//
// ZSWaterLayout.h
// 02-瀑布流
//
// Created by ZhuiYi on 14/12/27.
// Copyright (c) 2014年 ZhuiYi. All rights reserved.
//
#import <UIKit/UIKit.h>
@class ZSWaterLayout;
@protocol ZSWaterLayoutDelegate <NSObject>
/**
* 返回四周的间距(默认为10)
*
* @param waterLayout 布局
*
* @return 四周的间距
*/
- (UIEdgeInsets)insetsInWaterLayout:(ZSWaterLayout *)waterLayout;
/**
* Supplementary View的四周间距
*
* @param elementKind Supplementary View 类型
* @param indexPath IndexPath
*
* @return 四周间距
*/
- (UIEdgeInsets)insetsOfSupplementaryViewOfKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath;
/**
* 返回有多少列(默认为3)
*
* @param waterLayout 布局
*
* @return 有多少列
*/
- (NSInteger)columNumberInwaterLayout:(ZSWaterLayout *)waterLayout;
/**
* 返回每列的间距(默认为10)
*
* @param waterLayout 布局
*
* @return 每列的间距
*/
- (CGFloat)columInsetInWaterLayout:(ZSWaterLayout *)waterLayout;
/**
* 返回每行的间距(默认为10)
*
* @param waterLayout 布局
*
* @return 每行的间距
*/
- (CGFloat)rowInsetInWaterLayout:(ZSWaterLayout *)waterLayout;
- (CGFloat)supplementaryViewHeightOfKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath;
@required
/**
* 返回每个cell的高度
*
* @param waterLayout 布局
* @param indexPath cell的位置
* @param width cell的宽度
*
* @return 根据宽度来算出cell的高度
*/
- (CGFloat)waterLayout:(ZSWaterLayout *)waterLayout heightForItemAtIndexPath:(NSIndexPath *)indexPath width:(CGFloat)width;
@end
@interface ZSWaterLayout : UICollectionViewLayout
@property (nonatomic, weak) id<ZSWaterLayoutDelegate> delegate;
@end
#import "CommunityArticleWaterLayout.h"
// 默认每行最多显示多少列
static NSInteger defaultMaxCol = 3;
// 默认每行的间距
static CGFloat defaultRowInset = 10;
// 默认每列的间距
static CGFloat defaultColInset = 10;
// 默认的四周的间距
static CGFloat defaultInset = 10;
@interface ZSWaterLayout ()
// 最大Y值的数组,用于确定cell应该放在哪一列
@property (nonatomic, strong) NSMutableArray *maxYArray;
// 布局的数组
@property (nonatomic, strong) NSMutableArray *attributesArray;
@end
@implementation ZSWaterLayout
#pragma mark - 懒加载
- (NSMutableArray *)maxYArray
{
if (!_maxYArray)
{
_maxYArray = [NSMutableArray array];
}
return _maxYArray;
}
- (NSArray *)attributesArray
{
if (!_attributesArray) {
_attributesArray = [[NSMutableArray alloc] init];
}
return _attributesArray;
}
#pragma mark - 有新的可见范围时就刷新
- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds
{
return YES;
}
#pragma mark - 这个方法比下面的方法调用少,计算就放在这个方法中
- (void)prepareLayout
{
[self.maxYArray removeAllObjects];
[self.attributesArray removeAllObjects];
for (NSInteger i = 0; i < [self getColumNumber]; i ++)
{
self.maxYArray[i] = @0.0;
}
NSInteger count = [self.collectionView numberOfItemsInSection:0];
for (NSInteger i = 0; i < count; i ++)
{
NSIndexPath *indexPath = [NSIndexPath indexPathForItem:i inSection:0];
UICollectionViewLayoutAttributes *attrs = [self layoutAttributesForItemAtIndexPath:indexPath];
[self.attributesArray addObject:attrs];
}
}
#pragma mark - 可见范围内的cell布局
- (NSArray *)layoutAttributesForElementsInRect:(CGRect)rect
{
NSMutableArray *retArray = [NSMutableArray array];
for (UICollectionViewLayoutAttributes *att in _attributesArray) {
if (CGRectIntersectsRect(att.frame, rect)) {
[retArray addObject:att];
}
}
if ([self.delegate respondsToSelector:@selector(supplementaryViewHeightOfKind:atIndexPath:)]) {
CGFloat height = [self.delegate supplementaryViewHeightOfKind:UICollectionElementKindSectionHeader atIndexPath:[NSIndexPath indexPathForItem:1 inSection:0]];
if (([self getInsets].top + height) >= rect.origin.y) {
[retArray addObject:[self layoutAttributesForSupplementaryViewOfKind:UICollectionElementKindSectionHeader atIndexPath:[NSIndexPath indexPathForItem:1 inSection:0]]];
}
}
return retArray;
// return self.attributesArray;
}
#pragma mark - 对应位置的cell的布局
- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath
{
// 四周的间距
UIEdgeInsets inset = [self getInsets];
// 每列的间距
CGFloat colInset = [self getColumInset];
// 每行的间距
CGFloat rowInset = [self getRowInset];
// 总列数
NSInteger maxCol = [self getColumNumber];
CGFloat supplementaryHeight = [self getSupplementaryViewHeightOfKind:UICollectionElementKindSectionHeader atIndexPath:indexPath];
