Objective-C中帧的水平翻转

Question

我正在尝试为我的程序(流式传输网络摄像头)创建一个过滤器,使框架水平翻转,使网络摄像头就像一面镜子.

但是,在编译和运行时,过滤器似乎对它没有任何影响.

这是代码:

CIImage *resultImage = image;
CIFilter *flipFilter = [CIFilter filterWithName:@"CIAffineTransform"];
[flipFilter setValue:resultImage forKey:@"inputTransform"];

NSAffineTransform* flipTransform = [NSAffineTransform transform];
[flipTransform scaleXBy:-1.0 yBy:1.0]; //horizontal flip
[flipFilter setValue:flipTransform forKey:@"inputTransform"];

resultImage = [flipFilter valueForKey:@"outputImage"];

奇怪的是,其他过滤器似乎也有效.例如:

CIFilter * ciEffectFilter = [CIFilter filterWithName:@"CIGloom"];
[ciEffectFilter setDefaults];
CIImage *resultImage = image;
[ciEffectFilter setValue: resultImage forKey:@"inputImage"];
[ciEffectFilter setValue:[NSNumber numberWithFloat: 0.75]
                  forKey:@"inputIntensity"];
[ciEffectFilter setValue:[NSNumber numberWithFloat: 20]
                  forKey:@"inputRadius"];
resultImage = [ciEffectFilter valueForKey:@"outputImage"];


CIFilter *ciCropFilter = [CIFilter filterWithName:@"CICrop"];
[ciCropFilter setDefaults];
[ciCropFilter setValue: resultImage forKey:@"inputImage"];
[ciCropFilter setValue: [CIVector vectorWithX:50 Y:50 Z:300 W:
                         300] forKey:@"inputRectangle"];

resultImage = [ciCropFilter valueForKey:@"outputImage"];

它与NSAffineTransform有关吗？我环顾四周,但我没有找到任何答案.谢谢堆!

Answer 1

我不确定这是不是问题,但是在你的第一个代码片段中,你为同一个键设置了两个不同的值(你设置了inputTransform两次),我想第一个应该是inputImage.请尝试以下方法:

CIImage *resultImage = image;
CIFilter *flipFilter = [CIFilter filterWithName:@"CIAffineTransform"];
[flipFilter setValue:resultImage forKey:@"inputImage"];

NSAffineTransform* flipTransform = [NSAffineTransform transform];
[flipTransform scaleXBy:-1.0 yBy:1.0]; //horizontal flip
[flipFilter setValue:flipTransform forKey:@"inputTransform"];

resultImage = [flipFilter valueForKey:@"outputImage"];

此外,您可能需要将X轴平移图像的宽度

[flipTransform translateXBy:... yBy:0];