.frame);
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CGFloat height = CGRectGetHeight(self.collectionView.frame);
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self.itemWidth = width;
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self.itemSize = CGSizeMake(width, height);
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self.minimumLineSpacing = self.itemSpace_H;
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self.scrollDirection = UICollectionViewScrollDirectionHorizontal;
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}
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break;
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case CWCarouselStyle_H_1: {
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CGFloat width = self.itemWidth == 0 ? self.defaultItemWidth : self.itemWidth;
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self.itemWidth = width;
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CGFloat height = CGRectGetHeight(self.collectionView.frame);
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self.itemSize = CGSizeMake(width, height);
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self.scrollDirection = UICollectionViewScrollDirectionHorizontal;
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self.minimumLineSpacing = self.itemSpace_H;
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break;
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}
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case CWCarouselStyle_H_2:
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case CWCarouselStyle_H_3: {
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CGFloat width = self.itemWidth == 0 ? self.defaultItemWidth : self.itemWidth;
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self.itemWidth = width;
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CGFloat height = CGRectGetHeight(self.collectionView.frame);
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self.itemSize = CGSizeMake(width, self.style == CWCarouselStyle_H_3 ? height / self.maxScale : height);
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self.scrollDirection = UICollectionViewScrollDirectionHorizontal;
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self.factItemSpace = 0;
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if(width * (1 - self.minScale) * 0.5 < self.itemSpace_H) {
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self.factItemSpace = self.itemSpace_H - width * (1 - self.minScale) * 0.5;
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}
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self.minimumLineSpacing = self.factItemSpace;
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}
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break;
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default:
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break;
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}
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}
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- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds {
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return YES;
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}
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- (NSArray<UICollectionViewLayoutAttributes *> *)layoutAttributesForElementsInRect:(CGRect)rect {
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if(self.style != CWCarouselStyle_Normal &&
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self.style != CWCarouselStyle_Unknow &&
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self.style != CWCarouselStyle_H_1) {
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NSArray<UICollectionViewLayoutAttributes *> *arr = [[NSArray alloc] initWithArray:[super layoutAttributesForElementsInRect:rect] copyItems:YES];
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CGFloat centerX = self.collectionView.contentOffset.x + CGRectGetWidth(self.collectionView.frame) * 0.5;
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CGFloat width = self.itemWidth;
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__block CGFloat maxScale = 0;
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__block UICollectionViewLayoutAttributes *attri = nil;
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[arr enumerateObjectsUsingBlock:^(UICollectionViewLayoutAttributes * _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
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CGFloat space = ABS(obj.center.x - centerX);
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if(space >= 0) {
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CGFloat scale = 1;
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if (self.style == CWCarouselStyle_H_2) {
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scale = (self.minScale - 1) / (self.itemWidth + self.factItemSpace) * space + 1;
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}else {
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scale = -((self.maxScale - 1) / width) * space + self.maxScale;
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}
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obj.transform = CGAffineTransformMakeScale(scale, scale);
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if(maxScale < scale) {
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maxScale = scale;
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attri = obj;
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}
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}
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obj.zIndex = 0;
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}];
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if (attri) {
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attri.zIndex = 1;
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}
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return arr;
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}else {
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return [super layoutAttributesForElementsInRect:rect];
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}
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}
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- (CGPoint)targetContentOffsetForProposedContentOffset:(CGPoint)proposedContentOffset withScrollingVelocity:(CGPoint)velocity {
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// CGRect rect;
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// _adjustIndexPath = nil;
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// rect.origin.x = proposedContentOffset.x;
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// rect.origin.y = 0;
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// rect.size.width = CGRectGetWidth(self.collectionView.frame);
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// rect.size.height = CGRectGetHeight(self.collectionView.frame);
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//
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// CGFloat centerX = proposedContentOffset.x + CGRectGetWidth(self.collectionView.frame) * 0.5;
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// NSArray <UICollectionViewLayoutAttributes *> *tempArr = [super layoutAttributesForElementsInRect:rect];
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// __block CGFloat minSpace = MAXFLOAT;
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// __block UICollectionViewLayoutAttributes *attributes = nil;
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// [tempArr enumerateObjectsUsingBlock:^(UICollectionViewLayoutAttributes * _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
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// obj.zIndex = 0;
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// if(ABS(minSpace) > ABS(obj.center.x - centerX)) {
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// minSpace = obj.center.x - centerX;
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// attributes = obj;
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// }
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// }];
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// attributes.zIndex = 1;
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// _currentAttri = attributes;
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// if(velocity.x == 0) {
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// proposedContentOffset.x += minSpace;
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// _adjustIndexPath = nil;
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// }else if(attributes) {
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// if(ABS(minSpace) >= attributes.size.width * 0.15) {
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// NSInteger der = attributes.indexPath.row;
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// if(velocity.x > 0) {
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// der = (minSpace < 0 && velocity.x > 0) ? 1 : 0;
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// }else {
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// der = (minSpace > 0 && velocity.x < 0) ? -1 : 0;
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// }
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// _adjustIndexPath = [NSIndexPath indexPathForRow:attributes.indexPath.row + der inSection:attributes.indexPath.section];
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// }else {
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// _adjustIndexPath = attributes.indexPath;
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// }
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// }
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return proposedContentOffset;
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}
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#pragma mark - Property
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- (CGFloat)defaultItemWidth {
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switch (self.style) {
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case CWCarouselStyle_Unknow:
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case CWCarouselStyle_Normal:
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return self.collectionView.frame.size.width;
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break;
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case CWCarouselStyle_H_1:
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case CWCarouselStyle_H_2:
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case CWCarouselStyle_H_3:
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return self.collectionView.frame.size.width * 0.75;
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break;
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default:
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break;
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}
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}
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- (void)setMaxScale:(CGFloat)maxScale {
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_maxScale = maxScale;
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if(maxScale < 1) {
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_maxScale = 1;
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}
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}
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- (void)setMinScale:(CGFloat)minScale {
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_minScale = minScale;
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if(minScale < 0) {
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_minScale = 0.1;
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}
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if (minScale >= 1) {
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_minScale = 1;
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}
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}
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@end
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