// collection的宽度
CGFloat collectionWidth = self.collectionView.bounds.size.width;
// 每个cell的宽高
CGFloat cellWidth = (collectionWidth - inset.left - inset.right - (maxCol - 1) * colInset) / maxCol;
CGFloat cellHeight = [self.delegate waterLayout:self heightForItemAtIndexPath:indexPath width:cellWidth];
// 最小的Y值
CGFloat minMaxY = [self.maxYArray[0] doubleValue];
// 最小Y值的列号
NSInteger minCol = 0;
for (int i = 0; i < maxCol; i ++) {
CGFloat maxY = [self.maxYArray[i] doubleValue];
if (maxY < minMaxY) {
minMaxY = maxY;
minCol = i;
}
}
CGFloat cellX = inset.left + (colInset + cellWidth) * minCol;
UIEdgeInsets supplementaryInsets = [self getSupplementaryViewInsetsOfKind:UICollectionElementKindSectionHeader atIndexPath:indexPath];
CGFloat cellY = minMaxY == 0 ? (minMaxY + inset.top + supplementaryInsets.top + supplementaryHeight):(minMaxY+rowInset);
UICollectionViewLayoutAttributes *attribute = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:indexPath];
attribute.frame = CGRectMake(cellX, cellY, cellWidth, cellHeight);
// 刷新Y值的高度
self.maxYArray[minCol] = @(CGRectGetMaxY(attribute.frame));
return attribute;
}
- (UICollectionViewLayoutAttributes *)layoutAttributesForSupplementaryViewOfKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath {
UICollectionViewLayoutAttributes *attribute = [UICollectionViewLayoutAttributes layoutAttributesForSupplementaryViewOfKind:elementKind withIndexPath:indexPath];
if ([elementKind isEqualToString:UICollectionElementKindSectionFooter]) {
attribute.frame = CGRectMake(0, 0, 0, 0);
return attribute;
}
if ([self getSupplementaryViewHeightOfKind:elementKind atIndexPath:indexPath] == 0) {
attribute.frame = CGRectMake(0, 0, 0, 0);
}
else {
UIEdgeInsets insets = [self getSupplementaryViewInsetsOfKind:elementKind atIndexPath:indexPath];
attribute.frame = CGRectMake(insets.left, insets.top, self.collectionView.bounds.size.width - insets.left - insets.right, [self getSupplementaryViewHeightOfKind:elementKind atIndexPath:(NSIndexPath *)indexPath]);
}
return attribute;
}
#pragma mark - cellectionView的滚动范围
- (CGSize)collectionViewContentSize
{
if (self.maxYArray.count)
{
// 最大的Y值
CGFloat maxMaxY = [self.maxYArray[0] doubleValue];
for (int i = 0; i < [self getColumNumber]; i ++)
{
CGFloat maxY = [self.maxYArray[i] doubleValue];
if (maxY > maxMaxY)
{
maxMaxY = maxY;
}
}
return CGSizeMake(self.collectionView.bounds.size.width, maxMaxY+[self getInsets].bottom);
}
return CGSizeMake(0, 0);
}
#pragma mark - 根据代理得到列数
- (NSInteger)getColumNumber
{
if ([self.delegate respondsToSelector:@selector(columNumberInwaterLayout:)])
{
return [self.delegate columNumberInwaterLayout:self];
}
return defaultMaxCol;
}
#pragma mark - 根据代理得到四周的间距
- (UIEdgeInsets)getInsets
{
if ([self.delegate respondsToSelector:@selector(insetsInWaterLayout:)])
{
return [self.delegate insetsInWaterLayout:self];
}
return UIEdgeInsetsMake(defaultInset, defaultInset, defaultInset, defaultInset);
}
- (UIEdgeInsets)getSupplementaryViewInsetsOfKind:(NSString*)elementKind atIndexPath:(NSIndexPath *)indexPath {
if ([self.delegate respondsToSelector:@selector(insetsOfSupplementaryViewOfKind:atIndexPath:)]) {
return [self.delegate insetsOfSupplementaryViewOfKind:elementKind atIndexPath:indexPath];
}
return UIEdgeInsetsMake(0, 0, 0, 0);
}
#pragma mark - 根据代理得到每列之间的间距
- (CGFloat)getColumInset
{
if ([self.delegate respondsToSelector:@selector(columInsetInWaterLayout:)])
{
return [self.delegate columInsetInWaterLayout:self];
}
return defaultColInset;
}
#pragma mark - 根据代理得到每行之间的间距
- (CGFloat)getRowInset
{
if ([self.delegate respondsToSelector:@selector(rowInsetInWaterLayout:)])
{
return [self.delegate rowInsetInWaterLayout:self];
}
return defaultRowInset;
}
- (CGFloat) getSupplementaryViewHeightOfKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath {
if ([self.delegate respondsToSelector:@selector(supplementaryViewHeightOfKind:atIndexPath:)]) {
return [self.delegate supplementaryViewHeightOfKind:elementKind atIndexPath:indexPath];
}
return 0;
}
@end
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