公司产品需要实现点击个人主页头像可以放大头像、缩放头像、保存头像效果(和点击微信个人头像类似),故找个时间实现一下,记录下来,供自己查看,也给大家做个参考。
实现效果(GIF):
实现思路:
直接自定义 UIView(CYPhotoPreviewer),为了实现双击缩放,可以实现 UIScrollViewDelegate 对应的方法。如果需要模糊背景,可以在自定义的 UIView 中先添加模糊背景,再添加 UIScrollView,继而在 UIScrollView 中添加图片容器,这个容器就是要显示的图片的 superView,代码一目了然:
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- (void)setup { self.frame = [UIScreen mainScreen].bounds; self.backgroundColor = [UIColor clearColor]; UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(singleTap:)]; [self addGestureRecognizer:singleTap]; UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(doubleTap:)]; doubleTap.numberOfTapsRequired = 2; [singleTap requireGestureRecognizerToFail:doubleTap]; [self addGestureRecognizer:doubleTap]; UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPress:)]; [self addGestureRecognizer:longPress]; // 设置模糊背景 self.blurBackground = [[UIVisualEffectView alloc] initWithEffect:[UIBlurEffect effectWithStyle:UIBlurEffectStyleExtraLight]]; self.blurBackground.frame = self.frame; [self addSubview:self.blurBackground]; // 设置 UIScrollView 相关属性 self.scrollView = [[UIScrollView alloc] initWithFrame:[UIScreen mainScreen].bounds]; self.scrollView.delegate = self; self.scrollView.bouncesZoom = YES; self.scrollView.maximumZoomScale = 3.0; self.scrollView.multipleTouchEnabled = YES; self.scrollView.alwaysBounceVertical = NO; self.scrollView.showsVerticalScrollIndicator = NO; self.scrollView.showsHorizontalScrollIndicator = NO; [self addSubview:self.scrollView]; // containerView self.containerView = [[UIView alloc] init]; [self.scrollView addSubview:self.containerView]; // imageView self.imageView = [[UIImageView alloc] init]; self.imageView.clipsToBounds = YES; self.imageView.backgroundColor = [UIColor colorWithWhite:1.0 alpha:0.5]; [self.containerView addSubview:self.imageView]; } |
可以看到,我们给设置了模糊背景,给这个 CYPhotoPreviewer 添加了单击手势(关闭 PhotoPreviewer)、双击手势(缩放图片)、长按手势(使用 UIAlertController 菜单,比如保存图片等)。
好,确定了这个 CYPhotoPreviewer 中的显示内容,那么我们该如何显示这个 CYPhotoPreviewer 呢?
- 直接将这个 CYPhotoPreviewer 添加到 keyWindow 上
- 将这个 CYPhotoPreviewer 添加到控制器的 self.view 上
这两种方式的实现都差不多,不过如果使用第一种方式的话,会导致将 CYPhotoPreviewer 添加到 keyWindow 上之后,再长按继续将 UIAlertController 显示就比较麻烦了,因此,这里打算采用将 CYPhotoPreviewer 添加到控制器的 self.view 上,继而就可以很方便的显示 UIAlertController 了:
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- (void)previewFromImageView:(UIImageView *)fromImageView inContainer:(UIView *)container { _fromImageView = fromImageView; fromImageView.hidden = YES; [container addSubview:self]; // 将 CYPhotoPreviewer 添加到 container 上 self.containerView.origin = CGPointZero; self.containerView.width = self.width; // containerView 的宽度是屏幕的宽度 UIImage *image = fromImageView.image; // 计算 containerView 的高度 if (image.size.height / image.size.height > self.height / self.width) { self.containerView.height = floor(image.size.height / (image.size.width / self.width)); } else { CGFloat height = image.size.height / image.size.width * self.width; if (height self.height && self.containerView.height - self.height |
可以看到,我们将外面的图片 fromImageView 传递进来,是为了显示更好的动画效果;将控制器的 container(self.view)传递进来,是为了将 CYPhotoPreviewer 添加到 container 的细节不需要在调用处处理,即初始化 CYPhotoPreviewer 之后,CYPhotoPreviewer 就直接被 container 添加为 subview 了。动画很简单不再细说。
