从函数获取UIImage [英] Get UIImage from function

问题描述

我写了一个函数将滤镜应用于照片。为什么函数总是返回nil？

  func getImage（）-> UIImage？ {
 let openGLContext = EAGLContext（api：.openGLES2）
 let context = CIContext（eaglContext：openGLContext！）
 
 let coreImage = UIImage（cgImage：image.cgImage！）
 
 filter.setValue（coreImage，forKey：kCIInputImageKey）
 filter.setValue（1，forKey：kCIInputContrastKey）
 
如果让outputImage = filter.value（forKey：kCIOutputImageKey ）一样吗？ CIImage {
 let output = context.createCGImage（outputImage，from：outputImage.extent）
 return UIImage（cgImage：output！）
} 
 
返回nil 
} 
  

解决方案

使用<$ c $ iOS 中的c> coreImage 。您必须考虑coreImage类，例如

I wrote a function to apply the filter to a photo. Why the function always returns nil?

func getImage() -> UIImage? {
    let openGLContext = EAGLContext(api: .openGLES2)
    let context = CIContext(eaglContext: openGLContext!)

    let coreImage = UIImage(cgImage: image.cgImage!)

    filter.setValue(coreImage, forKey: kCIInputImageKey)
    filter.setValue(1, forKey: kCIInputContrastKey)

    if let outputImage = filter.value(forKey: kCIOutputImageKey) as? CIImage {
        let output = context.createCGImage(outputImage, from: outputImage.extent)
        return UIImage(cgImage: output!)
    }

    return nil
}

解决方案

When you working with coreImage in iOS.You have to considered coreImage classes such as CIFilter, CIContext, CIVector, and CIColor and the input image should be a CIImage which holds the image data. It can be created from a UIImage.

Note: You haven't mentioned about your filter definition or custom filter that you using.From your code, I can see you trying to change the contrast of an input image.So, I am testing the code using CIColorControls filter to adjust the contrast.

func getImage(inputImage: UIImage) -> UIImage? {
    let openGLContext = EAGLContext(api: .openGLES2)
    let context = CIContext(eaglContext: openGLContext!)

    let filter = CIFilter(name: "CIColorControls")
    let coreImage = CIImage(image: filterImage.image!)

    filter?.setValue(coreImage, forKey: kCIInputImageKey)
    filter?.setValue(5, forKey: kCIInputContrastKey)

    if let outputImage = filter?.value(forKey: kCIOutputImageKey) as? CIImage {
    let output = context.createCGImage(outputImage, from: outputImage.extent)
        return UIImage(cgImage: output!)
    }

    return nil
}

You can call the above func like below.

filterImage.image = getImage(inputImage: filterImage.image!)

Output:

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