如何将 UIImage 从上到下缓慢过渡以将滤镜应用于图像？

Question

我想让它看起来好像我的图像正在从上到下慢慢过滤。我正在添加两个图像视图。我处理过的图像在后台，未处理的在前面。我正在将未处理图像的高度设置为 0。这是我的代码。

imageView.frame = CGRect(x: 0, y: 100, width: self.view.bounds.size.width, height: 400)
imageView.image = processedImage


let nonProcessedImageView = UIImageView()
nonProcessedImageView.frame = CGRect(x: 0, y: 100, width: self.view.bounds.size.width, height: 400)
nonProcessedImageView.image = nonProcessedImage
view.addSubview(nonProcessedImageView)

UIView.transition(with: nonProcessedImageView,
                  duration: 5.0,
                  animations: {
   nonProcessedImageView.frame = CGRect(x: 0, y: 500, width: self.view.bounds.size.width, height: 0)
   },
                  completion: {_ in
   })

未处理的图像甚至不会出现在已处理的图像之上。

Answer 1

问题似乎是更改动画块中帧的 y 坐标会导致使用 UIView.Animate 函数时出现问题。

看到这个answer

引用最精华的部分：

You should change the center property (to move the view) and bounds property (to change its size) instead. Those properties behave as expected.

因为你只想降低高度，你不需要对y坐标做任何事情

let nonProcessedImageView = UIImageView()

var newImageFrame = imageView.frame

nonProcessedImageView.frame = newImageFrame
nonProcessedImageView.clipsToBounds = true
nonProcessedImageView.contentMode = .scaleAspectFit
nonProcessedImageView.image = imageView.image
view.addSubview(nonProcessedImageView)

// I set this to 1 instead of 0 as 0 does not show the image
// for some reason
newImageFrame.size.height = 1

// Update your processed image
imageView.image = processedImage

UIView.animate(withDuration: 5.0) {
    nonProcessedImageView.frame = newImageFrame
}
completion: { (isComplete) in
    if isComplete {
        nonProcessedImageView.removeFromSuperview()
    }
}

这给出了一些结果，但如您所见，动画不是很好，因为当您降低高度时，图像视图的 contentMode 开始并给出所见效果。

为获得最佳效果，请将新图像视图添加到 UIView 并减小 UIView 而不是 UIImageView 的高度

var newImageFrame = imageView.frame

let containerView = UIView(frame: newImageFrame)
containerView.clipsToBounds = true

let nonProcessedImageView = UIImageView()
nonProcessedImageView.frame = containerView.bounds
nonProcessedImageView.clipsToBounds = true
nonProcessedImageView.contentMode = .scaleAspectFit // same as original
nonProcessedImageView.image = imageView.image

containerView.addSubview(nonProcessedImageView)
view.addSubview(containerView)

newImageFrame.size.height = 1

imageView.image = processedImage

UIView.animate(withDuration: 3.0) {
    containerView.frame = newImageFrame
}
completion: { (isComplete) in
    if isComplete {
        containerView.removeFromSuperview()
    }
}

这应该能满足您的需求：

Answer 2

这适用于从上到下的过渡。

imageView.frame = CGRect(x: 0, y: 100, width: self.view.bounds.width, height: 400)
imageView.image = nonProcessedImage
view.addSubview(imageView)
    
let frontView = UIView(frame: CGRect(x: 0, y: 100, width: self.view.frame.width, height: 0))
frontView.clipsToBounds = true
view.addSubview(frontView)

let nonProcessedImageView = UIImageView(frame: CGRect(x: 0, y: 0, width: self.view.bounds.size.width, height: 400))
nonProcessedImageView.image = processedImage
nonProcessedImageView.clipsToBounds = true
frontView.addSubview(nonProcessedImageView)
    
UIView.transition(with: frontView, duration: 5, options: [.allowAnimatedContent], animations: {
    frontView.frame = CGRect(x: 0, y: 100, width: self.view.frame.width, height: 400)
}, completion: nil)

如何将 UIImage 从上到下缓慢过渡以将滤镜应用于图像？

How can I transition a UIImage slowly from top to bottom for applying filter to the image?

uiimageview

ios

swift