tederen_ios/smartRhino/Project/Base/SubClass/CollectionViewFlowLayout/TDHorizontalWaterFlowLayout.m

//
//  TDHorizontalWaterFlowLayout.m
//  TheoryNetwork
//
//  Created by tederen on 2019/9/24.
//  Copyright © 2019 tederen. All rights reserved.
//

#import "TDHorizontalWaterFlowLayout.h"
#import "ChannelModel.h"

@interface TDHorizontalWaterFlowLayout ()

@property (nonatomic, strong) NSMutableArray *attributesArray; //存放item的属性数组
@property (nonatomic, strong) NSMutableArray *deleteIndexPaths;
@property (nonatomic, strong) NSMutableArray *insertIndexPaths;
@end

@implementation TDHorizontalWaterFlowLayout

//lazy
- (NSMutableArray *)attributesArray {
    if (_attributesArray == nil) {
        _attributesArray = [[NSMutableArray alloc] init];
    }
    return _attributesArray;
}

- (void)prepareLayout {
    [super prepareLayout];
    [self.attributesArray removeAllObjects];
    [self computeAttributes];
}

- (nullable NSArray<__kindof UICollectionViewLayoutAttributes *> *)layoutAttributesForElementsInRect:(CGRect)rect {
    return self.attributesArray;
}

- (nullable UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath {
    NSInteger count = [self.collectionView numberOfItemsInSection:0];
    CGFloat radius = 180;
    CGFloat ox = self.collectionView.frame.size.width * 0.5;
    CGFloat oy = self.collectionView.frame.size.height * 0.5;
    CGFloat angle = 2 * M_PI * indexPath.item / count;
    CGFloat  centerX = ox + radius*cos(angle);
    CGFloat  centerY = oy  + radius*sin(angle);
    UICollectionViewLayoutAttributes *attrs = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:indexPath];
    attrs.center = CGPointMake(centerX, centerY);
    attrs.size = CGSizeMake(kGXScreenWidth / 6, 30);
    return attrs;
}

- (NSIndexPath *)targetIndexPathForInteractivelyMovingItem:(NSIndexPath *)previousIndexPath withPosition:(CGPoint)position {
    return [self.collectionView indexPathForItemAtPoint:position];
//    return [self getPath:position];
//    return [NSIndexPath indexPathForRow:9 inSection:0];
}

- (NSIndexPath*)getPath:(CGPoint)position {
    for (int i = 0; i < self.attributesArray.count; i++) {
        UICollectionViewLayoutAttributes *attr = [self.attributesArray objectAtIndex:i];
        if (CGRectContainsPoint(attr.frame, position)) {
            return attr.indexPath;
        }
    }
    return nil;
}

- (CGSize)collectionViewContentSize {
    return CGSizeMake(kGXScreenWidth / 6, 30);
}

- (void)prepareForCollectionViewUpdates:(NSArray *)updateItems {
    [super prepareForCollectionViewUpdates:updateItems];
    self.deleteIndexPaths = @[].mutableCopy;
    self.insertIndexPaths = @[].mutableCopy;
    
    for (UICollectionViewUpdateItem *update in updateItems) {
        if (update.updateAction == UICollectionUpdateActionDelete) {
            [self.deleteIndexPaths addObject:update.indexPathBeforeUpdate];
        }else if (update.updateAction == UICollectionUpdateActionInsert) {
            [self.insertIndexPaths addObject:update.indexPathAfterUpdate];
        }
    }
}

- (void)finalizeCollectionViewUpdates {
    [super finalizeCollectionViewUpdates];
    [self.deleteIndexPaths removeAllObjects];
    [self.insertIndexPaths removeAllObjects];
}

//计算每个单元格的属性
- (void)computeAttributes {
    //存贮每行个数
    NSMutableArray *lineNum = [[NSMutableArray alloc] init];
    [lineNum insertObject:@0 atIndex:0];
    //储存每行宽度
    NSMutableArray *lineWidth = [[NSMutableArray alloc] init];
    [lineWidth insertObject:@10.0 atIndex:0];
    //当前添加的行号
    int index = 0;
    
    //记录当前高度
    CGFloat verticalHeight = 0;
    CGFloat cellHeight = 42;
    CGFloat headerHeight = 40;
    CGFloat cellSpaceH = 10;
    CGFloat cellSpaceV = 13;
    CGFloat topMarginHeader = 0; // header 的 top
    CGFloat topMarginCell = 0; //  cell  的 top
    for (int k = 0; k < self.dataList.count; k ++) {
        NSArray *array = self.dataList[k];
        //添加一个组头
        if (k == 0) {
             topMarginHeader =  headerHeight * k + index * cellHeight  + index * cellSpaceV;
        }else{
             topMarginHeader =  headerHeight * k + (index-1) * cellHeight  + (index-1) * cellSpaceV;
        }
       

