如何在执行CIFilter时保留iOS UIImageView中的图像宽高比，如CISepiaTone [英] How to preserve image aspect ratio in iOS UIImageView when doing CIFilter, like CISepiaTone

问题描述

在iOS中，我的UIImageView是Aspect Fit，但是当我做CIFilter类型时，例如CISepiaTone，
我丢失了原始图像宽高比。图像被拉伸到整个UIImageView大小。

In iOS, my UIImageView is "Aspect Fit", but when I do CIFilter of type e.g. "CISepiaTone", I lose the original image aspect ratio. The image is stretched to whole UIImageView size.

如何保持宽高比？

推荐答案

如果使用imageWithCIImage创建过滤后的图像，则无法获得正确的宽高比。尝试从过滤器输出CIImage创建CGImageRef，然后从CGImageRef创建UIImage。

If you are creating the filtered image with imageWithCIImage, then you won't get the proper aspect ratio. Try creating a CGImageRef from the filter output CIImage and then creating the UIImage from the CGImageRef.

示例：

// assume you already have CIImage *outputImage and *inputImage declared

// convert to CGImage to maintain proper aspect ratio and dimensions
CIContext *context = [CIContext contextWithOptions:nil];
CGImageRef imageRef = [context createCGImage:outputImage fromRect:inputImage.extent];
UIImage *filteredImage = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);

然后你可以尝试用filteredImage设置imageView。

Then you can try setting the imageView with filteredImage.

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