显示的效果已经做好,单击关闭 CYPhotoPreviewer 也比较好实现,只需要从父类移除 CYPhotoPreviewer 即可:
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- (void)dismiss { [UIView animateWithDuration:0.18 delay:0.0 options:UIViewAnimationOptionCurveEaseInOut animations:^{ CGRect fromRect = [self.fromImageView convertRect:self.fromImageView.bounds toView:self.containerView]; self.imageView.contentMode = self.fromImageView.contentMode; self.imageView.frame = fromRect; self.blurBackground.alpha = 0.01; } completion:^(BOOL finished) { [UIView animateWithDuration:0.10 delay:0 options:UIViewAnimationOptionCurveEaseInOut animations:^{ self.fromImageView.hidden = NO; self.alpha = 0; } completion:^(BOOL finished) { [self removeFromSuperview]; }]; }]; } |
好了,显示和关闭 CYPhotoPreviewer 都实现了,如果需要双击缩放图片效果,就得实现 UIScrollViewDelegate 的两个方法以及 CYPhotoPreviewer 的双击手势:
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- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView{ return self.containerView; } - (void)scrollViewDidZoom:(UIScrollView *)scrollView { UIView *subView = self.containerView; CGFloat offsetX = (scrollView.bounds.size.width > scrollView.contentSize.width)? (scrollView.bounds.size.width - scrollView.contentSize.width) * 0.5 : 0.0; CGFloat offsetY = (scrollView.bounds.size.height > scrollView.contentSize.height)? (scrollView.bounds.size.height - scrollView.contentSize.height) * 0.5 : 0.0; subView.center = CGPointMake(scrollView.contentSize.width * 0.5 + offsetX, scrollView.contentSize.height * 0.5 + offsetY); } - (void)doubleTap:(UITapGestureRecognizer *)recognizer { if (self.scrollView.zoomScale > 1.0) { [self.scrollView setZoomScale:1.0 animated:YES]; } else { CGPoint touchPoint = [recognizer locationInView:self.imageView]; CGFloat newZoomScale = self.scrollView.maximumZoomScale; CGFloat xSize = self.width / newZoomScale; CGFloat ySize = self.height / newZoomScale; [self.scrollView zoomToRect:CGRectMake(touchPoint.x - xSize / 2, touchPoint.y - ySize / 2, xSize, ySize) animated:YES]; } } |
最后一个就是长按弹出菜单(UIAlertController)了:
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- (void)longPress:(UILongPressGestureRecognizer *)recognizer { // 为了避免弹警告:Warning: Attempt to present on which is already presenting ,最好加入状态判断 if (recognizer.state == UIGestureRecognizerStateBegan) { UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"QuoraDots" message:nil preferredStyle:UIAlertControllerStyleActionSheet]; [alertController addAction:[UIAlertAction actionWithTitle:@"保存" style:UIAlertActionStyleDefault handler:nil]]; [alertController addAction:[UIAlertAction actionWithTitle:@"取消" style:UIAlertActionStyleCancel handler:nil]]; UIViewController *vc = self.viewController; [vc presentViewController:alertController animated:YES completion:nil]; } } |
注意一点,longPress:
这个方法会调用很频繁,因此,为了避免 Attempt to present xxx on xxx which is already presenting xxx
这个警告,我们需要判断手势的状态。
后话:
这个只是显示单张图片的大图,如果需要显示多张图片类似微信微博的九宫格图片的大图显示,则需要将这个 CYPhotoPreviewer 搞成 UICollectionView 的 item 即可,大家可以尝试尝试。最后,如果需要或者 CYPhotoPreviewer 源码,可以前往 GitHub 下载查看:https://github.com/angelen10/PhotoPreviewer
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