IM-ios/AIIM/Common/CommonUI/ZoomableImageView.m

//
//  ZoomableImageView.m
//  AIIM
//
//  Created by qitewei on 2025/5/21.
//

#import "ZoomableImageView.h"

@implementation ZoomableImageView

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

- (void)setupView {
    // 设置滚动视图属性
    self.delegate = self;
    self.showsVerticalScrollIndicator = NO;
    self.showsHorizontalScrollIndicator = NO;
    self.decelerationRate = UIScrollViewDecelerationRateFast;
    
    // 添加图片视图
    _imageView = [[UIImageView alloc] initWithFrame:self.bounds];
    _imageView.contentMode = UIViewContentModeScaleAspectFit;
    _imageView.userInteractionEnabled = YES;
    [self addSubview:_imageView];
    
    // 添加手势
    UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleDoubleTap:)];
    doubleTap.numberOfTapsRequired = 2;
    [_imageView addGestureRecognizer:doubleTap];
}

- (void)setImage:(UIImage *)image {
    self.imageView.image = image;
    [self resetZoom];
}

- (void)resetZoom {
    [self layoutImageView];
}

- (void)layoutImageView {
    if (!self.imageView.image) return;
    
    CGSize imageSize = self.imageView.image.size;
    CGSize boundsSize = self.bounds.size;
    
    // 1. 计算使宽度匹配屏幕的缩放比例
    CGFloat widthScale = boundsSize.width / imageSize.width;
    
    // 2. 设置缩放范围
    self.minimumZoomScale = widthScale;
    self.maximumZoomScale = widthScale * 4.0;
    self.zoomScale = widthScale;
    
    // 3. 调整contentSize和imageView的frame
    [self updateContentSize];
    [self centerImageView];
}

- (void)updateContentSize {
    if (!self.imageView.image) return;
    
    CGSize imageSize = self.imageView.image.size;
    CGFloat scale = self.zoomScale;
    
    // 内容大小要基于缩放后的尺寸
    self.contentSize = CGSizeMake(imageSize.width * scale, imageSize.height * scale);
    self.imageView.frame = CGRectMake(0, 0, self.contentSize.width, self.contentSize.height);
}

- (void)centerImageView {
    CGSize boundsSize = self.bounds.size;
    CGSize contentSize = self.contentSize;
    
    // 计算水平和垂直偏移
    CGFloat horizontalInset = MAX(0, (boundsSize.width - contentSize.width) / 2);
    CGFloat verticalInset = MAX(0, (boundsSize.height - contentSize.height) / 2);
    
    // 设置contentInset保持居中
    self.contentInset = UIEdgeInsetsMake(verticalInset, horizontalInset, verticalInset, horizontalInset);
}

#pragma mark - UIScrollViewDelegate

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
    return self.imageView;
}

- (void)scrollViewDidZoom:(UIScrollView *)scrollView {
    [self centerImageView];
}

#pragma mark - Gesture Handlers

- (void)handleDoubleTap:(UITapGestureRecognizer *)gesture {
    if (self.zoomScale > self.minimumZoomScale) {
        [self setZoomScale:self.minimumZoomScale animated:YES];
    } else {
        CGFloat newZoomScale = self.maximumZoomScale;
        CGPoint touchPoint = [gesture locationInView:self.imageView];
        
        CGFloat w = self.bounds.size.width / newZoomScale;
        CGFloat h = self.bounds.size.height / newZoomScale;
        
        [self zoomToRect:CGRectMake(touchPoint.x - w/2, touchPoint.y - h/2, w, h)
               animated:YES];
    }
}

- (void)handleSingleTap:(UITapGestureRecognizer *)gesture {
    // 通知控制器单击事件
    if ([self.superview respondsToSelector:@selector(handleSingleTap:)]) {
        [self.superview performSelector:@selector(handleSingleTap:) withObject:gesture];
    }
}

@end