        UICollectionViewLayoutAttributes *headerAttributes = [UICollectionViewLayoutAttributes layoutAttributesForSupplementaryViewOfKind:UICollectionElementKindSectionHeader withIndexPath:[NSIndexPath indexPathForItem:0 inSection:k]];
        headerAttributes .frame = CGRectMake(0, topMarginHeader, kGXScreenWidth, headerHeight);
        [self.attributesArray addObject:headerAttributes];
        //相当于添加了一行
        [lineNum addObject:@1];
        [lineWidth addObject:@(kGXScreenWidth)];
        //添加组头，不需要计算组头的高度，单元格会自动适配到组头下面
    
        index ++;
        CGFloat X ;
      
        topMarginCell += topMarginHeader + headerHeight - 15;
        CGFloat Y = topMarginCell;
        for (int i = 0; i < array.count; i ++) {
            UICollectionViewLayoutAttributes *attributes = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:[NSIndexPath indexPathForItem:i inSection:k]];
            //计算宽度
            CGFloat width = 80;
            ChannelModel *model = array[i];
            if (model.Name.length <= 4) {}
            else{
                 width = [self computerWidthWithString:model.Name];
            }
            //计算位置
//            CGFloat X ;
//            CGFloat Y = topMarginCell;
            CGFloat indexWidth = [lineWidth[index] floatValue];  //当前行宽

            if ((indexWidth + width + cellSpaceH) <= self.collectionView.bounds.size.width) {
                //如果添加一个单元格，此行宽度还小于控件宽度，那就添加到此行
                X = [lineWidth[index] floatValue];
                Y = topMarginCell ;
                
                lineNum[index] = @([lineNum[index] intValue] + 1);
                lineWidth[index] = @([lineWidth[index] floatValue] + width + cellSpaceH);
            }else{
                //如果添加一个单元格，此行宽度大于控件宽度，那就另起一行
                index ++;
                topMarginCell += cellHeight + cellSpaceV;
                Y = topMarginCell;
                X = 12;
                
                [lineNum addObject:@(1)];
                [lineWidth addObject:@(width + cellSpaceH + cellSpaceH)];
            }
            attributes.frame = CGRectMake(X, Y-headerHeight, width, cellHeight);
            [self.attributesArray addObject:attributes];
            self.itemSize = CGSizeMake(width, cellHeight);
            
        }
        topMarginCell = 0;
//        // for (int i = 0; i < array.count; i ++) {
//                   UICollectionViewLayoutAttributes *attributes = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:[NSIndexPath indexPathForItem:i inSection:k]];
//                   //计算宽度
//                   CGFloat width = 80;
//                   ChannelModel *model = array[i];
//                   if (model.channelName.length <= 4) {}
//                   else{
//                        width = [self computerWidthWithString:model.channelName];
//                   }
//                   //计算位置
//                   CGFloat X ;
//                   CGFloat Y = topMarginCell;
//                   CGFloat indexWidth = [lineWidth[index] floatValue];  //当前行宽
//                   if ((indexWidth + width + cellSpaceH) <= self.collectionView.bounds.size.width) {
//                       //如果添加一个单元格，此行宽度还小于控件宽度，那就添加到此行
//                       X = [lineWidth[index] floatValue];
//                       Y = verticalHeight;
//                       lineNum[index] = @([lineNum[index] intValue] + 1);
//                       lineWidth[index] = @([lineWidth[index] floatValue] + width + cellSpaceH);
//                   }else{
//                       //如果添加一个单元格，此行宽度大于控件宽度，那就另起一行
//                       index ++;
//                       verticalHeight += cellHeight + cellSpaceV;
//                       Y = verticalHeight;
//                       X = cellSpaceH;
//                       [lineNum addObject:@(1)];
//                       [lineWidth addObject:@(width + cellSpaceH + cellSpaceH)];
//                   }
//                   attributes.frame = CGRectMake(X, Y-headerHeight, width, cellHeight);
//                   [self.attributesArray addObject:attributes];
//                   self.itemSize = CGSizeMake(width, cellHeight);
//
//               }
    }
}

//计算单元格宽度
- (CGFloat)computerWidthWithString:(NSString *)string {
    CGRect rect = [string boundingRectWithSize:CGSizeMake(1000, 9999) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:14]} context:nil];
    return rect.size.width + 20;
}

////计算最宽行
//- (int)computerMAXlineWithArray:(NSArray *)array {
//    int maxIndex = 0;
//    CGFloat maxfloat = 0;
//    for (int i=0; i<array.count; i++) {
//        CGFloat ifloat = [array[i] floatValue];
//        if (ifloat > maxfloat) {
//            maxIndex = i;
//            maxfloat = ifloat;
//        }
//    }
//    return maxIndex;
//}

@end