如何在 uiimage iOS 中围绕眼睛和嘴巴绘制正方形或圆形

Question

我是 iOS 编程新手，我已经搜索了很多核心图像链接、答案和教程，但我仍然不太了解。我有一个带有按钮的测试应用程序，简单的东西，当我按下某个过滤器按钮时，它会生成过滤器并显示它。

CIImage *inputImage = [[CIImage alloc]initWithImage:[UIImage imageNamed:@"pic1.JPG"]];
    CIFilter *colorControls = [CIFilter filterWithName:@"CIColorControls"];
    [colorControls setValue:inputImage forKey:@"inputImage"];
    [colorControls setValue:[NSNumber numberWithFloat:0.5f] forKey:@"inputSaturation"];
    [colorControls setValue:[NSNumber numberWithFloat:0.8f] forKey:@"inputContrast"];
    [colorControls setValue:[NSNumber numberWithFloat:0.4f] forKey:@"inputBrightness"];
    CIImage *outputImage = [colorControls valueForKey:@"outputImage"];
    CIContext *context = [CIContext contextWithOptions:nil];
    theImageView.image = [UIImage imageWithCGImage:[context createCGImage:outputImage fromRect:outputImage.extent]];

现在我想要一个按钮，它可以检测眼睛和嘴巴并在其周围绘制矩形或圆形，无论是什么颜色和什么颜色都没有关系。我一直到

- (IBAction)detectFace:(id)sender
{
    CIImage *inputImage = [[CIImage alloc]initWithImage:[UIImage imageNamed:@"pic1.JPG"]];
    CIDetector* detector = [CIDetector detectorOfType:CIDetectorTypeFace
                                              context:nil options:[NSDictionary dictionaryWithObject:CIDetectorAccuracyHigh forKey:CIDetectorAccuracy]];
    NSArray* features = [detector featuresInImage:inputImage];
   for (CIFaceFeature *faceFeature in features){}
}

现在我遇到了一个问题（我不确定这是否是正确的开始）。请帮助我想知道下一步该怎么做..提前谢谢你

Answer 1

怎么样（还没编译，但应该很接近）：

for (CIFaceFeature *faceFeature in features){
        CGRect faceRect = faceFeature.bounds;

    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextSetLineWidth(context, 1.0);

    CGContextAddRect(context, faceRect);
    CGContextDrawPath(context, kCGPathStroke);
}