cdts/xdts-ios 3/TreeHole/CYHResetCode/CYH/QMUIKit/QMUIComponents/QMUIFloatLayoutView.m

/**
 * Tencent is pleased to support the open source community by making QMUI_iOS available.
 * Copyright (C) 2016-2021 THL A29 Limited, a Tencent company. All rights reserved.
 * Licensed under the MIT License (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at
 * http://opensource.org/licenses/MIT
 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
 */

//
//  QMUIFloatLayoutView.m
//  qmui
//
//  Created by QMUI Team on 2016/11/10.
//

#import "QMUIFloatLayoutView.h"
#import "QMUICore.h"

#define ValueSwitchAlignLeftOrRight(valueLeft, valueRight) ([self shouldAlignRight] ? valueRight : valueLeft)

const CGSize QMUIFloatLayoutViewAutomaticalMaximumItemSize = {-1, -1};

@implementation QMUIFloatLayoutView

- (instancetype)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        [self didInitialize];
    }
    return self;
}

- (instancetype)initWithCoder:(NSCoder *)aDecoder {
    if (self = [super initWithCoder:aDecoder]) {
        [self didInitialize];
    }
    return self;
}

- (void)didInitialize {
    self.contentMode = UIViewContentModeLeft;
    self.minimumItemSize = CGSizeZero;
    self.maximumItemSize = QMUIFloatLayoutViewAutomaticalMaximumItemSize;
}

- (CGSize)sizeThatFits:(CGSize)size {
    return [self layoutSubviewsWithSize:size shouldLayout:NO];
}

- (void)layoutSubviews {
    [super layoutSubviews];
    [self layoutSubviewsWithSize:self.bounds.size shouldLayout:YES];
}

- (CGSize)layoutSubviewsWithSize:(CGSize)size shouldLayout:(BOOL)shouldLayout {
    NSArray<UIView *> *visibleItemViews = [self visibleSubviews];
    
    if (visibleItemViews.count == 0) {
        return CGSizeMake(UIEdgeInsetsGetHorizontalValue(self.padding), UIEdgeInsetsGetVerticalValue(self.padding));
    }
    
    // 如果是左对齐，则代表 item 左上角的坐标，如果是右对齐，则代表 item 右上角的坐标
    CGPoint itemViewOrigin = CGPointMake(ValueSwitchAlignLeftOrRight(self.padding.left, size.width - self.padding.right), self.padding.top);
    CGFloat currentRowMaxY = itemViewOrigin.y;
    CGSize maximumItemSize = CGSizeEqualToSize(self.maximumItemSize, QMUIFloatLayoutViewAutomaticalMaximumItemSize) ? CGSizeMake(size.width - UIEdgeInsetsGetHorizontalValue(self.padding), size.height - UIEdgeInsetsGetVerticalValue(self.padding)) : self.maximumItemSize;
    NSInteger line = -1;
    for (NSInteger i = 0, l = visibleItemViews.count; i < l; i++) {
        UIView *itemView = visibleItemViews[i];
        
        CGRect itemViewFrame;
        CGSize itemViewSize = [itemView sizeThatFits:maximumItemSize];
        itemViewSize.width = MIN(maximumItemSize.width, MAX(self.minimumItemSize.width, itemViewSize.width));
        itemViewSize.height = MIN(maximumItemSize.height, MAX(self.minimumItemSize.height, itemViewSize.height));
        
        BOOL shouldBreakline = i == 0 ? YES : ValueSwitchAlignLeftOrRight(itemViewOrigin.x + self.itemMargins.left + itemViewSize.width + self.padding.right > size.width,
                                                           itemViewOrigin.x - self.itemMargins.right - itemViewSize.width - self.padding.left < 0);
        if (shouldBreakline) {
            line++;
            currentRowMaxY += line > 0 ? self.itemMargins.top : 0;
            // 换行，每一行第一个 item 是不考虑 itemMargins 的
            itemViewFrame = CGRectMake(ValueSwitchAlignLeftOrRight(self.padding.left, size.width - self.padding.right - itemViewSize.width), currentRowMaxY, itemViewSize.width, itemViewSize.height);
            itemViewOrigin.y = CGRectGetMinY(itemViewFrame);
        } else {
            // 当前行放得下
            itemViewFrame = CGRectMake(ValueSwitchAlignLeftOrRight(itemViewOrigin.x + self.itemMargins.left, itemViewOrigin.x - self.itemMargins.right - itemViewSize.width), itemViewOrigin.y, itemViewSize.width, itemViewSize.height);
        }
        itemViewOrigin.x = ValueSwitchAlignLeftOrRight(CGRectGetMaxX(itemViewFrame) + self.itemMargins.right, CGRectGetMinX(itemViewFrame) - self.itemMargins.left);
        currentRowMaxY = MAX(currentRowMaxY, CGRectGetMaxY(itemViewFrame) + self.itemMargins.bottom);
        
        if (shouldLayout) {
            itemView.frame = itemViewFrame;
        }
    }
    
    // 最后一行不需要考虑 itemMarins.bottom，所以这里减掉
    currentRowMaxY -= self.itemMargins.bottom;
    
    CGSize resultSize = CGSizeMake(size.width, currentRowMaxY + self.padding.bottom);
    return resultSize;
}

- (NSArray<UIView *> *)visibleSubviews {
    NSMutableArray<UIView *> *visibleItemViews = [[NSMutableArray alloc] init];
    
    for (NSInteger i = 0, l = self.subviews.count; i < l; i++) {
        UIView *itemView = self.subviews[i];
        if (!itemView.hidden) {
            [visibleItemViews addObject:itemView];
        }
    }
    
    return visibleItemViews;
}

- (BOOL)shouldAlignRight {
    return self.contentMode == UIViewContentModeRight;
}

@end